ORIGINAL_ARTICLE
QUALITATIVE BEHAVIOR OF EIGENFREQUENCIES FOR FREE VIBRATION OF AEROSPACE VEHICLE APPENDAGES
In this work, the changes in eigenfrequencies of flexible appendages with • :various mass ratios of space vehicles due to the allowance of a rigid body. motion are studied. These changes are governed by the difference eigen-value problem [2] which is formulated in terms of the generated effective :mass and stiffness matrices. The computation techniques for calculating .• the upper and lower bounds of the dominant eigenfrequencies are performed :by the utilization of the bound formula approach [1] . An example of the transverse vibration analysis of the fuslage-wing combination with diff-erent mass ratios in different zones of vibratory motion is solved . A :'comparison between the computed calculations and previously published re-sults [0] is presented
https://amme.journals.ekb.eg/article_48575_2607e6b2ba0e761cd578a1e4708e02e7.pdf
1984-05-01
1
10
10.21608/amme.1984.48575
A.
MAHER
1
Chairman Department of Mechanics and Elasticity, Military Technical College, Cairo, Egypt.
AUTHOR
A.
SCHLACK
2
Professor of Engineering Mechanics. University of Wisconsin-Madison-U.S.A.
AUTHOR
ORIGINAL_ARTICLE
IMPROVED TECHNIQUES FOR DETERMINATION OF RESIDUES AND DAMPING FROM FREQUENCY AND IMPULSE RESPONSE CURVES
This paper describes the determination of modal parameters directly fromthe frequency and impulse response curves, and discusses the factors ef-fecting the accuracy of the measurements. It summarizes the effects of noise, weighting functions, resolution bias and excitation methods.A new technique, based on the Hilbert transform of the impulse response is described. The technique is used to obtain a large dynamic range of time, signals on a logarithmic axis and is shown used for determination of damp-. ing from the envelope of the impulse response and for separation of modes in the time domain.
https://amme.journals.ekb.eg/article_48579_48ed6067f12b7549359c3fc99936112e.pdf
1984-05-01
11
20
10.21608/amme.1984.48579
KAI
SORENSEN
1
M. SC., Bruel & Kjr, Denmark.
AUTHOR
ORIGINAL_ARTICLE
RECONSTRUCTION OF DISTORTED TARGET DATA DUE TO ELECTRONIC jAOHING
A novel approach is introduced by which the distorted signal due to elect-ronic jamming is reconstructed. An ideal measurement trajectory in the observation space is derived. Using an LOG approach the deviation between .the actual and ideal measurements are obtained. Measurements deviationcovariance matrix is formed and a signal distortion detection criterion isestablished. The distorted signal is disregarded and a reduced order estimator is derived to reconstruct the tracking data.
https://amme.journals.ekb.eg/article_48583_bb6f8f9993d43d489161455114b6fbba.pdf
1984-05-01
21
30
10.21608/amme.1984.48583
Mohammad
Wagdi
1
Professor and Dean, Faculty of Engineering & Technology, Suez Canal University, Port Said, Egypt.
AUTHOR
ORIGINAL_ARTICLE
THE UNBALANCE RESPONSE OF A FLEXIBLE ROTOR MOUNTED ON UNCENTRALIZED SQUEEZE-FILM DAMPER BEARINGS
This paper deals with the steady-state response of a single disc flexible. rotor supported on two uncentralized squeeze-film damper bearings and sub-jected to varying degrees of unbalance. The measured responseil-on an exp-erimental rotor operating to speeds exceeding its first bending critical show that the uncentralized squeeze-film damper bearing has a very desira-ble effect under the abusive conditions of large unbalance. The unbalance level was increased by a factor of three in some tests and yet the corresponding vibrational amplitude of the disc, at the first bending critical speed, was increased by less than 30 %. The results predicted :from a computer simulation study, where the equations of motion are in-tegrated forward in time until steady-state orbits are reached and aut-omatically plotted, show good qualitative agreement with the experimental results.
https://amme.journals.ekb.eg/article_48587_ca3a85686dca656b1a19f30e144b63ad.pdf
1984-05-01
31
40
10.21608/amme.1984.48587
S.
KOSSA
1
Lecturer, Aeronautical Department, Military Technical College, Cairo, EGYPT.
AUTHOR
R.
COOKSON
2
Head of Applied Mechanics Group, School of Mechanical Engineering, Cran-field Institute of Technology, Bedford, ENGLAND.
AUTHOR
ORIGINAL_ARTICLE
OPTIMUM CONTROL OF A GYROSCOPIC STABILIZER WITH STOCHASTIC DISTURBANCE
The problem of optimum control of a moment compensating vertical gyro frame is considered. The transfer function matrix of the stabilizer has been derived. The optimum compensator of the stabilizer had been obtained such that the dispersion of the error signal is minimized for a certain value of the 'settling time. The proposed technique had been compared by the conventional methods. The analytical methods as well as the simulation results proved the superiority of the proposed method over the conventional approaches.
https://amme.journals.ekb.eg/article_48590_63c4650cd4de05fce02c3df062057506.pdf
1984-05-01
41
50
10.21608/amme.1984.48590
F.
TOLBAH
1
Associate Professor, Dept. of Machine Design & Production Eng., The Faculty of Eng., Ain Shams University, Cairo, Egypt.
AUTHOR
ORIGINAL_ARTICLE
ANALYTICAL INVESTIGATION OF ELASTIC MECHANISMS
To achieve the performance of mechanisms and machines to a higtlet accuracy, the elastic deformations of their members, under dynamic conditions, are to be taken into account. In the presented work each member in the link-age is treated as being elastic. The kinematic equations of constraints at the kinematic pairs are presneted. These equations are introduced into the equations of motion through Lagrange multipliers, to obtain a coupled system of nonlinear algebric and differential equations. The later system will have the same form for each element. So, the total set of equations, describing the linkage, can be generated automatically. Illustrative examples are given and the agreement of the results with those previously solved using other techniques is satisfactory.
https://amme.journals.ekb.eg/article_48596_c983d59905c3671734747f89809a7de2.pdf
1984-05-01
51
61
10.21608/amme.1984.48596
E.
IMAM
1
Lt. Col. Drs, Department of Mechanics and Elasticity, Military Technical College, Cairo, Egypt.
AUTHOR
M.
EL-MADDAH
2
Lt. Col. Drs, Department of Mechanics and Elasticity, Military Technical College, Cairo, Egypt.
AUTHOR
ORIGINAL_ARTICLE
MODAL ANALYSIS BY STATE-SPACE APPROACH IN FREQUENCY DOMAIN
This paper tests a new procedure to identify the eigenvalue problem matrix "A", and thus the system's modal parameters, by utilizing the frequency response of the system in state-space. A sample identification test is performed with added random error in order to simulate real measuring conditions. Results indicate that it is slightly difficult to identify the "A" matrix of an undamped system. The error in that system must be very small for this type of system to be identified. However, when the identi-fication is repeated several times and then averaged, the identificationbecomes more accurate.
https://amme.journals.ekb.eg/article_48602_1bd49552ca61cd3c62d5d7a5cf3bcf37.pdf
1984-05-01
63
73
10.21608/amme.1984.48602
S.
Metwalli
1
Associate Professor, Dept. of Mech. Engr. & Aerospace Science, Unive. of Central Florida, Orlando, FL. U.S.A., Presently with Kuwait Univ., Kuwait.
AUTHOR
F.
Feijo
2
Graduate Student, University of Central Florida,Orlando FL. U.S.A.
AUTHOR
ORIGINAL_ARTICLE
SELF-EXCITED VIBRATION OF MULTI- DISC ROTOR SUPPORTED ON SEVERAL FLEXIBLE BEARINGS
A calculation method incorporating the transfer matrix method and the characteristic-vector locus method has been developed for stability analysis of the self excited vibration of a rotating shaft system with many bearings and discs. The analysis is made for an elastic bearing mass, relatively large damping forces due to types of rotors fit, anisotropic foundation and rotors gyroscopic effect. A two-rotors-model is presented to show the influence of rotor and its gyroscopic 'action, support stiffness characteristics, internal and external damping on stability. A computer solution of the transfer matrix method shows the rotor stability is improved by damped support. The shrinkage fit type rotors are more stable than force fit welding type and adhesion loctite or araldite type. The gyroscopic moment effect of the overhanging disc decreased the stability region of the rotor. A computer solution of the governing equations of motion is presented showing the shaft stability region for various speed ranges and the effect of the bearing stiffness ratio on the stability region. The effect of external damping on the stability 'region of a rotor supported on anisotropic bearings is obtained.
https://amme.journals.ekb.eg/article_48603_8357049e151b87dd2611fc89aa207e06.pdf
1984-05-01
75
85
10.21608/amme.1984.48603
E.
BADAWY
1
Professor, Dept. of Mechanical Engineering, Faculty of Eng., Alexandria Univ., Alexandria, Egypt.
AUTHOR
H.
METWALLY
2
Associated Professor, Dept. of Mechanical Engineering, Faculty of Eng., Alexandria Univ., Alexandria, Egypt.
AUTHOR
F.
SALMAN
3
Doctor student, Dept. of Mathematic, Faculty of Eng., Alexandria Univ., Alexandria, Egypt.
AUTHOR
ORIGINAL_ARTICLE
VIBRATION ANALYSIS OF FULLY AND PARTIALLY DAMPED AND RIGIDAMPED SANDWICH BEAMS WITH VISCOELASTIC CORE
The reduction of vibratory energy transmission has been the subject of investigation within past years. The present paper is concerned with the increase of the internal damping in mechanical systems as a method for their vibration control. The inclusion of viscoelastic materials within the structural configurations of the mechanical system is proposed to increase its internal damping.Analytical solutions are presented for the fully damped sandwich beam. In addition, laboratory experiments have been performed to verify the analytical predictions. Moreover, the optimal damping distribution for partially damped and the case of rigidamped sandwich beams are considered experimentally as a practical design proposition.
https://amme.journals.ekb.eg/article_48604_fbe785901b3ad9ebbe3120921ed8175b.pdf
1984-05-01
87
95
10.21608/amme.1984.48604
S.
FARGHALY
1
Assistant Prof. Dept. of Mech. Design. Faculty of Eng and Tech. ( Mataria). University of Helwan , Cairo, Egypt.
AUTHOR
M.
EL-Maddah
2
Lt.Col.Dr. Dept. of Mechanics and Elasticity;
AUTHOR
M.
Ismail
3
Maj. Gen. Dr., Head of Basic Sciences Dept.,liilitary Technical College, Cairo, Egypt.
AUTHOR
ORIGINAL_ARTICLE
THE DYNAMIC PERFORMANCE OF MACHINE TOOL JOINTS SUBJECTED TO NORMAL LOADS
ads paper deals with the dynamic characteristics of joints subjected to loading in the direction normal to the joint interface. Experimental results are provided for a variety of joints having different surface topographies. The viscosity of lubricant is shown to have a marked effect upon both the dynamic stiffness and damping of joints. The mechanism of the action of the lubricant layer is discussed and it has been shown that the behaviour of a lubricated joint could be explained in terms of the oil trapped inside both the fully and partially locked oil pockets within the joint interface.
https://amme.journals.ekb.eg/article_48606_d6697ef3d73294a885ca971a3210b44b.pdf
1984-05-01
97
109
10.21608/amme.1984.48606
S.
SHOUKRY
1
Lecturer, Dept. of Prod. Eng., Helwan University, Helwan, Cairo, Egypt.
AUTHOR
R.
THORNLEY
2
Professor, Dept. of Prod. Tech. & Prod. Management, The University of Aston in Birmingham, Dirmingham, England.
AUTHOR
ORIGINAL_ARTICLE
EFFECT OF VIBRATION FREQUENCY ON DYNAMIC CONTACT STIFFNESS OF JOINTS
In this paper, a method for the introduction of the effect of vibration frequency on dynamic contact stiffness of joints is presented. The 'method is based on the measurement of the natural modes of vibration of a simple mechanical system containing the joint to be investigated. The res-,ults of measurement are used, through a sensitivity technique, for the id-entification of a joint stiffness matrix. This matrix is assumed, at firs, to be invariant, i.e, independent on the mode of vibration. However, the utilization of the identified eigensolution and the equations of sensitivity .corresponding to a single mode of vibration, enable one to obtain, for this: mode, a correction joint stiffness matrix.The validity of the method has been tested by numerical simulation on a case of a plane prestressed joint between two beams.
https://amme.journals.ekb.eg/article_48607_ffb3e423a5b725acfe6cc7359659652b.pdf
1984-05-01
111
119
10.21608/amme.1984.48607
A.
ABDEL-MOHSEN
1
Lt. Col. Dr., Department of Mechanics and Elasticity, M.T.C., Cairo, Egypt.
AUTHOR
A.
BASSIOUNI
2
Col, Dr., Department of Mechanics and Elasticity, M.T.C., Cairo, Egypt.
AUTHOR
ORIGINAL_ARTICLE
BOND GRAPH MODEL AND INVESTIGATION OF DYNAMICS OF A CLASS OF HYDRAULIC FLOW CONTROL VALVES
Using bond graph, a model is developed for two-way pressure compensated flow Control valves with pressure balancing stage perior to the throttling section. The model, which carries the physical and mathematical structures of the valve, is in a ready form to be interconnected to models of other components to get the bond graph for a global system incorporating the valve. Equations governing the valve dynamic behaviour are obtained from the bond graph in the form of assignment statements. Simulation is realized on digital computer to investigate the valve transient response to step load-pressure variation, when the valve is used in a hydraulic circuit of a meter-in mode of speed control. Results showed that at low values of resistance of the passage connecting the load to the spring chamber of compensator, the response is of high initial load flow overshoot that decreases rapidly to the steady state value. At higher resistances, initial overshoot is reduced and the response is slower and of oscillatory nature.
https://amme.journals.ekb.eg/article_48793_308c15c228b3c4ebec9b5bb57b3c37d6.pdf
1984-05-01
121
130
10.21608/amme.1984.48793
S.
KASSEM
1
Associate Professor, Mechanical Design Dept., Faculty of Engineering, Cairo University, Cairo, Egypt.
AUTHOR
G.
RABIE
2
Col. Dr., Military Research Authority, Cairo, Egypt.
AUTHOR
ORIGINAL_ARTICLE
BASIC CONCEPTS IN liODAL ANALY IS
Modal analysis is the presentation of the dynamic properties of a system in terms of the contributions due to the independent modes of vibration of the system. This method of analysis is powerful and has become very useful in the analysis of .experimental test data due to recent developments in real time frequency analysis and digital data processing. This paper outlines the recent developments of the method with main emphasis is placed on the use of this approach in analysing the dynamic performance of complex systems and in solving their design problems.
https://amme.journals.ekb.eg/article_48795_6d40c5180326a8e430b4b202c1456068.pdf
1984-05-01
131
140
10.21608/amme.1984.48795
SAAD
ZAGHLOOL
1
Senior Lecturer, Design and Production Engineering Dept., Ain Shams University, Cairo, Egypt.
AUTHOR
ORIGINAL_ARTICLE
ON THE DYNAMIC ANALYSIS OF A CAM MECHANISM WITH BEARING CLEARANCES
The paper develops a procedure for the dynamic analysis of a cam mechanism with bearing clearances. The analysis mainly relies on determining the clearance angles Bij and its first and second derivatives. The governing equations of each clearance angle are developed on the condition that the variations in displacements and velocities due to clearance effect are very small and could be ignored. Also, the equations of these clearance angles: are developed such that the common normal at the point of contact at each clearance connection coincides with the direction of the clearance eccentricity vector which has the same direction of the normal reaction force at the point of contact. A straight sided cam operating a roller follower is considered to illustrate the procedure.
https://amme.journals.ekb.eg/article_48797_7dfb4d3495d59cd165ab1f90fddc3b57.pdf
1984-05-01
141
157
10.21608/amme.1984.48797
B.
Bahgat
1
Associate Professor , Mechanical Design Department Cairo University Cairo, Egypt, A.R.E.
AUTHOR
M.
Osman
2
Associate Professor,Machanical Design Department Cairo University Cairo, Egypt, A.R.E.
AUTHOR
ORIGINAL_ARTICLE
A LABORATORY TOOL FOR THE STUDY OF VEHICLE VIBRATION PERFORMANCE
The study of the vibration characteristics in machines has taken a front seat in engineering effort. This is particularly true in the automotive industry, where marketing a vibrating vehicle is unacceptable. Today's automobiles are a complex spring-mass-damper system which is excited into various modes of vibration. The vibrational modes falling in 10-200 Hz are termed "structure shake", and produce distrubances seen and felt by the vehicle occupant. The knowledge of an objectionable vibration in development programs. Therefore, the aim of this work is to introduce a method by which the vehicle vibration performance can be investigated in the laboratory. A chassis dynamometer was used to simulate the road-going conditions. The measurement and analysis techniques are presented herein. Samples from the results obtained for van and small saloon vehicles are included to illustrate the suitability of the measuring technique and the instrumentation system used.
https://amme.journals.ekb.eg/article_48800_a2bbb7266a11c2ebad6f8bd00c9e9f58.pdf
1984-05-01
159
169
10.21608/amme.1984.48800
S.
ABOU-EL-SEOUD
1
Associate Professor, Dept. of Mechanical Engineering, Faculty of Eng. , Technology, El-minia University, El-minia, Egypt.
AUTHOR
ORIGINAL_ARTICLE
SIMPLIFIED ANALYSIS OF THICK LAMINATED FIBROUS COMPOSITES USING A STATICAL APPROACH
Reissner's plate theory assumptions are chosen to approximate the stress field in which the longitudinal stresses are assumed to vary linearly along the plate thickness. For balanced, symmetric, laminates, a stiffness may be taken as the linear average of the corresponding ply stiffnesses. In that case, only 4 laminate stiffness moduli with simple stress strain relations can be utilized. Using the average laminate properties and following the variational analysis, the assumed stress functions and the corresponding displacements can be obtained. As a numerical example, we consider the problem of cylindrical bending of a symmetric cross-ply laminate, consists of 3 layers of graphite/ poxy unidirectional composites. For relatively thick laminates, where the classical plate theory gives a very poor estimate, our results are in a good agreement with the exact el-asticity solution, specially for the deflection and transversal stresses.
https://amme.journals.ekb.eg/article_48806_34f81d7bcc5aabe13292465190250de7.pdf
1984-05-01
1
8
10.21608/amme.1984.48806
E.
EL SOALY
1
Colonel Doctor Engineer, Dept. of Mechanics and Elasticity, Military Technical College, Kobri El Kobba, Cairo, Egypt.
AUTHOR
ORIGINAL_ARTICLE
ON THE PHENOMENOLOGICAL ASPECT OF CREEP FRACTURE
An inspection of experimental data obtained on ternary Nickel base alloy hardened by Ý-particles has shown that the dependence of the steady state creep rate, Ɛs, on time to fracture, tf, follows the correlation proposed by Milicka, taking the total deformation at fracture Ɛc , in account.log (tF/Ɛc) + mˋ log Ɛs = Cˋwhere mˋ and Cˋ are constants.The validity of this equation is verified. It indicatesra close connection between strain accumulation and deformation mechanisms from start to fracture of the creep deformation process, and is a symptom of one process controlling strain during the whole test in spite of the different fracture mechanisms which can be observed.
https://amme.journals.ekb.eg/article_48816_5a51a3d1a92cf88494fcbf7129785d90.pdf
1984-05-01
9
16
10.21608/amme.1984.48816
MOHAMMED
ABDOU
1
Associate Professor, Mechanical Engineering Department, AL-Azhar University, Nasr City, Cairo, Egypt.
AUTHOR
ORIGINAL_ARTICLE
ANALYSIS OF WING-FUSELAGE STRUCTURE INTERACTION UNDER ASYMMETRIC TORQUE
The present paper solves the arrangement of the wing and fuselage structures with respect to the relative position of the large cutouts in both airframe parts. The finite element method based on displacement field is used for the analysis of wing structure ,while the matrix force method as given by Prof. Argyris is used for the analysis of fuselage structure. A computer program for the combined displacement-force method is constructed. Numerical examples, representing different arrangements are included which illustrate the application of the method to practical problems.The ciculated results are compared with those obtained by measurements.
https://amme.journals.ekb.eg/article_48827_57f2635fc4736df20293bfacdfa15d5d.pdf
1984-05-01
17
29
10.21608/amme.1984.48827
M.
EL NOMROSSY
1
Lecturer of Aircraft Structural Mechanics, Aeronautical Department, Military Technical College.
AUTHOR
ORIGINAL_ARTICLE
ANALYSIS OF ELASTIC AND VISCOUS PROPERTIES OF LINEAR VISCOELASTIC BODIES
The use of plastics in manufacture is of great industrial importance to-day. In order to make the best economic use of plastics, their mechanical properties must be properly determined .In this paper some analysis of elastic and viscous properties of linear viscoeleastic bodies are made. A simulant of a solid propellant rocket fuel is subjected to this study. Gottenberg(2) made some experiments to find the relaxation function which represent the mechanical behaviour of this simulant of a solid propellant rocket fuel. A procedure is proposed here to find the mechanical constant of each element contained in a mathematical model for a linear viscoelastic material using experimental data. This model consisting of some suitable combination of springs, and viscous dashpots. The mechanical functions entering the constitutive relations of the theory of viscoelasticity are determined by experimental and theoritical means. Some experiments are made to find the mechanical behaviour of an availableviscoelastic material (PVC).
https://amme.journals.ekb.eg/article_48828_be7864bf89f37adc69dc4b752c9d58d8.pdf
1984-05-01
31
43
10.21608/amme.1984.48828
Farouk
Badran
1
Professor, Department of Mechanical Engineering, Faculty of Engineering, Assiut University.
AUTHOR
Mohamed
Gaballa
2
Assistant Lecturer. Department of Mechanical Engineering, Faculty of Engineering, Assiut University.
AUTHOR
ORIGINAL_ARTICLE
ELASTIC STRESS CONCENTRATIONS IN SIDE.MILLED HOLLOW AND SOLID KEYED CONNECTIONS.
Four, three-dimensional, photoelastic, frozen-stress models of keyed connections were loaded in torsion. This technique was applied to study the axial shear stress distributions in both solid and hollow, side milled and end-milled keyed connections. The dimensions of the key cross-section were according to the British Inch Standard. The coefficient of friction between the contact surfaces of shaft and hub was measured at the stress-freezing temperature. The surface conditions were arranged to simulate the typical prototype friction. Positions and magnitudes of the peak shear stresses were determined at the different positions of contact between key and shaft keyway. Results from all models are compared and a new key design is described.
https://amme.journals.ekb.eg/article_48833_3c25c29907181366e6fa3308613b4923.pdf
1984-05-01
45
54
10.21608/amme.1984.48833
M.
EISSA
1
Lecturer, Faculty of Electronic Engineering, Menoufia University, EGYPT.
AUTHOR
ORIGINAL_ARTICLE
FATIGUE CRACK GROWTH IN ALUMINUM ALLOYS UNDER PROGRAMMED BLOCK LOADING
Using fracture mechanics principles, crack growth rates can be predicted accurately for some simple crack configurations subjected to constant amplitude loading., However, for more complex loading sequences such as flight simulation loadings, the results are conservative by a factor 3 to 10 or more. The main objective of this study is to interpret the fatigue behaviour of two aluminum alloys under programmed block load-ings. The effects of cycle ratio R (61 min/6" max) and material thickness on crack propagation rate are analysed. Fatigue crack growth under programmed block loading is presented. Linear damage accumulation is established for some simple flight simulation tests. Aspects covered include microscopic. and fractographic observations. The incidence of crack closuro is examined and the agreement between predictions and test results is very promising.
https://amme.journals.ekb.eg/article_48837_4622847c55919acb3d0d74dada7c88e8.pdf
1984-05-01
55
65
10.21608/amme.1984.48837
M.
GABRA
1
Col. Dr. Engineer, Dept. of Aeronautical Mech. Engineering, Military Technical Collage, Cairo, Egypt.
AUTHOR
ORIGINAL_ARTICLE
CYCLIC PLASTIC DEFORMATIONS IN THIN TUBES UNDER. BILI-NEAR RADIAL THERMAL GRADIENT
The cyclic plastic behaviour of thin walled tubes subjected to internal pressu: and cyclic radial thermal gradient is investigated. Such structural problems find many applications in high temperature .nuclear plants, conventional power plants and chemical industr:.es where the integrity of mechanical components is governe•: by growth of inelastic strains due to plastic ratchetting and time dependent creep as well as the interaction between creep damage and low cycle fatigue damage.The tube problem is treated analytically with the aid of an approximate uniaxial model which compensates the effects of axial stress by magnifying the thermal stress in the hoop di-rection. The model is shown to provide conservative estimates' of observed strains. Linear kinematic hardening material model is used in the plastic analysis and an approximate tech-nique is employed to account for the cyclic hardening pheno-mena. Emphasis is placed upon the effects of the non-linear temperature distribution since ratchetting tests on thin tubes have shown that the observed temperature distribution is far from linear. The results of the analysis show that the bi-linear form of radial temperatures introduces new modes of cyclic deformation in which cyclic plasticity is confined to the inner skin of the tube wall.The results are compared with test data on AISI 304 stainless steel tubes under internal pressure and cyclic thermal shocks between 1100 °F and 800 °F with hold periods of 160 hr/cycle at 1100 °F. The stress fields obtained from rapid cycle solu-tions are used to estimate upper bounds for creep deformations which accumulate during the hold periods. The predictions of plastic and creep strains are seen to provide moderate conser-vative estimates of test results.
https://amme.journals.ekb.eg/article_48839_3f6c9e13c6c0b184cdc587213d35d95e.pdf
1984-05-01
67
82
10.21608/amme.1984.48839
M.
MEGAHED
1
Assistant Prof.,College of Eng.King Abdulaziz University. P.O.Box 9027, Jeddah, Saudi Arabia+
AUTHOR
ORIGINAL_ARTICLE
EXPERIMENTAL STUDY OF CRACK PROPAGATION BY BENDING IN AU4 G1 - T3 AND STEEL 316
The authors have applied fatigue crack bending test of thin sheets for the determination of the crack propagation rate in AU4 G1-T3 aluminium alloy and in type 316 austenitic stainless steel.In the first stage, the authorshave tested the Paris' law and shown its insufficienties, then they have interpreted the results with ELBER'sTheory of crack closure and have measured the crack opening by means of a strain gauge installed near the crack tip.In addition, the authors have explained the retardation phenomenon due to a single overload in Al. alloy.
https://amme.journals.ekb.eg/article_48843_0534e627327202569a4a245d4147dd95.pdf
1984-05-01
83
96
10.21608/amme.1984.48843
M.
MOSTAFA
1
Lt.Col.Dr., Department of Mechanics & Elasticity- M.T.C. - Cairo, EGYPT.
AUTHOR
M.
BOIVIN
2
Prof., Laboratoire de Mecanique des Solides-INSA-69621 Villeurbanne-FRANCE.
AUTHOR
ORIGINAL_ARTICLE
A REGULAR BOUNDARY ELEMENT METHOD 2 FOR TWO DIMENSIONAL STRESS ANALYSIS
The Boundary Method is now well established as a valid numerical technique for the solution of field problems, equal to the Finite Element Method in generality and surpassing it in computational efficiency in some cases [1] In this paper is presented a Regular Boundary Element Method as applied to two dimensional stress analysis. It involves the formation of a system of regular integral equations obtained by moving the singularity outside the domain of the given problem [2]. It is shown that continuous elements may be used here after the manner of Finite Element Method [3].
https://amme.journals.ekb.eg/article_48845_979d05d47219d348428ba866165a6f27.pdf
1984-05-01
97
106
10.21608/amme.1984.48845
N.
EL SEBAI
1
Lecturer, Department of Mechanics & Elasticity, Military Technical College, Kobry El Kobba, Cairo, EGYPT.
AUTHOR
ORIGINAL_ARTICLE
RE-APPFLAISAL ANALYSIS OF WELDED JOINTS; DEFECT-TOLERANCE APPROACH
The term fracture is a vague word used to describe the condition of obsoleteness of a structure. For welded joints, this term could take several forms of definitions. Therefore, it is of great importance to define this term, within a certain servicability condition. This is due to the fact that the welding process will produce a monolithic state in the weldedjoints and that fracture initiation in even a minor part can lead to catastrophic consequences. Also, the fact that there is no welded defect-free structures, thus the designer has no option but to reside himself to the so-called defect-tolerance Approach.In a country which applies different schools of quality assurance as for example, Egypt, unification of the different cods and specifi-cations of welding industry, is required. This unification should lead to the evolution of the Egyptian code of practice and hence the Egyptian Welding Standards and Specifications. This task is to be carried out with the aid of the defect-tolerance approach, proposed and discussed in the present paper.
https://amme.journals.ekb.eg/article_48854_d37ad65962176da291aeca9ec8d3d389.pdf
1984-05-01
107
117
10.21608/amme.1984.48854
M.
EL-GAMMAL
1
Ph.D., M.Sc.,Ass. Professor, Naval Architecture and Marine Engineering Department, Faculty of Engineering, University of Alexandria, EGYPT.
AUTHOR
ORIGINAL_ARTICLE
ON THE PLASTIC DEFORMATION OF HIGH PURITY IRON AND Cu-Zn BRASSES
Deformation characteristics of high purity iron was studied through both tension and rolling. The surfaces of the deformed specimens were observed by optical microscopy at magnifications up to 2000. Slip characteristics were studied for the tensile specimens up to 17% strain and for the cold rolled specimens up to about 72% reduction in thickness. Increasing the per cent of deformation gradually increased the dislocations density. It was observed that in case of tension the dislocations took the form of regular rows of parallel lines, which was not the case in the rolled specimens. α/β brass bicrystals made by the solid state diffusion tech-nique, have been used to clarify the slip characteristics in both α - and -β brass. The change of the slip traces morphology in α -iron (bcc) and β-brass (bcc) was attributed to the different constraint conditions in each case.
https://amme.journals.ekb.eg/article_48862_43666e3311149e67a9d297e87dc98e1d.pdf
1984-05-01
119
125
10.21608/amme.1984.48862
NABIL
FAT-HALLA
1
Associate professors, Mechanical Department, Faculty of Engineering, AL Azhar University.
AUTHOR
SALAH
EL GEMAE
2
Associate professors, Mechanical Department, Faculty of Engineering, AL Azhar University.
AUTHOR
MOHAMMED
ABDOU
3
Associate professors, Mechanical Department, Faculty of Engineering, AL Azhar University.
AUTHOR
ORIGINAL_ARTICLE
NOISE OF GEARS OF DOUBLE CIRCULAR-ARC TOOTH-PROFILE
The paper embodies the results of an experimental investigation carried out to study noise of a relatively new type ofgearing of double circular-arc tooth- profile. More than 300 magnetic tape recordings were taken and analysedsfor gears4 mm module running at different speeds and loads in a direct drive gear test rig installed in free field. Experimental results revealed that the largest single frequency component is double the tooth contact frequency and that patterns of the generalised generated noise are uniform in all directions. Generally, as either speed or load increases, overall noise levels increase from 95 dB at speed 400 r.p.m. and load =15kp to 115 dB at speed 2250 r.p.m. and load= 40kp.
https://amme.journals.ekb.eg/article_48879_a838ad979f447d55114ef59e34fd41c4.pdf
1984-05-01
1
9
10.21608/amme.1984.48879
A.
ATTIA
1
Professors Faculty of Engineering,Ain Shams University, Cairo.
AUTHOR
M.
MOHAMMED
2
Chair of Machine Designs, Military Technical College, Cairo.
AUTHOR
ORIGINAL_ARTICLE
IDENTIFICATION OF MATRIX PARAMETERS OF ACOUSTIC SYSTEMS VIA TRANSIENT TESTING
A transient testing technique has been developed for rapid testing of components of acoustic systems. Transient pressure data are digitized, recorded and utilized in frequency-domain to provide the dynamic characteristics of the system. The idea behind the method is to make use of the sampled time data of a sound source and two microphones measuring the pressure at two locations in a steel pipe attached to the component of the acoustic system. The analysis procedure is based on the construction of a mathematical model for the system from the experimental response data.Experiments were conducted for many acoustic components of various geometrical configurations such as partition pipes and expansion chambers and excellent agreement between experimental and theoretical results is illustrated. The proposed approach is applicable to field testing situations where short duration testing with a minimum of portable equipments is desi-rable and no special requirements such as anechoic terminations are available.
https://amme.journals.ekb.eg/article_48882_2e65bb50bb384c418491ba25b1e6e35c.pdf
1984-05-01
11
19
10.21608/amme.1984.48882
SAAD
ZAGHLOOL
1
Senior Lecturer, Design and Production Engineering Dept., Ain Shams University, Cairo, Egypt.
AUTHOR
ORIGINAL_ARTICLE
NONLINEAR RESPONSE ANALYS:LS OF PLATES UNDER RANDOM ACOUSTIC EXCITATION
This paper describes a perturbation technique to perform the nonlinear response analysis of plate structure under random acoustic excitation. In the analysis, use is made of triangular plate element together with a nonlinear plate stiffness element which is dependent on the modal response of the structure. The nonlinear plate stiffness elementrepresents the coupling term between the membrane and bending deformation. Applying these elements and the associated consistent mass matrices, the equivalent linear eigen matrix of the complete plate is organized. The eigen solution and the following modal spectral computation completes the iteration cycle. A flow diagram and a numerical example are included which illustrate the application of the method to practical problems.
https://amme.journals.ekb.eg/article_48884_cf6de207aafc23c1ace8fa8fd476d42a.pdf
1984-05-01
21
31
10.21608/amme.1984.48884
M.
EL NOMROSSY
1
Colonel Doctor, Aeronautical Department, M.T.C.
AUTHOR
M.
KHOLOUSSY
2
Major General Doctor, Head of Basic subject Departments, M.T.C.
AUTHOR
ORIGINAL_ARTICLE
NOISE AND VIBRATION OF A RECIPROCATING AIR COMPRESSOR
Noise occurs as a result of mechanical systems motion during normal operation and may be associated with its various moving parts. In this work vibration as well as noise measurements are carried out on two case studies; a simple beam structure and an air compressor. The comparison of vibration and noise spectra has been very useful in identifying dominant noise sources. This represents the first step in selecting an economic method for noise control. In the case of the compressor, the addition of rubber pads under its base has greatly reduced both the overall noise level and its fluctuations with time.
https://amme.journals.ekb.eg/article_48886_f692666094d339228d44fa2b99db4ed6.pdf
1984-05-01
33
43
10.21608/amme.1984.48886
M.
EL-MADDAH
1
Lt.Col.Drs. - Department of Mechanics and Elasticity- Military Technical College- Cairo - Egypt.
AUTHOR
E.
IMAM
2
Lt.Col.Drs. - Department of Mechanics and Elasticity- Military Technical College- Cairo - Egypt.
AUTHOR
A.
ABDEL-MOHSEN
3
Lt.Col.Drs. - Department of Mechanics and Elasticity- Military Technical College- Cairo - Egypt.
AUTHOR
ORIGINAL_ARTICLE
THEORETICAL ANALYSIS OF DOUBLE FILM BEARINGS
This paper is concerned with a theoretical analysis of two types of double film bearings; namely, circular-circular and rectangular-rectangular, lubricated with incompressible fluid.In order to have a clear understanding of the performance characteristics of these two types of double film bearings, the performance characterist-ics that include load carrying capacity, flow rate, power, and stiffness of single film circular and rectangular bearing is presented.The results revealed that, the given mathematical model can be used in the design of a double film bearings.A comparison between the performance characteristics of circular-circular and rectangular-rectangular double film bearings are presented, assuming that they have the same area and the same supply pressure.
https://amme.journals.ekb.eg/article_48888_962855e779fe246f81ddf388e77b6837.pdf
1984-05-01
1
7
10.21608/amme.1984.48888
E.
Salem
1
Prof. Faculty of Engineering Alex. University.
AUTHOR
A.
Nasser
2
Prof. Faculty of Engineering & Tech. Shiben El-Kom, Menoufia Univ.
AUTHOR
S.
Serage
3
Asst. Prof. Faculty of Eng. & Tech. Shiben El-Kom, Menoufia Univ.
AUTHOR
O.
Khedre
4
Lecturer Faculty of Eng. & Tech. Shiben El-Kom, Menoufia-University.
AUTHOR
ORIGINAL_ARTICLE
A DIRECT TECHNIQUE FOR JOURNAL BEARING ANALYSIS
Todate the design of journal bearings depends on the solutions of Reynolds equation by-iterative techniques. In this paper, the Tri Diagonal Matrix Algorithm (TDMA) is modified to fit boundary valued two dimensional prob-lems and is used to find direct and rapid reliable solutions. With this direct technique, Sommerfeld numbers and attitude angles are derived with less than 2 percent deviation from the results of conventional bearing numerical analysis but around 50 times faster. The pressure distributions obtained from both iterative and direct techniques are compared with those acquired from experimental testing. The TDMA solutions show reliability for wide ranges of L/D and eccentricity ratios.
https://amme.journals.ekb.eg/article_48889_691881fcfdbed7e0074368fc83bc5b7c.pdf
1984-05-01
9
17
10.21608/amme.1984.48889
Y.
YOUNES
1
Assistant Prof., Mechanical Design Dept., Faculty of Eng. and Technology, Mataria-Helwan University.
AUTHOR
N.
GADALLAH
2
Dr. Eng., Machine Design Dept.,Military Technical College.
AUTHOR
N.
ASHOUR
3
Teaching assistant Mech.Design Dept., Mataria-Helwan University.
AUTHOR
ORIGINAL_ARTICLE
AN ANALYTICAL STUDY OF DAMPING CHARACTERISTICS OF HYDROSTATIC BEARINGS
A theoretical analysis is presented to predict the dynamic performance characteristics of a circular thrust bearing with a central recess and integrated with a restrictor of finite fluidic resistance. The gmerning equations of flow are solved in closed forms to obtain pressure distribu-tions in the bearing clearances. Assuming a sinusoidal variation in the oil film thickness, the damping load, flow rate and damping coefficient are evaluated for squeezed disks, Results are presented in dimensionless terms describing the cyclic variation of the different squeeze parameters and the different geometrical aspects. They show the non-linearities of these parameters especially at high amplitude ratios.
https://amme.journals.ekb.eg/article_48890_5e2a59b07af70bda36860ebfe2605d38.pdf
1984-05-01
19
27
10.21608/amme.1984.48890
Y.
YOUNES
1
Assistant Professor, Dept. of Mechanical Design,Helwan University, ( Mataria), Cairo, Egypt.
AUTHOR
M.
MOKHTAR
2
Associate Professor, Dept. of Mechanical Design and Prod. Eng., Cairo University, Cairo,Egypt.
AUTHOR
ORIGINAL_ARTICLE
MIXED MODE CUMULATIVE FATIGUE DAMAGE
The present work attempts to understand early fatigue damage accumulation in a mechanical sense. The effect of changing the mode of load, application from torsion cycling to push-pull cycling and vise-versa, on the same specimen,during the course of its life was investigated. Torsion prior to push-pull and push-pull prior to torsion mixed mode cumulative damage tests in both low and high cycle fatigue regimes were conducted. The cumulative damage tests were carried out between two strain levels selected such that when applied individually and separately, in each mode, would give the same endurance. It was found that when torsion cycling had been applied first, a 'decrease in the residual life in push-pull was observed indicating a positive damage due to the prior torsion. On the otherhand, prior push-pull cycling caused an increase in the residual torsional fatige life, which reached a max. of 170% after a push-pull damage of 70%, in the high cycle fatigue regime.
https://amme.journals.ekb.eg/article_48891_dafbccb785ad7052af78abdab0ccf9e4.pdf
1984-05-01
29
37
10.21608/amme.1984.48891
M.
IBRAHIM
1
Lecturer,Mech.Equip.Dpt.,Military Technical College, Cairo, Egypt.
AUTHOR
M.
HAMMOUDA
2
Lecturer,Mech.Eng.Dpt., Azhar University, Cairo, Egypt.
AUTHOR
K.
MILLER
3
Professor, Mech.Eng.Dpt., Sheffield University, Sheffield, U.K.
AUTHOR
ORIGINAL_ARTICLE
EMPIRICAL EQUATION FOR TREATING CUMULATIVE FATIGUE DAMAGE
Cumulative damage in fatigue has received a great deal of attention in recent years and many methods have been developed for predicting fatigue life. However, it does not yield predictions that are in all cases in agreement with the experimental results. In the following a simple equation was developed to interpet the cumulative damage occured by the stress levels and cycles ratio. The derivation is based on analogy and on intuition rather than on well-established natural laws due to the complicated process of cumulative damage and the many factors encountered in it.Comparison of the results obtained from the proposed empirical equation with the most commonly known methods of linear damage ruleLDR, double linear damage rule DLDR and the experimental results, available in the literature for SAE 4130 steel and maraging 300 CVM steel, proved its true validity. The proposed equation give better life prediction than DLDR and LDR. On average its estimate for life prediction approximately 8% higher or lower than experimental while the DLDR provide estimates 12% high and LDR provide estimates 37% high. However more study is needed to obtain the good perspective of its merits.
https://amme.journals.ekb.eg/article_49092_bb1f1c291a04e0422ba4f4a8fe9022fd.pdf
1984-05-01
39
51
10.21608/amme.1984.49092
A.
Abd El Latif
1
Professor, Dept. of Prod. Eng. and Mech. System Design King Abdulaziz University, Jeddah, Saudi Arabia.
AUTHOR
ORIGINAL_ARTICLE
COMPRESSION HELICAL SPRINGS, A METHOD OF DESIGN FOR A MINIMUM WEIGHT
This paper discusses an approach for the design of compression closely c:oild helical springs subjected to axial load. With the presented proposed method, one can specify the significant characteristics of the spring that contains the least possible volume of material while still providing suff-icient strength and stiffness. To do so, the classic design equations are developed so that they can be graphically represented in a (weight-diame-ter)-plane from which the global optimum design point can be determined. Also, a computation flow chart is given, as an alternative way to the graphical method. Based on the computation flow chart, a digital computer program can be written for the optimum design problem.
https://amme.journals.ekb.eg/article_49094_8489fcbd9d9ee3be6011ae0627836920.pdf
1984-05-01
53
61
10.21608/amme.1984.49094
M.
FATTOUH
1
Assistant Professor ,Production Engineering & Machine Design Department, Faculty of Engineering & Technology, Menoufia University, Shebin El-Kom, Egypt.
AUTHOR
M.
HEWEIDY
2
Assistant Professor ,Production Engineering & Machine Design Department, Faculty of Engineering & Technology, Menoufia University, Shebin El-Kom, Egypt.
AUTHOR
M.
ELKHABEERY
3
Assistant Professor ,Production Engineering & Machine Design Department, Faculty of Engineering & Technology, Menoufia University, Shebin El-Kom, Egypt.
AUTHOR
ORIGINAL_ARTICLE
WEARING RATE IN DIESEL ENGINES USING LOCAL FUELS
In the present study, corrosive wear is investigated in cylinders of locomotive, vehicle, tank and stationery diesel engines. Investigation was carried out in the field and under controlled laboratory conditions. Local fuels of different sulphur content and lubricating oils having different total base number (TBN) were used. Wear was determined qualitatively by a scanning electron microscope and quantitatively by bore dial guages and lubricating oil analysis using atomic absorption spectroscopy. The results show that the range of local wear coefficients is considerably higher than the international range. Wear rates for chrome plated liners are much smaller than that of cast iron liners. Simplelgeneralised relations for predicting the rate of wear as a function of oil TBN are proposed.
https://amme.journals.ekb.eg/article_49106_d81b3155cdc96a57d2930059ab06941f.pdf
1984-05-01
63
74
10.21608/amme.1984.49106
ELKOTB,
M.
1
Professor, Mechanical Power Department, Faculty of Engineering, Cairo University, Giza, Egypt.
AUTHOR
KOUSSA,
S
2
Assistant Professor, Mechanical Power Department, Faculty of Engineering, Cairo University, Giza, Egypt.
AUTHOR
SALEM,
H.
3
Lecturer, Mechanical Power Department, Faculty of Engineering, Cairo University, Giza, Egypt.
AUTHOR
SAYED,
S.
4
Graduate student, Military Technical College, Cairo, Egypt.
AUTHOR
ORIGINAL_ARTICLE
REAPPRAISAL OF GEARS LUBRICATION IN LIGHT OF ELASTOHYDRODYNAM1C THEORIES
The present work comprises a computer-aided analysis of the lubrication performance of Involute and Novikov gears. Due to the complexity of gears geometry and their kinematics, gears meshing is simulated by equivalent cylinders loaded and moving in such a way to fairly describe gears load sharing effect and the combined rolling/sliding speeds along the line of action. Different theories to describe Elastohydrodynamic lubrication (EHD) have been considered. Both oil film thickness and coefficient of friction are chosen to represent the lubrication performance characteristics due to their paramont effect on major modes of gear failure. The trend to increase power and efficiency, especially in military applications, has created the need for a more accurate, efficient and quality gears. One of such development is the introduction of circular-are gear, known as Novikov/Wildhaber or Circ-arc gears. This type of gears has been herein analysed. Results show that efficient lubrication (maximum oil film thic-kness and minimum frictional loss) could be attained whenever the involute gears geometry renders higher pressure angles and smaller tooth modules. However, the Novikov gears are more advantageous over the common involute gears as they render oil film thickness ten times greater and a relatively reduced coefficient of friction under the same loading conditions. Lower values for both pressure angles and helix angles are prefered in case of Novikov gears.
https://amme.journals.ekb.eg/article_49114_aa125f55aa320729dd2550e6a9627a74.pdf
1984-05-01
75
89
10.21608/amme.1984.49114
H.
HANNA
1
Professor,Head of Mech. Dept.,Zagazig University.
AUTHOR
M.
MOKHTAR
2
Associate Professor, Dept. of Mechanical Design and Prod. Eng.,Cairo University.
AUTHOR
A.
KOTB
3
Col.Eng.,Military Tech. Research Center.
AUTHOR
ORIGINAL_ARTICLE
OPTIMUM DESIGN OF HYDROSTATIC JOURNAL BEARINGS FOR MINIMUM POWER LOSSES
This paper presents the results of an optimization study aim-ing at minimizing the total power losses in hydrostatic journal bearings. Results illustrating the optimum values of area ratio,pressure ratio, axial land width,and circumferential land width are presented. It is found that some of the design variables tend to settle at extreme values of either upper or lower constraints. It is also found that within the limitations imposed by the governing equations the optimum pressure ratio is 0.5.
https://amme.journals.ekb.eg/article_49116_db2e67ab68adfb1f2be6831cd4cd7c6f.pdf
1984-05-01
91
102
10.21608/amme.1984.49116
M.
EL-SHERBINY
1
Associate Profs.,Dept.of Mech. Design, Cairo University, Cairo, Egypt.
AUTHOR
F.
SALEM
2
Associate Profs.,Dept.of Mech. Design, Cairo University, Cairo, Egypt.
AUTHOR
N.
EL-HEFNAWY
3
Lt.Colonel, Egyptian Army.
AUTHOR
ORIGINAL_ARTICLE
THEORETICAL AND EXPERIMENTAL INVESTIGATION OF TUBE BULGING: PROFTLE SHAPE AND LIMIT STRAINS .
This paper presents a theoretical and experimental investigation of tube-bulge-forming. The study is concerned with bulging deformations together with the limiting strains and the factors affecting instability. Theoretical analysis considers bulging of open thin-walled tuhes made of strain-hardening material. A simple approach is adopted in which the bulge profile shape is assumed to be elliptical and the ellipticity ratio is obtained by calculating the constant pressure required to retain this assumed profile shape 4 Results obtained according to this assumption and the assumption of circular profile shape when compared with bulging experiments of commercially pure aluminium tubes, reveal that the actual profile shape approaches an elliptical arc rather than being circular. Limiting strains during tube bulging have also been investigated for long tubes subjected to an internal hydrostatic pressure together with an external axial force. A strain instability criterion which takes into consideration the inevitable geometrical defects in the tube-wall is developed. The results revealed that small eccentricities produce a substantial decrease in the amount of deformation sustained by the tube at instability conditions. Moreover, the sensitivity to such defects increases for tubes made of low strain-hardening materials. The developed strain instability criterion has been subjected to an experimental verification where commercially pure aluminium tubes have been bulged to fracture. Experimental results are found to be in good agreement with theory, thus justifying the validity of this instability criterion and the resulting limit strains.
https://amme.journals.ekb.eg/article_49128_996136ad1e8fef78d64645c6acad314b.pdf
1984-05-01
103
118
10.21608/amme.1984.49128
S.
KHORSHID
1
Dept. Mech. Design & Prod. Engineering - Cairo University, Giza, Egypt.
AUTHOR
A.
RAGAS
2
College of Engineering, Kuwait University, Kuwait.
AUTHOR
M.
TAKLA
3
Dept. Mech. Design & Prod. Engineering - Cairo University. Giza, Egypt.
AUTHOR
ORIGINAL_ARTICLE
COMPARISON OF METHODS OF SELECTING GEAR RATIOS OF AUTOMOBILE TRANSMISSION
Inspite the fact that conventional gear boxes of automobiles have several -disadvantages, they can be made more efficient if the number of gear ratios and their selection are properly chosen. Inereasing the number of speeds improves the vehicle's dynamic performance which is expected to be optimal with steplesscontinuously variable speed drive. However, for a fixed number of speeds, selection of individual gear ratios plays an important role in improving the vehicle's dynamic performance. Selection can be done according to various mathematical progressions such as: arithmatic, harmonic, geometric with constant and increasing roots. The goal of this work is to compare these commonly used methods. Comparison is based on calculating the wasted energy represented by the difference between areas under the curves of discret and continuous power transmission. The wasted energy corresponding to each progression was calculated by a special computer Fortran program considering the technical data of a Jeep car as a real example.
https://amme.journals.ekb.eg/article_49132_50e2927b2ec568224511fd74f51a4473.pdf
1984-05-01
119
134
10.21608/amme.1984.49132
Saycd
Shaaban
1
Col. Dr., Lecturer s in the Department of Motor Vehicles, Militry Technic-al College, Cairo, Egypt.
AUTHOR
Said
Hassan
2
Lt. Col. Dr., Lecturer s in the Department of Motor Vehicles, Militry Technic-al College, Cairo, Egypt.
AUTHOR
ORIGINAL_ARTICLE
PERFORMANCE OF HYDROSTATIC BEARINGS I- DESIGN OF EXTERNALLY PRESSURIZED CIRCULAR PAD INCOMPRESSIBLE LUBRICANT BEARINGS
This paper is concerned with a new design procedure of externally pressurized incompressible circular bearings. New charts have been developed, according to the method of bearing compensation, for evaluating of the performance characteristics of the bearing which are, the load carrying capacity, the volume flow rate and the static stiffness of fluid film. This procedurewill give a good result for designer.
https://amme.journals.ekb.eg/article_49165_15003ed3566b185bb1c9cdd0c7040ba7.pdf
1984-05-01
135
141
10.21608/amme.1984.49165
M.
NASSER
1
Assistant Professor, Production Engineering & Machine Design Department, Faculty of Engineering & Technology, Menoufia University, Shebin El-Kom, Egypt.
AUTHOR
ORIGINAL_ARTICLE
WEAR PARTICLES ANALYSIS AND RUNNING-IN OF LUBRICATED HERTZIAN CONTACTS
In running-in period, wear plays an important role in the service-life of machines. Wear is beneficial if it occurs smoothly and gradually. The object of this work is to assess the effectiveness of wear particles analysis in characterising the running-in period. A high performance dise machines, with two discs running edge-to-edge, under steady load and different slide-rolling ratios was used. The behaviour of this lubricated Hertzien contact has been followed by three analysing methods:- Ferrography analysis of the concentration, size and morphology of wear particles.- Spectrometry oil analysis of iron content in lubricants.- Micro-geometry analysis of tested surfacesThe results are compared and analysed with respect to running-in phenomena.Results show that the running-in period has been detected well by two methods, ferregraphy analysis of wear particles and micro-geometry analysis. The spectrometry failed to detect this phenomena due to its insensitivity to large particles.
https://amme.journals.ekb.eg/article_49171_3edbd98fb98ff9378aadc35e0b72c585.pdf
1984-05-01
143
154
10.21608/amme.1984.49171
S.
KHALIFA
1
Colonel Dr. Eng., Machine Design Dept., Military Technical College, Cairo, Egypt.
AUTHOR
ORIGINAL_ARTICLE
WEAR PARTICLES ANALYSIS AND RUNNING-IN OF LUBRICATED HERTZIAN CONTACTS.
https://amme.journals.ekb.eg/article_49173_2d8ec961e9f4148e42142f5088f57148.pdf
1984-05-01
154
156
10.21608/amme.1984.49173
ORIGINAL_ARTICLE
IMPROVED PERFORMANCE IN MODERN MACHINING PROCESSES (A REVIEW)
In an era of rapid and continuous changes in technological, economical and social conditions, demands are constantly being made towards increased. performance in both productivity and surface quality. The present work reviews the highlights of various trends to attain to an ever-increasing degree this goal. The two main trends to attain such a goal of improved performance are the optimization of process parameters and the modification of tool design with improved consitions for EDM dielectric, ECM electrolyte and USM slurry systems. The objective is to furnish the production engineers with recommendations in the form of empirical approaches, special tool deign or improved flow system to enable him reach a reasonable solution towards improved performance.
https://amme.journals.ekb.eg/article_49177_455685ae12054c4188805e3655460412.pdf
1984-05-01
1
11
10.21608/amme.1984.49177
S.
GHABRIAL
1
Professor, Department of Design and Production Engineering, Ain Shams University, Cairo, Egypt.
AUTHOR
S.
EBEID
2
Associate Professor, Department of Design and Production Engineering, Ain Shams University, Cairo, Egypt.
AUTHOR
ORIGINAL_ARTICLE
EXPERIMENTAL DETERMINATION OF THE PARAMETERS AFFECTING PRODUCTIVITY CHARACTERISTICS OF ELECTROCHEMICAL MACHINING PROCESSES
The effect of working conditions, namely gap voltage, tool feed-rate, electrolysing current, additives to electrolyte and metal removal rate has been investigated for the electrochemical drilling process(ECD). Tests were also performed using small additions of hydrogen. peroxide (H202) as an oxygen supplier to the electrolysis bath. Some disadvantages, are discussed and merits are critically evaluated. The results are also compared with the available data in the literature. Finally, the effects of various parameters are discussed in details.
https://amme.journals.ekb.eg/article_49183_d76d34231961d54cc6b96debbb29bce0.pdf
1984-05-01
13
28
10.21608/amme.1984.49183
H.
Asfour
1
Professor,Dean, Faculty of Eng. Minia University, Egypt.
AUTHOR
M.
EL-Dardiry
2
Associate Professor,Prod.Eng.Dept.College of Eng.King Abdulaziz Univ. Jeddah, Saudi Arabia.
AUTHOR
H.
Osman
3
Assistant Lecturer Prod.Eng.Dept.Minia University, Egypt.
AUTHOR
ORIGINAL_ARTICLE
OXY-ACETYLENE DIFFUSION WELDING OF PLAIN CARBON STEELS
A simple practical method for diffusion welding of steel components, in air, was developed. Specially designed oxy-acetylene ring burner was used for heating the specimens up to 1273 K. Two main advantages could be gained by using the designed burner. Firstly, very short heating up times were obtained. Secondly, the reducing zone of the oxy-acetylene flame was used as a protective atmosphere during the welding process. A series of plain carbon steel specimens ranging from 0.17% C to 1.1% C were, successfully, diffusion welded in air. A thin carbon rich layer was wrapped around the specimen at the periphery of the welding zone to act as a sealing ring and reduce oxidation. The specimens were heat treated and microhardness, impact, bending and tensile tests were conducted. The yield strength of the welded joints was found to decrease with increasing carbon content up to the eutectoid composition. However, above 0.8%C the yield strength increased with increasing carbon content. Metallographic examinations of the diffusion welded joints revealed the existence of ferritic bands close to the welding interface. The observed microstructure features were correlated with the differences in strength of various steels.
https://amme.journals.ekb.eg/article_49189_d27f15aa8a79468f15f621adf7f74ccc.pdf
1984-05-01
29
37
10.21608/amme.1984.49189
A.
DARWISH
1
Professor, Mechanical Engineering Department, AL-Azhar University Nasr City, Cairo. Egypt.
AUTHOR
M.
ABDOU
2
Associate professor, Mechanical Engineering Department, AL-Azhar University Nasr City, Cairo. Egypt.
AUTHOR
S.
EL-GEMAE
3
Associate professor, Mechanical Engineering Department, AL-Azhar University Nasr City, Cairo. Egypt.
AUTHOR
A.
MORSY
4
Research Assistant, Mechanical Engineering Department, AL-Azhar University Nasr City, Cairo. Egypt.
AUTHOR
ORIGINAL_ARTICLE
PERFORMANCE OF ULTRASONIC MACHINING WITH COMPLEX FORM TOOL
At present many special materials such as heat resistant steels, geramin-ium, quartz,... are utilised in modern engineering.Such material are difficult to be machined by the conventional methods. Ultrasonic macfeining stands as one of the appropriate methods to handle such situation.The scope of the present work is to study the performance of ultrasonic machining with form tools (three dimensional tools), where the process parameters such as amplitude of tool vibration,static pressure and slurry circulation can be adversely influenced during tool penetration. A set of experimental work with different tool forms was carried out. Problems associated with form tool machining and different methods for inhancing the process were introduced.
https://amme.journals.ekb.eg/article_49193_360c12622a781ea54a0413894c3f6c50.pdf
1984-05-01
39
49
10.21608/amme.1984.49193
S.
Saleh
1
Col.Dr.,Head of the machining and production management department,Military Technical College,Cairo,Egypt.
AUTHOR
S.
Ghabrial
2
Professor, Department of design and production Engineering,Ain Shams university,Cairo,Egypt.
AUTHOR
ORIGINAL_ARTICLE
EXPERIMENTAL DETERMINATION OF THE PARAMETERS AFFECTING THE SURFACE QUALITY OF ELECTROCHEMICAL MACHINING PROCESSES
An experimental study was made to investigate the role of cell voltage, electrolysing current, tool feed rate and additives to electrolyte, in the quality of drilled specimens, with respect to hole over-size, hole conicity and surface finish. Tests were carried with the objective of finding the operating conditions of electrochemical drilling (ECD) which can lead to good accuracy and dimensional control of the products. The results are also compared with the available literature data Finally the effects of various parameters are discussed in some detail.
https://amme.journals.ekb.eg/article_49196_3cb147c6415c8192588cc9b1a640eb09.pdf
1984-05-01
51
63
10.21608/amme.1984.49196
H.
Asfour
1
Professor,Dean,Faculty of Eng. Minia University, Egypt.
AUTHOR
M.
EL-Dardiry
2
Associate Professor, Prod.Eng.Dept.College of Eng. King Abdulaziz Univ.Jeddah, Saudi Arabia.
AUTHOR
H.
Osman
3
Assistant Lecturer Prod.Eng.Dept. Minia University,Egypt.
AUTHOR
ORIGINAL_ARTICLE
WATER SAND GUN AS A TOOL.
The object of this research is to investigate the effect of water sand jets on the erosion of metals. A test apparatus was designed and constructed to carry out this investigation. It was capable to eject water jets, carrying sand particles in its stream, on metal specimens. The jets were directed at angles of impact varying between 15 and 90 degrees.Computer programs were used to correlate the experimental data in a suitable form with reasonable accuracy using dimensional and regression analysis; then the variance analysis was used to check and compare these relationships. The obtained relationships can be used to estimate the erosion losses in specimens surfaces as well as to determine the effect of each test variable on the amount of erosion which may take place. It was found that maximum erosion losses occurred at an impingement angle of 33° i.e. exhibit ductile erosion responses. This is approximately 2.5 times its value at 90° andabout 1.3 its value at 15°. The obtained results were found to be in good agreement with the corresponding results obtained by previous investigators.
https://amme.journals.ekb.eg/article_49199_ad847119945389cfce9be374aad99f66.pdf
1984-05-01
65
74
10.21608/amme.1984.49199
A.
EL-Sibaie
1
Professor, Dept. of Mech. Eng., Ain-Shams University, Cairo, Egypt.
AUTHOR
M.
Abd-El Monem
2
Col. Eng. (M.Sc.), Armed Forces.
AUTHOR
ORIGINAL_ARTICLE
COMPARATIVE STUDY OF HOT WORKED DIE STEEL H13 PRODUCED BY A NEW TECHNOLOGY
This paper contains a comparative study of the die steel characteristics of both new technology (Osprey) and conventionally produced H13 hot worked die steel. Die-life, cost analysis, metallographic and fractographic examination were performed on 5% chrome steel H13 of Osprey dies which hot forged to a different reduction and then heat treated to a hardness of 42 RC with a case nitriding depth of 80 microns.
https://amme.journals.ekb.eg/article_49201_c36ec7c702537a964aebff15ff52ea73.pdf
1984-05-01
75
86
10.21608/amme.1984.49201
M.
NEGM
1
Associate Professor, Al-Azhar University, Cairo, Egypt.
AUTHOR
ORIGINAL_ARTICLE
SOME ECONOMICAL ASPECTS OF ECM PROCESSES
The main drawback of the ECM process, despite its suitability in performing special types of workpieces, lies not only in the difficulty of knowing how to use it effectivly, but also how to justify its initial costs . Consequently, it is extremely important to carefully estimate the economic Merit of the ECM process before utilizing it in manufacuring processes. In this work, an attempt is made to apply the electrochemical to certain applications that are considered to be impossible to be performed by conv-entional means, such as drilling of fine deep holes or cutting haled and / or brittle materials. An analysis of the factors affecting electrochemical machining costs is made. However, no generalization is possible since each application has to be considered on its own merits. Power consumption, machining time, electrolyte and labor costs are the main factors that have been taken as controlling factors. Experimental results revealed that amperage values are extremely affected by any change in either tool geometry of volumetric metal removal rate. Minimizing the costs of tooling system is achieved successfuly in this work by using simple manufacturing tools. Furthermore, the results provide production engineers with realistic information to reach an economical power consumption and a minimum operation cost when using ECM processes.
https://amme.journals.ekb.eg/article_49203_cbf6ba76ddbf550b1a5fcd2df997442a.pdf
1984-05-01
87
94
10.21608/amme.1984.49203
M.
HEWIDY
1
Assistant Professor, Production Engineering & Machine Design Department, Faculty cf Engineering & Technology, Menoufia. University, Shebin El-Kum, Egypt.
AUTHOR
M,
FATTOUH
2
Assistant Professor, Production Engineering & Machine Design Department, Faculty cf Engineering & Technology, Menoufia. University, Shebin El-Kum, Egypt.
AUTHOR
M.
ELKHABEERY
3
Assistant Professor, Production Engineering & Machine Design Department, Faculty cf Engineering & Technology, Menoufia. University, Shebin El-Kum, Egypt.
AUTHOR
ORIGINAL_ARTICLE
A METHOD FOR ASSESSING THE TRANSFERABILITY OF ALUMINUM GMAW SET-UP PARAMETERS
The transferability of aluminum GMAW parameters was assessed using statistical analyses which found binary correlation coefficients between the independent/dependent parameters of the welding system. The parameters have been arranged descendently according to their relative importance based on the values of correlation coefficients. The descending order of the independent parameters was used to perform a significant multiple-regression with the dependent parameters. The multiple correlation coefficients obtained by this method are very close to unity.
https://amme.journals.ekb.eg/article_49204_9dd69014c6ffbd99bd6fd325ec1a69e4.pdf
1984-05-01
95
104
10.21608/amme.1984.49204
AHMED
EL-SAWY
1
Associate Professor, Dept. of Mechanical Design and Production Engineering Faculty of Engineering, Cairo University, Guiza, Egypt.
AUTHOR
ORIGINAL_ARTICLE
AN ELECTRON FRACTOGRAPHIC STUDY OF THE INFLUENCE OF ANNEALING CONDITIONS UPON DUCTILE RUPTURE PROCESS IN Cu-Zn BRASSES
An investigation on the fracture phenomena of (α+β) brass, polycrystalline alloys, has been conducted using the scanning electron microscope(S.E.M.). The as-rolled alloys (starting material) were subjected to different conditions of annealing. Then, tensile tests were carried out at room temperature on three categories of specimens being; (i) as-rolled, (ii) an-nealed at 923K for 86.4ks, and (iii) annealed at 873K for 2 Ms plus 1.4 Ms at 800k. All types of specimens showed ductile fracture. Fracture surfaces were then observed by the S.E.M. on both the macro-and micro-scopic scales. All specimens exhibited a transgranular mode of fracture. Fracture surfaces revealed some changes in the pattern observed on each phase due to annealing conditions. Dimple pattern was observed on the (β-phase, although different dimple size existed for different types of specimens. On the other hand, on the α-phase, fracture surface, smooth ripple pattern was observed, additionally, large dimples were detected on the α-surface. In essence, the present results not only confirmed previous results on single-and bi-crystals of brass but also throw the light on more details about the fracture phenomena of brass which was not reported before.
https://amme.journals.ekb.eg/article_49276_55c2ff2407161a1a41ee9086c277ae43.pdf
1984-05-01
105
111
10.21608/amme.1984.49276
TAHA
GOMAA
1
Graduate school,Mechanical Department, Faculty of Engineering, AL Azhar University.
AUTHOR
NABIL
FAT-HALLA
2
Mechanical Department, Faculty of Engineering, AL Azhar University.
AUTHOR
MAZEN
NEGM
3
Mechanical Department, Faculty of Engineering, AL Azhar University.
AUTHOR
MOHAMMAD
REFAI
4
Mechanical Department, Faculty of Engineering, AL Azhar University.
AUTHOR
ORIGINAL_ARTICLE
THE INFLUENCE OF SOME FACTORS ON SURFACE FINISH AND GRINDING WHEEL WEAR IN DRY SURFACE GRINDING.
Workpiece of EN-8 plain carbon steel have been dry surface ground using Alumina grit,vitreous bonded wheels(WA 46 HV) under constant metal removal rate.The effect of the crossfeed and the downfeed in addition to the workpiece speed on the surface finish of the ground workpiece,and the wheel wear have been investigated. Empirical formulae have been derived, by which the grinding ratio,and the surface finish of the ground surfaces have been expressed in terms of the grinding parameters.Basically,three series of tests were performed.Each series was performed with on of the above parameters,and the product of the other two parameters fixed. Firstly, the workpiece speed was fixed at 43.2 mm/sec. and the product of the downfeed and the crossfeed was fixed at .032 mm4. Secondly, the downfeed was fixed at 0.05 mm. and the pr9duct of the workpiece speed and crossfeed was fixed at 27 mm / sec. Thirdly,the crossfeed was fixed at 0.625 mm. and the product of the downfeed and the workpiece speed was fixed at 2.16 mm2/sec.It has been found that the grinding ratio and the workpiece surface roughness are both affected by the grinding conditions in the following order of significance: crossfeed,workpiece speed and downfeed. It has also been found that the grinding ratio increase is always accompanied by a decrease in the surface roughness of the ground workpiece.
https://amme.journals.ekb.eg/article_49278_7d816afd0765d0621b5059030cdaee67.pdf
1984-05-01
113
129
10.21608/amme.1984.49278
H.
NAGI
1
Assistant Professor,Dept.Of Mech. Engneering Al Azhar Uni. ,Cairo ,Egypt.
AUTHOR
ORIGINAL_ARTICLE
RELIABILITY EFFECTIVENESS AND LIFE TIMES DETECTION OF COMPLEX SYSTEMS
The deterioration of materials and finished products in manufacturing, or in use or in storage is an important problem now in our modern industries to both producers and users. Economical, reliable evaluation, and engineering judgement applied to reliability effectiveness and life times detection provide management with deterioration curves, maintenance requirements and remedy feedback informations to maximize life and product serviceability, thus minimizing costs. To attain these goals some essential elements should be encompassed. Developing and implementing economic new techniques to solve these problems are needed. The ultimate objective of these techniques is to provide reliability assurance for the finished product and to assure optimum reliability costs for that product through the detection of life times. The formulation of an optimize statistical model of these the basic condition of obtaining objective results. It is important in this case to arrange the method of formulation of these problems in good agreement with the objective of the research taking into account the main and auxilary factors. By the essence of statistical simulation the process of functioning of the complex system were used to represent a mathematically formulated model which was isomorphic in all essential aspects to the total and required main of research objectives. This model was repeatedly tested to determine the required statistical characteristics, based on the complex stochastic process which was regarded as a sequence of the finite element.
https://amme.journals.ekb.eg/article_49284_1167189a585146151d3b246a30def514.pdf
1984-05-01
1
7
10.21608/amme.1984.49284
Metwally,
M
1
Prof. Dr., Gulf Polytechnic, Engineering Department, Bahrain.
AUTHOR
Abdulla,
G.
2
Senior Lecturer, Chairman of Mech. Engg, Dept. Gulf Polytechnic, Bahrain.
AUTHOR
Rashed,
F.
3
Prof. Dr., Abdelaziz Univ. Engg, College, Saudi Arabia.
AUTHOR
ORIGINAL_ARTICLE
UTILIZATION OF THE PARAMETRIC TRANSPORTATION PROBLEM IN MECHANICAL ENGINEERING
In many practical transportation problems, the optimal solution is stated. But the question is always raised by the decision maker: What happens to this optimal solution when changes due to dynamic situations occur and /or due to inaccurate estimation of the system parameters.This paper presents a computer FORTRAN program solving the practical trans-portation problem considering possible variations of its parameters both in the objective function and in the constraints. This program is based on theoritical results obtained in another paper written by the same authors that solves this problem directly on the transportation matrix [1].These results can be used in many practical engineering applicationsin the distribution of spare parts, raw materials, and final products. As an example, the program was used for solving the distribution of final prod-ucts from different stores to the individual governorate in Egypt with the objective to minimize the total transportation cost.
https://amme.journals.ekb.eg/article_49287_f890895441a57b89a8d2cd024b660eac.pdf
1984-05-01
9
19
10.21608/amme.1984.49287
Said
HASSAN
1
Lt. Col. Dr., Department of Motor Vehicle, M.T.C, Cairo, Egypt.
AUTHOR
M.
OSMAN
2
Brig. Dr., Department of Mathematics, M.T.C., Cairo, Egypt.
AUTHOR
A.
ABOUEL NOUR
3
Dr., Professor, Fac. of Engineering, Zagazig University, Egypt.
AUTHOR
ORIGINAL_ARTICLE
ON MATERIALS HANDLING MACHINES Minimizing Adhesive Tractive Forces, Using GPOT
The ability of application of GPOT(Geometric Programming Optimization Technique) to design some members of materials handling machines with preventing the tipping over phenomenon is discussed. The application is done on FEL (Front-End-Loaders) and finds out the values of the design variables which are the nominal value of minimum machine weight and of maximum lifting load. These values are used to compute the minimum value of the adhesive tractive forces with avoiding the tipping over of the machine. The signomial GPOT is applied to construct design nomograms by which the designer of FEL can easily estimate values of the design variables and make correlation between these values and other parameter value. Then the preliminary information concern the method of determining stochastically the optimum real values of such design variables is given.
https://amme.journals.ekb.eg/article_49304_54345b1e3bdb749cf3e218656c7ef299.pdf
1984-05-01
21
30
10.21608/amme.1984.49304
Sabry
El -Shakery
1
Lecturer, Dept. of Prod. Eng. & Design, Faculty of Engineering & Tech., Menoufia University Shebin El-Kom, EGYPT.
AUTHOR
ORIGINAL_ARTICLE
IMPROVING THE PERFORMANCE OF TEMPERATURE CONTROL LOOP IN A CRUDE OIL REFINERY THROUGH THE DIGITAL SIMULATION TECHNIQUE
Due to the rapid growth in digital control technology because of their great advantages, it now possible to consider implementing a digital programmable controller for many industerial processes. In this paper some software aspects of digital controllers for temperature control loop in crude oil refineries have been discussed and a new method has been developed for rapid tuning of these controllers'parameters through the implementation of digital simulation technique. Different structures of the control loop have been investigated with main emphasis is given to cascaded and feedforward/feedbackward loops. Cascaded structures is shown to reduce the effect of the time delays and yield better dynamic character-istics for the control loop. Preview of the future system disturbance inputs through the feedforward path is shown to be effective to improve the performance of the overall control system. The results of the present investigation indicate that the proposed method is capable to detune the parameters of each controlling action either on-line or off-line with sub-stantial improvement in the dynamic performance of the control loop. Illustrative examples as well as practical applications are also included.
https://amme.journals.ekb.eg/article_49308_dbc6039b3989944e95fab63f6d883bd8.pdf
1984-05-01
31
40
10.21608/amme.1984.49308
HASSAN
KAMEL
1
ENG., Engineering Office,Cairo Oil Refining CO., Mostorod,Egypt.
AUTHOR
SAAD.
ZAGHLOOL
2
DR., Mechanical Engineering Dept. Ain Shams University,Cairo,Egypt.
AUTHOR
M.
AFIFI
3
PROF.DR., Mechanical Engineering Dept. Ain Shams University,Cairo,Egypt.
AUTHOR
ORIGINAL_ARTICLE
A PRODUCTION FLOW ANALYSIS AS A TOOL FOR FACILITIES LAYOUT
Production flow analysis is effectively used in planning methods and tooling which are at present being used in the factory. It is also used in group technology when considering design features or shape of components. One of the basic data for computerized facilities layout procedures is the interdepartmental flow. Most,if not all of such computerized procedures require such data in an almost one form- a matrix. It is often assumed that this matrix is readily available, which is not always the case. Moreover a change in the production programme would affect the current status of the layout and therefore appropriate changes are inevitable which normally take a long time to account for changes and its impact on the data and in turn the configuration of the layout. On the other hand the analysis of the problem of layout would require several computer runs with different data set for the same problem. This paper uses the methodology of the production flow analysis with an ultimate objective of automated data preparation based on actual data of production e.g process sheet,operation sheet ..etc. A computer model is designed and tested using a real life problem.The model requires data which normally used in the factory without ulteration. The flow matrix is obtained based on the pattern of component movements.Other outputs are also available by the model.
https://amme.journals.ekb.eg/article_49309_3e55e3dd3a5260881fbc56b4daca2343.pdf
1984-05-01
41
51
10.21608/amme.1984.49309
SALAH
ABDEL BARR
1
Lecturer, Dept. of Design and Production Engineering, Ain Shams University, Cairo, EGYPT.
AUTHOR
NAHID
AFFIA
2
Demonistrator, Dept. of Design and Production Engineering, Ain Shams University, Cairo, EGYPT.
AUTHOR
ORIGINAL_ARTICLE
OPTIMAL DESIGN OF HELICAL COMPRESSION SPRINGS SUBJECTED TO STATIC LOADS
Computer aided optimal design of helical compression springs is urgently required to promote the establishment of a national Egyptian standard specifications for such springs. The study covers the optimal assignment of spring variables for maximum modulus of resilience and achieving some functional constraints required for the satisfactory operation of the designed springs. Appropriate models and a fast optimization technique are used in solving the constrained optimizationproblem in hand. Springs having more resilience and less weight were obtained in comparison with the standard springs. The results are presented for loads from 182.5 N to 2080 N and covers: resilience, stress, volume, spring mass saving and spring stiffness.
https://amme.journals.ekb.eg/article_49314_2c0f6a8b36a75cb3c0cafca415b1f575.pdf
1984-05-01
53
62
10.21608/amme.1984.49314
G.
Hassan
1
Assistant Professor, Department of Mechanical Design, Faculty of Engineering, Cairo University, Giza, Egypt.
AUTHOR
A.
Abdel-Moaty
2
Graduate Student, Department of Mechanical Design, Faculty of Engineering, Cairo University, Giza, Egypt.
AUTHOR
ORIGINAL_ARTICLE
FINITE ELEMENT ANALYSIS OF MULTI-VENT MULTI-SPAN FOLDED-PLATE STRUCTURES
A general finite element computer code for the space analysis of folded-plate structures has been developed based on the stiffness Method. A direct access peripheral storage is used as a scratch file in the formulation of the overall stiffness and load matrices. This made it possible to analyze large multi-vent, multi-Span, folded-plate structures. The stiffness matrix of a one dimensional space frame element assuming nodal forces and displacements at the top points of the cross-sections was derived and used for the simulation of edge beams. The triangular plane-stress element was used for modeling the in-plane action of diap-hragms. Check problems of single-vent simply supported folded-platestructures with and without edge beams have been solved assuming infinitely stiff end-diaphragms and the results of both displacements and internal stresses were compared with the available "exact" analytical solution. This showed complete agreement in both displacements and stresses. Practical examples of three-vent simply supported and continuous folded-plate roofs have been solved. Effect of edge beams andties were considered. In case of continuous folded-plates, the effect of the inner supports as point supports on the ridges or as a diaphragm supported at the ridge points was considered and discussed. Several practical conclusions have been made.
https://amme.journals.ekb.eg/article_49317_3d2ec799de1439c3f0f5da555f0574d7.pdf
1984-05-01
1
17
10.21608/amme.1984.49317
Sami
Mikhaiel
1
Dr. Lecturer, Struct. Eng. Dept., Cairo Univ.
AUTHOR
Atef
Gindy
2
Eng., Demonstrator, Struct. Eng. Dept., Cairo Univ.
AUTHOR
ORIGINAL_ARTICLE
A STUDY OF THE EQUATION OF THE IMPLIED CURVE FOR ISOPARAMETRIC QUADRATIC TRIANGULAR FINITE ELEMENT
Many practical problems solved by the finite element method have curved boundaries which are mainly approximated by use of isoparametric elements. These curved elements have a wide applications in mechanical engineering, e.g. design of gearing, dynamics of shell structure, ... etc. The use of isoparametric quadratic triangular elements of Lagrange andHermite type is well established in the finite element method. In this paper the derivation of the equation of the implied curve when a curved edge is approximated using isoparametric quadratic triangles. The implied curve depends only on the parameters of the nodes associated with the curved side and does not depend on the basis function used. The .general six point isoparametric transformation is analysed with respect to a triangle with two sides and one curve side. Special case of the trans-formation is considered which lead to implied curve of the form of symmetric parabola, thus enabling isoparametric transformations to match a :variety of boundary shapes. The above study of the isoparametric quadratic curve is applied on the circle which is divided into equal angle sectors. The continuity of this curve between elements was studied for different angle sectors.
https://amme.journals.ekb.eg/article_49325_796b4b0364e2752aa340368b6e500004.pdf
1984-05-01
19
29
10.21608/amme.1984.49325
S.
SHEHATA
1
DR., Lecturer, Mathematic Dept., Faculty of Science, Zagazig University.
AUTHOR
A.
MOHAMED
2
Post—graduate student.
AUTHOR
ORIGINAL_ARTICLE
THE EFFECT OF HEAT TRANSFER PARAMETERS UPON THE BRINE HEATERS DESIGN IN A DESALINATION PLANTS
A new trend to a brine heater design with a sprayed saline water on horizontal tubes, where condensation takes place inside the tube bundle while the cooling evaporating film flows over the outside of the tubes. For the condensation inside and film evaporation outside the tube, the analysis of potion and energy equations with each boundary conditions and the laminar theory were undertaken. The resulting system of first order ordinary differential equations were solved numerically by computer program using Runge-Kutta-type method for a wide range of parameters. It was found from the numerical results that the heat transfer coefficients for the condensation and evaporation were inversly proportional to the film thickness around the tube. The average overall heat transfer coefficients increases by decreasing the saline water Reynolds number and the tube radius.
https://amme.journals.ekb.eg/article_49326_07f56c95107205fbc2256d912ca806cf.pdf
1984-05-01
31
41
10.21608/amme.1984.49326
M.
SHAMLOUL
1
Dr., Mechanical Dept., Faculty of Engineering, Zagazig University, El-Sharkia, Egypt.
AUTHOR
ORIGINAL_ARTICLE
INTERFERENte STRESS INTENSITY IN TUBES AS AFFECTED BY 11411CKNEsS TO DIAMETER RATIO AND LENGTH
In the recent years the finite element method was used to determine the contact pressure distribution between any twoelastic bodies, however the effect of friction at the mating surfaces are ignored and no manageable solution for the behaviour of an axi-symmetrical hollow components of finite length has been available. In the present work, the authors consider the problem of fitted tubes with different thickness to diameter ratio and length. The finite element method is used to determine the stress in-tensity-double value of that determined by the maximum shear stress theory. Computed results showed that the stress intensity across tube thickness and along its length is greatly affected by the tube. thickness to diameter ratio, t/di, and tends to approach a constant value for t/di ≥ 0.05. The length ratio between outer and inner tubes, L/L1 , have also a pronounced effect. The stress values on the inner tube increases with the increase in length ratio, while on the outer tube it decreases with the increase in length ratio and tends to have a constant value for L/L1 ≥ 3. Comparing stress intensity results with that evaluated for the hoop stresses showed a slight difference on tube thickness and length, with a maximum difference of 10%.
https://amme.journals.ekb.eg/article_49328_3db9dda8d71898d462e90db986643c0f.pdf
1984-05-01
43
50
10.21608/amme.1984.49328
H.
Ziada
1
Assistant Professor, Dept. of Mechanical Eng. king Abdulaziz University, Saudi Arabia.
AUTHOR
A.
Abd El Latif
2
Professor, Dept. of Mechanical Eng. king Abdulaziz University, Saudi Arabia
AUTHOR
ORIGINAL_ARTICLE
A NEW METHOD FOR CALCULATING COMPRESSIBILITY EFFECT ON AIRFOILS
Numerical methods for calculating compressibility effect on airfoils play a significant role in aeronautics because the experimental investigation in wind tunnels is more expensive. In literature, there are three well known methods i.e method of Prandtl-Glauert, Karman-Tsien and Christie-novitch. The last method is the most accurate one but it has some weak points. This paper presents a new method based on a non linearized approach in the Hodograph plane. The local velocity distribution and the pressure coefficient in the compressible fluid flow can be determined in terms of their corresponding values in the incompressible flow and the required Mach number and vice versa; because the formulae are explicit. This method is programmed on a digital computer consequantly, the compressibility effect is determined in a short time. The present method exhibits an order of magnitude reduction in computing time over other methods with comparable accuracy.
https://amme.journals.ekb.eg/article_49330_7db69f2d7206a78d234e8b659cfaf896.pdf
1984-05-01
53
57
10.21608/amme.1984.49330
M.
ESSAWY
1
Lecturer of Aerodynamics, Dpt, of Aeronautics, Military Technical College, Cairo, Egypt. (Member AIAA).
AUTHOR
ORIGINAL_ARTICLE
OPTIMUM DIMENSIONS FOR AN AXIAL TURBOMACHINE STAGE
The main dimensions of an axial turbomachine stage may be estimated to have a maximum hydraulic effeciency. Design formulae are obtained by writing the momentum equation for the rotor end stator of the machine and by assuming that the head produced at any section is proportional to the radius. The only variable has to be chosen is the mean vane angle of the stator, such that the hydraulic effeciency is maximum, while the ather main dimension are calculated.
https://amme.journals.ekb.eg/article_49339_845c3a4c089fba89b72c41aea9d895f0.pdf
1984-05-01
59
64
10.21608/amme.1984.49339
Ali
Barakat
1
Dr., Mechanical Power Department, Military Technical College, Kobry EL Kobba, Cairo.
AUTHOR
Ibrahin
Saleh
2
Dr., Mechanical Power Department, Military Technical College, Kobry EL Kobba, Cairo.
AUTHOR
ORIGINAL_ARTICLE
THEORETICAL A D EXPERIMENTAL INVESTIGATION OF FLOW FIELD IN RADIAL VANED IMPELLER
The flow field in radial impeller of a centrifugal pump has been predicted by assuming two dimensional ideal flow. The Poisson's equation, describing the flow field, is solved numerically by relaxation method, for both circulatory and flow fields. The theoretical impeller head was calculated as the mean value of the head generated by each stream tube in the impeller flow pattern. In spite of neglecting the boundary layer effect, the experimental results show a satisfactory agreement with the theoretical results, at part loads. this shows that the main predominant factor controlling the pump characteristics at part loads is the vortex formation in the impeller channel, and that the boundary layer has a minor effect in that operating region.
https://amme.journals.ekb.eg/article_49346_757465b6f5ae8bedc48d8335f5b6c3dd.pdf
1984-05-01
65
71
10.21608/amme.1984.49346
Ibrahim
SALEH
1
Dr., Mechanical Power Department, Military Technical College, Kobry Elkobba, Cairo, Egypt.
AUTHOR
Ali
BARAKAT
2
Dr., Mechanical Power Department, Military Technical College, Kobry Elkobba, Cairo, Egypt.
AUTHOR
A.
LOTFY
3
Mechanical Power Department, Military Technical College, Kobry Elkobba, Cairo, Egypt.
AUTHOR
ORIGINAL_ARTICLE
ON THE OSCILLATIONS OF A BOUNDED LIQUID WITH A. TIME DEPENDENT DISCONTINUOUS BOUNDARY
The stability of the free surface of an inviscid liquid partially filling a rigid rectangular container with an outlet at its base is investigated. The container executes vertical vibrations in the direction of the gravitational field. The initial-bOundary value problem has been formulated and solved. The wave height and pressure have been determined. By specializ-ing the obtained results to special cases,it has been found that they agree favourably with prev-ious investigations.
https://amme.journals.ekb.eg/article_49361_e769dbd6477f4766bdcdd145e1fbaed1.pdf
1984-05-01
73
91
10.21608/amme.1984.49361
H.
SAFWAT
1
Assoc. Prof., Dept. of Engrg. Mathematics, Faculty of Engrg., University of Alexandria El-Hadhrah, Alexandria, Egypt .
AUTHOR
ORIGINAL_ARTICLE
DISCONTINUOUS BOUNDARY ELEMENTS FOR TWO DIMENSIONAL INVISCID LAMINAR FLUID FLOW
In the Boundary Element Method the familiar infinite system of integral equations is discretized by the introduction of boundary elements here ranging from constant through linear, quadratic ... etc. Hitherto, in the case of linear and higher order elements, interelement continuity of the unknown functions has been imposed in applications, un-doubtedly in analogy with finite element practice. In the Boundary Element Method there is no such requirement; so that interelement continuity issimply not necessary.
https://amme.journals.ekb.eg/article_49365_4d486ff213c38b9d294046febb52cef0.pdf
1984-05-01
93
94
10.21608/amme.1984.49365
N.
EL-SEBAI
1
Lecturer, Department of Mechanics & Elasticity, Military Technical College, Kobry El Kobba, Cairo, EGYPT.
AUTHOR
ORIGINAL_ARTICLE
AN ALGORITHM FOR IRE SOLUTION OF AVISCO PLASTIC MODEL IN A STEADY- STATE OF CREEP USING A NON CONFORM FINITE ELEMENT
A non-conform finite element proposed for viscous fluid flow satisfying zero divergent condition is adapted to our model, This needs some numerical aspects aspects which characterize our algorithm and precise the method of solution on digital computers. The variational formulation of the model permits the use of optimization techniques. A descent technique, thqt of Flecher-Reeves with re-initalization and a proposed line search. t-chnique are used. For our model the vanishing divergence condition is not sufficient to sustain our problem as an unconstrained optimization problem. A penalty method (exterior penalty function) is now necessary for the numerical solution. Apractical example is solved using our algorithm and the corresponding stress distributions are obtained.
https://amme.journals.ekb.eg/article_49373_db059886ed5d73efe475a4a3e2da1680.pdf
1984-05-01
103
110
10.21608/amme.1984.49373
Mohamed
ABDEL FATAH
1
Dr.Eng., Department of Math.,M.T.C. , Cairo.
AUTHOR