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Design and Manufacturing of a Multi Functional Device For Experimental Fatigue Test and Special Facilities for Symmetric and Anti Symmetric Loading on Gears
, M.Sc. Thesis Sharif University of Technology ; Durali, Mohammad (Supervisor)
Abstract
The goal of this research is design and manufacturing of a device for fatigue test and 3D crack propagation in spur gear roots. Clearly it should be able to test gear in oscillated bending load and control the amplitude and period of loading. Designed setup in this project using a electro hydraulic actuator can do it up to 50 KN and 10 Hz in amplitude and frequency and a PLC controls it during the test time. System can load gears symmetric or anti symmetric and simulate the effect of shaft misalignments, bearing damage and gear production tolerances on the gear loading. System completely designed, built and tested during this project and using experimental data, its performance was...
Three dimensional calculation of meshing stiffness for spur gears
, Article DETC2005: ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Long Beahc, CA, 24 September 2005 through 28 September 2005 ; Volume 5 , 2005 , Pages 869-873 ; 079184742X (ISBN); 9780791847428 (ISBN) ; Saryazdi, M. Gh ; Sharif University of Technology
American Society of Mechanical Engineers
2005
Abstract
This article presents a new method for determination of meshing stiffness of the gear teeth using three dimensional analysis of tooth stiffness. The teeth are treated as explicit capacitive fields and their compliance matrix is determined by considering virtual interconnected springs located at defined nodes on tooth profile. The stiffness of any arbitrary point on the profile can then be determined as a linear function of neighboring nodes stiffness. The results of this analysis help in determination of load distribution for a pair of meshing gears under real operation conditions where deflections and misalignments are inevitable. Copyright © 2005 by ASME
Simulation of Three Dimensional Crack in Spur Gears due to Misalignment
, Ph.D. Dissertation Sharif University of Technology ; Durali, Mohammad (Supervisor)
Abstract
Fatigue crack is one of the most important causes of defect for gear systems. This effect results tooth fracture and failure of other elements of the power transmission systems. As a result, much effort has been devoted to the modeling of fatigue crack and improving the methods of crack detection. Simulations of three dimensional crack growth in spur gears due to misalignment and examination of this effect on vibration response of gear system are the main goals of this research. To model the crack growth, a new method of gear meshing modeling was proposed. In this method, the effects of pinion on the gear and vice-versa are modeled by a finite set of virtual interconnected springs. The...
An analytical and experimental study of precision forging of aluminum spur gear
, Article Steel Research International, 16 September 2012 through 19 September 2012, Krakow ; Volume SPL. ISSUE , September , 2012 , Pages 163-166 ; 16113683 (ISSN) ; 9783514007970 (ISBN) ; Taheri, A. K ; Sharif University of Technology
Wiley-VCH Verlag
2012
Abstract
An important aspect of production of gears by precision forging process is the prediction of load required to perform the process and to design the forging die. In this research a new kinematically admissible velocity field is presented to predict the forging load by an upper bound analysis. The analysis considers the shape of tooth profile, number of teeth, and frictional conditions between the die/punch and deforming material. To verify the predicted results the 7075 aluminum alloy billets were forged at temperature of 150 to 250 °C in a precision forging die designed to produce a spur gear of 5 teeth. A good agreement was found between the two sets of results at the filling stage of the...
Determination of transition curves for a gear system with coulomb friction
, Article 2006 ASME International Mechanical Engineering Congress and Exposition, IMECE2006, Chicago, IL, 5 November 2006 through 10 November 2006 ; 2006 ; 01608835 (ISSN); 0791837904 (ISBN); 9780791837900 (ISBN) ; Durali, M ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2006
Abstract
This paper discusses the determination of the transition curves for a pair of spur gear with coulomb friction. Transition curves are the loci of periodic response of parametrically excited systems and separate the stable and unstable solutions. A discrete model of a pair of spur gear is developed and the friction forces are calculated base on instantaneous dynamic force between gear teeth. The dynamic equation of the system is a linear ordinary differential equation with periodic coefficients. Periodic friction torque, as the parametric excitation is represented by Fourier series. The loci of periodic solutions are determined in μ - Γ plane (coefficient of friction-contact ratio) by strained...
The effect of three-dimensional crack growth on the force distribution and meshing stiffness of a spur gear: Ideal and misaligned contacts
, Article Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science ; Volume 223, Issue 7 , 2009 , Pages 1633-1644 ; 09544062 (ISSN) ; Durali, M ; Sharif University of Technology
2009
Abstract
This article presents a routine for prediction of the crack growth path in gears. Crack simulation helps in determining failure modes and crack detecting by vibration monitoring. To simulate crack propagation an effective method is developed by which the meshing force is calculated based on the compliance of meshing teeth in every stage of crack growth. In this method the compliance matrix of the tooth is calculated using three-dimensional boundary element analysis without the need for simultaneously modelling two meshing gears. The force distribution on the contact area is then calculated using Hertz theory and compliance matrices of meshing teeth. The method is used in prediction of the...
Vibration Analysis of Spur and Helical Geared-rotor System under Residual Shaft Bow Effect
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor)
Abstract
The purpose of this study is to establish a lateral-torsional-axial dynamic model for spur and helical geared rotor systems subject to shaft bow manufacturing error. Timoshinko shaft element, elastic bearings and rigid disks used to simulate different element in the model. Tooth contacts is modeled with linear spring and damper along the pressure line.Results show that the vibration pattern of the unbalanced load and shaft bow effect is different. These obtained patterns might help with the fault diagnostics of rotating machinery. The vibration will be lowest if the unbalanced load and the shaft bow amplitude locates out of phase. The previous researches show that different pattern of the...
The determination of meshing force distribution for spur gears
, Article 2008 ASME International Mechanical Engineering Congress and Exposition, IMECE 2008, Boston, MA, 31 October 2008 through 6 November 2008 ; Volume 11 , 2009 , Pages 451-458 ; 9780791848722 (ISBN) ; Ghasabzadeh Saryazdi, M ; Sharif University of Technology
2009
Abstract
This article presents a method for determination of meshing force distribution on contact region of spur gear teeth. In this method it is assumed that there are inter-connected springs on the teeth profile. These springs treat as capacitive fields. The compliance matrices of these fields are determined from the results of finite element analysis done on 3-D model of a gear. The tooth compliance matrix is used as a reference data to determine the tooth deformations for any meshing situation. The meshing force distribution is calculated using this reference data and Hertz theory for contacting bodies. The results of this analysis help in stress analysis under real operation conditions and more...
Analysis of nonlinear oscillations in spur gear pairs with approximated modelling of backlash nonlinearity
, Article Mechanism and Machine Theory ; Volume 51 , 2012 , Pages 14-31 ; 0094114X (ISSN) ; Salarieh, H ; Sharif University of Technology
2012
Abstract
Due to international competition and strict limitations of standards regarding the noise level, investigation of gear vibration is of great importance. In this paper, nonlinear oscillations of spur gear pairs including the backlash nonlinearity is studied. Dynamic system is described through the classical single degree of freedom (SDOF) model in terms of dynamic transmission error (DTE). Using multiple scale method, forced vibration responses of the gear system including primary, super-harmonic and sub-harmonic resonances are investigated. In each case, the jump phenomenon and stability analysis are studied. In addition, the effect of dynamic and manufacturing parameters of the gear system...
Effect of forging temperature on homogeneity of microstructure and hardness of precision forged steel spur gear
, Article Materials Chemistry and Physics ; Volume 112, Issue 3 , 2008 , Pages 1099-1105 ; 02540584 (ISSN) ; Karimi Taheri, A ; Sharif University of Technology
2008
Abstract
Precision forging is a suitable process to produce spur gears due to its advantages such as reduction in machining time and production cost. The homogeneity in microstructure and mechanical properties of precision forging products can highly affect the performance of the gears during their service. In this research the effect of precision forging temperature on homogeneity of microstructure and hardness of forged gears of low carbon steel is studied. The microstructure and hardness map of the gears forged at a temperature range of 750-1150 °C revealed that the forging temperature of 950 °C is an optimum temperature to produce a spur five teeth gear with minimum inhomogeneity in the...