Three-Dimensional Analyses by Finite Element Method of a Spur Gear and Helical Gear: Effect of Cracks in the Teeth Foot on the Mesh Stiffness

Tan, Kai Lin (2011) Three-Dimensional Analyses by Finite Element Method of a Spur Gear and Helical Gear: Effect of Cracks in the Teeth Foot on the Mesh Stiffness. Final Year Project (Other), Tunku Abdul Rahman University College.

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Abstract

Abstract In this paper, a finite element method with a three-dimensional survey is presented. The effect of crack dimension and the direction of crack propagation, in the teeth foot, on the mesh stiffness is studied. For spur gears, the mesh stiffness is affected in a meaningful manner by the presence of a foot crack of one or more teeth. This study is an attempt to estimate the effect of crack size, position, and direction on the spectrum of the gear mesh stiffnes. Gear transmission systems are considered one of the critical aspects of vibration analysis, and it contains various potential faults such as misalignment, cracks, and noise. Therefore, it requires vibration monitoring to ensure the system is operating properly. Case mounted accelerometers are frequently used to monitor frequencies in a system. However, it is not a simple task to identify and interpret the acceleration data since there are many gear mesh frequencies present. One of the approaches utilized by researchers to perform gear diagnostic is Finite Element Modeling. This study focuses on meshing stiffness of finite element modeling. The comparisons of meshing stiffness will concentrate on the type of elements, the integration methods, the meshing quality, plane stress , sensitivity of model tolerance, and crack modeling. The results show that the FEA approach is extremely sensitive to tolerance, mesh density, and element choice. Also, the results indicate that a complete sensitivity and convergence studies should be carried out for a satisfactory stiffness match. The comparative analysis for various combinations of design, manufacturing, and performance parameters are illustrated graphically and discussed briefly. The results will allow for a better understanding of existing limitations in the current standards applied in engineering practice as well as provide a basis for future improvements and unifications of gear standards.