Contact stresses analysis in spur gears by finite element method

In this study the contact stresses in meshing spur gear pairs are investigated by using finite element method, under static conditions. The value of contact stress on the gear tooth pair's engagement determines that the gear can transmit the power without harm. The contact stress in gears has been a high point of importance for last years, but still, extensive research is required to understand the several parameters that affecting this stress. Among such parameters, number of teeth, module, face width, pressure angle, profile shift and friction coefficient, which have played a critical role in the magnitude of contact stress. In the present study, the contact stress in spur gear is calculated by employing Hertz's equations, AGMA's equations and finite element method (FEM). A homemade computer program was used to obtain the precise geometry of gears. This geometry of gear transferred to Solidworks to make surfaces and then to MSC Software SimXpert to prepare Finite Element mesh. The results of the FEM analyses from MSC Software Marc are compared with the theoretical results of Hertz's and AGMA's equations. The contact stress achieved by FEM is lower than about 10 % when comparing with the results obtained by theoretical equations. The analysis specify that increasing the geometrical parameters (number of teeth, module, face width, pressure angle and profile shift) lead to decrease in the tooth contact stress. Also, the results obtained for wear rate have shown a decreasing tendency, with a decrease in sliding velocity or vice versa.