Investigation of the effect of load distribution along the face width and load sharing between the pairs in contact on the fracture parameters of the spur gear tooth with root crack

摘要

The magnitude and location of stress intensity factor (SIF) in mode I (K-I) mode II (K-II) mode III (K-III) relies mainly on the geometry and location of the crack tip, variation in magnitude of load due to multiple pair contact along the active profile and the distribution of the load along the face width of a spur gear drive. Mostly, in literature the calculation of SIF in gear were carried out either by using a two dimensional (2D) Finite element model (FEM) with point load for unit width or a three dimensional (3D) FEM with uniform/parabolic load distribution along the face width without considering load sharing effect between the multiple pairs in contact. In the present study, an attempt has been made to explore the significance of the load distribution along the face width and the load sharing between the pairs when the contact moves from the highest point of tooth contact (HPTC) to the lowest point of tooth contact (LPTC) on the SIF calculation. A comparative study has been made by using a validated 3D single tooth spur gear FEM with four different load cases such as case 1: Uniform load distribution along face width without considering load sharing between the pairs, case 2: Uniform load distribution along face width by including the effect of load sharing between the pairs, case 3: Actual load distribution along the face width without considering load sharing between the pairs, case 4: Actual load distribution along the face width by including the effect of load sharing between the pairs. The stiffness based approach was used to calculate the load distribution ratio (LDR) of a contact point along the contact line and the load sharing ratio (LSR) between the pairs in contact. The detailed analysis showed that case 1, case 2 and case 3 load cases overestimate the SIFs comparing to the case 4. The first three load cases overestimate the K-I by 39%, 2.5%, and 45% and K-II by 390%, 36%, and 129% and K-III by 282%, 47%, and 132% respectively when compared to load case 4. The results of this study provide valuable guidelines for the crack propagation as well as life prediction calculations for spur gear drives.