Impact Elastohydrodynamic Lubrication Analysis of Transversely Isotropic Materials in Point Contact

In the traditional elastohydrodynamic lubrication (EHL) field, surface elastic deformation is usually determined using an elastic half-space model for isotropic materials. However, this theory may be inefficient when applied to point contact problems involving inherently anisotropic materials, such as transversely isotropic (TI) materials. Accordingly, the present study proposes a method for solving the EHL point contact problem between a rigid ball and a TI substrate under impact loading using a direct-solving numerical method, in which the mechanical properties of the TI material are expressed in the form of a stiffness matrix. For comparison purposes, the TI material is also approximated as an isotropic material using Turner's approximation method based on the equivalent modulus property of the material. It is found that the direct-solving method outperforms Turner's approximation in interpreting the mechanical properties of the TI substrate. In addition, it is shown that the initial velocity of the rigid ball and the stiffness of the TI material (i.e., the transverse elastic modulus, longitudinal modulus, and shear modulus) have significant effects on the load, impact velocity, and acceleration of the ball; central pressure and film thickness of the lubricant; and deformation and von Mises stress of the TI substrate, during the impact process. Overall, the results show that the proposed EHL model provides a useful tool for solving impact-EHL problems involving TI materials.