A NURBS-based isogeometric analysis model for soft EHL contacts

This paper presents a NURBS-based isogeometric analysis framework for modeling both hard and soft elastohydrodynamic lubrication (EHL) contacts under the fully flooded condition. Unlike conventional approaches, the framework incorporates nonlinear solid deformation within a unified weak formulation and employs a mortar method to flexibly couple the fluid and solid domains with independent discretizations. Benchmark tests show excellent agreement with reference ANSYS FSI simulations while reducing the computational time by about 99% for both hard and soft EHL line contacts. The framework is further applied to a soft EHL point contact between a hyperelastic hemisphere and a rigid plane, confirming that nonlinear solid deformation strongly affects the film thickness and frictional response. Finally, the influence of surface roughness is investigated, revealing that transversely oriented topographies yield superior lubrication performance, as indicated by a higher transition load and a lower friction coefficient.