Study on stiffness of elastohydrodynamic line contact

•The film thickness and deformation of an elastohydrodynamic line contact is analyzed.•The stiffness of oil film, contact bodies and the composite stiffness are compared.•The conditions of approximating the stiffness by the Hertzian stiffness are presented.•The critical conditions are verified by the dynamics simulation of a valve train.

The stiffness of oil film, contact body and the resultant stiffness of elastohydrodynamic line contacts with various radii of curvature, loads and entrainment velocities are studied based on the numerical analysis of oil film thickness and elastic deformation. It is found that the elastohydrodynamic contact stiffness is close to the Hertzian contact stiffness in the cases of high loads, low speeds and small radii of curvature. The critical conditions in which the elastohydrodynamic stiffness can be approximated by the Hertzian stiffness are investigated and verified by the dynamic simulation of the valve train in a diesel engine.