Abstract: The compressibility of the oil film and the influence of the bearing inertia force on oil film pressure are usually neglected in the traditional research of the pressure behavior of the oil film. But, oil film pressure changes greatly along with time when subjected to transient shock, which leads to unworthiness of the incompressibility assumption, considering the density and the viscosity of oil film changing greatly along with the oil film pressure. Besides, the velocity of bearing location is very high. And the inertia force due to the high velocity of bearing location can’t be overlooked. By introducing the compressibility and the bearing inertia force into the numerical calculation of oil film pressure, the calculation results will be more tally with the actual physical phenomenon. So the equilibrium equation considering the bearing inertia force and the Reynolds equation considering the compressibility of oil film are established. And the pressure behavior of the oil film is studied to get the influence of the load amplitude, pulse width and relative gap on the oil film pressure when subjected to transient shock loads, such as the rectangular pulse, triangular pulse and sine pulse. And it is shown that the decay rate of the oil film pressure has no monotonic relation with the load amplitude. The decay rate is high either the load amplitude is very big or very small; The pulse width has little influence on the decay rate of the oil film pressure; The bigger the size of the gap is, the bigger the influence of the bearing inertia force on the pressure of the oil film will be. In addition, the beat vibration can be seen on the pressure-time curve when the compressibility and the bearing inertia force are considered.

Key words: Compressibility, Inertial force, Oil film pressure, Transient shock load