Axial Shock-Induced Motion of the Air-Oil Interface of Fluid Dynamic Bearings of a Non-Operating Hard Disk Drive

We investigated the axial shock-induced motion of the air-oil interface of the fluid dynamic bearings (FDBs) of a non-operating (HDD) by experiment and simulation. We empirically determined the motion of the rotor with respect to the stator and the oil leakage due to axial shock. We applied the finite volume method and the volume of fluid method to simulate the axial shock-induced motion of the fluid lubricant of FDBs considering the two-phase flow of air and oil and the surface tension at the air-oil interface. The thrust plate and shaft were assumed to move as a rigid body. Our findings allow us to explain the phenomenon of the break-up of the air-oil interface of FBDs caused by axial shock. We also discuss the effects of the magnitude of the shock and oil viscosity on the break-up of the air-oil interface.