Dynamics of a HDD spindle system due to the change of FDBs

This research investigates the effect of FDBs on the dynamics of a HDD spindle system. Flying height of the HDD spindle system is determined by using the static analysis of the FDBs, and the stiffness and damping coefficients are calculated by using the dynamic analysis of the FDBs. Free vibration characteristics and shock response of the HDD spindle system are analyzed by using the finite element method and the mode superposition method. Experimental modal test is also performed to verify the accuracy of the proposed method. This research shows that the stiffness coefficients of journal bearing mostly affect the rocking frequencies because their magnitudes are within the range of the stiffness of supporting structure. It also shows that the damping coefficients of thrust bearing mostly affect the axial frequency because the stiffness of thrust bearing is much smaller that that of supporting structure.