In this paper, the effect of tooth wear on the vibration spectrum variation of a rotating spur gear pair is studied. In order to approximate the dynamic characteristics of an engaging spur gear pair, the load sharing alternation, position dependent mesh stiffness, damping factor and friction coefficient are considered in the mathematical model. The wear prediction model proposed by Flodin et al. is used to simulate the tooth profile wear process. The variation of the vibration spectra introduced from the interaction between the sliding wear and the dynamic load is simulated and analyzed. Numerical results indicate that the dynamic load histogram of an engaging spur gear pair may change greatly with the tooth wear. This finding implies that the variation of the gear vibration spectrum might be used to monitor the tooth wear of an engaging spur gear pair.

No abstract

No abstract

In the ACF packaging process, a bonding force will be applied to the ACF structure. The finite element analysis is used to simulate the ACF packaging process. Material behavior is assumed to be superelastic for resin, viscoelastic for polymer matrix, and elastic-plastic for metal, such as bump, pad, chip, and Au-film. The axis-symmetric model is employed in FEA simulation with time-varying bonding force and operating temperature. In this study, the parameters, including conductive particle diameter, Au-film thickness, and bonding force, are analyzed with nonliner and temperature-dependent material properties. The simulation results indicate that bonding force and operating temperature have strong effects on the formation of concave on Au-film. In addition, surface wrinkle of Au-film will be induced by the bonding force. Both of the concaving and the wrinkling on Au-film will decrease the contact area between the conductive particle and the bump and the contact area between the conductive particle and the pad. Decrease of the contact area means increase of the total resistance for the ACF structure. The results show that the smaller the conductive particle diameter, the smaller the contact area. Generally, increasing the thickness of Au-film will decrease the contact areas, except at the Au-film thickness of 0.05 μm.

Dynamic equations of the intermittent-motion of a globoidal cam driven system were derived in this study. The effects of roller mesh flexibility and cam profile curve on the residual vibration of a globoidal cam system were studied experimentally and numerically. Time varying roller mesh stiffness and damping coefficients were used to account for the periodic variation of the mesh stiffness in the dwell and the active periods respectively. Dynamic responses of a globoidal cam system in the active and the dwell periods were simulated and measured. The effects of cam profile and input shaft speed on the residual vibration were also studied in this work. Results indicated that the proposed model was feasible for the dynamic simulation of a globoidal cam system.