The Effect of Load Phase Angle on Roof Components of Electric Driven Bus Fatigue Damage

In this study, the effect of phase shift under multiaxial excitation on fatigue damage was investigated for the roof components of electrical driven bus. The experiments were performed using a servo-hydraulic controlled multiaxial shaker. Firstly, phase degree and concurrence of servo-hydraulic actuators were calculated and compared for in-phase and out-of-phase loading cases. Following response signals of both loadings were acquired to investigate the dynamic response of the structure and roof components. Both test loadings were compared by level crossing counting and damage calculations in the frequency domain. The results indicate that the out-of-phase loading can reduce the acceleration and strain values on the flaps induced damage significantly compared to in-phase loading. Furthermore, the out-of-phase loading of bench testing corresponds well to the experimental results of rough road, which represent customer drive conditions.