The Random Vibration Analysis and Optimization of MCU of a HEV Transmission

MCU of a HEV transmission was failed in random vibration test, the failure form is manifested in foot desoldering of chip solder and cable base on the control board. According to the structural characteristics and random vibration test conditions of the MCU, a finite element model of random vibration was established. Through random vibration analysis, the critical modal frequency that cause vibration failure was found, and the maximum RMS of the analysis result is also consistent with the test failure location. On this basis, two optimized schemes of B and C are proposed. The simulation indicates the RMS stress of the soldering foot of the cable base of scheme C reduced by 13%, the RMS stress of the chip soldering foot is reduced by 23%, therefore, the vibration stress at the failure location is significantly improved. The verification scheme made according to C successfully passed the random vibration test, the improvement reached the expected effect.