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Aiming at of solving the cracking problem of an alternator bracket. Firstly, the engine time domain-acceleration curve were tested, and they were converted to frequency domain acceleration curve. The alternator bracket was frequency response analyzed based on the frequency domain acceleration curve, the analysis results show that the maximum stress value exceeded the yield strength of the material. Secondly, the alternator bracket was vibration fatigue analyzed by adopting power spectrum density function, the analysis results show that the minimum life was lower than target, and it was consistent with the strength analysis weak region and actual failure position. Thirdly, the alternator bracket was optimal designed by adopting large scale generalized reduced gradient algorithm, it can meet fatigue and strength performance requirements after optimization. Lastly, the alternator bracket optimization scheme was certificated by vehicle road test, the test results show that the alternator bracket vibration amplitude is obviously decreased, and the alternator bracket cracking is avoided, so the cracking problem is effectively solved. A scientific references are provided for the high frequency response bracket failure solution by the analysis method and its optimization method.

Aiming at solving the cracking problem of a light card fuel filter bracket in the vehicle road test. Firstly,each road vibration acceleration were collected,the test results show that the washboard road vibration acceleration is the largest.Secondly,the frame end was taken an exciting point and the measured frequency domain signal were load,the bracket was vibration analyzed based frequency response method,the analysis results show that the bracket Z direction maximum von Mises stress value exceed the yield strength of the material. It is located at the circular tube bend and it was consistent with the actual failure position. Lastly,the fuel filter bracket was multi-objective optimization analyzed based on Isight platform integrated CATIA,HYPERMESH and NASTRAN by adopting non-dominated sorting genetic algorithm. So the circular tube optimal parameters are obtained and the bracket maximum stress value are lower than the allowable stress after optimization. The optimization effects are obvious and it could meet fatigue strength performance requirements. The optimization scheme had passee the road test,so the cracking problem was successfully solved. The analysis method wad integrated with road test,finite element technology,frequency response method and vehicle reliability road test,the advanced reference and practical engineering application for the similar brackets vibration analysis and optimization design were provided.