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Aiming at solving a horizontal stabilizer bar fracture failure, firstly, the forward horizontal stabilizer assembly model and the front suspension dynamics model were established based finite elements method and rigid flexible coupled multi-body dynamics method, the horizontal stabilizer bar displacement were extracted in limit working condition, so the strength analysis force displacement was 49.5 mm. And then the horizontal stabilizer bar was strengh analysised by adopting Nastran software, the analysis results show that the maximum stress was 977.6 MPa, it located in the horizontal stabilizer and stabilizer bar bracket and bushing joint position, there was a fatigue injury risk about it. The horizontal stabilizer bar was fatigue life analysised by adopting FEMFAT software, the analysis results showed that the minimum life was 3.37×10~4 times, the weakest place was consistent with the maximum stress position for strength analysis, it was below design requirements. And then the horizontal stabilizer bar was multi-objective optimization analysised by adopting Isight optimization integration platform, its optimal diameter was obtained, its fatigue performance meets the design requirements after optimization. The horizontal stabilizer bar bench test platform was established by loading with sine wave, the results show test results were agree with the fatigue simulation results,and it passed the test of the vehicle road. Finally, the horizontal stabilizer fracture problem was successfully solved. The analysis method combined finite elements, multi-body dynamics, fatigue mechanics, bench test and road test, It provided advanced scientific guidances for the similar structures fatigue strength analysis and optimization design.

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.

In order to research the shiftability of a transmission synchronizer,the synchronizer model,shifting control mechanism model and shifting robot model are built by adopting Simulation X integrated ADAMS,ABAQUS and CATIA based on shifting control and test specification of synchronous durability test bench,two kinds of shifting process conditions of 1-2 upshift and 2-1 downshift are simulated,so the shifting force,shifting displacement and input shaft speed are obtained. The simulation data are compared with test data,the analysis results show that they are basically identical,the difference is that the simulation shifting time is slightly ahead of the bench test time,the feasibility and accuracy of simulation results are verified.

For the problem of gear shaft resonance,the gear shaft is analyzed with adopting finite element method,the inherent frequency and vibration mode are obtained.The maximum of first and second inherent frequency and the minimum quality are set as objective function,based on Isight integrated optimization platform,the AMGA,NCGA,NSGA-II is adopted to the optimization design in respect of the diameter of neck of shaft.After optimization,the first inherent frequency and second inherent frequency are improved by 6.16% and 6.13%.The low inherent frequency are outside the range of excitation frequency,the quality of gear shaft is reduced,so the resonance will be effectively avoided.

In order to improve the reliability and rationality of a automobile transmission shaft design,the free modal,torsional stiffness,static strength and fatigue strength of a transmission shaft are analyzed based on the finite element method. The result shows that the first-order natural frequency is 15% higher than the excitation frequency,so the resonance will be effectively avoided. The torsional rigidity is 27 685. 5 N·m / rad,it meets the stiffness requirement. The maximum stress is located at the shaft tube,its value is 185. 2 MPa,the safety factor is 1. 32,it meets the strength requirements. The minimum life is 8. 165 × 107,it meets the fatigue life requirements.