Studies On Load Spectrum And Accelerated Durability Test Methods To Typical Automotive Parts

The durability is important properties of automotive parts that should be strictly verified before it used in the product.And the laboratory accelerated durability test is the widely used method to evaluate the durability of automotive components.In order to improve the accuracy and efficiency of the laboratory accelerated durability test,the aspects including load history acquisition method,load spectrum editing technology and automotive component bench test are studied in this research.The main works in the disseration are summaried as follows:(1)The modified down-sampling algorithm of the signal pre-process is proposed to avoid the damage calculation error of the load history,and the wavelet-based uniaxial load spectrum edition algorithm is established.The load spectrum after pre-processed has been shortened by using the time wavelet-based load spectrum edition method and correlated fatigue damage method,respectively.The edition load spectrums are used in the durability test of the mount to validate the effectiveness of the load spectrum edition method.(2)Taking the channel phase relationship into consideration,the wavelet-based multi-axial load spectrum edition algorithm is estibalished based on the uniaxial load spectrum edition method.The muti-axis load spectrum of the control arm is edited by the wavelet-based edition method and time correlated fatigue damage method,respectively.The parameters including damage retaintion,statistical parameter,level crossing and power spectrum density of the edited load spectrums are compared with the original load spectrum.The results show that the edition method could shorten the load spectrum effectively.The edited load sptrums are used in the fatigue life evaluation of the control arm.The damage and fatigue life of the control are basically the same by using the eidited load spectrum and the original load spectrum.It is further illustrating the effectiveness of the multi-axis load spectrum edition method.(3)The damage and pseudo-damage theory-based load spectrum edition method has been compared.The force history of the mount is edited by using the pseudo-damage theory-based load spectrum edition method.The force-transformed strain history is edited by using the damage theory-based load spectrum edition method.The differences between this two edited load spectrums are analysised and compared.(4)The test fixture of wear with four axes is developed,and the movement at each axis is independent based on analysis of movement degrees of freedom at each axis.The relationship of wear experiment for ball joints at the road and at the test equipment with remote parameter control technology(RPC)is presented.The multi-axis load spectrum edition method based on wavelet transformation is applied to the load spectrum edition of the four-axis load spectrum.And one ball joint is used to measure the wear characteristics using the developed test fixture and the RPC technologies with the edited load spectrum at the proving ground.The wear performances of the ball joint before and after experiment are compared and analyzed.It is shown that the developed test fixture and the proposed test procedures can be used for accelerating wear test of ball joint with the equipment at lab.