Research On Service Reliability Of Automatic Brake Adjuster In The Failure Physics Mode

The statistics indicates that large number of trucks,buses and other large commercial vehicles' service life of the automatic brake adjuster produced durability damage within the required number of times,seriously endangering people's lives and property safety.However,the existing reliability prediction methods usually rely on the real vehicle test,which waste a lot of time and money.To a great extent,this approach also reduces the production efficiency.For this reason,a method of reliability evaluation of the automatic brake adjuster based on failure physics is proposed in this dissertation.The main research content of the dissertation involves:(1)According to the failure physical theory,the failure mode and failure mechanism of the automatic brake adjuster are analyzed.It is determined that the weak components in the automatic brake adjuster are rectangular compression springs.On this base,the self-adjusting and durable test bench is used to analyze the fatigue and durability test of the automatic brake adjuster.And the experimental results further verified that the rectangular compression spring is the most likely failure component in automatic brake adjuster.(2)The fatigue life data of the automatic brake adjuster is fitted based on the three-parameter Weibull distribution.And the three parameters of the Weibull distribution are estimated using the mean,variance and median of the lifetime data.By analyzing the working principle of the automatic brake adjuster,a mechanical model is built for the rectangular compression spring.Finally,the P-S-N curve of the automatic brake adjuster fatigue life is fitted by combining the three-parameter power function.(3)The automatic brake adjuster was tested by the self-designed self-regulating durability test table at different stress levels.Then,test data were processed by the analytical method.The results show that the correctness,stability and reliability of the reliability evaluation results of the automatic brake adjuster based on the failure physical.