Failure Mode And Thermal Fatigue Life Research Of Passenger Elevator Block Brake

The block brake is the core component of the passenger elevator transmission device.In the elevator accidents,the sliding and the topping accidents of the elevators caused by the insufficient braking force of the block brakes caused a lot of property loss and casualties in recent years.And once the brakes fail,it may cause heavy casualties such as personnel shearing accident.Therefore,it is of great theoretical and practical value to analyze the failure mode and thermal fatigue life of passenger elevator brakes.The paper takes a certain type of passenger elevator block brake as the research object,and the working principle,failure mode and thermal fatigue life of the passenger elevator brake are analyzed and studied.The specific work contents are as follows:According to the parameters of the block brake provided by Hangzhou Theo Company,the three-dimensional model of the brake is constructed,and the composition and working principle of the brake are analyzed.The brake static and dynamic working conditions are separately modeled,so the quantitative relationship between the parameters of the block brake is established.The fault mode analysis is carried out based on the established relationship,and the fault bottom events of the block brake are finally determined.According to the determined bottom events,block brake failure mode table is established,and passenger elevator block brake fault tree model is constructed,and a corresponding qualitative analysis is performed on each bottom event.The established fault tree is converted into a Bayesian network.Based on four experts,the level of failure probability of the bottom event is evaluated,and the fuzzy function is used to convert the bottom event failure rate into a fuzzy probability.The mean area method is used to solve the fuzzy process to determine the exact probability of the block brake bottom event failure.According to the Bayesian network,the posterior probability of each node is caculated to determine the key factor of insufficient braking torque caused by the impact caused in the brake emergency braking condition.According to the simplified model of the block brake wheel and brake shoe,the block brake thermalmechanical coupling simulation analysis is carried out based on the finite element analysis software Abaqus/Explicit to determine the thermalmechanical coupling characteristics of the block brake.The block brake temperature field and stress field are analyzed.Based on the thermalmechanical coupling relationship,the distribution of the temperature field and stress field in the axial,circumferential and radial directions of the brake is determined.The failure mode of brake wheel that is subjected to the alternating thermal cycle stress is mainly the plastic deformation of the contact area of the brake wheel surface,which is easy to cause fatigue crack,and result in brake failure.According to the thermal machine coupling simulation model,Three-way stress of the block brake is analyzed during emergency braking.Three-way stress determine the dangerous part of the brake wheel,determine the maximum stress that affects the thermal fatigue life of the block brake.The fatigue life of the block brake is determined based on Manson-Coffin.