Design,Optimization And Motion Function Reliability Analysis For Aircraft Door Mechanism

The motion function reliability of the aircraft door mechanism affects the quality,safety and reliability of the aircraft seriously,the aircraft door mechanism with low motion function reliability has security risks,the use of the aircraft door mechanism with low motion function reliability may cause huge property losses and even endanger life.Using new theories and methods to study the motion function reliability of aircraft door mechanism has important theoretical significance and practical value for improving manufacturing technical level of aircraft and the safety of aircraft in service.Aiming at the main structure of the aircraft door of Boeing 737,this thesis proposes a design method of the "semi-clogging" aircraft door mechanism,through the analysis of the main operating mechanism of the aircraft door,the design key point is focused on guiding the aircraft door movement of the door suspension mechanism,through the establishment of the mathematical model of the CAM four-bar mechanism using the complex vector method and envelope curve method,the trajectory synthesis of S-shaped guide disk for the hatch door suspension mechanism is conducted.Security analysisis is used to analyze the failure causes of aircraft door motion function,a multi-objective optimization mathematical model of aircraft door mechanism is established,the function relationship between design parameters and optimization index is established by LM algorithm based on BP neural network,the multi-objective optimization of the aircraft door mechanism is carried out by genetic algorithm,the optimal parameter combination is obtained,the optimal design of the aircraft door mechanism is realized.The dynamics simulation of the aircraft door suspension mechanism is carried out by using the ‘Motion simulation’ module of Solidworks,the allowable error of maximum warpage angle for the aircraft door suspension mechanism,with a limition that open torque not exceeding allowable driving torque is obtained,the positioning failure analysis of the aircraft door suspension mechanism is carried out,the calculation model of the positioning reliability of the aircraft door suspension mechanism is established.the first order second moment method and direct sampling MC method are used respectively to calculate the positioning reliability failure probability of the aircraft door suspension mechanism,the advantages and disadvantages of the two calculation methods are compared.On basis of above researches,the machining accuracy and maintenance suggestions for the aircraft door suspension mechanism are put forward.Based on the continuous contact model and Archard model,the time-varying wear depth of the hinged pair of aircraft door suspension mechanism is calculated,the analysis model of motion function reliability for aircraft door mechanism considering hinge wear is established,the changes of motion function reliability for aircraft door mechanism with the increase of wear cycle are analyzed.The method of increasing and maintaining of the motion function reliability of the aircraft door mechanism is studied by adjusting the rod length of the guide arm to compensate the wear depth of the hinge of the moving pair,the reference value of rod length adjustment is given considering the time-varying wear of the hinge of the moving pair,to maintain the high motion function reliability of the aircraft door mechanism.