The Research Of Structure Fatigue Damage Assessment Methods For Civil Aircraft Maintenance Program

The maintenance of civil aircraft is the basic tools and important way of the airline to ensure the safety of aircraft and to maintain the continuing airworthiness of aircraft and is an important safeguard for civil aviation industry and aviation industry. The assessment of fatigue damage of Aircraft structural is the key issues to develop aircraft structural MRBR. Therefore, it is of great significance to study the assessment of structural fatigue damage for aircrafts during the period of researching on independent intellectual property rights of aircrafts.Based on the engineering background, the fatigue damage assessment of the process of maintenance program formulation is deeply studied in this paper. For the main contents of fatigue damage assessment, the following three aspects studies are carried out:First, the method to assessment the effectiveness to detect fatigue damage is analyzed, then the fuzzy hierarchical analysis method is proposed to be used to determine the detectable rate, the weights of each factor can be determined by FAHP effectively, the shortcoming that the AHP is too subjective is avoided, making the maintenance tasks and maintenance intervals more reasonable;Second, for the assessment of the reliability of the detection of fatigue damage in the maintenance program, Mechanism of DTR evaluation methods is studied, assessment steps of the DTR method and the application of DTR in the actual maintenance program are carried out in analysis, DTR method is proposed to assess the reliability of the detection of fatigue damage. The DTR values under different check interval and different crack number are calculated;Third, for the new requirement of airworthiness regulations, the content and procedures of widespread fatigue damage assessment are analyzed, it is studied to apply Franc2D/L finite element analysis software for structural fatigue crack growth analysis, and crack propagation of finite plate with single hole hole, double hole and multiple hole with multiple site damage is analyzed by the software, the crack propagation life in different injury models is calculated. The results show that some factors affect cracks propagation life, such as hole spacing, the space between cracks or between the crack and the boundary. For the WFD assessment of aircraft skin rivet hole in the process of development of MRBR and the detement, the results provide some valuable conclusions.