Key Technology Of General Aircraft Crash Simulation And Crashworthiness Design

Aircraft crashworthiness design and crash simulation is an important parts of aircraft design. This paper focuses on several key techniques about aircraft crash simulation and crashworthiness design. The content is listed below:1) General methods in developing an aircraft finite element model under crash environment have been discussed firstly. Test data and simulation result evaluation and filtering methods have been summarized.2) Global approximation model is employed for optimization of the energy absorption structure under crashworthiness requirement. The response surface of both object and constraint obtained through global approximation model is coupled with Genetic Algorithms to perform the objective optimization. A mixture method for response surface iteration and objective optimization has been developed to reduce total optimization work.3) Components synthesis methods have been integrated into crash simulation. In order to accurately model the dynamics of the structure, the flexibility matrix is calculated through a weighted-orthogonal matrix formulated in this paper. Based on the weighted-orthogonal matrix, a new free interface components synthesis method for damping structure is developed. In order to obtain the real coefficients synthesis equation, a general transformation decoupled method is developed, through which the complex coefficients decoupled equations can be converted into the real coefficiets ones. Left and right weighted-orthogonal matrix compatible with the transformation decoupled method has been obtained. Based on these works, a free interface component synthesis method for damping structure is formulated. The synthesis equation is a real coefficient function, and the form of the equation is compatible with the central differential integration methods. The validation of this method is demonstrated through analytical simulation subsequently.4) Finite element model of a fuselage section with fuel tank has been developed. In order to accurately model the dynamics and failure of the fuel tank, the complicated fluid/structure interaction model has been considered in. Simulation result reveals the relationship of the the fuel weight and the responses and failure of fuselage section. The energy absorption capabilities of each part of the fuselage section have been discussed. Recommends have been proposed for the pilots to deal with emergency landing and survival crash.5) The differences of the body characteristics between 50% Hybrid III dummy and ordinary Chinese people are discussed. 5%, 50% and 95% Hybrid III dummies head responses have been calculated out to illustrate the effection of the differences of the body characteristic upon the simulation results. The adaptability of 50% Hybrid III dummy for full scale crash test has been evaluated. Corresponding suggestions have been proposed.6) A full scale finite element model of a light fixed wing aircraft integrated with a dummy model has been developed. Influence of strain rate dependent of the material effects on the total simulation results has been discussed. Criterion for material modeling has been suggested. The crashworthiness of the light aircraft has been evaluated through analytical methods, and the unfavourable factors of the aircraft have been found out. Modifications have been carried out to improve the protection of the seat system for the occupants. The validation of the modifications has been demonstrated by simulation method.