The Establishment And Application Of Two-Degree-of-Freedom Occupant Restraint System Dynamic Model In Vehicle Crash

There are two fields of study in automobile passive safety. One is the study in vehicle crashworthiness and the other is the study in occupant restraint system matching. The restraint system matching work depends on CAE and sled test presently. This development method uses DOE and repeat simulation to optimize the system characteristic. But with the application of more and more advanced restraint devices, the simulation model is more and more complex and the calculation time is longer and longer. So the develop method depends on repeat simulation will be costly and time-consuming.The study objective of this paper is to establish dynamic equations by studying the relationship between the occupant and the restraint system in vehicle crash. The parameter effects on the restraint system are known by using dynamic equations and the optimal range of design parameter can be narrowed. The initial design parameter to the simulation model can be achieved. As result of that, the repeat calculation will be avoided, the development time will be reduced and it will lead to a high-speed development process with design objective, concept design, simulation and test validation.The structure character of restraint system is studied in this paper and the sub-system's simplified model is built on the basis of the effect on protecting occupants. The occupant's motion in vehicle crash is analyzed by using Lagrange function. By integrating the sub-system simplified model and the occupant model, a two-degree-of-freedom occupant restraint model is built, and its resolution of dynamic equation is achieved. All the dynamic equation's calculation process is derived by iteration method and computer program.The two-degree-of-freedom occupant restraint model is applied to the word of a vehicle restraint system matching. As the result of the application, the effect on occupant chest injury by safety belt stiffness and load limiter level are analyzed and the initial design parameters are derived. A simulation model with the initial parameters is built and the robust analysis is done by this model. At the end, all the restraint system parameters are identified by sled tests. The development objective is achieved. The mechanical relationship between the occupant dynamic response and the restraint system design parameter is studied in this paper. By the study, a two-degree-of-freedom occupant restraint model is established. Its dynamic equation can be resolved quickly and its results are of high coherence with the simulation and the sled test. By using the model, the repeat calculation of simulation is avoided. The development time and cost are reduced. After the repeat sled test, the simulation technology study and the optimal method study, this paper makes the study of restraint system back to the basic theories and it is going to use all the theories to form a new development method with concept design.