Research On The Front Longitudinal Beam Composite Desing And Obsorption Characteristics

Auto safety has become the focus of attention because of the frequent accident and high deaths. Lots of regulations are put forward by some institutes organized by many countries and organizations, aimed to evaluate auto safety. As the vehicle front collision probability is the largest, so vehicle frontal crash safety has always been researched. Along with the increase of auto possession, energy became a major factor restricting the development of car, and reducing the car's weight became an important way to solve this problem. Composite is one of the best choices to evaluate the safety and reduce the weight of the car. In this thesis, a type of composite tube material was designed for the front longitudinal beam. The material model was optimized by finite element analysis in LS-DYNA.The vehicle front crash simulation was did according to FMVSS 208 regulations in LS-DYNA, using the whole car finite element model, Hybrid III 50% male dummy and sled finite element model. The key problems were fixed out through the simulation. According to the original car frontal crash simulation and sled test simulation, the original car energy-absorption ability, kinematics characteristic and occupant head injuries were analyzed. The result that the biggest energy-absorption component is the longitudinal beam during the front crash was gotten. The feasibility that analyzing the occupant head injury by sled test using crash pulse was discussed.The composite tube material was introduced. The insert metal tube and composite tube finite element model were built in LS-DYNA, and the key problems during the process of building model were fixed out. A composite tube was impacted in its axial direction in the simulation. Comparing the simulation and experiment results, the validity of the model was proved.Front vehicle crash models were used to analyze the influence of material parameters of the composite tube material on the injury value of the occupant head during the impact. We found that the four factors of orthogonal test are the metal materials, metal layer thickness, composites layer thickness and composite material layer style.The composite material parameters which have the best function of reducing the occupant head injury value were studied by using orthogonal test method. The most significant factors were ascertained through the analysis of variance. Using this kind of composite materials, the occupant safety protection was effectively improved and the weight of the longitudinal beam was greatly reduced according to the original one.This thesis research work provides a new design method for the use of composite in the impact resistance component of the car, and offers a reference to design a longitudinal beam which can evaluate the safety and reduce the weight of the vehicle.