Study On Car Crashworthiness In Car-to-truck Rear-end Collisions

In China, traffic accidents as a product of the automobile era have emerged in front of the public, while car-to-truck rear-end collisions have been widespread concerned because of its high casualty rate. How to improve the automotive crash safety has become an important issue in automotive industry. Aiming at car-to-truck rear-end collision accident form, this paper studies the variation law of crashworthiness during collision process and the crashworthiness optimization of car body. It is desirable to provide a reference for vehicle crash safety improvements, upgrade the rear-end car crashworthiness and reach the purpose of protecting vehicle occupants.The paper analyzes the theory of nonlinear finite element and key issues of crash simulation modeling in basic theory study. Car-to-truck rear-end collision simulation model is built using finite element modeling method, and make a comparison with real vehicle test. The paper also conducts a harsh condition assessment to verify the validity and accuracy of the model.During the study process of rear-end car crashworthiness, the paper investigates and analyzes the occurrence characteristics and collision feature based on real car-to-truck rear-end accidents. Meanwhile collision force transmission route is studied from a mechanical point. With the well-established car-to-truck rear-end simulation model, this paper focuses on the two factors of impact velocity and offset rate to analyze the truck’s rear protection deformation and changes of car’s acceleration and incursion.Aiming at hazardous form of car-to-truck rear-end accidents, the car body structure crashworthiness is upgraded. The paper optimizes the best crashworthiness material combination with the method of orthogonal design from the perspective of high-strength materials, which makes the A-pillar intrusion volume and intrusion velocity reduce by 19.11%, 42.02% respectively. Hamersley experimental design is used for thickness of different parts of car A-pillar area from the perspective of stiffness matching. Meanwhile response surface approximation model and Kriging approximation model are built with the test results and the appropriate approximate models are chosen for different crashworthiness indicators through accuracy analysis. On the basis of the approximate model, stiffness optimization design is conducted for the A-pillar area with the method of portfolio-gradient optimization algorithm combined by multi-objective genetic algorithm and sequential quadratic programming, which makes A-pillar intrusion volume and intrusion velocity decrease by 15.70%, 10.09% respectively without increasing the weight of car body. Car crashworthiness has been significantly promoted through improvement and optimization.This paper perfects the research system of vehicle crashworthiness safety field. It not only provides a useful reference for vehicle crashworthiness study, but also explores a feasible path for car rear-end crashworthiness improvement.