Performance Improvement Of Restraint System And Dashboard Optimization Based On Occupant Lower Extremity Injury

With the increasing of the number of the vehicle possession and the high frequency of traffic accidents, so vehicle safety is taken more attention. A large numbers of the accident was caused by frontal impact in all the traffic accidents. In recent years, as a result of the use of safety belts and airbags systems have been greatly lessened the upper extremity injuries of occupant in the frontal impact. At the same time, more attention has been focused on the lower extremity injuries increasingly. Based on concerned literatures, more than 70% of femur injuries happen in frontal impact, while the half of the injuries has exceeded AIS2. Though the passenger life are rarely threatened by the femur injuries, they can cause chronic damage and even lead to permanent disability, making passengers bear the enormous double pains in physiology and psychology. Therefore, there is a practical significance to study the injury mechanism and reduce lower extremity injuries heavily.Firstly, on the basis of studying the methods about occupant lower extremity injury and fundamental theory, combined with achieved experience and results about the lower extremity injury of occupant recently, the author introduces to the anatomical structure of human lower extremity, discusses and summarizes the occupant injury mechanism of femur injury in frontal impact, and describes the femur and knee injuries criteria comprehensively; Adopt computer simulation to establish the occupant restraint system of a minibus, validate the relevant components, subsystems and whole vehicle system to make the simulation model can be used to optimize. In the interest of problem that femur injuries index don't satisfy the regulation of our country, method of experimental design is applied to determine the optimal constraint system parameters and dashboard stiffness. And the author also sums up the influence which design parameters of the vehicle occupant restraint system are as for the femur injuries. The simulation result showed that: A lower stiffness of the knee bolster can be a good lower femur and knee injuries; The belt characteristic and the upper and lower fixed point relative to A pillar of the vehicle have a certain extent to occupant femur and knee injury; The unstable impact acceleration field may be aggravated by the femur and knee injuries; The intrusion of dashboard and footwell caused by impact deformation of the frontal parts of vehicle has a great influence on occupant femur and knee injury; The anti-R design of dashboard has prominent efficiency on knee injyry. Finally, establish finite element model of minibus dashboard in the foregoing foundation, and adopt Hybrid and adaptive metamodel-based global optimization method to optimize dashboard structure, material and property so as to determine the optimal dashboard structure, so as to reduce knee injuries of passengers. The method of paper will contribute to occupant knee injury mechanism and developments of injury protective device which has a practical effect.