Study On The 30°Angular Impact And 40% Offset Deformable Barrier Impact Crashworthiness Of Minibus

1. Preface Safety trouble is getting more and more critic with automobile possession quantity rising in our country recent years. The number of traffic accidents has increased continuously in this year, and this trend is severed. The problem of vehicle safety becomes more and more important, so it's urgent and necessary to do some research in the field. Frontal impact is one of the normal crash types, which cause sever injure and death. Research on frontal crashworthiness of body structure will decrease the injury to passenger. Frontal impact includes three parts: full impact, degree impact, offset impact. Among them degree impact and offset impact have more frequency and severely injury. Now the research on full impact is done in china, but little research on degree impact, offset impact. Clients'requirement and statement rules are two power pushing technology progress of automobile, so it's necessary and meaningful to do research on the degree impact and offset impact. Minibus with poor frontal crashworthiness, the cab will deform greatly in degree impact and offset impact. Research is made on the improvement of minibus'30o angular impact and 40% offset deformable barrier impact crashworthiness based on numerical Simulation technique using explicit nonlinear finite element software ESI/PAM-CRASH. 2. Main content of this paper 2.1 Evaluating parameters of 30o angular and 40% offset crashworthiness After analyzing the meaning of vehicle frontal crashworthiness and the methods to evaluate frontal crashworthiness using in several countries'NCAP and vehicle impact regulations home and abroad, combing the characteristic of minibus'body structure, this paper proposes several parameters to evaluate minibus'frontal crashworthiness: instrument panel displacement rearward( ΔL 1),steering wheel displacement upward ( ΔL2)and rearward( ΔL 3), brake pedal displacement rearward( ΔL4), front door frame deformation( ΔL 5,ΔL 6和ΔL 7), and the maximum value of body deceleration (measured from the lower end of driver-side B pillar) (amax). 2.2 Analysis of minibus'frontal crashworthiness First, minibus's 30o angular impact and 40% offset deformable barrier impact finite element model is built up, and effictive. Then the cause of minibus's poor 30o angular and 40% offset crashworthiness is analyzed utilizing Simulation results, and it is concluded that MINIBUS's poor 30o angular and 40% offset crashworthiness is mainly because the stiffness of the structure before cab is low and its power to absorb energy is limited, and the stiffness of the cab is low too, as it receive great force from the frontal structure, the cab deform greatly. So the improvement direction is decided: on one side to improve cab's stiffness, on the other side to modify the structure before cab to absorb more energy. 2.3 Studying the improvement of 30o angular and 40% offset crashworthiness In order to match the two aspects of improving MINIBUS's 30o angular and 40% offset crashworthiness, a process is established. Then, following the process, the improvement of the management of the front structure's energy absorbing characteristic and cab's stiffness characteristic are studied. When studying the energy absorbing characteristic of front structure, the straight box beam is chose as the research object, which is determined by referring to the main energy absorbing components of the front structure, i.e. the front side beam. By virtual experiments, the strategy of how to manage the energy absorbing characteristic of the straight box beam by changing the thickness of the parts, adding strengthening panel is discussed, and the following conclusion are derived from the study: The existing straight box beam's energy absorbing characteristic is excellent, it can absorb more energy but apply less force on the back structure; Increasing the thickness of parts and adding strengthening panel are two effective approaches to increase the straight box beam's permitted absorbing energy, while it cause the increasing of Fp and Fl mt. Add another same structure has the same effect with adding structure. According to engineering experience and computing, a reference of target absorbing energy is provided. Then the requirement of the stiffness of the cab is made. After analysis of the improvement potential of different parts of the cab, it is determinated that the energy can be absorbed in two routes. Adding absorbing parts in front of side structure and raise the stiffness of side structure. According to this idea ,modification scenario is provided. And the simulation result satisfy the requirement of 30o angular impact 40% offset deformable barrier impact.