Influence Of Forming History On Crash Behavior Autobody Hat Structure And Full Vehicle

With the development of modern automotive technology, automotive safety, energy economy and environment protection have become three main topics of automotive development. Automotive passive safty mainly depends on structure design and reasonable material application, including two research methods: test and simulation. At present, how to improve the precision of crash simulation is a major difficulty. Most BIW parts are producted through stamping process, with a wide range of applications of AHSS in body structure, its stamping process will bring about following forming effects: thickness change, plastic strain and residual stress, which will affect the structure crash simulation result which are usually neglected in former research. Therefore, analyze parts with stamping method and bring the forming history in structure before the crash simulation, acquire the crash model more close to actual situation and more precise result, which can provide some references in the later crash simulation research.In this paper, the contents and conclusions of the study are as follows :1) For the reason that the main energy-absorbing body parts are hat-type structure parts, design a set of simplified hat-type structure parts used for impact test research, compare the influence of stamping process. The hat-type structure parts are produced through bending and stamping techniques, in which bending technique will not change material property and sheet thickness too much. Test result shows that forming history will have great impact on the deformation and energy-absorbing of structure, especially lead to perturbation in structure axial deformation.2) Stamp the hat-type structure parts with one step and incremental methods, import the forming history in original crash model to build new crash simulation model. Study shows that although one step method's precision can not compare with incremental method, its computation effeciency is high and the impact on crash simulation precision can be accepted, proper for engineering application. At last, the contrast between simulation result and test result indicates that the crash simulation result considering forming history is more close to impact test result.3) For the complexity and diversity of vehicle structure, take a domestic car for example, proceed traditional crash simulation analysis, then pick up several main energy-absorbing auto body structure parts used for one step forming process and import the forming history in vehicle crash simulation model. The contrast of two different results demonstrates that the forming history will affect the deformation and energy-absorbing of parts and vehicle structure, internal energy differs nearly 10% , the B-pilliar curve with forming history is similar with crash test situation. Based on above analysis, considering the forming history of key energy-absorbing structural parts is a necessary condition to improve the crash simulation accuracy.