基于FFLD分析的汽车在极限凹坑路面工况下车身结构失效CAE新方法研究

Research on a New CAE Method for Body Structure Failure Under Extreme Pothole Road Conditions Based on FFLD Analysis

在车身前期设计阶段,为了考核车辆在极限坑洼路面的冲击下对车身结构的影响,根据通用全球相关方坑道路试验标准,本文针对极限冲击的方坑#3路面,以某车型在方坑#3路试中出现了车身结构失效的问题为研究对象,找出了传统钣金失效准则CAE方法的不足,不能复现出试验失效的问题,进而通过大量料片试验建立了断裂成形极限图(fracture forming limit diagram,FFLD),来作为钣金失效准则的CAE新方法。随后基于该CAE新方法,通过车辆动力学科计算的方坑#3虚拟路谱作为载荷输入,对车身结构进行有限元仿真分析,成功复现了试验失效。根据CAE新方法分析的结果,对车身结构进行改进,最终通过了方坑#3路试验证,且试验和CAE仿真结果对标具有良好的一致性。证明了基于该方法,可以在车身开发前期阶段,准确预测出钣金在复杂变形条件下的真实破坏情况,从而减少了后期试验中出现的车身结构失效的风险。

In the early design stage of the vehicle body,in order to assess the impact of the extreme pot⁃hole road conditions on the vehicle body structure,according to the related universal global pothole road test stan⁃dard,for the extreme impact of the pothole#3,the body structure failure of a vehicle in the road test of pothole#3 is taken as the research object in this paper,to find out the shortcomings of the traditional sheet metal failure criteria CAE method,which can’t reproduce the problem of test failure.The Fracture Forming Limit Diagram(FFLD)is es⁃tablished through a large number of sheet metal coupon tests as a new CAE method for sheet metal failure criteria.Then,based on this new CAE method,the Virtual road load data of pothole#3 calculated by the vehicle dynamics discipline is taken as load input to carry out finite element simulation analysis on the body structure,and the test failure is successfully reproduced.According to the analysis results of the new CAE method,the body structure is improved,and the pothole#3 road test certificate is finally passed.The test and the finite element analysis have high correlation.It is proved that the method can accurately predict the real damage condition of sheet metal under com⁃plex deformation conditions in the early stage of body development,thus reduce the risk of body structure failure in the later test.