Research On Fatigue Properties Of Auto Body Structure Component Considering The Effect Of Forming Process

With the amount of the global auto product increasing rapidly, the three problem, safety of product, energy consumption and environment contamination become focus, which have to be concerned and solved in the automotive engineering industry. Lightening the product weight in design is a good idea, which can not only help to reduce the energy consumption and make use of resource effectively, but also let out less exhaust and relief environment contamination. Auto body is a one of three assemblies (engine, chassis and body) take 40 percent-60 percent of the whole vehicle weight. So, it is significant and practical to lighten the structure weight in auto body design.Auto body design using Fatigue CAE Analysis is widely adopted in a lot of motor company. Based on one step forming inverse approach, The accuracy and durability of CAE analysis result is a key to realize the lightweight structure design. Because auto exterior panel and structure component are formed by cold forming process, which will result in thickness variation of deformed parts, reduce the strength and stiffness, especially have effect on the fatigue durability .so, prior to analyze the structure fatigue strength and predict lifetime, it is necessary to pre-process these effect factors result from forming process, such as thinning thickness, hardening material and including residual stress, so that more valid and practical simulation results can be taken. These results considering the effect of forming process can provide amount of data as reference to auto body structure weight-lighten design and optimization. The research group the author worked in has finished a project funded by the national natural scientific fund, Basic theory ,computational methods and key technology used in stamp-forming and die design (No:1983020) , the key algorithms developed to simulate sheet metal forming process is known, including prediction of the initial blank, thickness and residual distribution. Based on predicting rapidly the thickness variation and residual distribution using one-step forming analysis code, a method considering the effect of forming process is presented. Integrating the one step forming analysis into fatigue virtual design is performed. Compared the fatigue analysis result considering and ignoring the effect due stamping process, the effect is observed. The research aspects of this paper as following:1. The basic theory study, including fundamental theory and analysis philosophy on one-step inverse FEM, fatigue theory and fatigue analysis method,...