| A body structure joint is one of the most important parts which connect two or more load-carrying members. Previous studies on joints have assumed that the overall stiffness of frame structures are very sensible to the stiffness of joints, governing up to 60 % of the global stiffness. In initial stages of the body design, we should build a simplified model for controlling the performance of the unborn body structure. By researching the simplified model, we design the body stiffness and ensure the realization of safety,wear and NVH performance . Therefore, how to consider the relative joint parameters, understand the mechanic performance, investigate the joint parametric modeling, will play an important role in body structure concept design. The purpose of this paper is developping a kind of method about joint parametric modeling. Based on reading overseas documents about body structure joint investigation, we develop some research work: Using software named MSC.PATRAN,a detailed joint finite element model is set up. Based on the joint finite element model, all parameters about simplified models have been calculated. At the same time, we built joint parametric models, certificate the stiffness and mode of the parametric models, which provide body design guidance and support the development of parametric models. In chapter 1, the significance of joint parametric modeling and the domestic and alien status of body structure joint investigation and the research content and method of parametric modeling are presented. In chapter 2, introduce the concept,principle and essential idea of FEM, combine with the FEM analysis of the joint structure, we show the approach of the joint FEM modeling and the questions about the joint FEM analysis which include of joint modeling,structure simplifying,junction method simulating and element estimating. In chapter 3, after digested the software, the detailed joint models (B pillar to roof rail) were set up using MSC.PATRAN. According with the mechanics performance of joint structure, we built the joint local coordinate and calculate the compliance matrix of each joint branch, so we can confirm the important parameters of simplified joint models, such as tortional stiffness,inboard/outboard(I/O) stiffness,fore/aft (F/A) stiffness and the vector directions,and based on acquiring parameters of simplified joint models, parametric modeling ,which consisted of confirming the beam element section parameters,setting short beams,the junction of joint element and beams. At last, validate the parametric models by contrasting the stiffness of the detailed joint models, and prove the feasibility of joint parametric modeling. In chapter 4, the detailed joint models and the parametric models (include with B pillar to roof rail, B pillar and B pillar to rocker) were set up, moreover, the load and the constrain were bring forward by simulating the bending case on body structure. Finally, validate the parametric models by contrasting the displacements of the detailed joint models on loading point, and the parametric models would be provided with its usability in simplified modeling works. The significances of this paper are: Firstly, based on the study in this paper, the finite element analysis method of joint stiffness were summarized and provided other people some useful experience. Secondly, based on the mechanics performance of joint structure, we calculate all important parameters about implified joint models by FEM software, these analysis methods will have important significance for the unborn joint parametric modeling. Thirdly, master the method of joint parametric modeling by FEM software, offer the crucial reference for the global body parametric...
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