基于PBM的轿车车身简化模型的建立与仿真

Creation and Simulation of Simplified Car Body Model Based on PBM Method

基于材料性质的建模(PBM)方法和某乘用车车身详细有限元模型,对用于概念设计阶段的车身简化模型的建模方法进行了研究。梁构件用同长度的等效直梁单元来模拟,并根据等刚度原则,利用截面面积、两个主轴惯性矩和扭转常数来描述其截面力学性质,进而决定梁单元的整体刚度,采用超单元来模拟接头,采用分块的平面板单元并赋予材料属性和厚度来模拟板件。分别以B柱和悬架支座为例,建立了等效接头超梁单元和板件简化模型,并对比验证了其等效刚度。通过对梁构件和板件添加非结构质量的方法实现了质量等效。利用上述方法建立了车身简化模型,并从整车扭转和弯曲刚度、1阶扭转和弯曲模态和主要开口部位的变形5个方面验证了简化模型的有效性。结果表明,本文中所建立的车身简化模型能较准确地预测要开发车身结构的力学性能,为概念设计阶段简化车身建模提供了一种可行的方法。

Based on the method of property-based modeling and the detailed finite element model for a carbody, the modeling method for car body simplified model in concept design phase is studied. The beam part is simulatedby equvalent staright beam element with same length and its sectional mechanical properties are described bythe area of section, the inertia moments of two principal axes and torsion constant, with the overall stiffness of beamelement determined. Joints are simulated by superelements and panels are simulated by planar plate elements withmaterial properties and thickness defined. With B pillar and suspension support as examples, the equivaent superelementsfor joints and the simplified model for panels are built with their equivalent stiffness verified. The massequivalence is achieved by adding non-structural mass on beam parts and panels. All the above-mentoned methodsare used to build the simplified model for car body with its effectiveness verified from five aspects torsional andbending stiffnesses,1st order torsional and bending modes and the deformations of main opening localities. The resultsindicate that the simplified model for car body built can accurately predict the mechanics perforances of carbody structures to be developed, providing a feasible method for building the simplified model for car body in conceptdesign phase.