六面体网格体积成形有限元分析关键技术

为提高三维体积成形有限元分析软件的计算精度、减少网格数量,基于六面体网格特性研究了六面体网格体积成形有限元分析系统的关键技术,通过对STL文件的索引重构建立了模具实体模型顶点和三角形面片拓扑连接关系,提出了一种局部坐标系建立方法保证触模和对称约束条件的正确施加,给出了相对速度和相对位置两种节点触模判断方法,并提出了调整触模节点位置的最短距离法,与初矢修正法和原长修正法比较,其调整距离短,体积损失小.基于以上技术,开发了基于三维六面体网格的体积成形有限元分析系统,对典型体积成形工艺进行了有限元模拟,并与Deform模拟结果进行对比,二者吻合较好,验证了所建立模型与相应处理技术的可行性.

Key technologies of 3D FEM analysis system for bulk forming with hexahedral mesh

To improve the calculation accuracy and reduce the number of mesh,several key technologies were researched about the 3D FEM analysis system for bulk forming using hexahedral mesh based on the characteristics of hexahedral mesh.Through topological reconstruction of STL data,the topological relationship between the vertex and the triangle face of mould solid model was built.A new method of building a local coordinate system is proposed for accurately loading the contact mould and symmetrical constraint conditions.Relative velocity method and relative position method for judging if the free node will touch the mould are proposed respectively.A new method of modifying the position of node touched on the mould is proposed.By this new method,the displacement of node is shortened and the volume loss is reduced compared with the Original Normal Method and the Original Length Method.Based on these key technologies,a 3D FEM analysis system for bulk forming using hexahedral mesh is developed.The feasibility of the established model and key techniques was demonstrated by the simulation of the typical bulk forming process and the comparison with the data obtained by Deform.