刚架模型驱动网格曲面保特征变形

摘要

将刚架结构受力变形原理应用于网格曲面的变形设计中,提出一种新的曲面造型方法.通过建立与网格拓扑关系一致的刚架模型,运用刚架模型驱动网格曲面变形:即对刚架节点施加载荷或添加几何约束反算出刚架节点载荷,在载荷作用下刚架变形驱动网格曲面变形.针对几何约束变形问题,建立以节点位移为变量,由载荷最小和节点位移最小组成的目标函数,组合使用两种不同的最小化模型,实现不同的变形需求.在变形过程中,采用增大网格曲面特征区域所关联单元体弹性模量的方法,达到整体变形中局部形状特征的保持,避免了传统方法中繁琐的特征信息记录公式.实验结果表明,该变形方法直观方便,可以产生理想的变形效果.%Based on the deformation principle of rigid frame under force in FEM, a novel surface modeling method is proposed. A rigid frame is created according to topological relation of mesh, so the mesh surface deformation can be driven by rigid frame deformation. Two ways are introduced to get loads that urge rigid frame to deform, that is, directly exerting loads on nodes of rigid frame and adding geometric constraint Interactively to get the inverse calculation of load. Aiming at geometric constrain deformation, a constrained optimization problem is established with minimization of external load and node displacement. In deformation process , the elastic modulus of elements associating with features of mesh is increased to preserve form feature. Compared with traditional method, sophisticate equations describing geometric feature information are avoided. Experimental results show that the method is straightforward and can generate desired deformation results.