Bao Zhaosheng, Hong Jeong-Mo, Teran Joseph, Fedkiw Ronald
Department of Computer Science, Stanford University, CA 94305, USA.
IEEE Trans Vis Comput Graph. 2007 Mar-Apr;13(2):370-8. doi: 10.1109/TVCG.2007.39.
We propose a novel approach to fracturing (and denting) brittle materials. To avoid the computational burden imposed by the stringent time step restrictions of explicit methods or with solving nonlinear systems of equations for implicit methods, we treat the material as a fully rigid body in the limit of infinite stiffness. In addition to a triangulated surface mesh and level set volume for collisions, each rigid body is outfitted with a tetrahedral mesh upon which finite element analysis can be carried out to provide a stress map for fracture criteria. We demonstrate that the commonly used stress criteria can lead to arbitrary fracture (especially for stiff materials) and instead propose the notion of a time averaged stress directly into the FEM analysis. When objects fracture, the virtual node algorithm provides new triangle and tetrahedral meshes in a straightforward and robust fashion. Although each new rigid body can be rasterized to obtain a new level set, small shards can be difficult to accurately resolve. Therefore, we propose a novel collision handling technique for treating both rigid bodies and rigid body thin shells represented by only a triangle mesh.
我们提出了一种用于破碎（和凹陷）脆性材料的新方法。为了避免显式方法严格的时间步长限制或隐式方法求解非线性方程组所带来的计算负担，我们将材料在无限刚度极限下视为完全刚体。除了用于碰撞的三角化表面网格和水平集体积外，每个刚体都配备了一个四面体网格，可在其上进行有限元分析以提供用于断裂准则的应力图。我们证明常用的应力准则可能导致任意断裂（特别是对于刚性材料），因此提出将时间平均应力的概念直接纳入有限元分析。当物体断裂时，虚拟节点算法以直接且稳健的方式提供新的三角形和四面体网格。尽管每个新刚体都可以进行光栅化以获得新的水平集，但小碎片可能难以精确解析。因此，我们提出了一种新颖的碰撞处理技术，用于处理由三角形网格表示的刚体和刚体薄壳。
