This means that the length of every edges of the elments can not change greatly and this has limited applications of the finite element method in some enginering problem such as those of anisotropic structures 传统有限元收敛性分析要求单元剖分满足非退化条件，即要求多面体单元的各条边的长度不应相差太大。这极大地限制了有限元方法在一些工程领域的应用，如具有各向异性结构的问题。
