說說我在看文獻時看到一個特例吧，在編織物變形中，文獻中選擇的是三角形單元，這種選擇據我所知，已經出現在有限元成型軟件Pam-form和AniForm中。

下面我先直接摘抄一些原文句子

An important problem that has to be solved in FE simulations of fibre reinforced materials is intra-ply shear locking. Intra-ply shear locking isthe incapability of the element displacement field to represent the correct deformation mechanism of the fibre reinforced material. It is a numerical problem that is not related to the physical jamming of the reinforcement. It leads to overestimation of fibre stresses, forces and stiffnesses and often leads to spurious wrinkles in 3D simulations.Intra-ply shear locking can occur in all FE simulation that use the continuum or the semi-discrete approach. 

Triangular meshes are preferred, since mesh generators for triangular meshes tend to be more robust than those for quadrilaterals when meshing arbitrarily shaped blanks.

as shown in the previous paragraph, it exhibits severe locking if the mesh is unaligned. Three possible ways to avoid locking are discussed in this paper:
1. Aligned meshes
2. Selective reduced integration
3. Multi-field elements

大概意思是說為了避免數值上出現intra-ply shear locking，應該選擇Triangular meshes ，而且還要使纖維方向與單元的邊界平行（即上面1中的要求）。

因為我是做復合材料成型模擬的，所以比較關注這一點，不過我目前用的是abaqus模擬，選擇的是S4R單元，以后有機會也會對上文中說的情形進行驗證。