The functionally graded layers are inhomogeneous along the thickness direction, while the piezoelectric layer is homogeneous;both possess material orthotropy.

假设能梯度层的材料参数沿厚度连续变化，而电层则是均匀材料，并且它们都是正交各的。

Complex analysis of anisotropic elasticity indicates that the degree of anisotropy (orthotropy) is characterized by two basic complex parameters.

正交各可以表征复合材料的各特征。