The direction factor of the bending stiffness was defined in terms of the proportional coefficient of the bending stiffness corresponding to the identical ply orientations, as well as a new iterative mode, cycle after symmetry, of the laminate. On the basis of the quasi-isotropic laminate, the method of the direction factor of bending stiffness considerably reduces the computational capacity with respect to the quasi-homogeneity. By means of the method of the direction factor and comparison of the direction factors corresponding to three kinds of laminates, the iterative mode of cycle after symmetry has superior performance than the common iterative modes, which is applicable to the design and optimization of the laminate, especially for the homogeneous laminate.

弯曲刚度的方向因数是根据与相同的层片取向相对应的弯曲刚度的比例系数以及层压材料的对称性后的新的迭代模式来定义的。在准各向同性叠层的基础上，抗弯刚度的方向因数的方法大大降低了关于准均质性的计算能力。通过方向因子的方法和三种层压板对应的方向因子的比较，对称后的循环迭代方式具有比普通迭代方式优越的性能，适用于层压板的设计与优化，特别是对于均质层压板。