有限元三角形单元刚度矩阵计算我要分享

中文说明：有限元中三角形单元的刚度矩阵计算，先计算每个单元的刚度，在组装成总刚，最后位移求解

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English Description：

Triangular element stiffness matrix in FEM calculation, calculating the stiffness of each unit, assembled in total, finally solving displacement