element.py 文件源码

def _calc_B_for_tetra3d11(nodes,volume):
    A = np.ones((4,4))
    belta = np.zeros(4)
    gama = np.zeros(4)
    delta = np.zeros(4)
    for i,nd in enumerate(nodes):
        A[i,1:] = nd.coord

    for i in range(4):
        belta[i] = (-1)**(i+1)*np.linalg.det(np.delete(np.delete(A,i,0),1,1))
        gama[i] = (-1)**(i+2)*np.linalg.det(np.delete(np.delete(A,i,0),2,1))
        delta[i] = (-1)**(i+1)*np.linalg.det(np.delete(np.delete(A,i,0),3,1))

    B =  1./(6.*volume)*np.array([[belta[0],0.,0.,belta[1],0.,0.,belta[2],0.,0.,belta[3],0.,0.],
                                  [0.,gama[0],0.,0.,gama[1],0.,0.,gama[2],0.,0.,gama[3],0.],
                                  [0.,0.,delta[0],0.,0.,delta[1],0.,0.,delta[2],0.,0.,delta[3]],
                                  [gama[0],belta[0],0.,gama[1],belta[1],0.,gama[2],belta[2],0,gama[3],belta[3],0.],
                                  [0.,delta[0],gama[0],0.,delta[1],gama[1],0.,delta[2],gama[2],0.,delta[3],gama[3]],
                                  [delta[0],0.,belta[0],delta[1],0.,belta[1],delta[2],0.,belta[2],delta[3],0,belta[3]]])
    return B