def METHOD_NAME(self, uh):
    """
    @brief 给定一个位移，计算相应的应变，这里假设是线性元
    ____
    Notes:
    mfront 二维平面应变的默认保存顺序为[0, 0] [1, 1] 未知 [1, 0]
    ___
    """
    cell = self.mesh.entity('cell')
    NC = self.mesh.number_of_cells()
    gphi = self.mesh.grad_lambda()  # NC x 3 x 2
    s = np.zeros((NC, 4), dtype=np.float64)
    uh = uh.T
    s[:, 0] = np.sum(uh[:, 0][cell] * gphi[:, :, 0], axis=-1)
    s[:, 1] = np.sum(uh[:, 1][cell] * gphi[:, :, 1], axis=-1)
    val = np.sum(uh[:, 0][cell] * gphi[:, :, 1], axis=-1)
    val += np.sum(uh[:, 1][cell] * gphi[:, :, 0], axis=-1)
    val /= 2.0
    s[:, 3] = val
    s[:, 2] = 0
    return s