主弯曲;助率

principal radius of curvature principal direction of curvature curvature principal curvature effect blade curvature ray curvature asymptotic curvature curvature movement sectional curvature quadratic curvature track curvature affine principal curvature principal centers of curvature center of principal curvature direction of principal curvature radius of principal curvature principal curvature of a surface terminal curvature