meridianal curvature of field

The difficulty in analyzing bellows with abrupt change in meridional curvature is overcome by discretizing the bellows with curved elements of shells of revolution.

由于选取两结点非协调曲边旋转壳单元作为离散单元 ,解决了某些波纹管因子午线曲率有突变而在求解上造成的困难。