In the initial stage, the deformation of the flange is most the same as the upper and lower region but the two flange deformations became unsymmetrical with the roller stoke increased.

• 在初始阶段，边缘的变形几乎和上部与下部的区域一样，但是两边缘的变形形状随着滚轮位移的增加变得不对称。