When Select EJ giving bending stiffness, Equation is "K[bend]=(1/2)(K[ax])(D)^2(pi/180)".
But, for zero length EJ; K[bend]=(1/8)(K[ax])(D)^2(pi/180).

I want to know obvious for difference of two equation.

One More question..

Anything use if I know all stiff of bellows from Vendor??

Replying to your post #12715 - Fri Aug 17 2007 07:05 AM.

Put in the vendor provided values..........instead of using formulaes you mentioned in post # 12712. In the absence of vendor data, it is recommended to specify K (transverse) instead of k(bending)

The reason for this factor of 4 difference is given on this website in our newsletter article of May, 1993 on the expansion joint modeler. Read this article and you will understand why the difference in the equation.