XANSYS Message: 92814 [Go back to message list] [bookmark on del.icio.us]
No rating yet Subject: STRUCT - radius/thickness error for Shell99 Author: Pete Winslow Date: 2008-04-11 12:07:25Hi all,
I am using SHELL99 elements with KeyOpt(2) = 4, so that I can input user-defined material stiffness matrices. In the real constant set I define these stiffness (A(1)-A(6), B(1)-B(6) etc.) and also define the average element thickness THICK=1.
I then use the mesh tool to apply a free quad mesh to an area, with AESIZE=10. After applying some loads, displacement contraints etc. this model solves as expected.
However, if I now remesh the area with AESIZE=5 the model will not solve, and I get the following errors:
***ERROR*** Element 1has a radius/thickness ratio of -39664.5437 (minimum radius of curvature of 174.5 and a maximum thickness of -4.399395122e-3) this violates the assumption of a shell element.
***ERROR*** Element 2 has a radius/thickness ratio of -39664.5437 (minimum radius of curvature of 174.5 and a maximum thickness of -4.399395122e-3) this violates the assumption of a shell element.
etc. etc.....
It appears to me that because I set the AVERAGE thickness, ANSYS makes up values for the actual thickness profile. And in the case of the smaller elements it doesnt do this particularly well... but perhaps I am missing something??
Has anyone else had the same problem? If you are able to give me any advice/help it would be much appreciated.
many thanks Pete
Pete Winslow Research Student Cambridge University Engineering Department