I'm studing a centrally compressed hollow circular tube. Modeling of the tube is performed with plate elements. At the first stage, the calculation is carried out with ideal supports: the central nodes that simulate the supports are connected to the end-section assemblies with the help of the RBE2 elements.
At the second stage it is necessary to simulate an elastic restraint around one of the axes. I tried to simulate such a support using a spring element, but with different options I get a message about a fatal error. Tell me what decisions can be made here?
You need to use a grounded CBUSH element, use the CUSTOM TOOLS API, you need to define by advanced the CBUSH property, next simply select the INDEPENDENT node of the RBE2 elements (delete all existing constraints at that node)
In the CBUSH property you can enteer the stiffness in the six DOF. Make sure to activate the orientation of the CBUSH element.
CBUSH is a structural scalar element connecting two noncoincident grid points, or two coincident grid points. The CBUSH element contains all the features of the CELASi elements plus it avoids the internal constraint problem. If you use CELASi elements and the geometry isn’t aligned properly, internal constraints may be induced.
Best regards, Blas.
Blas Molero Hidalgo, Ingeniero Industrial, Director IBERISA • 48004 BILBAO (SPAIN) WEB: http://www.iberisa.com Blog Femap-NX Nastran: http://iberisa.wordpress.com/