Frictionless support as Symmetry condition with linear elements.

disla

Hi,

A curious effect related with FEA modeling.
Pressure, Force (centrifugal included) or tractions applied to curved linear elements constrained with Frictionless support may cause some unexpected displacements. The result is correct but may be nonintuitive for some users.

Frictionless support plane is built with the normal to the selected face. Linear elements cannot adjust that normal direction as well as a quadratic element giving as a result a frictionless plane non orthogonal to what the user may expect.

Frictionless support is often used to apply symmetry conditions. Be careful if the constrained elements are lineal as the model will not be symmetric.

I thought it could be useful to post it as it almost burned my mind.

Thanks Victor.