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FAQ 004252 EN

29 November 2019

Gerhard Rehm Results RFEM

In a model with surface supports, the calculation does not converge or the result is very large deformations and implausible stresses. What are the reasons for this?

Answer

The definition of surface supports should be as realistic as possible. Experience shows that the equation solver works most effectively. To simplify matters, degrees of freedom are often defined as "fixed". However, this can have a big impact on the overall stiffness matrix and cause numerical problems (see Figure 01).

It is better to work with springs in order to avoid the numerical problems. It is often sufficient to define very stiff springs (see Figure 02). The same applies to the foundation perpendicular to the surface. You can find more information in [1] as well as in the links below this FAQ.

Keywords

Surface support Convergence

Reference

[1]   Christian Barth und Walter Rustler. Finite Elemente in der Baustatik-Praxis. Bauwerk, Berlin, 2010.

Links

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