Static friction must always be taken into account when two transversely loaded solids transfer a compressive force at a contact point. The compressive force changes the shear force resistance at the contact area.
The forces are related as follows:
| FRmax | Maximum force of friction |
| μ0 | Coefficient for friction |
| FN | Axial force perpendicular to the support |
Since the shear force resistance between two elements has an influence on the force play in the entire model, RFEM and RSTAB allow a static friction coupling to support, hinge, and release definitions. This approach simulates the friction using an automated iterative calculation process that checks the static friction conditions after each iteration and applies the appropriate measures to maintain the equilibrium. The function was designed in such a way that the user directly specifies the coupling degrees of freedom in the direction in which the frictional force runs and from the direction the compressive force comes.
The friction coefficient μ can then be defined in the detail settings.
If the static friction is exceeded, a yielding process is initiated. This means: If a greater force than the static friction force occurs for the degree of frictional freedom, the coupling situation only takes over the static friction force and then reacts with a free deformability.
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