Rigid Wall (/RWALL)

A rigid wall is a nodal constraint applied to a set of secondary nodes in order to avoid the node penetration to the wall. If contact is detected, then the secondary node acceleration and velocity are modified.

There is no gap to determine whether or not a secondary node is in contact. Contact occurs only when the secondary node impacts the rigid wall surface. The secondary node's tangential velocity can also be modified depending on the flag Slide. The default value (=0) enables the model pure sliding during contact. If set to 1, no sliding is allowed, the secondary nodes are "tied" in the tangential direction. If set to 2, friction based on Coulomb model is enabled.

Four types of rigid walls are available in Radioss:

The rigid walls can be fixed or moving. A fixed wall is a pure kinematic condition on all impacted nodes; whereas a moving wall is similar to a main secondary option. A main node defines the wall position at each time step and imposes velocity on impacted secondary nodes. Impacted secondary node forces are applied to main node. The secondary node forces are computed with momentum conservation. The mass of a secondary node is not transmitted to a main node, assuming a large rigid wall mass compared to impacted secondary nodes mass.

Infinite Rigid Wall

An infinite rigid wall is a planar surface which extends to infinity. It is defined by two points representing the rigid wall normal (Figure 1).

Infinite Cylindrical Wall

An infinite cylindrical wall is a cylinder which extends to infinity. It is defined with two points (or one point and one node) and a diameter.
Note: contact is only possible from outside the cylindrical wall.

Spherical Wall

A spherical wall is a sphere defined by a point M (or a node N) and a diameter.

Finite Planar Wall

A finite planar wall is a parallelogram defined by three points M, M1 and M2. In case of a moving wall, M will be considered as the main node.