Spring Foundation (Rigid Domain)

The subnode is used to specify a spring or damper connecting the rigid domain to a fixed ground. The spring can act at an arbitrary position in space. A translational spring implicitly contributes also to the moment if it is not applied at the center of mass of a rigid domain. The data that you specify is interpreted in the selected coordinate system.

Select an option from the list: , , or. This is the location where the spring will be attached.

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For , the location of the spring is taken as the center of rotation as defined in the parent node.

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For select an — , , or .The available choices depend on physics interface and geometrical dimension. The spring is attached at the centroid of the selected entities, which do not need to be related to rigid domain itself. As a special case, you can select a single point, and thus attach the spring at that point.

	Once chosen, a default Location: Boundary, Location: Edge, or Location: Point subnode is automatically added.

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For , enter the ,Xc, in the table.

Select the check box to add an optional offset vector to the definition of the location. Enter values for the offset vector Xoffset.

When is selected, the translational spring matrix can be entered as , , , or . For the same spring constant is used in all the diagonal elements of the spring matrix.

When is selected, enter the force vector Fs. It must be a function of the built-in variables describing the spring extension. The default value indicates the correct variable name, for example, solid.rd1.uspring1_spf1.

When is selected, the rotational spring matrix can be entered as , , , or . For the same spring constant is used in all the diagonal elements of the spring matrix.

When is selected, enter the moment vector Ms. It must be a function of the built-in variables describing the spring extension. The default value indicates the correct variable name, for example, solid.rd1.thspring1_spf1.

	In 2D the Spring constant is only a single scalar, representing the stiffness for rotation around the out-of-plane direction. Similarly, the Moment as function of rotation is a single scalar.

From the list, select or .

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For enter a single ηu,s, which is used to multiply all values of the spring matrix or spring force vector.

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For select , , , or , then enter values or expressions in the table for the ηu,k or ηf based on space dimension. The loss factors act on the corresponding components of the spring matrix or spring force vector. If you select , the effect is the same as when you select and enter the same value for all diagonal elements.

All settings in the section are analogous to the corresponding settings in the section. In 2D, only one scalar loss factor, corresponding to rotation around the out-of-plane axis, is given.

Select , , , or , then enter values or expressions for the damping constants du in the table. If you select , the effect is the same as when you select and enter the same value for all diagonal elements.

All settings in the section are analogous to the corresponding settings in the section. In 2D, only one scalar viscous damping, corresponding to rotation around the out-of-plane axis, is given.

Physics tab with node selected in the model tree: