Notes

The SHSD command creates a shell-solid interface to be used in shell-to-solid assemblies, or deletes a previously-created shell-solid interface. “Virtual” shell elements and additional CONTA175 elements are created at the contact pair identified by RID when Action = CREATE. Set Action = DELETE to remove the generated nodes and elements at the contact pair identified by RID.

The SHSD command is active only when the following element KEYOPTs of associated CONTA175 and TARGE170 element types are predefined:

The method used to build shell and contact elements depends on the KEYOPT(5) setting of the target element type associated with the real constant set identified by the RID argument. If KEYOPT(5) = 1 (projected constraint with translational degrees of freedom only), the virtual shell elements are built perpendicular to the pre-existing shell elements attached to the contact elements. They geometrically follow the contact interface edge and are built on both sides of this interface in such a way that each new shell element (SHELL181) has two nodes that belong to the associated pre-existing shell element in the shell edge. (See Figure 15: Virtual Shell Elements Following the Contact Interface Edge.) The width of the new shell elements is half the thickness of the pre-existing shell element. The CONTA175 elements are then created at each node of the virtual shell elements where no CONTA175 element exists. The new contact elements are identified by the same contact pair ID as the pre-existing contact elements.

Figure 15:  Virtual Shell Elements Following the Contact Interface Edge

If KEYOPT(5) = 2 (projected constraint with uncoupled translational and rotational degrees of freedom), the virtual shell elements (SHELL181 - low order; SHELL281 - high order) overlap the existing high or low order target elements identified with the RID argument, and share their nodes. Only those target elements close enough to the contact interface (identified using the PINB real constant) are overlapped. The program uses the FTOLN real constant (defaults to half the shell element thickness) to define an influence distance. The associated virtual shell elements are created only for target elements that lie partially inside the influence distance region (see Figure 16: Virtual Shell Elements Overlapping Target Elements).

Figure 16:  Virtual Shell Elements Overlapping Target Elements

For the bonded always option (KEYOPT(12) = 5), any contact node inside the pinball region (gap < PINB) is included in the KEYOPT(5) = 2 process. A relatively small PINB value may be used to prevent false contact. PINB defaults to 25% of the contact depth for small deformation analyses.

For the bonded initial option (KEYOPT(12) = 6), only those contact nodes which initially lie inside the adjustment zone (gap < ICONT) are always included in the KEYOPT(5) = 2 process. ICONT defaults to 5% of the contact depth.

For both processes, the new nodes and elements are stored in internally-named components. The internal naming convention is based on the real constant set ID specified by RID, as illustrated in the following table.

Issuing SHSD,RID,DELETE deletes components based on their generated names. Only components whose names match the internal naming convention will be deleted.

See Modeling a Shell-Solid Assembly in the Contact Technology Guide for more information.

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