Notes

This command creates a new spot weld set. You can add more surfaces to the set using SWADD after the initial SWGEN command. However, the maximum number of allowable surfaces (including the two surfaces used for the original set) for each spot weld set is 11.

Ecomp, SWRD, NCM1, NCM2, and SND1 must be specified. SND2, SHRD, DIRX, DIRY, DIRZ, ITTY, ICTY are optional inputs. If the second spot weld node (SND2) is specified, that node is used to determine the spot weld projection direction, and DIRX, DIRY and DIRZ are ignored.

To reduce the spot weld generation time of large assembly models where multiple SWGEN commands are issued, define the multiple SWGEN commands within a block initiated with SWGEN,START and finished with SWGEN,END. The block must be ended with SWGEN,END if it is started with SWGEN,START. Do not use any commands other than SWGEN and CMGRP within the block. Select all elements and nodes, and create all components prior to the SWGEN,START command.

If NCM1 is defined as a component group name to add multiple surfaces to the node-to-surface configuration of the spot weld, no SWADD command is needed. NCM2 is ignored. The component group of multiple surfaces must be defined using the CMGRP command prior to the SWGEN. The maximum allowed number of surfaces for each spot weld set is 8. Using SWGEN to generate multiple spot welds is only supported for node-to-surface configuration of spot welds

If ITTY (target element ID) is specified, the following corresponding target element key option must be set: KEYOPT(2) = 1.

If ICTY (contact element ID) is specified (only valid for pilot node configuration), the following corresponding contact element key options must be set: KEYOPT(2) = 2, KEYOPT(4) = 1, KEYOPT(12) = 5.

If ICTY (contact element ID) is specified as NTOS or NTS2, node-to-surface configuration of spot-welds is defined. In this configuration, each spot weld consists of a beam element and two node-to-surface MPC contact pairs. Each contact pair has contact element (CONTA175) which is defined by the associated spot-weld node. The target elements (TARGE170) are formed by a group of surface nodes lying within the region of the search radius on the spot weld surfaces. The program creates real constant IDs for each layer, and proper contact and target element type IDs. The following corresponding contact element key options are set: KEYOPT(2) = 2, KEYOPT(12) = 5. For ICTY=NTOS, target elements KEYOPT(5) = 4 is set for defining the force-distributed constraint type. For ICTY=NTS2, target elements KEYOPT(5) = 7 is set for defining the rigid surface constraint type.

After SND1 and SND2 are projected onto surface 1 and surface 2, respectively, two new pilot-nodes (which represent the spot weld nodes) are generated at the locations of SND1 and SND2 and meshed with TARGE170 target elements (TSHAPE,PILO).

By default, the contact pair created at each spot weld surface is an MPC-based force-distributed constraint. To use force-distributed constraints based on the Lagrange multiplier method, you must set KEYOPT(2) = 3 for the contact elements after SWGEN is issued. To use rigid constraints instead of force-distributed constraints, you must set KEYOPT(4) = 0 for the contact elements after SWGEN is issued.

To automatically define multiple spot welds between two surfaces, use tabular input in the SND1 field. The table array that you input must be a 2D array parameter. For more information, see Generation of Multiple Spot Welds in the Contact Technology Guide.

To use the relaxation method to eliminate overconstraint, you must set KEYOPT(11) = 1 for the target elements after SWGEN is issued.

Issue SWLIST and SWDEL to list or delete spot welds, respectively. SWLIST and SWDEL are not supported for node-to-surface configuration. For more information about defining spot welds, see Creating a Basic Spot Weld Set with SWGEN.

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