#### CONNECTOR_SPOT_WELD

###### Connectors
*CONNECTOR_SPOT_WELD
"Optional title"
coid
entype, enid, tid, $tol$
$R$, $h$, $m$, $k$, $F_t$, $F_s$, $W_t$, $W_s$
##### Parameter definition
VariableDescription
coid Command ID
entype Entity type of sheets to be connected
options: P, PS, ALL
enid Entity ID of sheets to be connected
tid Table ID of spot weld list
$tol$ Maximum allowed distance between surfaces to be connected
$R$ Spot weld radius
$h$ Spot weld height
$m$ Spot weld mass
$k$ Spot weld stiffness
$F_t$ Failure force - tear
$F_s$ Failure force - shear
$W_t$ Energy absorption - tear
$W_s$ Enery absorption - shear
##### Description

This command is used to define spot weld connectors between two or more layers of material. The spot weld ID's and positions are defined in a TABLE (see example below). The formulation is penalty based and a spot weld mass $m$ is required in order to define the critical spot weld time step size.

The height parameter $h$ is used to identfy the correct sheets in cases where more than two layers are welded together. Apart from that both $h$ and $R$ are only used for visualization purposes.

The load carrying capacity of a spot weld is direction dependent. $F_t$ is the maximum force in pure vertical loading and $F_s$ is the capacity in pure shear. For directions in-between the capacity $F_{max}$ is defined as:

$\displaystyle{ F_{max}(\alpha) = F_t \mathrm{cos}^2 \alpha + F_s \mathrm{sin}^2 \alpha}$

The definition of $\alpha$ is shown in the figure below. A similar interpolation is assumed for the energy absorption (ductility). The elongation at complete fracture $\delta_{max}$ is adjusted such that:

$\displaystyle{ W(\alpha) = \frac{1}{2} F_{max} \delta_{max} = W_t \mathrm{cos}^2 \alpha + W_s \mathrm{sin}^2 \alpha}$
##### Example
###### Spot welded steel sheets

Two steel sheets with six spot welds.

*UNIT_SYSTEM
SI
*COMPONENT_BOX
"upper sheet"
1, 1, 20, 10, 1
-0.025, -0.025, 0.0, 0.075, 0.025, 0.002
*COMPONENT_BOX
"lower sheet"
2, 2, 20, 10, 1
-0.075, -0.025, -0.002, 0.025, 0.025, 0.0
*CHANGE_P-ORDER
ALL, 0, 3
*MAT_LIBRARY
"Docol 600 DL_SSAB_G.Gruben(2015)_DE_ISO_YVM_SR", 1
*PART
"upper sheet"
1, 1
"lower sheet"
2, 1
*CONNECTOR_SPOT_WELD
"spot weld (P1 to P2)"
1
PS, 12, 1000, 1.0e-4
0.002, 0.004, 1.0e-4, 1.0e7, 2.0e3, 3.0e3, 2.0, 4.0
*TABLE
"spot weld (P1 to P2)"
1000, 4
1, -0.01, -0.015, 0.0
2, -0.01, 0.0, 0.0
3, -0.01, 0.015, 0.0
4, 0.01, -0.015, 0.0
5, 0.01, 0.0, 0.0
6, 0.01, -0.015, 0.0
*SET_PART
12
1, 2
*END