MPC184-Weld
Multipoint
Constraint Element: Weld Joint
MPC184 Weld Joint Element Description
The MPC184 weld joint element is a two-node element that has all relative degrees of freedom fixed.
MPC184 Weld Joint Input Data
Set KEYOPT(1) = 13 to define a two-node weld joint element.
Figure 184weld.1: MPC184 Weld Joint Geometry shows the geometry and node locations for this element. Two nodes (I and J) define the element.
A local Cartesian coordinate system must be specified at the first node, I, of the element. The local coordinate system specification at the second node is optional. The local coordinate systems specified at node I and J evolve with the rotations at the respective nodes. Use the SECJOINT command to specify the identifiers of the local coordinate systems.
Other input data that are common to all joint elements (material behavior, etc.) are described in "Joint Input Data" in the MPC184 element description.
Note: The weld joint may also be simulated by using the CE command. See the CE command description for additional details.
MPC184 Weld Joint Input Summary
This input summary applies to the weld joint element option of MPC184: KEYOPT(1) = 13.
- Nodes
I, J
Note: For a grounded joint element, specify either node I or node J in the element definition and leave the other node (the grounded node) blank.
- Degrees of Freedom
UX, UY, UZ, ROTX, ROTY, ROTZ
- Real Constants
None
- Material Properties
None
- Surface Loads
None
- Body Loads
None
- Element Loads
None
- Special Features
- KEYOPT(1)
Element behavior:
- 13 --
Weld joint element
- KEYOPT(2)
Element constraint imposition method:
- 0 --
Lagrange multiplier method (default)
- 1 --
Penalty-based method
MPC184 Weld Joint Output Data
The solution output associated with the element is in two forms:
Nodal displacements included in the overall nodal solution
Additional element output as shown in Table 184weld.1: MPC184 Weld Joint Element Output Definitions and Table 184weld.2: MPC184 Weld Joint Element - NMISC Output.
These tables use the following notation:
A colon (:) in the Name column indicates the item can be accessed by the Component Name method (ETABLE, ESOL). The O column indicates the availability of the items in the file Jobname.out. The R column indicates the availability of the items in the results file.
In either the O or R columns, Y indicates that the item is always available, a number refers to a table footnote that describes when the item is conditionally available, and a - indicates that the item is not available.
Table 184weld.1: MPC184 Weld Joint Element Output Definitions
| Name | Definition | O | R |
|---|---|---|---|
| EL | Element number | - | Y |
| NODES | Element node numbers (I, J) | - | Y |
| FX | Constraint force in X direction | - | Y |
| FY | Constraint force in Y direction | - | Y |
| FZ | Constraint force in Z direction | - | Y |
| MX | Constraint moment in X direction | - | Y |
| MY | Constraint moment in Y direction | - | Y |
| MZ | Constraint moment in Z direction | - | Y |
The following table shows additional non-summable miscellaneous (NMISC) output available for the weld joint element.
Note: This output is intended for use in the Ansys Workbench program to track the evolution of local coordinate systems specified at the joint element nodes.
Table 184weld.2: MPC184 Weld Joint Element - NMISC Output
| Name | Definition | O | R |
|---|---|---|---|
| E1X-I, E1Y-I, E1Z-I | X, Y, Z components of the evolved e1 axis at node I | - | Y |
| E2X-I, E2Y-I, E2Z-I | X, Y, Z components of the evolved e2 axis at node I | - | Y |
| E3X-I, E3Y-I, E3Z-I | X, Y, Z components of the evolved e3 axis at node I | - | Y |
| E1X-J, E1Y-J, E1Z-J | X, Y, Z components of the evolved e1 axis at node J | - | Y |
| E2X-J, E2Y-J, E2Z-J | X, Y, Z components of the evolved e2 axis at node J | - | Y |
| E3X-J, E3Y-J, E3Z-J | X, Y, Z components of the evolved e3 axis at node J | - | Y |
| JFX, JFY, JFZ | Constraint forces expressed in the evolved coordinate system specified at node I | - | Y |
| JMX, JMY, JMZ | Constraint moments expressed in the evolved coordinate system specified at node I | - | Y |
Table 184weld.3: MPC184 Weld Joint Item and Sequence Numbers - SMISC Items and Table 184weld.4: MPC184 Weld Joint Item and Sequence Numbers - NMISC Items list output available via ETABLE using the Sequence Number method. See The General Postprocessor (POST1) in the Basic Analysis Guide and The Item and Sequence Number Table for further information. The table uses the following notation:
- Name
Output quantity as defined in the Element Output Definitions table
- Item
Predetermined Item label for ETABLE command
- E
Sequence number for single-valued or constant element data
Table 184weld.4: MPC184 Weld Joint Item and Sequence Numbers - NMISC Items
| Output Quantity Name | ETABLE and ESOL Command Input | |
|---|---|---|
| Item | E | |
| E1X-I | NMISC | 1 |
| E1Y-I | NMISC | 2 |
| E1Z-I | NMISC | 3 |
| E2X-I | NMISC | 4 |
| E2Y-I | NMISC | 5 |
| E2Z-I | NMISC | 6 |
| E3X-I | NMISC | 7 |
| E3Y-I | NMISC | 8 |
| E3Z-I | NMISC | 9 |
| E1X-J | NMISC | 10 |
| E1Y-J | NMISC | 11 |
| E1Z-J | NMISC | 12 |
| E2X-J | NMISC | 13 |
| E2Y-J | NMISC | 14 |
| E2Z-J | NMISC | 15 |
| E3X-J | NMISC | 16 |
| E3Y-J | NMISC | 17 |
| E3Z-J | NMISC | 18 |
| JFX | NMISC | 19 |
| JFY | NMISC | 20 |
| JFZ | NMISC | 21 |
| JMX | NMISC | 22 |
| JMY | NMISC | 23 |
| JMZ | NMISC | 24 |
MPC184 Weld Joint Assumptions and Restrictions
Boundary conditions cannot be applied on the nodes forming the weld joint.
Rotational degrees of freedom are activated at the nodes forming the element. When these elements are used with solid elements, the rotational degrees of freedom must be suitably constrained. Because boundary conditions cannot be applied to the nodes of the weld joint, a beam or shell element with very weak stiffness can be used with the underlying solid elements at the nodes forming the joint element to avoid any rigid body modes.
Stops (SECSTOP) and locks (SECLOCK) are not applicable to this element.
In a nonlinear analysis, the components of relative motion are accumulated over all substeps. It is essential that the substep size be restricted such that these rotations in a given substep are less than π for the values to be accumulated correctly.
Element birth and death options are not available.
For the Lagrange multiplier element formulation (KEYOPT(2) = 0) and the penalty-based element formulation (KEYOPT(2) = 1), the equation solver (EQSLV) must be the sparse or PCG solver.
Lagrange multiplier-based joint elements (KEYOPT(2) = 0) and penalty-based joint elements (KEYOPT(2) = 1) cannot be connected to each other.
The element coordinate system (/PSYMB,ESYS) is not relevant.