Multipoint Constraint Element: Orient Joint
The MPC184 orient joint is a two-node element. In this joint, the relative rotational degrees of freedom are fixed while the displacement degrees of freedom are left free.
Set KEYOPT(1) = 14 to define a two-node orient joint element.
Figure 184orie.1: MPC184 Orient 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.
The constraints imposed on an orient joint element are easily described by referring to Figure 184orie.1: MPC184 Orient Joint Geometry. At any given instant of time, the constraints imposed are as follows:
Other input data that are common to all joint elements (material behavior, etc.) are described in "Joint Input Data" in the MPC184 element description.
This input summary applies to the orient joint element option of MPC184: KEYOPT(1) = 14.
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.
UX, UY, UZ, ROTX, ROTY, ROTZ
Orient joint element
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 184orie.1: MPC184 Orient Joint Element Output Definitions and Table 184orie.2: MPC184 Orient 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 184orie.1: MPC184 Orient Joint Element Output Definitions
|NODES||Element node numbers (I, J)||-||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 orient 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 nodes of joint elements.
Table 184orie.2: MPC184 Orient Joint Element - NMISC Output
|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 184orie.3: MPC184 Orient Joint Item and Sequence Numbers - SMISC Items and Table 184orie.4: MPC184 Orient Joint Item and Sequence Numbers - NMISC Items list output available via the ETABLE command 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:
output quantity as defined in the Element Output Definitions table.
predetermined Item label for ETABLE command
sequence number for single-valued or constant element data
Table 184orie.3: MPC184 Orient Joint Item and Sequence Numbers - SMISC Items
Table 184orie.4: MPC184 Orient Joint Item and Sequence Numbers - NMISC Items
|Output Quantity Name||ETABLE and ESOL Command Input|
Boundary conditions cannot be applied on the nodes forming the orient joint.
Rotational degrees of freedom are activated at the nodes forming the element. When these elements are used in conjunction with solid elements, the rotational degrees of freedom must be suitably constrained. Since boundary conditions cannot be applied to the nodes of the orient joint, a beam or shell element with very weak stiffness may 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 the 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.
The element currently does not support birth or death options.
The equation solver (EQSLV) must be the sparse solver or the PCG solver. The command PCGOPT,,,,,,,ON is also required in order to use the PCG solver.
The element coordinate system (/PSYMB,ESYS) is not relevant.