MPC184-Orient

Multipoint Constraint Element: Orient Joint

MPC184 Orient Joint Element Description

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.

Figure 184orie.1: MPC184 Orient Joint Geometry

MPC184 Orient Joint Input Data

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.

MPC184 Orient Joint Input Summary

This input summary applies to the orient joint element option of MPC184: KEYOPT(1) = 14.

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

Large deflection

Linear perturbation

KEYOPT(1)

Element behavior:

14 --: Orient joint element

MPC184 Orient 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 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

Name	Definition	O	R
EL	Element number	-	Y
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

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 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:

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 184orie.3: MPC184 Orient Joint Item and Sequence Numbers - SMISC Items

Output Quantity Name	ETABLE and ESOL Command Input
Output Quantity Name	Item	E
MX	SMISC	4
MY	SMISC	5
MZ	SMISC	6

Table 184orie.4: MPC184 Orient Joint Item and Sequence Numbers - NMISC Items

Output Quantity Name	ETABLE and ESOL Command Input
Output Quantity Name	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 Orient Joint Assumptions and Restrictions

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.

MPC184 Orient Joint Product Restrictions

When used in the product(s) listed below, the stated product-specific restrictions apply to this element in addition to the general assumptions and restrictions given in the previous section.

ANSYS Mechanical Pro

Linear perturbation is not available.