# PJOINTG

Bulk Data Entry Defines the properties for a joint connection between two grids via the JOINTG Bulk Data Entry.

## Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PJOINTG PID
If PROPERTY=STOP or LOCK
PROPERTY DOF LB UB TYPE LDOF
If PROPERTY=ELAS
PROPERTY DOF
STIFFNESS
If PROPERTY=NELA
PROPERTY DOF
F1 U1
etc etc
Fi Ui
If PROPERTY = RIGID
PROPERTY DOF
If PROPERTY=DAMP
PROPERTY DOF
DAMP
If PROPERTY=CREF
PROPERTY DOF
CREF

## Example

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PJOINTG 2
STOP 2 2.0 4.0
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PJOINTG 2
ELAS 123
200.0

## Definitions

Field Contents SI Unit Example
PID Joint property identification number.

No default (Integer > 0)

PROPERTY Property type applied to the corresponding degrees of freedom in the joint.
STOP
The relative displacement of the grid points associated with the joint is constrained within [LB, UB] along the specified degree of freedom (DOF).
LOCK
The relative displacement of the grid points associated with the joint is constrained to move only within [LB, UB] along the specified degree of freedom (DOF). The additional attribute of LOCK, when compared to STOP is that if the relative displacement value reaches either LB or UB, then the joint motion is locked, and further relative motion is not allowed.
ELAS (Linear Elasticity)
A stiffness value can be assigned to each degree of freedom associated with the joint. The degrees of freedom are listed in the DOF field and the corresponding stiffness value can be specified on the STIFFNESS field.
NELA (Nonlinear Elasticity)
A force-displacement curve can be assigned to each degree of freedom associated with the joint. The degrees of freedom are listed in the DOF field and the corresponding force-displacement curve values can be specified on the Fi and Ui
fields.
RIGID
The grid points associated with the joint are rigidly connected along the specified degrees of freedom listed in the DOF field.
DAMP
The specified value of damping is applied to degrees of freedom listed in the DOF field.
CREF
Reference lengths and angles for constitutive responses are to be specified. These are applied to degrees of freedom listed in the DOF field. 3, 4

No default

If PROPERTY=STOP or LOCK
DOF Degree of freedom which the specified property applies.

No default (1 ≤ Integer ≤ 6, single or multiple integers can be specified with no embedded blanks)

LB Lower bound of the degree of freedom at which the specified property is activated. Lower bound implies a negative value should be specified which indicates the relative displacement the grid points associated with a joint are allowed to move towards each other in the specified DOF before the STOP/LOCK conditions are applied.

Default = blank (Real < 0.0)

UB Upper bound of the degree of freedom at which the specified property is activated. Upper bound implies a positive value should be specified which indicates the relative displacement the grid points associated with a joint are allowed to move away from each other in the specified DOF before the STOP/LOCK conditions are applied.

Default = blank (Integer > 0.0)

TYPE Identifies the displacement value interpretation for bounds of STOP/LOCK options.
blank (Default)
The corresponding STOP/LOCK bounds on PJOINTG entry are interpreted based on the relative motion between the two grid points of the joint.
1
The corresponding STOP/LOCK bounds on the PJOINTG entry are interpreted based on the length of the joint.

LDOF If one of the degrees of freedom locks, then by default the other degrees of freedom of the joint also lock. However, if any degrees of freedom are specified on the LDOF field, then only these degrees of freedom lock if any degree of freedom enters locking phase.

Default = blank (1 ≤ Integer ≤ 6, single or multiple integers can be specified with no embedded blanks)

If PROPERTY=ELAS
DOF Degree(s) of freedom to which the stiffness value applies.

No default (1 ≤ Integer ≤ 6, single or multiple integers can be specified with no embedded blanks)

STIFFNESS Value of stiffness for the specified degree(s) of freedom.

No default (Real)

If PROPERTY=NELA
DOF Degree(s) of freedom to which the stiffness value applies.

No default (1 ≤ Integer ≤ 6, single or multiple integers can be specified with no embedded blanks)

Fi, Ui Force-Displacement values for the degree(s) of freedom associated with the specified DOF.

No default (Real)

If PROPERTY=RIGID
DOF Degree(s) of freedom to which are rigidly connected.

No default (1 ≤ Integer ≤ 6, single or multiple integers can be specified with no embedded blanks)

If PROPERTY=DAMP
DOF Degree(s) of freedom to which damping value is applied.

No default (1 ≤ Integer ≤ 6, single or multiple integers can be specified with no embedded blanks)

DAMP Damping value.

No default (Real)

If PROPERTY=CREF
DOF Degree(s) of freedom to which the constitutive reference values are applied.

No default (1 ≤ Integer ≤ 6, single or multiple integers can be specified with no embedded blanks)

CREF Constitutive reference values.

No default (Real)

1. PJOINTG entries can be referenced on the JPID field of the JOINTG Bulk Data Entry to define corresponding joint properties.
2. The LB and UB values are interpreted based on the following considerations.
• The TYPE field on the PJOINTG entry. If TYPE field is blank, then the LB and UB fields identify the lower and upper bounds of the relative motion of the joint
• The coordinate systems defined on the JOINTG entry
• The G1 and G2 grid points of the JOINTG entry
3. The ELAS and NELA properties are supported for AXIAL, CARTESIAN, TRANSLATOR, CYLINDRICAL, and ROTATION joints.

For HINGE joint, only ELAS is currently supported.

The RIGID property is only supported for AXIAL, CARTESIAN, TRANSLATOR, CYLINDRICAL, and ROTATION joints.

The ELAS continuation line and the associated stiffness can be repeated if different stiffness values are required for the each of the different degrees of freedom for the same joint.

The NELA continuation line and the associated force-displacement curve can be repeated, if different curves are required for the each of the different degrees of freedom for the same joint. Similarly, the RIGID continuation line can be repeated. The different degrees of freedom of a joint can have linear, nonlinear elasticity, or RIGID definitions.

The CREF continuation line is supported for all joints listed on the JOINTG Bulk Data Entry.

4. CREF allows you to specify reference positions of the joints where the force and/or moment is zero, if such a position is not the same as the initial position. For such joints, you can specify up to six values of constitutive reference (depending on the joint type). These values influence multiple joint behaviors, including elastic behavior of joints (ELAS) and STOP/LOCK(with TYPE=Default), along the corresponding DOFs. CREF is not supported with MOTNJG. CREG is also not supported for STOP/LOCK if TYPE=1 is set. CREF is currently only supported for large displacement nonlinear static, implicit large displacement nonlinear transient analysis, and explicit analysis.
5. The OptiStruct joints defined using JOINTG are different from the Multibody Dynamics (OS-MBD) joints which are defined using the JOINT Bulk Data Entry with OptiStruct-MotionSolve integration.
6. The analysis support information for PJOINTG is as follows:
ELAS, RIGID, DAMP, and CREF
All analysis types except Explicit Dynamic Analysis.
NELA, STOP, LOCK
Nonlinear Static and Nonlinear Transient Analysis for small and large displacement analysis cases.