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=ELAS (Dependency, CARTESIA only)
PROPERTY DOF1 DOF2
STIFFNESS
If PROPERTY=FRICTION
PROPERTY TDOF NDOF
MU
If PROPERTY=MASS
PROPERTY DOF
MASS
If PROPERTY=NELA
PROPERTY DOF1 FLAT
F1 U1
etc etc
Fi Ui
If PROPERTY=NELA (Dependency, CARTESIA only)
PROPERTY DOF1 FLAT DOF2
F1 U1
etc. etc.
Fi Ui
If PROPERTY = RIGID
PROPERTY DOF
If PROPERTY=DAMP
PROPERTY DOF
DAMP
If PROPERTY=DAMP (Dependency, CARTESIA only)
PROPERTY DOF1 DOF2
DAMP
If PROPERTY=CREF
PROPERTY DOF
CREF
If PROPERTY=NDAMP
PROPERTY DOF FLAT
F1 v1
etc. etc.
Fi vi
If PROPERTY=NDAMP (Dependency, CARTESIA only)
PROPERTY DOF FLAT VDOF
F1 v1
etc. etc.
Fi vi
If PROPERTY=NDAMP (Dependencies, CARTESIA only)
PROPERTY DOF FLAT VDOF UDOF
F1 v1 u1
etc. etc. etc.
Fi vi ui

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
FRICTION 12 3
0.3

Example 2: Define Off-diagonal Terms of Stiffness Matrix using ELAS and Two DOF Values

1. Define the same values for K12, K13, K21, K31, K23, K32 and same values of K11, K22, K33. 15
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PJOINTG 2
+ ELAS 123
+ 2.0
+ ELAS 123 123
+ -10
2. Define different values of K12, K21 but same value for K13, K31 and same value for K23, K32. 15
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PJOINTG 2
+ ELAS 123
+ 2.0
+ ELAS 1 2
+ -10
+ ELAS 2 1
-5.0
ELAS 13 13
-6.0
ELAS 23 23
-0.8
3. Define the same off-diagonal terms but different diagonal terms. 15
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PJOINTG 2
+ ELAS 1
+ 2.0
+ ELAS 2
+ -10
+ ELAS 3
-5.0
ELAS 123 123
-6.0

Example 3: Define Off-diagonal Terms of Damping Matrix using DAMP and Two DOF Values

1. Define the same off-diagonal terms but different diagonal terms. 16
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PJOINTG 2
+ DAMP 1
+ 2.0
+ DAMP 2
+ -10
+ DAMP 3
-5.0
DAMP 123 123
-6.0

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.
NDAMP
A force-velocity-displacement curve is applied to each degree of freedom associated with the joint, listed in the DOF, VDOF and UDOF fields. The force, velocity and displacement values used to define the curve can be specified in the Fi, vi and ui fields. NDAMP is only supported for CARTESIAN joints.
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
FRICTION
In the case of a SLIPRING joint, the specified value of friction is applied to degrees of freedom listed in the TDOF field. The NDOF field must be left blank. Only the DOF=1 option is supported.
In the case of a CARTESIA joint, the specified value of friction is applied to the tangential degrees of freedom listed in the TDOF field. The normal force component is specified in the NDOF field. Friction in tangential direction can be specified using either 1 or 2 degrees of freedom as shown in the example. This is currently only supported for JOINTG type CARTESIA. 9
MASS
The specified value of mass is applied to degrees of freedom listed in the DOF field. This is currently only supported for the SLIPRING joint and only the DOF=1 option is supported.

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
DOF1 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)
DOF2 Degrees of freedom to which off diagonal stiffness value applies. If DOF1 is defined alone, it applies to only diagonal terms of stiffness matrix.

No default (1 ≤ Integer ≤ 3, 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=FRICTION (currently only supported for SLIPRING and CARTESIA JOINTG elements)
TDOF Tangential degree(s) of freedom to which the friction value applies. It can either be defined in tangential direction (single DOF) or in a tangential plane (2 DOFs). 10

No default (1 ≤ Integer ≤ 3, single or multiple integers can be specified with no embedded blanks)

NDOF The normal force component.

No default (Integer)
MU Value of coefficient of friction for the specified degree(s) of freedom.

No default (Real)
If PROPERTY=MASS
DOF Degree(s) of freedom to which the mass value applies. This is currently only supported for SLIPRING and only DOF=1 is applicable.

No default (Integer = 1)

MASS Value of mass for the specified degree(s) of freedom.

No default (Real)
If PROPERTY=NELA
FDOF Degree(s) of freedom to which the force value applies.

No default (1 ≤ Integer ≤ 6, single or multiple integers can be specified with no embedded blanks)
FLAT Specifies the handling method for Fi values outside the specified range of Ui values in the table.
= 0
If an Ui value input is outside the range of Ui values specified on the table, the corresponding Fi value look up is performed using linear extrapolation from the two start or two end points.
= 1 (Default)
If an Ui value input is outside the range of Ui values specified on the table, the corresponding Fi value is equal to the start or end points, respectively.
UDOF Degrees of freedom to which displacement values apply. 13, 17

No default (1 ≤ Integer ≤ 3, 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
DOF1 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)
DOF2 Degrees of freedom to which the off-diagonal damping value applies. If DOF1 is defined alone, it applies to only diagonal terms of damping matrix. 16, 17

No default (1 ≤ Integer ≤ 3, single or multiple integers can be specified with no embedded blanks)
DAMP Damping value.

No default (Real)
If PROPERTY=NDAMP
FDOF Degree of freedom to which the damping force values apply.

No default (1 ≤ Integer ≤ 6, single integer can be specified)
VDOF Degree of freedom to which the velocity values apply. 17

Default = DOF (1 ≤ Integer ≤ 3, single integer can be specified)
UDOF Degree of freedom to which the displacement values apply. 14, 17

Default = BLANK (1 ≤ Integer ≤ 3, single integer can be specified)
FLAT Specifies the handling method for Fi values outside the specified range of vi or ui values in the table.
= 0
If a vi or ui value input is outside the range of vi or ui values specified on the table, the corresponding Fi value look up is performed using linear extrapolation from the two start or two end points.
= 1 (Default)
If a vi or ui value input is outside the range of vi or ui values specified on the table, the corresponding Fi value is equal to the start or end points, respectively.
Fi, vi, ui Force-Velocity and displacement values (respectively) for the degrees of freedom associated with the specified DOFs.

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)

Comments

  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 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.

  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. CREF is also not supported for STOP/LOCK if TYPE=1 is set.
  5. The JOINTF and JOINTD I/O Option Entries can be used to output JOINTG forces and displacements respectively.
  6. SLIPRING joints are used to model a chain of rope segments passing through consecutive rings/pulleys. SLIPRING only supports one degree of freedom (1) and the angle of the slipring is calculated geometrically, but can be adjusted via dof 2 on CREF. Friction and Mass can be defined via the corresponding PROPERTY. For stiffness defined for SLIPRING joints, the specified value is in units of force (not force/length). The value of stiffness is internally adjusted based on the corresponding rope length during the analysis. For more details and support information, see the JOINTG entry.
  7. For PROPERTY=NELA, both JOINTG forces (total joint forces) and JOINTG elastic forces are output.
  8. SLIPRING joints are used to model a chain of rope segments passing through consecutive rings/pulleys. SLIPRING only supports one degree of freedom (1) and the angle of the slipring is calculated geometrically, but can be adjusted via dof 2 on CREF. Friction and Mass can be defined via the corresponding PROPERTY. For stiffness defined for SLIPRING joints, the specified value is in units of force (not force/length). The value of stiffness is internally adjusted based on the corresponding rope length during the analysis. See the JOINTG entry for more details and support information.
  9. Tangential direction can be defined for a single motion component or spatially, or there can be two separate FRICTION definitions in PJOINTG, one for each tangent direction.
  10. In the case of a SLIPRING joint, the TDOF field specifies the degree of freedom to which the friction value applies. For SLIPRING, only DOF=1 is applicable. NDOF field must be left blank.
  11. Coupling between two different degrees of freedom of the stiffness matrix can be defined using an additional ELAS continuation line .The first ELAS definition defines the diagonal terms of the stiffness matrix, that is, stiffnesses along the same degree of freedom. The second ELAS definition defines the off-diagonal terms of the stiffness matrix, that is, the coupling stiffnesses between two different degrees of freedom (see Table 1).
  12. When two DOF definitions follow the ELAS/DAMP keyword, the value is not applied to the diagonal terms of the stiffness/damping matrix.
  13. The second DOF specification defines a nonlinear force at DOF1 as a function of the displacement at DOF1, plus a nonlinear force at DOF1 as a function of joint displacement at DOF2.
  14. UDOF must be defined to specify ui values. NDAMP definition is currently supported for CARTESIA joint.
  15. The DOF1 and DOF2 entries represent Kij terms of the stiffness matrix, where I = 1 to 3, j = 1 to 3, and ij refers to all combinations of I and j except for i = j. So, DOF1 = 123 and DOF2 = 123 refers to all combinations of 1, 2, 3 with 1, 2, 3 except 11, 22, 33; that is, DOF1 and DOF2 = 123, applies the stiffness value to K12, K21, K13, K31, K23, K32 but not K11, K22, K33. Similarly, when DOF1 and DOF2 = 13 it refers to K13 and K31. Examples 1, 2 and 3 generate the following stiffness matrices respectively:
    Table 1. Example 1
    K
    2.0 -10.0 -10.0
    -10.0 2.0 -10.0
    -10.0 -10.0 2.0
    Table 2. Example 2
    K
    2.0 -10.0 -6.0
    -5.0 2.0 -0.8
    -6.0 -0.8 2.0
    Table 3. Example 3
    K
    2.0 -6.0 -6.0
    -6.0 -10.0 -6.0
    -6.0 -6.0 -5.0
  16. The same DOF1 and DOF2 definition in ELAS applies to DAMP. The Second DOF specification implies that the damping value specified in the next line applies to off-diagonal terms only. Example 1 generates the following matrix:
    Table 4. Example 1
    C
    2.0 -6.0 -6.0
    -6.0 -10.0 -6.0
    -6.0 -6.0 -5.0
  17. The second DOF specification in ELAS, DAMP, NELA and NDAMP is only available for the CARTESIA joint type.