ansys.mapdl.core.Mapdl.secjoint#

Mapdl.secjoint(kywrd='', val1='', val2='', val3='', val4='', val5='', val6='', **kwargs)#

Defines local coordinate systems at joint element nodes and other data for joint elements.

Mechanical APDL Command: SECJOINT

Parameters:
kywrdstr

Keyword that indicates the type of joint element data being defined.

  • LSYS or blank - Define local coordinate systems at the nodes that form the MPC184 joint element.

  • RDOF - Define the relative degrees of freedom to be fixed for an MPC184-General joint element.

  • PITC - Define the pitch of an MPC184-Screw joint element.

  • FRIC - Define the geometric quantities required for Coulomb frictional behavior in the MPC184-Revolute, MPC184-Slot, MPC184-Translational, or MPC184-Spherical joint element.

  • PNLT - Define the penalty factors for the penalty-based joint element formulation.

val1str

The meaning of Val1 through Val6 changes, depending on the value of Kywrd.

If Kywrd = LSYS (or blank), Val1 and Val2 are Identifiers of the local coordinate systems at nodes I and J, respectively, of the joint element. Val3 through Val6 are not used.

If Kywrd = RDOF, Val1 through Val6 are the relative degrees of freedom to be fixed for a general joint element. Input 1 for UX, 2 for UY, 3 for UZ, 4 for ROTX, 5 for ROTY, and 6 for ROTZ. You may input the DOFs in any order.

If Kywrd = PITC, Val1 is the pitch of the screw joint element; pitch is defined as the ratio of relative axial displacement (length units) to relative rotation (in radians). Val2 through Val6 are not used.

If Kywrd = FRIC, Val1 through Val3 are defined as follows.

  • For Revolute Joint:

  • Val1 = outer radius

  • Val2 = inner radius

  • Val3 = effective length

  • For Translational Joint:

  • Val1 = effective length

  • Val2 = effective radius

  • For Spherical Joint:

  • Val1 = effective radius

If Kywrd = PNLT, Val1 and Val2 are defined as follows, and Val3 through Val6 are not used.

  • Val1 - Constraint type:

    • DISP - Displacement-based constraint

    • ROT - Rotation-based constraint

  • Val2 - Scaling factor (input a positive number) or penalty factor (input a negative number) used with the penalty-based joint element formulation:

    • Positive number - the number is used as a scaling factor to scale the internally calculated penalty values.

    • Negative number - the absolute value of the number is used as the penalty factor in calculations.

val2str

The meaning of Val1 through Val6 changes, depending on the value of Kywrd.

If Kywrd = LSYS (or blank), Val1 and Val2 are Identifiers of the local coordinate systems at nodes I and J, respectively, of the joint element. Val3 through Val6 are not used.

If Kywrd = RDOF, Val1 through Val6 are the relative degrees of freedom to be fixed for a general joint element. Input 1 for UX, 2 for UY, 3 for UZ, 4 for ROTX, 5 for ROTY, and 6 for ROTZ. You may input the DOFs in any order.

If Kywrd = PITC, Val1 is the pitch of the screw joint element; pitch is defined as the ratio of relative axial displacement (length units) to relative rotation (in radians). Val2 through Val6 are not used.

If Kywrd = FRIC, Val1 through Val3 are defined as follows.

  • For Revolute Joint:

  • Val1 = outer radius

  • Val2 = inner radius

  • Val3 = effective length

  • For Translational Joint:

  • Val1 = effective length

  • Val2 = effective radius

  • For Spherical Joint:

  • Val1 = effective radius

If Kywrd = PNLT, Val1 and Val2 are defined as follows, and Val3 through Val6 are not used.

  • Val1 - Constraint type:

    • DISP - Displacement-based constraint

    • ROT - Rotation-based constraint

  • Val2 - Scaling factor (input a positive number) or penalty factor (input a negative number) used with the penalty-based joint element formulation:

    • Positive number - the number is used as a scaling factor to scale the internally calculated penalty values.

    • Negative number - the absolute value of the number is used as the penalty factor in calculations.

val3str

The meaning of Val1 through Val6 changes, depending on the value of Kywrd.

If Kywrd = LSYS (or blank), Val1 and Val2 are Identifiers of the local coordinate systems at nodes I and J, respectively, of the joint element. Val3 through Val6 are not used.

If Kywrd = RDOF, Val1 through Val6 are the relative degrees of freedom to be fixed for a general joint element. Input 1 for UX, 2 for UY, 3 for UZ, 4 for ROTX, 5 for ROTY, and 6 for ROTZ. You may input the DOFs in any order.

If Kywrd = PITC, Val1 is the pitch of the screw joint element; pitch is defined as the ratio of relative axial displacement (length units) to relative rotation (in radians). Val2 through Val6 are not used.

If Kywrd = FRIC, Val1 through Val3 are defined as follows.

  • For Revolute Joint:

  • Val1 = outer radius

  • Val2 = inner radius

  • Val3 = effective length

  • For Translational Joint:

  • Val1 = effective length

  • Val2 = effective radius

  • For Spherical Joint:

  • Val1 = effective radius

If Kywrd = PNLT, Val1 and Val2 are defined as follows, and Val3 through Val6 are not used.

  • Val1 - Constraint type:

    • DISP - Displacement-based constraint

    • ROT - Rotation-based constraint

  • Val2 - Scaling factor (input a positive number) or penalty factor (input a negative number) used with the penalty-based joint element formulation:

    • Positive number - the number is used as a scaling factor to scale the internally calculated penalty values.

    • Negative number - the absolute value of the number is used as the penalty factor in calculations.

val4str

The meaning of Val1 through Val6 changes, depending on the value of Kywrd.

If Kywrd = LSYS (or blank), Val1 and Val2 are Identifiers of the local coordinate systems at nodes I and J, respectively, of the joint element. Val3 through Val6 are not used.

If Kywrd = RDOF, Val1 through Val6 are the relative degrees of freedom to be fixed for a general joint element. Input 1 for UX, 2 for UY, 3 for UZ, 4 for ROTX, 5 for ROTY, and 6 for ROTZ. You may input the DOFs in any order.

If Kywrd = PITC, Val1 is the pitch of the screw joint element; pitch is defined as the ratio of relative axial displacement (length units) to relative rotation (in radians). Val2 through Val6 are not used.

If Kywrd = FRIC, Val1 through Val3 are defined as follows.

  • For Revolute Joint:

  • Val1 = outer radius

  • Val2 = inner radius

  • Val3 = effective length

  • For Translational Joint:

  • Val1 = effective length

  • Val2 = effective radius

  • For Spherical Joint:

  • Val1 = effective radius

If Kywrd = PNLT, Val1 and Val2 are defined as follows, and Val3 through Val6 are not used.

  • Val1 - Constraint type:

    • DISP - Displacement-based constraint

    • ROT - Rotation-based constraint

  • Val2 - Scaling factor (input a positive number) or penalty factor (input a negative number) used with the penalty-based joint element formulation:

    • Positive number - the number is used as a scaling factor to scale the internally calculated penalty values.

    • Negative number - the absolute value of the number is used as the penalty factor in calculations.

val5str

The meaning of Val1 through Val6 changes, depending on the value of Kywrd.

If Kywrd = LSYS (or blank), Val1 and Val2 are Identifiers of the local coordinate systems at nodes I and J, respectively, of the joint element. Val3 through Val6 are not used.

If Kywrd = RDOF, Val1 through Val6 are the relative degrees of freedom to be fixed for a general joint element. Input 1 for UX, 2 for UY, 3 for UZ, 4 for ROTX, 5 for ROTY, and 6 for ROTZ. You may input the DOFs in any order.

If Kywrd = PITC, Val1 is the pitch of the screw joint element; pitch is defined as the ratio of relative axial displacement (length units) to relative rotation (in radians). Val2 through Val6 are not used.

If Kywrd = FRIC, Val1 through Val3 are defined as follows.

  • For Revolute Joint:

  • Val1 = outer radius

  • Val2 = inner radius

  • Val3 = effective length

  • For Translational Joint:

  • Val1 = effective length

  • Val2 = effective radius

  • For Spherical Joint:

  • Val1 = effective radius

If Kywrd = PNLT, Val1 and Val2 are defined as follows, and Val3 through Val6 are not used.

  • Val1 - Constraint type:

    • DISP - Displacement-based constraint

    • ROT - Rotation-based constraint

  • Val2 - Scaling factor (input a positive number) or penalty factor (input a negative number) used with the penalty-based joint element formulation:

    • Positive number - the number is used as a scaling factor to scale the internally calculated penalty values.

    • Negative number - the absolute value of the number is used as the penalty factor in calculations.

val6str

The meaning of Val1 through Val6 changes, depending on the value of Kywrd.

If Kywrd = LSYS (or blank), Val1 and Val2 are Identifiers of the local coordinate systems at nodes I and J, respectively, of the joint element. Val3 through Val6 are not used.

If Kywrd = RDOF, Val1 through Val6 are the relative degrees of freedom to be fixed for a general joint element. Input 1 for UX, 2 for UY, 3 for UZ, 4 for ROTX, 5 for ROTY, and 6 for ROTZ. You may input the DOFs in any order.

If Kywrd = PITC, Val1 is the pitch of the screw joint element; pitch is defined as the ratio of relative axial displacement (length units) to relative rotation (in radians). Val2 through Val6 are not used.

If Kywrd = FRIC, Val1 through Val3 are defined as follows.

  • For Revolute Joint:

  • Val1 = outer radius

  • Val2 = inner radius

  • Val3 = effective length

  • For Translational Joint:

  • Val1 = effective length

  • Val2 = effective radius

  • For Spherical Joint:

  • Val1 = effective radius

If Kywrd = PNLT, Val1 and Val2 are defined as follows, and Val3 through Val6 are not used.

  • Val1 - Constraint type:

    • DISP - Displacement-based constraint

    • ROT - Rotation-based constraint

  • Val2 - Scaling factor (input a positive number) or penalty factor (input a negative number) used with the penalty-based joint element formulation:

    • Positive number - the number is used as a scaling factor to scale the internally calculated penalty values.

    • Negative number - the absolute value of the number is used as the penalty factor in calculations.

Notes

Use this command to define additional section data for MPC184 joint elements. To overwrite the current values, issue another secjoint command with the same Kywrd value. The data input on this command is interpreted based on the most recently issued sectype command.

The command secjoint,PNLT is only applicable to penalty-based joints (KEYOPT(2) = 1 on most joint elements). The default penalty factor (common to all constraints of the joint element) is of the order of 102E:sub:avg, where E:sub:avg is the average Young``s modulus of the elements attached to the joint element or deduced from the connections to other elements. The default value may be overridden by specifying user-defined penalty factors via secjoint,PNLT. The choice of penalty factors can affect the constraint satisfaction as well as overall solution convergence.