rigid cylindrical joint¶

Module: solid

Category: nlconstraint

Type string: "rigid cylindrical joint"

Parameters¶

Name	Description	Default	Units
`body_a`	body_a	-842150451	[]
`body_b`	body_b	-842150451	[]
`laugon`	Enforcement method	1	[]
`tolerance`	tolerance	0	[]
`gaptol`	gaptol	0	[]
`angtol`	angtol	0	[]
`force_penalty`	force_penalty	1	[]
`moment_penalty`	moment_penalty	1	[]
`joint_origin`	joint_origin	{0,0,0}	[]
`joint_axis`	joint_axis	{0,0,0}	[]
`transverse_axis`	transverse_axis	{0,0,0}	[]
`minaug`	minaug	0	[]
`maxaug`	maxaug	10	[]
`prescribed_translation`	prescribed_translation	false	[]
`translation`	translation	0	[]
`force`	force	0	[]
`prescribed_rotation`	prescribed_rotation	false	[]
`rotation`	rotation	0	[]
`moment`	moment	0	[]
`auto_penalty`	auto_penalty	false	[]

Description¶

A rigid cylindrical joint connects rigid bodies a and b at a point in space, allowing one degree of freedom for rotation about an axis through that point, and another degree of freedom for translation along that axis.

The tolerance parameter defines the augmentation tolerance. That is, when the relative change in the constraint forces and moments (the Lagrange multipliers) are less than this value. The gaptol parameter defines the tolerance for spatial separation of the joint origin on the two bodies (in units of length). The angtol element defines the tolerance for angular separation of the joint axis on the two bodies (in units of radians). Setting any of these three elements to zero disables the enforcement of that tolerance. The force_penalty parameter (with units of force per length) represents the stiffness that prevents the joint origin on the two bodies from separating. The moment_penalty parameter (with units of moment per radians) represents the torsional stiffness that enforces parallelism of the joint axis on the two bodies. The body_a and body_b elements are the material numbers of the two rigid bodies. The joint_origin parameter defines the position of the joint (the origin of the basis \(\left\{ \mathbf{e}_{1},\mathbf{e}_{2},\mathbf{e}_{3}\right\}\)) in world coordinates at the start of the analysis. Note that this point does not have to be inside or on the surface of either of the two bodies. The joint_axis element defines the orientation \(\mathbf{e}_{1}\) of the joint rotation and translation axis in world coordinates at the start of the analysis.

Optionally, the rotation of body b relative to body a may be prescribed using the additional tags

<prescribed_rotation>1</prescribed_rotation>
<rotation lc="1">1.570796327</rotation>

The prescribed_rotation parameter is a flag that indicates that the motion of the joint is prescribed (1 for prescribed, 0 for free). The rotation parameter specifies the amount of rotation (with units of radians) with an optional associated load curve.

Optionally, the translation of body b relative to body a may be prescribed using the additional tags

<prescribed_translation>1</prescribed_translation>
<translation lc="2">10.0</translation>

Optionally, a moment may be prescribed about the joint axis using the additional tag

<moment lc="1">5.e-3</moment>

The moment parameter specifies the magnitude of the moment, with an optional associated load curve. The moment parameter should not be used simultaneously with a prescribed rotation.

Optionally, a force may be prescribed along the joint axis using the additional tag

<force lc="1">2.0</force>

The force parameter specifies the magnitude of the force, with an optional associated load curve. The force parameter should not be used simultaneously with a prescribed translation.

Example:

<rigid_connector type="rigid cylindrical joint" name="Joint03">
  <tolerance>0</tolerance>
  <gaptol>1e-4</gaptol>
  <angtol>1e-4</angtol>
  <force_penalty>1e0</force_penalty>
  <moment_penalty>1e0</moment_penalty>
  <auto_penalty>1</auto_penalty>
  <body_a>1</body_a>
  <body_b>2</body_b>
  <joint_origin>0,0,0</joint_origin>
  <joint_axis>0,0,1</joint_axis>
</rigid_connector>