rigid planar joint

Module: solid

Category: nlconstraint

Type string: "rigid planar 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}	[]
rotation_axis	rotation_axis	{0,0,0}	[]
translation_axis_1	translation_axis_1	{0,0,0}	[]
minaug	minaug	0	[]
maxaug	maxaug	10	[]
prescribed_rotation	prescribed_rotation	false	[]
rotation	rotation	0	[]
prescribed_translation_1	prescribed_translation_1	false	[]
translation_1	translation_1	0	[]
prescribed_translation_2	prescribed_translation_2	false	[]
translation_2	translation_2	0	[]
auto_penalty	auto_penalty	false	[]

Description

A rigid planar joint connects rigid bodies \(a\) and \(b\), allowing one degree of freedom for rotation about the axis \(\mathbf{e}_{1}\) through that point, and two degrees of freedom for translations in the plane perpendicular to that axis, along \(\mathbf{e}_{2}^{a}\) and \(\mathbf{e}_{3}^{a}\).

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 parameter defines the tolerance for angular separation of the joint axes 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 along the rotation axis. The moment_penalty parameter (with units of moment per radians) represents the torsional stiffness that enforces parallelism of the joint rotation axis on the two bodies. The body_a and body_b elements are the material numbers of the two rigid bodies. The joint_origin element 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 rotation_axis parameter defines the orientation of the joint rotation axis \(\mathbf{e}_{1}\) in world coordinates at the start of the analysis. The translation_axis_1 element defines the orientation of the joint translation axis \(\mathbf{e}_{2}^{a}\) in the plane perpendicular to the joint rotation 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 element 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 along \(\mathbf{e}_{2}^{a}\) using the additional tags

<prescribed_translation_1>1</prescribed_translation_1>
<translation_1 lc="2">10.0</translation_1>

Optionally, the translation of body b relative to body a may be prescribed along \(\mathbf{e}_{3}^{a}\) using the additional tags

<prescribed_translation_2>1</prescribed_translation_2>
<translation_2 lc="2">10.0</translation_2>

Example:

<rigid_connector type="rigid planar joint" name="Joint01">
  <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>
  <rotation_axis>0,-0.5,0.8660254</rotation_axis>
  <translation_axis_1>1,0,0</translation_axis_1>
</rigid_connector>