Copyright 2006 ABAQUS, Inc.
Connection Elements and Connection
Library
Lecture 2
Flexible Multibody Systems with ABAQUS
L2.2
Copyright 2006 ABAQUS, Inc.
Overview
• Introduction
• Defining Connector Elements
• Understanding Connector Sections
• Understanding Connection Types
• Understanding Connector Local Directions
• Rotational Degrees of Freedom at Nodes
• Components of Relative Motion
• Connector Local Kinematics
• Summary of Orientations and Local Directions
Copyright 2006 ABAQUS, Inc.
Introduction
Flexible Multibody Systems with ABAQUS
L2.4
Copyright 2006 ABAQUS, Inc.
Introduction
• General characteristics of connector elements
• Connector elements model discrete (point-to-point) physical connections
between deformable or rigid bodies or can be connected to ground.
• Example: typical connections in automotive suspension systems
Typical connections in automotive suspension
Rack and pinion Control arm
Tie rod Knuckle
Strut
JOIN CYLINDRICAL
AXIAL
CYLINDRICAL LINK
Flexible Multibody Systems with ABAQUS
L2.5
Copyright 2006 ABAQUS, Inc.
Introduction
• Connector elements have relative displacements and rotations that are
local to the element, which are referred to as components of relative
motions (CORM).
• Connector elements impose kinematic constraints. For example:
• Door connected to a frame through a hinge
• Two panels of sheet metal spot welded together
• Constant velocity joints
• Connector elements may include (nonlinear) force-versus-
displacement (or velocity) behavior in their available components of
relative motion.
• Example: muscle force resisting the rotation of a knee joint in a
crash-test occupant dummy model.
• Connector elements can provide comprehensive kinematic and
kinetic output describing the connection.
Flexible Multibody Systems with ABAQUS
L2.6
Copyright 2006 ABAQUS, Inc.
Introduction
• Connector elements are functionally defined by specifying the connection
attributes.
• Connection types
• For example: axial, hinge, weld, constant velocity joints, link,
beam, etc.
• Local connector directions
• Connector behaviors
• Uncoupled or coupled
response
• Linear or nonlinear response
• Elasticity and damping
• Plasticity
• Friction
• Damage and Failure
• Stops and locks
AXIAL connection in a shock absorbing
strut uses a variety of connection behaviors,
including spring, damping and stop
behaviors
AXIAL
Copyright 2006 ABAQUS, Inc.
Defining Connector Elements
Flexible Multibody Systems with ABAQUS
L2.8
Copyright 2006 ABAQUS, Inc.
Defining Connector Elements
• Connector elements are 2-node elements.
• Element type:
• CONN2D2
• Two-dimensional analysis
• Axisymmetric analysis
• CONN3D2
• Three-dimensional analysis
• Both types of element have at most two nodes.
• The position (location, orientation) and motion (displacement, velocity,
acceleration) of the second node on the element are measured relative to
the first node.
Flexible Multibody Systems with ABAQUS
L2.9
Copyright 2006 ABAQUS, Inc.
Defining Connector Elements
• Defining a connector element – Keywords interface
• To connect two points:
*ELEMENT, TYPE=[CONN2D2 or CONN3D2]
element number, first node number, second node number
• Example: Shock absorber
*ELEMENT, TYPE=CONN3D2
101, 11, 12
Simplified connector model of a shock absorber
a
b
1
Flexible Multibody Systems with ABAQUS
L2.10
Copyright 2006 ABAQUS, Inc.
Defining Connector Elements
• To connect a point to ground:
• The ground “node” can be the first or second node on the connector
element.
*ELEMENT, TYPE=name
element number, , node number on the body
or
*ELEMENT, TYPE=name
element number, node number on the body
• The ground node is fixed.
2
Flexible Multibody Systems with ABAQUS
L2.11
Copyright 2006 ABAQUS, Inc.
Defining Connector Elements
• Defining connector geometry – ABAQUS/CAE interface
• Create assembly-level wire features to define
connector geometry in the Interaction module.
• disjoint wires
• chained wires
• wires to ground.
• Click Add to add points
• Tip: two coincident points can be
selected simultaneously by double-clicking
on the location of the points
• Click Delete to delete the selected point pair.
• Click Swap to swap the points of the selected
point pair.
• Tip: the point pair needs to be selected by
click its index number.
Flexible Multibody Systems with ABAQUS
L2.12
Copyright 2006 ABAQUS, Inc.
Defining Connector Elements
• A geometry set including all of the wires can be
created when creating the wire feature.
• The set can be used during the subsequent
selection procedures.
• For example, you can use sets to assign
connector sections, request output, or
prescribe motions.
• Note: Multiple sets can be merged
into a new set using the set merge
feature.
• Assembly-level wire features cannot be modified
directly once created.
• Wires can be removed by selecting Remove
Wires From Feature.
Flexible Multibody Systems with ABAQUS
L2.13
Copyright 2006 ABAQUS, Inc.
Defining Connector Elements
• Example: Truck door hinges
• In this example, hinge connectors connect a
truck door to the truck body.
ABAQUS/CAE interface
Create wire geometry
Keywords interface
Define a connector element
*ELEMENT, TYPE=CONN3D2, ELSET=CONN_DOOR_HINGE
620601, 9000009, 9000010
620602, 9000011, 9000012...
2 nodes per element
RP-2
node
9000010
HINGE connectors
at door hinges
Copyright 2006 ABAQUS, Inc.
Understanding Connector Sections
Flexible Multibody Systems with ABAQUS
L2.15
Copyright 2006 ABAQUS, Inc.
Understanding Connector Sections
• Connector section defines:
• The connection type.
• The local directions associated with the connector’s nodes
• The connector behaviors.
• Note: Details of connector behavior will be discussed in lectures 4
and 5.
• Creating a connector section
*CONNECTOR SECTION, ELSET=name
ABAQUS/CAE interfaceKeywords interface
Flexible Multibody Systems with ABAQUS
L2.16
Copyright 2006 ABAQUS, Inc.
Understanding Connector Sections
• Defining the connection type
• Basic connection components
• Translations
• Rotations
• Assembled connection components
• Combination of basic connection components
Keywords interface
ABAQUS/CAE interface
*CONNECTOR SECTION, ELSET=name
basic connection type,
or
*CONNECTOR SECTION, ELSET=name
assembled connection
Flexible Multibody Systems with ABAQUS
L2.17
Copyright 2006 ABAQUS, Inc.
Understanding Connector Sections
• Example: Truck door hinges – Keywords interface
• Define and assign a connector section
*ELEMENT, TYPE=CONN3D2, ELSET=CONN_DOOR_HINGE
620601,9000009,9000010
620602,9000011,9000012
*CONNECTOR SECTION, ELSET=CONN_DOOR_HINGE
HINGE
...
Assembled connection; one can also use basic
connection types: JOIN and REVOLUTE.
Connector elements
CONN_DOOR_HINGE
(assignment)
Flexible Multibody Systems with ABAQUS
L2.18
Copyright 2006 ABAQUS, Inc.
Understanding Connector Sections
• Example: Truck door hinges – ABAQUS/CAE interface
• Define and assign a connector section
• Define a connector section
Assembled Hinge connection;
one can also use basic connection types:
JOIN and REVOLUTE.
No behavior options are specified (default).
Note: Details will be discussed in lectures 4 and 5.
1
Flexible Multibody Systems with ABAQUS
L2.19
Copyright 2006 ABAQUS, Inc.
Understanding Connector Sections
• Assign a connector section
• Connector section assignment is used to
assign a connector section to a region (wires)
of the model.
Assign the connection section
DOOR_HINGES to the wire
Wire-1-DOOR_HINGES.
2
Copyright 2006 ABAQUS, Inc.
Understanding Connection Types
Flexible Multibody Systems with ABAQUS
L2.21
Copyright 2006 ABAQUS, Inc.
Understanding Connection Types
• Connection types
• The connection-type library contains:
• Translational basic connection components, which affect
translational DOFs at both nodes and may affect rotational DOFs at
the first node of the connector element.
• Rotational basic connection components, which affect only rotational
DOFs at both nodes of the connector element
• Assembled connections, which are a predefined combination of
translational and rotational basic connection components.
• The above choices determine which element local DOFs exist.
• Given the number of connection types available, it is clear that connector
elements can easily be customized to suit an application.
Flexible Multibody Systems with ABAQUS
L2.22
Copyright 2006 ABAQUS, Inc.
• Examples of translational basic connections:
• AXIAL – Provide a connection between two nodes that
acts along the line connecting the nodes.
• CARTESIAN – Provide a connection between two nodes
that allows independent behavior in three local Cartesian
directions.
• JOIN – Join the position of two nodes.
• ACCELEROMETER – Provide a connection between
two nodes to measure the relative acceleration, velocity,
and position of a body in a local coordinate system.
• Available only in 3D analysis in ABAQUS/Explicit.
• Will be converted internally to a CARTESIAN
connector type in ABAQUS/Standard.
b
a
u1
b
a
b
a
AXIAL
JOIN
CARTESIAN
ACCELEROMETER
Understanding Connection Types
Flexible Multibody Systems with ABAQUS
L2.23
Copyright 2006 ABAQUS, Inc.
• Examples of rotational basic
connections:
• REVOLUTE – Provides a
revolute connection between
two nodes.
• CARDAN – Provides a
rotational connection between
two nodes parameterized by
Cardan angles.
• EULER – Provides a rotational
connection between two nodes
parameterized by Euler angles
REVOLUTE
CARDAN
EULER
Understanding Connection Types
Flexible Multibody Systems with ABAQUS
L2.24
Copyright 2006 ABAQUS, Inc.
Understanding Connection Types
Basic rotationalBasic translational
ROTATION-ACCELEROMETERSLOT
ROTATIONSLIDE-PLANE
UNIVERSAL
REVOLUTERADIAL-THRUST
PROJECTION FLEXION-TORSIONPROJECTION CARTESIAN
FLEXION-TORSIONLINK
EULERJOIN
CONSTANT VELOCITYCARTESIAN
CARDANAXIAL
ALIGNACCELEROMETER a
b
1
2
3
φ
a
2
3
b
1
Summary of basic connection types
Flexible Multibody Systems with ABAQUS
L2.25
Copyright 2006 ABAQUS, Inc.
• Examples of assembled connections:
• BEAM – provides a rigid beam connection
between two nodes (JOIN + ALIGN)
• HINGE – joins the position of two nodes, and
provides a revolute connection between their
rotational degrees of freedom (JOIN +
REVOLUTE)
• UJOINT – joins the position of two nodes,
and provides a universal connection between
their rotational degrees of freedom at the
nodes (JOIN + UNIVERSAL)
a
b
BEAM
HINGE
UJOINT
Understanding Connection Types
Flexible Multibody Systems with ABAQUS
L2.26
Copyright 2006 ABAQUS, Inc.
Understanding Connection Types
JOIN
JOIN
SLOT
SLIDE-PLANE
JOIN
SLOT
JOIN
PROJECTION
CARTESIAN
JOIN
Equivalent basic connection components
(translational + rotational)Assembled
ALIGNWELD
UNIVERSALUJOINT
ALIGNTRANSLATOR
REVOLUTEPLANAR
REVOLUTEHINGE
REVOLUTECYLINDRICAL
CONSTANT VELOCITYCVJOINT
PROJECTION
FLEXION-TORSIONBUSHING
ALIGNBEAM
Summary of assembled connection types
Flexible Multibody Systems with ABAQUS
L2.27
Copyright 2006 ABAQUS, Inc.
• More advanced connection types, such as FLOW-CONVERTER,
RETRACTOR and SLIPRING, are also available.
• These connectors are special pulley-type connectors used to model
seatbelt kinematics.
• These connection types will not be discussed here but are discussed
further in Appendix 1.
• Example: Three-point belt model with retractor and pretensioner.
Understanding Connection Types
Video Clip
Video Clip
Copyright 2006 ABAQUS, Inc.
Understanding Connector Local
Directions
Flexible Multibody Systems with ABAQUS
L2.29
Copyright 2006 ABAQUS, Inc.
• Understanding connector local directions
• Orientations are used to define local directions for connection types that
use local directions (local directions may be required or optional)
• The local directions are defined by reference to a local orientation or
coordinate system.
• Example: HINGE connector requires an orientation to be associated
with the first node a.
• The hinge axis is aligned with the orientation X-direction.
(local orientation)
X
Understanding Connector Local Directions
Flexible Multibody Systems with ABAQUS
L2.30
Copyright 2006 ABAQUS, Inc.
• Not all connection type require the local directions (e.g.
LINK).
• In some cases default local directions are chosen (e.g.
CARTESIAN)
• Local directions at the second node are not used by all
connection types.
• Example: SLOT connection
• The line of the slot is defined by the first local
direction at node a and the initial position of
node b. (fig. a)
• The SLOT connection constrains the position
of node b (xb) to remain on the line of the slot.
• Note: different results would be obtained if
different orientations are used for the local
directions. (figs. b, c)
2
1
u1
u1
12
b. Orientation pointing
from node a to node b
c. 45o counterclockwise
rotation of the slot
a. SLOT connection
a
Understanding Connector Local Directions
Flexible Multibody Systems with ABAQUS
L2.31
Copyright 2006 ABAQUS, Inc.
Understanding Connector Local Directions
• The default directions at the second node are the local directions at the
first node.
• It may be necessary to define local directions at the second node to
model the mechanism correctly, e.g. UJOINT.
• In geometrically nonlinear analyses, the element local directions
associated with the nodes rotate with the rotational degrees of freedom
at the nodes.
• A summary of connector local directions will be in the section “Summary
of Orientations and Local Directions” in this lecture.
Flexible Multibody Systems with ABAQUS
L2.32
Copyright 2006 ABAQUS, Inc.
• Defining connector orientation
• Example: Truck door hinges
Z
Y
X
ORI_CONN_DOOR
ABAQUS/CAE interface
Define orientation using a datum
coordinate system
Keywords interface
Define orientation using local CSYS
*ORIENTATION, NAME=ORI_CONN_DOOR
0.,0.,1., 1.,0.,0.
3,0
Understanding Connector Local Directions
Flexible Multibody Systems with ABAQUS
L2.33
Copyright 2006 ABAQUS, Inc.
• Example: Truck door hinges
*ORIENTATION, NAME=ORI_CONN_DOOR
0.,0.,1.,1.,0.,0.
3,0
*ELEMENT, TYPE=CONN3D2, ELSET=CONN_DOOR_HINGE
620601,9000009,9000010
620602,9000011,9000012
*CONNECTOR SECTION, ELSET=CONN_DOOR_HINGE
HINGE
ORI_CONN_DOOR
Connector elements
CONN_DOOR_HINGEKeywords interface
Z
Y
X
ORI_CONN_DOOR
Understanding Connector Local Directions
Flexible Multibody Systems with ABAQUS
L2.34
Copyright 2006 ABAQUS, Inc.
• Specify local orientations for the endpoints of the wires –
ABAQUS/CAE interface.
• Connector section assignment is used to specify local orientations for
the endpoints of the wires.
• Example: Truck door hinges
Z
Y
X
ORI_CONN_DOOR
Understanding Connector Local Directions
Copyright 2006 ABAQUS, Inc.
Rotational Degrees of Freedom at the
Nodes
Flexible Multibody Systems with ABAQUS
L2.36
Copyright 2006 ABAQUS, Inc.
Rotational Degrees of Freedom at the Nodes
• Overview
• In geometrically nonlinear analyses, the element local directions
associated with the nodes rotate with the rotational degrees of
freedom at the nodes.
• In linear or perturbation analyses, the element local directions
remain fixed.
• In cases where an orientation definition is permitted for defining
connection directions (either required or optional), the connector
element will activate rotational degrees of freedom at the nodes if they
do not exist already.
• The only exception is JOIN (will be discussed later).
Flexible Multibody Systems with ABAQUS
L2.37
Copyright 2006 ABAQUS, Inc.
Rotational Degrees of Freedom at the Nodes
• Example: The BEAM connection activates rotational degrees of freedom.
The solid elements do not provide rotational stiffness at these DOFs; the
connector does NOT transmit rotation into the solid.
Flexible Multibody Systems with ABAQUS
L2.38
Copyright 2006 ABAQUS, Inc.
Rotational Degrees of Freedom at the Nodes
• Other connections where an orientation definition is permitted activate
rotational degrees of freedom (e.g. BEAM, …):
• If local directions are used and either the element's nodes do not possess
rotational DOFs or if rotational constraints such as,
• Equations
• Multi-point constraints
• Boundary conditions
are not applied to the nodes, numerical singularities associated with
unconstrained degrees of freedom will exist.
• Solutions:
• Attach the connector element to a structural element.
• Add rotational boundary conditions.
• Use coupling constraints (Recommended)
Flexible Multibody Systems with ABAQUS
L2.39
Copyright 2006 ABAQUS, Inc.
Rotational Degrees of Freedom at the Nodes
• JOIN connection does NOT activate rotational degrees of freedom
• This allows the user to define a join constraint between two solids
expressed only in terms of translations.
• Example 1: Two deformable solids connected by the JOIN connection
type rotate under certain loading and boundary conditions.
• Orientation at node a does not rotate with the rotation of the
deformable body since the solid element does not have rotational
DOFs actived.
Deformable
1
2
X
Y
Z
JOINDeformable
C3D8R C3D8R
Deformable
CLOAD
CLOAD
Deformable
1
2
JOINa
b
Note: The examples discussed here and the next two slides consider geometric nonlinearity.
Flexible Multibody Systems with ABAQUS
L2.40
Copyright 2006 ABAQUS, Inc.
Rotational Degrees of Freedom at the Nodes
• Example 2: Make one solid in Example 1 rigid.
• Orientation at node a rotates with the rotation of the rigid body since
the rigid body has rotational DOFs.
• Node b will move accordingly with node a.
1
2
X
Y
Z
JOINRigid
C3D8R C3D8R
Deformable
CLOAD
CLOAD
1
2 JOI
N
Rigid
Deformable
RP
a
b
Flexible Multibody Systems with ABAQUS
L2.41
Copyright 2006 ABAQUS, Inc.
Rotational Degrees of Freedom at the Nodes
X
Y
Z
JOIN b
2
13
a
Surface-based
coupling constraintDeformable
C3D8R
Deformable
C3D8R 1
2 JOI
N
Deformable
Deformable
CLOAD
CLOAD
• Example 3: Define a surface-based coupling constraint on the surface of
one of the deformable solids in Example 1; choose the reference point
of the surface-based coupling constraint as node a.
• Orientation at node a rotates with the rotation of the deformable
body since the coupling constraint actives rotational DOFs.
• Node b will move accordingly with node a.
Copyright 2006 ABAQUS, Inc.
Components of Relative Motion
Flexible Multibody Systems with ABAQUS
L2.43
Copyright 2006 ABAQUS, Inc.
Components of Relative Motion
• Components of relative motion
• Connector elements have internal DOFs that do not exist at any node,
but are a part of the connector element itself.
• The connector local degrees of freedom, that is, the three translations
and three rotations relative to the connector element local coordinate
system (in three dimensions), are called the components of relative
motion (CORM).
• The three translations are in the element local coordinate directions.
• The three rotations are angular quantities that depend on the
specific connection definition and may or may not be rotations about
orthogonal directions.
• All components of relative motion are either constrained or available.
• The definitions of constrained and available components of relative
motion will be discussed in next two slides, respectively.
Flexible Multibody Systems with ABAQUS
L2.44
Copyright 2006 ABAQUS, Inc.
Components of Relative Motion
• Constrained components of relative motion
• Constrained components of relative motion are displacements and
rotations that are fixed by the connector element.
• ABAQUS/Standard uses Lagrange multipliers to enforce the kinematic
constraints.
• The constraint forces and moments carried by the element appear
as ad
本文档为【connector-element-connection-library】,请使用软件OFFICE或WPS软件打开。作品中的文字与图均可以修改和编辑,
图片更改请在作品中右键图片并更换,文字修改请直接点击文字进行修改,也可以新增和删除文档中的内容。
该文档来自用户分享,如有侵权行为请发邮件ishare@vip.sina.com联系网站客服,我们会及时删除。
[版权声明] 本站所有资料为用户分享产生,若发现您的权利被侵害,请联系客服邮件isharekefu@iask.cn,我们尽快处理。
本作品所展示的图片、画像、字体、音乐的版权可能需版权方额外授权,请谨慎使用。
网站提供的党政主题相关内容(国旗、国徽、党徽..)目的在于配合国家政策宣传,仅限个人学习分享使用,禁止用于任何广告和商用目的。