Building Models in ADAMS/View - Mechanical and Mechatronics

512 Pages·2000·4.04 MB·English

Building Models in
ADAMS/View
About This Guide 3
About Parts 5
Creating Parts 17
Modifying Parts 79
About Constraining Your Model 125
Working with Joints 139
Applying Motion 177
Applying Forces to Your Model 195
Working with Contacts 271
Storing and Accessing Data 315
Using System Elements to Add Equations 365
Editing Modeling Objects 391
Positioning and Rotating Objects 439
2 Building Models in ADAMS/View
Copyright
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All other product names are trademarks of their respective companies.
Part number: 110VIEWBM-01
Building Models in ADAMS/View 3
About This Guide
About This Guide
Welcome to ADAMS/View
ADAMS/View is a powerful modeling and simulating environment that lets you
build, simulate, and refine models of mechanical systems.
This guide explains how build models in ADAMS/View. It assumes you know the
basics of using ADAMS/View. For an introduction to ADAMS/View, see the guide,
Getting Started Using ADAMS/View.
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About This Guide
1 About Parts
Overview
Parts define the objects in your model that can have mass and
inertia properties and can move. All forces and constraints that
you define in your model act on these parts during a simulation.
This chapter explains how to create and modify parts. It
contains the following sections:
(cid:1) Overview of ADAMS/View Parts, 6
(cid:1) Before You Begin Creating Parts, 9
(cid:1) About Rigid Bodies, 10
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About Parts
Overview of ADAMS/View Parts
ADAMS/View provides a complete library of parts that you can create. The following
sections explains more about ADAMS/View parts.
(cid:1) Types of Parts, 6
(cid:1) About the Ground Part, 7
(cid:1) Local Coordinate Systems, 7
(cid:1) Degrees of Freedom for Parts, 8
(cid:1) Part Naming Conventions, 8
Types of Parts
ADAMS/View provides you with three different types of parts that you can create:
(cid:1) Rigid Bodies - Parts in your model that have mass and inertia properties.
They cannot deform.
(cid:1) Flexible Bodies - Parts that have mass and inertia properties and can bend
when forces are applied to them. Basic ADAMS/View provides you with
the ability to create discrete flexible links. For more functionality, you can
purchase ADAMS/Flex. For information on purchasing ADAMS/Flex, see
your MDI sales representative, and for information on using ADAMS/Flex,
refer to the guide, Using ADAMS/Flex.
(cid:1) Point Masses - Parts that have only mass. They have no extent and,
therefore, no inertia properties.
In addition, ADAMS/View provides a ground part that is already created for you.
Building Models in ADAMS/View 7
About Parts
About the Ground Part
The ground part is the only part in your model that must remain stationary at all times.
ADAMS/View creates the ground part automatically when you create a model. The
ground part does not have mass properties or initial velocities and does not add
degrees of freedom into your model. (For more on degrees of freedom, see Constraints
and Degrees of Freedom on page128.)
The ground part acts as the global coordinate system that defines the global origin
(0,0,0) and axes about which you create your model. You cannot specify its position.
You can add geometry to the ground part.
In addition, by default, the ground part also acts as the inertial reference frame with
respect to which all of the part velocities and accelerations are calculated. You can
also select another part as the inertial reference frame. You can select another part
through the Command Navigator.
Note that although the ground part is the only part in your model that must remain
stationary at all times, you can move the geometry and constraints attached to the
ground part. Since geometry and constraints are tied to markers, you can use the Select
List Manager to select all the markers on ground and then translate and rotate the
ground entities with the rest of your model. For information on selecting objects, see
Selecting and Deselecting Objects on page392, and for information on moving
objects, see Positioning and Rotating Objects on page439.
Local Coordinate Systems
As you create parts, ADAMS/View assigns a coordinate system to each part, known
as its local coordinate system. A part’s local coordinate system moves with the part
and its original position defaults to that of the global coordinate system.
The local coordinate system is a convenient way to define the position and location of
objects. ADAMS/View also returns simulation results, such as the position of a part,
as the displacement of a part’s local coordinate system with respect to the global
coordinate system. It returns object results, however, as the displacement of a part’s
center of mass relative to the global coordinate system.
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About Parts
Degrees of Freedom for Parts
Each rigid body that you create can move within all degrees of freedom; a point mass
can move within three translational degrees of freedom. You can constrain the
movement of parts by:
(cid:1) Adding them to the ground part, which means they are fixed to the ground
and cannot move in any direction. Each time you create geometry,
ADAMS/View gives you the option to add it to ground, create a new part,
or add it to an existing part.
(cid:1) Adding constraints, such as joints, to define how the parts are attached and
how they move relative to each other. For more on adding constraints and
limiting the movement of parts, see Working with Joints on page139.
Part Naming Conventions
As you create parts, ADAMS/View automatically generates names for them based on
their type and the number of objects of that type in your model. For example, when
you create a point mass, ADAMS/View names it POINT_MASS_1. For all rigid
bodies, except points and coordinate system markers, ADAMS/View uses the name
PART regardless of the type of geometry. For example, if you create a box,
ADAMS/View names it PART_1. When you create a second box, ADAMS/View
names it PART_2, and so on. You can rename your parts. For more information, see
Renaming Objects on page425.
Building Models in ADAMS/View 9
About Parts
Before You Begin Creating Parts
Before you begin creating the parts of your model, you might want to take some time
to set up your modeling environment and learn some drawing and placement
techniques. To help you place parts accurately, do the following, which are outlined
in the guide, Learning ADAMS/View Basics:
(cid:1) Turn on the working grid so that the points snap to a grid. In addition,
ADAMS/View draws objects parallel to the current working grid so by
displaying it you can better see how your objects are being drawn. For
information on displaying the working grid, see Setting Up the Working
Grid on page127.
(cid:1) Display the coordinate window so that you can view the coordinate values
as you place points. For more information, see Working with the Coordinate
Window on page124.
(cid:1) Be sure to set the current units to those required for your model. See
Specifying the Type of Coordinate System on page30.
(cid:1) Review the different tools for drawing and placing objects in Techniques
for Creating and Placing Objects on page191.
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About Parts
About Rigid Bodies
The most common type of part in your model is a rigid body. Rigid bodies are parts
that cannot deform. They are physical objects in which the distance between any two
points within the body remains constant. The rigid body can move relative to other
parts and can be used as a reference frame to measure another part’s velocity or
acceleration. ADAMS/View provides a library of geometry that you can use to create
rigid bodies.
In ADAMS/View, you create rigid bodies by drawing the geometric objects that
represent them. A part can be made up of many different geometric objects.
ADAMS/View calculates the mass and inertia of the rigid body based on its solid
geometry and its material type, which is steel by default. You can modify the default
properties for the part and change how ADAMS/View calculates the mass and inertia
of a solid rigid body. For more information, see Modifying Parts on page79.
The next sections explain more about creating rigid bodies:
(cid:1) Ways to Create Rigid Bodies, 11
(cid:1) Building Parameterization into Your Model as You Create Parts, 11
(cid:1) Types of Rigid Body Geometry, 13
(cid:1) Accessing the Geometric Modeling Tools, 14