Transcript
7/28/2019 Adams Solver Guide
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VERSION 12.0
PART NUMBER
120BSOLTR-01
Visit us at:www.adams.com
Basic ADAMS/SolverTraining Guide
http://www.adams.com/http://www.adams.com/7/28/2019 Adams Solver Guide
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U.S. Government Restricted Rights: If the Software and Documentation are provided in connection with a
government contract, then they are provided with RESTRICTED RIGHTS. Use, duplication or disclosure issubject to restrictions stated in paragraph (c)(1)(ii) of the Rights in Technical Data and Computer Software
clause at 252.227-7013. Mechanical Dynamics, Incorporated, 2300 Traverwood Drive, Ann Arbor, Michigan
48105.
The information in this document is furnished for informational use only, may be revised from time to time,
and should not be construed as a commitment by Mechanical Dynamics, Incorporated. Mechanical
Dynamics, Incorporated, assumes no responsibility or liability for any errors or inaccuracies that may
appear in this document.
This document contains proprietary and copyrighted information. Mechanical Dynamics, Incorporated
permits licensees of ADAMSsoftware products to print out or copy this document or portions thereof
solely for internal use in connection with the licensed software. No part of this document may be copied for
any other purpose or distributed or translated into any other language without the prior written permission of
Mechanical Dynamics, Incorporated.
2002 by Mechanical Dynamics, Incorporated. All rights reserved. Printed in the United States of America.
ADAMSis a registered United States trademark of Mechanical Dynamics, Incorporated.
All other product names are trademarks of their respective companies.
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3
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About Mechanical Dynamics 8
Content of Course 9
Getting Help at Your Job Site 10
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Virtual Prototyping Process 12
Basic ADAMS/Solver Course 13
Four File Types in ADAMS/Solver 14
ADAMS/Solver Dataset File 15
ADAMS/Solver Command File 16
ADAMS/Solver Analysis Files 17
ADAMS/Solver Message File 18Simulating a Model in ADAMS/Solver 19
Workshop 1Process Overview 20
9LHZLQJ5HVXOWV25
PostProcessing Interface Overview 26
Animating 27
Plotting 28
Getting Help 29
Workshop 2Viewing Results 30
)DOOLQJ6WRQH41
System-Level Design 42
Coordinate Systems 43
Part Coordinate System 44
Coordinate System Marker 45
Differences Between Parts and Graphics 46
Parts, Graphics, and Markers 47
Types of Parts in ADAMS 48Part Properties (Mass and Inertia) 49
Graphic Properties 50
Workshop 3Falling Mass 51
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4 Content
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Constraints 58
Use of Markers in Constraints 59
Three-Point Orientation Method 61
Degrees of Freedom (DOF) 62
Workshop 4One DOF Pendulum 63
/LQHDU6SULQJ'DPSHU,69
Initial Condition Simulation 70
Types of Simulations 71
Simulation Hierarchy 72
Forces in ADAMS 73
Spring Dampers in ADAMS 74
Magnitude of Spring Dampers 75
Workshop 5Spring Damper I 76
/LQHDU6SULQJ'DPSHU,,81
Single-Component Forces: Action-Reaction 82
Functions in ADAMS 83
Measuring Displacement (Functions continued) 84
Measuring Velocity (Functions continued) 85
Workshop 6Spring Damper II 86
%UDNH6\VWHP,91Applying Motion 92
STEP Function 93
REQUESTing Measurement Data 94
Workshop 7Brake System I 95
%UDNH6\VWHP,,105
Multi-Component Forces 106
Incorporating Test Data (Splines) 108
AKISPL Function 109Workshop 8Brake System II 110
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Contents
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%UDNH6\VWHP,,,117
Design Study: Quasi-static 118
Workshop 9Brake System III 119
6XVSHQVLRQ125
Bushings 126
Workshop 10Suspension 127
%RXQFLQJ%DOO143
Modeling Contact: IMPACT Function 144
Workshop 11Bouncing Ball 146
7DEOHV153
Constraints Tables (Incomplete) 154
Forces Tables (Incomplete) 155Constraint Tables (Complete) 156
Forces Tables (Complete) 157
Mass Moments of Inertia 158
6DPSOH'DWDVHWV161
.acf files 162
ball.adm file 163
brake.adm file 164
susp1.adm file 165
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ADAMS is a powerful modeling and simulating environment that lets you
build, simulate, refine, and ultimately optimize any mechanical system, from
automobiles and trains to VCRs and backhoes.
Basic ADAMS/Solver training teaches you how to build, simulate, and refine
a mechanical system using Mechanical Dynamics, Inc.s ADAMS/Solver and
ADAMS/PostProcessor.
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About Mechanical Dynamics, 8
Content of Course, 9
Getting Help at Your Job Site, 10
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8/1118 Welcome to Basic ADAMS/Solver Training
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http://www.adams.com/mdi/product/partner.htm
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http://support.adams.com/training/training.html
Or your local support center
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9/111Welcome to Basic ADAMS/Solver Training 9
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Build simple ADAMS models.
Understand ADAMS product nomenclature and terminology.
Understand basic modeling principles.
Use the crawl-walk-run approach to virtual prototyping.
Debug your models for the most common modeling challenges (for example,
redundant constraints, zero masses, and so on).
Use and be informed about all methods of ADAMS product support.
Use the product documentation optimally.
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This guide is organized into modules that get progressively more complex. Each module
focuses on solving an engineering-based problem and covers mechanical system simulation
(MSS) concepts that will help you use ADAMS most optimally. The earlier workshops provide
you with more step-by-step procedures and guidance, while the later ones provide you with less
Each module is divided into the following sections:
1 Problem statement
2 Concepts
3 Workshop
4 Module review
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12/11112 Virtual Prototyping with ADAMS
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Build
Test
Validate
Refine
Iterate
Automate
...a model of your design usingBodies ForcesContacts Joints
Motion generators
...your design usingMeasures AnimationsSimulations Plots
...your model byImporting test data
Superimposing test data
...your model by addingFriction Forcing functionsFlexible partsControl systems
...your design throughvariations usingParametricsDesign variables
Validate
Refine
Iterate
Do resultscompare withmeasureddata?
DESIGNPROBLEM
Cut timeand costs
Increasequality
Increaseefficiency
IMPROVEDPRODUCT
...your design usingDOEsOptimization
...your design process usingCustom menusMacrosCustom dialog boxes
Optimize
Automate
No
Yes
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Build(design) a virtual prototype of a mechanical system using an ADAMS dataset
file.
Testyour mechanical system using ADAMS/Solver.
Validate (review) the results of your output files using ADAMS/PostProcessor.
Build
Test
Validate
...a model of your design usingBodies Forces
Contacts JointsMotion generators
...your design usingMeasures AnimationsSimulations Plots
...your model by
Importing test dataSuperimposing test data
Validate
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ADAMS dataset
.adm .req
Analysis files
.res
.gra
.out
Command file
.acf
1 - Build (Input) 3 - Validate (Output)
Message file
.msg
2 - Test (ADAMS/Solver)
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Statements define an element of a model, such as a part, constraint, or force.
Functions are a numeric expression that define the magnitude of an element, such as
force or motion.Sample .adm file
FunctionStatement
TITLE LINE
!-------------------------------- SYSTEM UNITS --------------
UNITS/FORCE = NEWTON, MASS = KILOGRAM, LENGTH = MILLIMETER,
,TIME = SECOND
!
PART/1, GROUND
!
MARKER/5, PART = 1, QP = 175, -225, 0
!
PART/2, MASS = 70.94, CM = 3, IP = 2.01E+006, 1.80E+005
, 2.01E+006, MATERIAL = steel
!
MARKER/2, PART = 2, REULER = 37.87498365D, 90D, 0D
!
MARKER/3, PART = 2, QP = 175, -225, 0, REULER = 37.87498365D, 0D, 0D
!
GRAPHICS/1, CYLINDER, CM = 2, LENGTH = 570.08, RADIUS = 71.26
!
JOINT/1, REVOLUTE, I = 4, J = 1
!
REQUEST/1, DISPLACEMENT, I = 3, J = 5, RM = 5
ACCGRAV/JGRAV = -9806.65
OUTPUT/REQSAVE, GRSAVE
RESULTS/
!
MOTION/1, ROTATIONAL, JOINT = 1, FUNCTION = 30.0d * time
!
END
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Commands are actions that you issue during an analysis to make changes to your
model or analysis settings.
You can enter commands interactivelyone at a timeor you can enter them from acommand file.
Sample .acf file
model_name.adm
output_name
SIMULATE/STATIC
SIMULATE/DYNAMIC, END=3.0, STEPS=30DEACTIVATE/JOINT, ID=3
SIMULATE/DYNAMIC, DURATION=2.0, STEPS=200
STOP
Command
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The output corresponds to these statements in your dataset: REQUEST, RESULT, GRAPHICS,
and OUTPUT.
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Key system measurements:
toe angle or displacement in a local markers coordinate system.
Data for plotting in ADAMS/PostProcessor.
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Default calculations in Global Coordinate System:
part displacements and constraint reaction forces
Data for plotting in ADAMS/PostProcessor.
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Data for animating in ADAMS/PostProcessor.
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Tabular output of request data.
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Warning messages
Error messages
Excerpts from a .msg file
---- WARNING ----
IP data specified for PART test.PAR5200 is not physically
meaningful, since it does not satisfy the requirement
that Iyy + Izz must be greater than or equal to Ixx.
The moments of inertia about the Center of Mass are:
Ixx = 500.80, Iyy = 115.29, Izz = 98.147
---- ERROR ----
The simulation stopped at time = 7.82641E-02.
ADAMS cannot solve the equations of motion.
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Non scripted: lets you enter commands one by one.
Scripted: lets you enter commands from the command file (.acf).
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Runs multiple jobs using a log file and one or more command files (.acf).
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UNIX shell (what you might type to simulate)
NT DOS shell (what you might type to simulate)
adams12 -c
ru-standard
interactive
my_file.acf
adams12
ru-standard
my_file.acf
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Simulate a dynamic model and review the associated output files.
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The model you will use in this workshop represents a quarter-front, short-long-arm (SLA) car
suspension.
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1 Open a UNIX shell and enter the commands to locate and change to your working
directory.
Use the ls command to review a list of files and directories.
Use the cd command to change from one directory to another.
For example, to change your location from the directory, bso_exercises, to mod_01_intro,
enter the following:
cd bso_exercises
lscd mod_01_intro
ls
2 Once you have located your working directory, enter the command to start ADAMS, for
example, adams12 -c.
A text menu appears inside of your command shell window.
At your site, your systems administrator determines the alias to start ADAMS/Solver.In class, ifadams12 -c does not launch ADAMS/Solver, see your class instructor for thecorrect command.
3 Enter ru-standard (or use the shortcut ru-s) to run standard ADAMS/Solver.
4 Enter interactive (or use the shortcut i)to run ADAMS/Solver in interactive mode.Skip to Step 1 in Simulating your model on page 23.
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1 Do one of the following:
From the Start menu, point to Programs, and then select Command Prompt.
The Command Prompt window appears.
From the Start menu, select Run and enter cmd.
The Command Prompt window appears.
2 Enter the commands to locate and change to your working directory.
Use the dir command to display your list of files and directories.
Use the cd command to change from one directory to another.
For example, to change your location from the directory, bso_exercises, to mod_01_intro,
enter the following:
cd bso_exercises
dir
cd mod_01_intro
dir
3 Once you have changed to your working directory, enter the command to start ADAMS,for example, adams12.
A text menu appears inside of your Command Prompt window.
At your site, your systems administrator determines the alias to start ADAMS/Solver.In class, ifadams12 does not launch ADAMS/Solver, see your class instructor for thecorrect command.
4 Enter ru-standard (or use the shortcut ru-s) to run standard ADAMS/Solver.
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1 Enter the name of the ADAMS command file sla.acf.
The command file gives ADAMS/Solver instructions on how to simulate your model, for
example, it defines the run time and type of simulation.
2 Enter exit to close the ADAMS menu.
3 To list the files that are in your working directory, enter ls on UNIX or dir on NT.
Your directory should contain more files than before you ran the simulation.
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Quickly set up and run a simulation entering all of the necessary commands on one
line. For example, from a UNIX prompt, enter:
adams12 -c ru-s i sla.acf exit
17RSWLRQDOWDVNV
Quickly set up and run a simulation entering all of the necessary commands on one
line. For example, from a command prompt, enter:
adams12 ru-s sla.acf
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1 What are the three categories of syntax used in the ADAMS language?
________________________________________________________________________
2 Which two out of the three are used in the .adm file?
________________________________________________________________________
3 Which two out of the three are used in the .acf file?
________________________________________________________________________
4 In this course, we are going to use ADAMS/Solver to process the results and ADAMS/
PostProcessor to view the results. What are we going to use as a pre-processor?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
5 When you use ADAMS after this course, you will probably be using a pre-processor (that
is, ADAMS/Pre, ADAMS/View, ADAMS/Car, and so on). Why, then, do you need to
learn how to write .adm and .acf files on your own?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
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In this module you will use ADAMS/PostProcessor to manipulate, review, and
refine the results of the suspension model you simulated in the previous module
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PostProcessing Interface Overview, 26
Animating, 27
Plotting, 28
Getting Help, 29
Workshop 2Viewing Results, 30
Module review, 40
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Animation
Plotting
([DPSOH
The tools in the Main toolbar change if you load an animation or a plot into the viewport
The elements shown above are common to both modes.
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Viewport
Reset, Rev, Pause,Animation settings
Slider barDashboard
Treeview
Property
editor
Main toolbar
Fwd, Record
categories
Mode type
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Viewport
List of simulation results
Types of List of requests/ Manage
results to curves
be displayed
Treeview
Property
editor
Main toolbar
results
Mode type
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Use ADAMS/PostProcessor to manipulate, review, and refine the results of the suspension
model you simulated in the previous module.
0RGHOGHVFULSWLRQ
This model represents a quarter-front, short-long-arm (SLA) car suspension.
You can use the files you generated in Module 1, or use the ones in the directory,exercise_dir/mod_02_view_results.
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1 Go to the directory where your analysis files are stored.
If youre using the files you generated, the directory should be mod_01_intro.
If youre using the files we provided for you, the directory should be
mod_02_view_results.
2 Open the ADAMS Selection menu.
For UNIX, enter adams12 -c.
For NT, enter adams12.
The ADAMS Selection Menu appears.
3 At the command line, enter appt.
The ADAMS/PostProcessor Main window appears.
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ADAMS/PostProcessor has two modes: animation and plotting. It switches its modes
automatically depending on the contents of the active viewport. For example, the tools in the
Main toolbar change if you load an animation or a plot into the viewport.
Figure 1 on page 31 shows a conceptual sketch of the ADAMS/PostProcessor window. The
elements shown are common to both modes.
Figure 1. ADAMS/PostProcessor Window
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1 From the File menu, point to Import, and then select AnalysisFiles.
The File Import dialog box appears.
2 Right-click the File Name text box, and then select Browse.
The Select File dialog box appears.
3 Select any one of the files that starts with sla_output.
4 In the Select File dialog box, select OK.
5 In the File Import dialog box, select OK.
The graphics representing the initial conditions of your simulation appear in the viewport
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Adjust your view of the model on your screen using the tools above the viewport. The
figure below highlights some of the tools that are available. Try experimenting withthe rotate, zoom, and translate tools.
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Play an animation of your model using the tools that are located above the viewport
and in the dashboard. Experiment with the play and pause tools.
Select
Dynamic Rotate
Dynamic TranslateCenter
View Zoom
View Fit
Front View
Reset Animation
Play Animation Backward
Pause Animation
Play Animation
Record Animation
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Select the View tab in the dashboard.
Your view options appear below the View button.
Experiment with the options that are available.
7RFKDQJHWKHFRORURIWKHZKHHO
1 From the treeview, expand the model by clicking on the + sign.
2 Select PART_5, which is the wheel.
3 Below the treeview, in the property editor, select the arrow next to the Color text box.
4 Select Coral for the color setting.
7RHQODUJHWKHJUDSKLFVWKDWLOOXVWUDWHIRUFH
1 From the Edit menu, select Preferences.
The PPT Preferences dialog box appears.
2 In the Force Scale text box, enter a value that is greater than 1, and then select Enter.
3Experiment with changing the scale of the force graphics.
7RPDNHPRUHJUDSKLFHQKDQFHPHQWV
1 From the same PPT Preferences dialog box, select the Geometry tab, and check the Graphics
Endcaps box.
Selecting the box adds endcaps to cylinders.
2 Change the view from shaded to wireframe.
3 On the top tool bar, select Wireframe/shaded.
Icon Visibility
Wireframe/shaded
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1 Create a new page by clicking the Create a New Page tool above the viewport.
You should now have two pages in your session.
2 Change the viewport to plotting by right-clicking in the viewport, and choosing Load Plot
from the pop-up menu.
Notice how the dashboard changes from animation tools to plotting tools.
3 Create a plot on this page by doing the following:
From the Simulation list, select the only simulation in your session, sla_output.
From the Request list, select REQUEST_2.
From the Component list, select X.
Below the Independent Axis: heading, make sure Time is selected.
Select Add Curves.
Create a New Page
Delete a PagePrevious Page
Next Page
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Notice the dashboard settings in the following figure:
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1 Go back to page_1 in ADAMS/PostProcessor.
2 Split the screen by right-clicking on the Page Layout tool above the viewport and choosing
the Split Screen tool.
3 Set the new viewport to Plotting by right-clicking in the viewport and choosing Load Plot
from the pop-up menu.
4 Plot Toe Angle vs. Vertical Wheel Position by doing the following:
In the Simulation list, select the only simulation in your session, sla_output.
In the Request list, select REQUEST_2.
In the Component list, select X.
Below the Independent Axis: heading, toggle Data.
The Independent Axis Browser appears.
In the Request list, select REQUEST_1.
In the Component list, select Z.
Select OK.
Select Add Curves.
Split Screen
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1 From the Help menu, select ADAMS/PostProcessor Guide.
2 Search for the phrase plot statistics and see where it leads you.
If you are unable to find the phrase ask the instructor for help.
3 Use the plot statistics toolbar to find the maximum Toe Angle value.
4 Once you find the maximum toe angle value, use it to answer Question 1 in Module
review on page 40.
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1 Left-click the viewport that contains your graphics so the dashboard changes to animation
tools.2 Play an animation.
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1 Modify the plot title by doing the following:
In the treeview, expand page_1 by clicking the + sign.
Select plot_2.
Clear the selection ofAuto Title.
In the Property Editor below, enter the title Toe Angle vs. Wheel Height.
Select Enter.
2 Label the vertical axis as Toe Angle (radians) by doing the following:
In the treeview, expand the plot by clicking the + sign.
select vaxis.
In the Property Editor below, toggle Labels.
Change the label from NO UNITS to Toe Angle (radians).
3 Modify the legend text by doing the following:
In the treeview, select curve_1.
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In the Property Editor, change the Legend text box to sla_output.
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1 Save your session by doing the following:
From the File menu, select Save As.
Name your file in the File Name text box.
Select OK.
This saves the results from your entire session in one file.
2 Exit ADAMS/PostProcessor by doing the following:
From the File menu, select Exit.
Select Exit, Dont Save.
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1 What was the maximum toe angle value?
________________________________________________________________________
2 What is the difference between the two search tools (the ones with the binoculars)
available in Adobe Acrobat Reader, which is the software we use to view the online
users guides?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
3 To view an animation, which file type will you need to import?
________________________________________________________________________
4 Both the results (.res) and the request (.req) file can be imported and used to plotinformation. What is the difference between the results (.res) and the request (.req) files?
(You may need to refer back to Virtual Prototyping with ADAMS on page 11 for help on
this.)
________________________________________________________________________
________________________________________________________________________
_______________________________________________________________________
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41/1114
)$//,1*6721(
Find the displacement, velocity, and acceleration of a lumped mass after one
second, when it falls under the influence of gravity, with zero initial velocity
:KDWVLQWKLVPRGXOH
System-Level Design, 42
Coordinate Systems, 43
Part Coordinate System, 44
Coordinate System Marker, 45
Differences Between Parts and Graphics, 46
Parts, Graphics, and Markers, 47
Types of Parts in ADAMS, 48
Part Properties (Mass and Inertia), 49
Graphic Properties, 50
Workshop 3Falling Mass, 51
Module review, 56
g
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Do not build the entire mechanism at once.
As you add a new component, make sure that it works correctly.
Check your model at regular intervals.
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A coordinate system is essentially a measuring stick to define kinematic and dynamic
quantities.
7\SHVRIFRRUGLQDWHV\VWHPV
Global coordinate system (GCS):
Rigidly attaches to the ground part.
Defines the absolute point (0,0,0) of your model and provides a set of axes
that is referenced when creating local coordinate systems.
Local coordinate systems (LCS):
Part coordinate systems (PCS)
Markers
Point O
Point P
zG
RR Rxx Ryy Rzz+ +=
xG
yG
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Only one exists per part.
Location and orientation is specified by providing its location and orientation with
respect to the GCS.
For the purpose of this class, and because most pre-processors do so, it is recommended that
each parts PCS has the same location and orientation as the GCS.
Global coordinate system
Part coordinate systemPart 1 at location (10, 5.5, 0)
ground body at location (0, 0, 0)
10
5.5
xG
yG
zG
xP1
yP1
zP1
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It attaches to a part and moves with the part.
Several can exist per part.
Its location and orientation can be specified by providing its location and orientation
with respect to PCS.
It is used wherever a unique location needs to be defined. For example:
The location of a parts center of mass.
The reference point for defining where graphical entities are anchored.
It is used wherever a unique direction needs to be defined. For example:
The axes about which part mass moments of inertia are specified.
Directions for constraints.
Directions for force application.
All marker locations and orientations are expressed in PCS.
Part coordinate systemMarker 1 on Part 1at location (-5, -1, 0)
Part 1 at location (10, 5.5, 0)-5-1
xG
yG
zG
xP1
yP1
zP1
Ground Body at location (0, 0, 0)
xM1
yM1
zM1
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To understand the relationship between parts, graphics, and markers in ADAMS, it is
necessary to understand the dependencies shown next:
MARKER/Corner Marker
(CM)
MARKER/Center Marker
(CM)
GRAPHIC/BLOCK
MARKER/Center of Mass
(CM)
GRAPHIC/CYLINDER
PART/
CYLINDER
BLOCK
PART
CM
GRAPHIC CMs
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Must exist in every model.
Defines the GCS and the global origin and, therefore, remains stationary at all times.
Acts as the inertial reference frame for calculating velocities and acceleration.
Are movable parts.
Possess mass and inertia properties.
Cannot deform.
Are movable parts.
Possess mass and inertia properties.
Can bend when forces are applied to them.
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Provide the mass for a rigid body.
Provide the inertia matrix for a rigid body.
Assign mass to a marker that represents the parts center of mass (CM).
Assign inertia to a marker about which the moments of inertia are defined (CM or
IM).
([DPSOH
PART/20, MASS = 63.71, CM = 2000, IP = 1.50E5, 1.68E6, 1.68E6
MARKER/2000, PART = 20, QP = -75, 200, 0
ADAMS willnot use the dimensions of the graphics to define the mass and inertia.
No IM marker was defined in this example, therefore, the CMs orientation is
referenced for inertia.
Inertia can be calculated for some simple shapes using the Mass Moments of Inertia
sheet in Tables on page 153.
Many pre-processors leave the QG argument out of the statement (as seen above),
which is the equivalent to it being all zeros.
X
Z
YMARKER/2000
(center of mass)
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Define the shape type (cylinder, circle, and so on).
Provide the dimensions for the chosen shape.
Assign graphic to a marker, which defines:
which part the graphic will follow
the location of the graphic
the orientation of the graphic
([DPSOH&
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Find the displacement, velocity and acceleration of a lumped mass after one second, when it
falls under the influence of gravity, with zero initial velocity.
MASS
g
mass=1kg
radius=50mm
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1 Go to the/mod_03_falling_stone directory.
2 Open a text editor to create a new file.
UNIX: Use jot or vi.
NT: Use Notepad or WordPad.
3 Define the title by entering ! Falling Stone Model on the first line of the dataset.
4 Define the units by entering UNITS/.
To get help with the various statements, go to the ADAMS online documentation, andopen the guide, Using ADAMS/Solver.
5 Define the acceleration due to gravity for the model by entering ACCGRAV/.
6 Create the ground part by entering PART/.
7 Create the stone part by entering PART/, and defining the mass, inertia, and location of
center of mass.
The inertia can be calculated using the Mass Moments of Inertia sheet in Tables on
page 153.8 Define the location of the center of mass to be at the global origin by entering MARKER/.
9 Create a circle graphic to represent the stone by entering GRAPHICS/.
Use the CM marker for the part and the CM marker for the graphic.
10 Generate a graphics (.gra) file for animating later by entering OUTPUT/GRSAV.
11 Generate a results (.res) file for plotting later by entering RESULTS/.
12Signify that this is the end of the dataset by entering END.
13 Save the file as stone.adm in the mod_03_falling_stone directory.
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In this section, you will create a command file (*.acf) to dynamically simulate the model for
1 second with 100 output steps.
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1 Open a text editor.
2 Enter stone.admas the first line of the command file.
This is the name of the .adm file you are going to simulate.
3 Enter stone_output as the second line of the command file.
This is the name that you want assigned to your output files.
4 Enter SIMULATE/DYNAMICS, END=1, STEPS=100 as the third lineof your command file.
To get help with the various commands, go to the ADAMS online documentation.
5 Enter STOP to signify the end of the commands.
6 Save the file as stone.acf.
7 Run the simulation.
Ensure that the file was simulated properly (no errors or unexpected warning messages).
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1 Open ADAMS/PostProcessor.
2 Import the stone_output Solver analysis files (.req, .res, .gra).
Because you did not generate a .req file, ADAMS/PostProcessor only imports the .res and
.gra files.
3 Animate the model to ensure the movement you expected.
4 Create a new page.
5 Right-click in the viewport and select Load Plot.
6 Set Source to Result Sets.
7 Choose the part whose results you want to plot.
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8 Above the Add Curves button, on the right side of the dashboard, toggle the Surf tool.
Surf lets you view a selected result component without using the Add Curves button.
9 Now, select different components from the Component section and see the plot refresh
with each new selection.
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1 Find the value of the stones displacement after 1 second. Use the plot tracking tool on the
ADAMS/PostProcessor main toolbar.
2 Determine if this result makes sense.
If not, check for mistakes in your model and correct them.
3 If the results do make sense, answer Question 1 in the Module review on page 56.
4 Find the value of the stones velocity after 1 second.
Use it to answer Question 2 in the Module review, 56.
5 Find the value of stones acceleration after 1 second.
Use it to answer Question 3 in the Module review, 56.
6 Exit ADAMS/PostProcessor without saving the session.
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1 Edit the stone.adm file so that the part has an initial velocity of6 m/sec, at an angle of60o
with respect to the horizontal.
Use VX and VY parameters for the PART/statement.
Plot Tracking
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2 Save the file as projectile.adm.
3 Edit the stone.acf file, so that it will run the new file, projectile.adm.
4 Save the file as projectile.acf.
5 Simulate the model.
6 Animate and plot to see the stones new displacement and velocity values.
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Displacement after 1 sec = -4903.3 mm
Velocity after 1 sec =-9806.6 mm/sec
Acceleration after 1 sec = -9806.6 mm/sec2
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s = (at2) = 4903.325 mm
v = at = 9806.65 mm/sec
a= g = 9806.65 mm/sec2
:KHUH
s = Distance (mm)
a = Acceleration (mm/sec2)
t = Time (sec)
v = Velocity (mm/sec)
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1 What is the stones displacement after one second?
________________________________________________________________________
2 What is the stones velocity after one second?
________________________________________________________________________
3 What is the stones acceleration after one second?
________________________________________________________________________
4 What do many pre-processors write for the QG argument in the PART/statement?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
5 The CM argument appears in both the PART/statement and certain GRAPHIC/
statements. What is the difference in each case?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
6 Can the CM be the same marker in both the PART/statement and the GRAPHIC/
statement?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
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21('2)3(1'8/80
Find the initial force supported by the pin at A, for a bar that swings in a vertical
plane about a pivot, given the initial angular displacement (o).
qo=45o
mass=1 kgradius=25 mmlength=250 mm
g
A
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Constraints, 58
Use of Markers in Constraints, 59
Three-Point Orientation Method, 61
Degrees of Freedom (DOF), 62
Revolute Joint, DOF Removed by, 154
Workshop 4One DOF Pendulum, 63
Module review, 68
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Restricts relative movement between parts.
Represents idealized connection.
Removes rotational and/or translational DOF from a system.
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5RWDWLRQDOFRQVWUDLQWVRIWKHKLQJH
(about x-axis)
(about y-axis)
Therefore,
Wall
Door
Wall
Door
Zw
Xw
Yw
ZD
XD
YD
XD XW 0=
YD YW 0=
ZD ZW 0=
D W 0=
D W 0=
D and W are free
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Constraints are represented as algebraic equations in ADAMS/Solver.
These equations describe the relationship between two markers.
Joint parameters, referred to as I and J markers, define the location, orientation, and
the connecting parts:
First marker, I, is fixed to the first part.
Second marker, J, is fixed to the second part.
$QDWRP\RIDFRQVWUDLQWLQ$'$06
JOINT/0120(hinge)
PART/20(door)
PART/01(wall)
MAR/2001(I marker)
MAR/0101(J marker)
Model(example.adm)
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The I and J markers referenced in the joint (and therefore, the parts to which they
belong), move with respect to each other as follows:
The I and J markers overlap at time = 0.
During simulation, the z-axes of both markers stay aligned.
([DPSOH5HYROXWH-RLQW,DQG-PDUNHUV
JOINT/0120, REVOLUTE, I=0103, J=2003
MAR/0103, PART=01, QP = 3,5,0
MAR/2003, PART=20, QP = 3,5,0
zi zj,
y i yj
x i
xj
zi zj,
xi xj,
yi yj,
PART/01
PART/20
MAR/0103
MAR/2003
The Magical Cactus
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You can define a coordinate systems orientation using two methods:
Rotation sequence method (Euler angles). See the guide, Using ADAMS/Solver for
more details.
Three-point method.
'HILQHWKHRULHQWDWLRQRIDFRRUGLQDWHV\VWHPXVLQJWKHWKUHHSRLQWPHWKRG
In the MARKER/statement, definethree points:
QP - origin of the coordinate system
ZP - coordinates of a point that you want the z-axis to point at
XP - coordinates of a point that you want the x-axis to point at
([DPSOH0$5.(5
MARKER/2003, PART=20, QP=3, 5, 0, ZP=9, 5, 0, XP=3, 10, 0
Zm
Xm
Ym
Yg
ZgXg
QP (3,5,0)
XP (3,10,0)
ZP (9,5,0)
(0,0,0)
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Each DOF corresponds to at least one equation of motion.
A freely floating rigid body in three-dimensional space is said to have six DOF.
A constraint removes one or more DOF from a system, depending on its type.
'HWHUPLQHWKHQXPEHURIV\VWHP'2)
ADAMS/Solver will provide an estimated number of system DOF by using the
Grueblers Count:
ADAMS/Solver also provides the actual number of system DOF, as it checks to see
whether:
Appropriate parts are connected by each constraint.
Correct directions are specified for each constraint.
Correct type of DOF (translational versus rotational) are removed by each
constraint.
Redundant constraints exist in the system.
Rigid body
zx
y
System DOF = number of movable parts 6 DOF/ part( )
# Constraints # DOF (Constraint)[ ]i type=
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Find the initial force supported by the pin at A for a bar that swings in a vertical plane about a
pivot, given the initial angular displacement, o.
o=45o
mass=1kgradius=25mm
length=250mm
g
A
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1 Change to the/mod_04_pendulum directory.
2 Open a text editor:
UNIX: Use jot or vi.
NT: Use Microsoft Notepad or WordPad.
3 Enter ! Pendulum Model as the first line of the dataset.
This is the title.
4 Define the units by entering UNITS/.
5 Define the acceleration due to gravity by entering ACCGRAV/.
6 Create the ground part by entering PART/.
7 Create the pendulum part by entering PART/and setting the inertia properties.
8 Define the location and orientation of the center of mass by entering MARKER/.
Location is very important in this model because the pendulum is going to start at an
angle.
Orientation is also important because the inertia values (Ixx, Iyy, and Izz) are not allthe same for this part. In the last module, you created a sphere (where: Ixx = Iyy = Izz).
A cylinder is not that simple. In addition, the orientation is dependent on the initial
conditions of the part.
To define the orientation, use the three-point method.
9 Create a cylinder graphic to represent the pendulum by entering GRAPHICS/.
10 Define the location and orientation of the center marker for the cylinder graphic by
entering MARKER/.
The orientation for this marker is dependent on the initial conditions for the cylinder.
Again, use the three-point method.
11 Generate a graphics (.gra) file for output by entering OUTPUT/GRSAV.
12 Generate a results (.res) file for output by entering RESULTS/.
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13 Signify that this is the end of the dataset by entering END.
14 Save the file as pendulum.adm in the mod_04_pendulum directory.
7HVWLQJWKHPRGHO
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1 Create a command file (*.acf) to dynamically simulate the model for 1 second with
50 output steps.
2 Run the simulation.
Ensure that the file was simulated properly (no errors or unexpected warning messages).
3 View the animation to visually check for errors.
At this point you have no constraints in the model, so the pendulum should just fall.
But you can check your initial conditions and make sure they are acceptable.
You may want to turn on the global triad in ADAMS/PostProcessor.
Toggle the View button in the dashboard below your viewport.
Check the Display Triad box.
4 If anything in the results does not make sense, modify your .adm file.
&RQVWUDLQLQJWKHSHQGXOXP
7RFRQVWUDLQWKHSHQGXOXP
1 Open a text editor to modify your .adm file.
2 Create the appropriate joint between the pendulum and ground by entering JOINT/.
3 Create the I marker for the constraint by entering MARKER/.
4 Create the J marker for the constraint by entering MARKER/.
5 Run the simulation and check your results.
6 Plot the FX and FY components of force for the revolute joint.
Use the values to answer Question 1 in the Module review on page 68.
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Visualize the reaction forces in the joint by entering GRAPHICS/.
7RYLHZWKHDQLPDWLRQDQGWKHSORWVDWWKHVDPHWLPH
1 Right-click the Page Layout tool.
2 Choose a layout that has enough viewports to view your plots and the animation.
3 In the viewport where you would like to put your animation, right-click and select Load
Animation.
4 In the other ports, right-click and select Load Plot.
5 Set up your plots (if they are not set up already).
6 Animate the results.
7 You may need to modify the scale of the force graphics in ADAMS/PostProcessor.
From the Edit menu, select Preferences.
In the PPT Preferences dialog box, in the upper left corner, toggle Animation.
To modify the scale, from the upper right corner use the Force and Torque Scale text
boxes.
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1 What are the initial values of force in the global x and y directions?
________________________________________________________________________
2 If a markers QP=10,14,2, and you want its z-axis to point in the global y direction, what
could ZP equal?
________________________________________________________________________
3 In the JOINT/statement, how do you indicate which two parts are being connected?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
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Investigate the linear spring-damper system shown in the following figure, using
different types of simulations in ADAMS.
MASS
kc
g
:KDWVLQWKLVPRGXOH
Initial Condition Simulation, 70
Types of Simulations, 71
Simulation Hierarchy, 72
Forces in ADAMS, 73
Spring Dampers in ADAMS, 74
Magnitude of Spring Dampers, 75
Workshop 5Spring Damper I, 76
Module review, 80
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Attempts to resolve any conflicts in the initial conditions specified for the entities in
the model (for example, broken joints).
Is also known as an assemble simulation.
,QLWLDOORFDWLRQDQGRULHQWDWLRQRISDUWV
You specify the initial position and orientation for a part when you create it.
For a part to be held fixed during the initial condition simulation, you can specify up
to three positions ( ) and up to three orientations (psi, theta, phi).
To do so, use the EXACTargument in thePART/statement
Use initial positions sparingly. If you fix the initial positions of too many parts, theinitial conditions simulation can fail.
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SIMULATE/INTIAL_CONDITIONS
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System DOF > 0.
System velocities and accelerations set to zero.
Can fail if the static solution is a long way fromthe initial condition.
([DPSOHSIMULATE/STATIC
System DOF > 0.
Driven by a set of external forces and excitations.
Nonlinear differential and algebraic equations
(DAEs) are solved.
([DPSOHSIM/DYNAMIC, END=1, STEP=100
System DOF = 0.
Driven by constraints (motions).
Only constraint (algebraic) equations are beingsolved.
Calculate (measure) reaction forces in constraints.
([DPSOHSIM/KINEMATIC, END=1, STEP=100
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Often a linear simulation is preceded by a static equilibrium or dynamic simulation. We
are not going to use linear simulations in the next workshop.
Initial Condition Simulation
Transient* Static*
Kinematic* Dynamic*
Nonlinear
MotionStudy Equilibrium
Nonlinear
DOF = 0 DOF > 0
* Automatically performs an assemble simulation
Linear
Eigensolution
or State Matrices
Linear
Calculation(s)
Initial Condition
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Try to make parts move in certain ways.
Do not perfectly connect parts together the way constraints do.
Do not absolutely prescribe movement the way motion drivers do.
Neither add nor remove DOF from a system.
&KDUDFWHULVWLFVRIIRUFHV
The characteristic: Defines:
Bodies Which parts are affected
Points of application Where the parts are affected
Vector components How many vector components there are
Direction/Orientation How the force is oriented
Magnitude Whether the force is pre-defined or user-defined
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See also: Characteristics of a translational and rotational spring damper, page 155.
They are pre-defined forces.
They represent compliance:
Between two bodies.
Acting over a distance.
Along or about one
particular direction.
The characteristic: Defines:
Bodies Two (A, B)
Points of application Two (I and J marker)
Vector components One
Orientation (only fortranslational)
Acts along the line of sight between the I and J markers
Positive force repels the two parts
Negative force attracts the two parts
MagnitudePre-defined equation based on stiffness and damping
coefficients (linear)
I marker
J marker
BA
(+)
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Linear spring-damping relationship can be written as:
ForceSPDP = k(q - L0) c + F0
where:
q - Distance between the two locations that define the spring damper
- Relative speed of the locations along the line-of-sight between them
k - Spring stiffness coefficient (always > 0)
c - Viscous damping coefficient (always > 0)
F0 - Reference force of the spring (preload)
L0 - Reference length (at preload, always > 0)
Spring damper forces become ill-defined if endpoints become coincident because of
undefined direction.
([DPSOH7UDQVODWLRQDO6SULQJ'DPSHU,DQG-PDUNHUV
SPRINGDAMPER/0120, I=0107, J=2006, K=5, C=.1, L=400, TRANSLATION
MAR/0107, PART=01, QP=0,100,0
MAR/2006, PART=20, QP=0,500,0
q
q
Fk= k(q-L0) +
Fk
kL0+F0
F0
L0
r
-k
free length
c
Fc
Fc = c(dq/dt)
dq/dt
Linear Spring Linear Damper
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Investigate the linear spring-damper system shown in the following figure, using different types
of simulations in ADAMS.
MASS
k=5.0 N/mmc=0.05N-sec/mm
Lo=400mm g
m=187.224kg
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1 Change to the /mod_05_springdamper_1 directory.
2 Open a text editor.
UNIX: Use jot or vi.
NT: Use Microsoft Notepad or WordPad.
3 Enter ! SpringDamper Model as the first line of the dataset.
This is the title.
4 Enter UNITS/to define the units.
5 Enter ACCGRAV/to define the acceleration due to gravity for the model.
6 Create the ground part by entering PART/.
7 Create the mass part by entering PART/.
Because you are going to constrain the mass with a translational joint, you dont needinertia properties.
8 Define the location of the center of mass by entering MARKER/.
9 Enter GRAPHICS/to create a circle graphic representing the mass.
10 Define the location and orientation of the center marker for the circle graphic by entering
MARKER/.
Orientation is very important for this graphic.
11 Enter JOINT/to constrain the mass to move only in the Global-Y direction using a
translational joint.
12 Create the I marker for the translational joint by entering MARKER/.
The orientation of the I and J markers are what define the orientation of the joint.
13 Answer Question 1 in the Module review on page 80.
14 Create the J marker for the translational joint by entering MARKER/.
15 Enter OUTPUT/GRSAV to generate a graphics (.gra) file for output.
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16 Enter RESULTS/to generate a results (.res) file for output.
17 Signify that this is the end of the dataset by entering END.
18 Save the file as spring_1.adm in the mod_05_springdamper_1 directory.
7HVWLQJWKHPRGHO
7RFUDZOZDONUXQWHVWWKHPRGHOVRIDU
1 Create a command file (spring_1dyn.acf) to dynamically simulate the model for 2 seconds
with 50 output steps.
2 Simulate the model.
Ensure that the file was simulated properly (no errors or unexpected warning messages).
3 Play the animation to visually check for errors.
Because you have only the translational joint in the model, the mass should just fall.
4 If needed, modify your .adm file.
+DQJLQJWKHPDVV
7RKDQJWKHPDVVIURPDVSULQJDQGGDPSHULQSDUDOOHO
1 Open a text editor to modify your .adm file.
2 Create a spring between the mass and ground by entering SPRINGDAMPER/.
3 Create the I marker for the spring by entering MARKER/.
If the I marker is going to be on the mass, then you could just use the center of mass marker
4 Create the J marker for the spring by entering MARKER/.
The J marker should be located 400 mm above the I marker.5 Save the file.
6 Run a dynamic simulation.
7 View the animation of the model.
Does the animation make sense?
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8 Plot the Magnitude of Force in the SpringDamper vs. the Position of the Mass Part.
9 Answer Question 2 in the Module review on page 80.
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7RILQGWKHVSULQJGDPSHUIRUFHDWVWDWLFHTXLOLEULXP
1 Run an equilibrium simulation.
2 Create a new command file (spring_1static.acf) to find the static equilibrium.
3 Open ADAMS/PostProcessor.
4 Using the Result Sets as the source, plot the spring dampers force magnitude (FMAG).
The results of an equilibrium simulation, may be just one data point; therefore, if you usethe Plot Tracking tool, it is easier to find the value of the single point.
5 Use the values to answer Question 3 in the Module review on page 80.
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1 Use the GRAPHICS/command to add a graphic to visualize the spring (coils, and so on).
2 Use the GRAPHICS/command to add graphics to see the reaction forces on the I and J
markers of the spring.
3 When you animate the results, you may need to modify the scale of the force graphics in
ADAMS/PostProcessor.
From the Edit menu, select Preferences.
In the upper left corner of the PPT Preferences dialog box, select Animation.
To modify the scale, use the Force and Torque Scale text boxes in the upper right
corner.
0RGXOHUHYLHZ
1 Which axis of theI and J markers defines the axis of translation for the translational joint?
________________________________________________________________________
2 What is the approximate slope of the Spring Force versus Mass Position plot? Does this
value make sense?
________________________________________________________________________
________________________________________________________________________________________________________________________________________________
3 What is the value of spring damper force at static equilibrium?
________________________________________________________________________
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Replace the linear spring damper created in the previous module with a single-
component force that enables you to provide an equation that describes the force
magnitude, allowing for more flexibility.
MASS
F=-k*(q-Lo)-c*q.
g
:KDWVLQWKLVPRGXOH
Single-Component Forces: Action-Reaction, 82
Functions in ADAMS, 83
Measuring Displacement (Functions continued), 84
Measuring Velocity (Functions continued), 85
Workshop 6Spring Damper II, 86
Module review, 89
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They are user-defined forces.
They represent forces:
Between two bodies.
Acting over a distance.
Along or about one
particular direction.
See also: Characteristics of an action-reaction S-force, page 155
ADAMS applies action and reaction forces to the I and J markers that are created.
The characteristic: Defines:
Bodies Two (A, B)
Points of application Two (I and J markers)
Vector components One
Orientation Acts along the line of sight (between the I and J
markers)
Positive force repels the two parts
Negative force attracts the two parts
Magnitude User-defined
Sforce
I marker
(+)
BA
J marker
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You use functions to define magnitudes of input vectors used in motions and applied
forces.
Every function evaluates to a single value at each particular point in time.
Motions can only be a function of time:
M = f(time)
Applied forces can be a function of just about any measurement in your model
F = f(displacement, velocity, reaction force in a joint, ...)
([DPSOH6)25&(UHSUHVHQWLQJDGUDJIRUFH
SFORCE/2080, I=2010, J=8013, TRANSLATIONAL
, FUNCTION = 0.5*0.0032*(VX(2010, 8013, 8013)**2)*1.4*19.3
The equation for drag force looks like:
Fdrag1
2--- Vx( )
2C
DA
=
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Translational displacement returns scalar portions of vector components
(measurements are taken to a marker (I) from another (J), resolved in Rs CS), as
shown in the example below.
Rotational displacement returns angles associated with a particular rotation sequence.
6\QWD[IRUWUDQVODWLRQDOGLVSODFHPHQWIXQFWLRQV
DM(I,J)
DX, DY, DZ(I,J,R)
([DPSOH
DY(I,J,R)
R
yR x
R
DX(I,J,R)
DM(I,J)I J
(-)(+)
y y
x x
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Returns scalar portions of velocity vector components (translational or rotational).
6\QWD[IRUWUDQVODWLRQDOYHORFLW\IXQFWLRQV
VM(I,J)
VR(I,J)
VX, VY, VZ(I,J,R,L)
The velocity function, VR, is used to define velocity along the line of sight, which is
commonly used in spring dampers.
If the markers are separating: VR > 0.
If the markers are approaching: VR < 0.
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3UREOHPVWDWHPHQW
Replace the linear spring damper created in the previous module with a single-component force
that enables you to provide an equation that describes the force magnitude, allowing for more
flexibility.
MASS
F=-k*(q-Lo)-c*qg.
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1 Copy the .adm and .acf files from that last module to the directory,
/mod_06_springdamper_2.
If you did not finish the last module workshop, you can use the files that are provided in the
completed directory in mod_05_springdamper_1. You should copy those to the
mod_06_springdamper_2 directory.
UNIX: Make sure the current directory is /mod_05_springdamper_1
directory and use the cp command.
cp *.adm *.acf. ./mod_06_springdamper_2
This UNIX command copies (cp) all files that end with .adm and .acf to a particular directory(mod_06_springdamper_2).
NT: Use the mouse and the exploring capabilities to move files.
2 Change to the /mod_06_springdamper_2 directory.
(GLWLQJWKHPRGHOGDWDVHW
7RHGLWWKHPRGHOGDWDVHWEDVHGRQWKHILJXUHJLYHQ
1 Open your .adm file in a text editor.
2 Enter ! SPRINGDAMPER/to comment out the SPRINGDAMPER/ statement lines that you
created during the first module.
3 Add a single-component force that will behave exactly as the spring did, by entering
SFORCE/:
Use the same I and J markers you used with the SPRINGDAMPER/.
The function syntax should be:
where q = DM( _ , _ ) and qdot = VR( _ , _ )
For help with the DM and VR functions, look them up in the guide, Using ADAMS/
Solverin the Functions section.
4 Save the file as spring_2.adm in the mod_06_springdamper_2 directory.
k q Lo
( ) cq
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1 Edit the command file, spring_1dyn.acf to dynamically simulate the new model
spring_2.adm.
2 Simulate the model.
Ensure that the file was simulated properly (no errors or unexpected warning messages).
3 Play the animation to visually check for errors.
4 If needed, modify your .adm file.
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7RILQGWKHVSULQJGDPSHUIRUFHDWVWDWLFHTXLOLEULXP
1 Edit the command file, spring_1static.acf, to find the static equilibrium of the model
spring_2.adm.
2 Run an equilibrium simulation.
3 Open ADAMS/PostProcessor.
4
Using the result sets as the source, plot the SFORCEs force magnitude (FMAG).5 Use the values to answer Question 1 in the Module review on page 89.
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Change the single-component force so that its function describes a nonlinear force.
For example, add an exponential to the deformation portion of the force:
F k q Lo
( )2
cq
=
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0RGXOHUHYLHZ
1 Does the force magnitude at static equilibrium equal the value that was derived in the
previous module?
________________________________________________________________________
2 What is the benefit of using an SFORCE/instead of a SPRINGDAMPER/?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
3 What is the drawback of using an SFORCE/instead of a SPRINGDAMPER/?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
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Joint motion
Point motion (marker based)
-RLQWPRWLRQ
There are two types:
Translational: applied to translational or cylindrical joints (removes 1 DOF)
Rotational: applied to revolute or cylindrical joints (removes 1 DOF).
You define the joint to which motion is applied.
ADAMS uses the joints I and J markers and a single DOF.
You define motion magnitude as a:
Displacement function of time
Velocity function of time
Acceleration function of time
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MOTION/2010, JOINT=2010, DISPLACEMENT, FUNCTION=80D*sin(360D*time)
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93/111Brake System I 93
67(3)XQFWLRQ
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In ADAMS, the STEP function approximates an ideal mathematical step function
(but without the discontinuities).
Avoid discontinuous functions because they lead to solution convergence difficulties.
The STEP function steps quantities, such as motions or forces, up and down, or on
and off.
A STEP function is used when a value needs to be changed from one constant toanother.
6\QWD[IRU67(3IXQFWLRQ
STEP (q, q1, f1, q2, f2)
where:
q - Independent variable
q1 - Initial value for q
f1 - Initial value for f
q2 - Final value for q
f2 - Final value for f
([DPSOH
STEP (time,1,5,3,10)
Time
q1 < q2
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Indicates a set of data you want written to the request (.req) file.
7KHUHDUHWZRW\SHVRI5(48(67V
Pre-defined
Displacements
Reaction forces
And so on
User-defined
User-written functions
User-written subroutines
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Results (.res) files do not allow you to write your own functions to be evaluated
during the simulation.
Results (.res) files are often very large. A large amount of CPU time can be spentgenerating the data in these files, when you may only be concerned with certain
measurements.
([DPSOH3UHGHILQHG5(48(67
REQUEST/01, DISPLACEMENT, I=0201, J=0103
, COMMENT=CRANK CENTER OF MASS DISPLACEMENT
Requesting the displacement ofMAR/0201 with respect to MAR/0103.
When you import the .req file into ADAMS/PostProcessor, it offers you all
translational and rotational components (x,y,z,mag) of displacement.
You will also see the COMMENT in ADAMS/PostProcessor if you include one.
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95/111Brake System I 95
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Constrain the given brake system, and approximate the effort (force) required to fully engage
the brake.
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The given model is a simplified model of a brake system that currently has three parts
and the associated graphics defined.
In addition, there is a single-component force (SFORCE) already defined that
describes a linear force between the cylinder and ground. The SFORCE represents the
tension in the brake cable.
You are going to add constraints to the brake system.
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1 Change to the /mod_07_brake_1 directory.
2 Simulate the given model.
Use the given files, brake.adm and brake.acf.
Pedal
Cylinder
Connecting RodCable Tension
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3 View the animation in ADAMS/PostProcessor.
You should see the connecting rod and pedal fall due to gravity.
The cylinder will swing around some but it should not fall off of the screen because it is
attached to the SFORCE that is described in the Model Description on page 95.
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(Pedal)
PART/10
PART/30
(Connecting Rod)
PART/20
(Cable Tension)SFORCE/3001
(0,0,0)
(-225,-150,0)(-175,-150,0)
(-125,-150,0)
(25,-300,0)
(100,-500,0)
(16.33,-200,0)
(Cylinder)
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97/111Brake System I 97
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1 Open the brake.adm file in a text editor.
Adding constraints to the model will involve JOINT/ and MARKER/ statements. Also,
dont forget that the orientation and the location of the I and J markers define the
location and orientation of the joints.
2 Constrain the pedal to the ground.
Save the brake.adm file.
Simulate the model.
Animate the output to ensure this joint is placed correctly.
3 Constrain the connection rod to the pedal.
Save, simulate, and animate again.
4 Constrain the cylinder part to the connection rod.
Save, simulate, and animate again.
5
Constrain the cylinder part to the ground.Save, simulate, and animate again.
When you animate the constrained model, it will not have much movement due to gravity.
Next, you drive the model with a motion.
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98/11198 Brake System
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1 Use the MOTION/statement to apply a motion to the joint that is between the pedal and the
ground) to move the cylinder at least 30 mm.
To get 30 mm of cylinder movement, you must rotate the pedal about 9o.
For the motion function, use the following equation to represent displacement with
respect to time: STEP(time,0,0,0.1,-9D). Depending on the positive direction in your
model, the last argument -9D may need to be positive in your model.
2 Simulate the model.
3 View the animation to check if the brake system is moving properly.
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99/111Brake System I 99
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1 Request the displacement of the cylinder by entering REQUEST/. Use the I and J markers of
the translational joint between the cylinder and the ground.
2 Request the torque (force) in the motion by entering REQUEST/.
3 Add the REQSAV argument to the OUTPUT/statement that is near the top of the .adm file.
4 Simulate the model.
5 Use requests as your source in ADAMS/PostProcessor and plot the displacement through
which the cylinder goes.
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100/111100 Brake System
6 Use your other request and plot the torque applied to the model by the motion.
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Approximate the moment arm.
Later, in the next module, you will apply a force to the pedal at a location that is
directly in between markers 1081 and 1082.
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101/111Brake System I 10
To approximate the needed force magnitude, you can divide the torque plot by the
length of the moment arm. First, however, you must calculate the length of the
moment arm.
7 Answer Questions 1 and 2 in the Module review on page 103.
8 Scale the curve:
From the View menu, point to Toolbars, and then select Curve Edit Toolbar.
From the toolbar that appears, select the Scale tool.
Type the reciprocal of the moment arm value in the text box to the right of the Curve
Edit toolbar.
Select Enter.
Left-click the curve you want to scale.
A new curve appears.
You may want to delete the original curve to clean up the view and improve the scale
Answer Question 3 in the Module review on page 103.
(Pedal)PART/10
MAR/1081
MAR/1082
(Connecting Rod)
PART/20
Location?
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102/111102 Brake System
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1 By using the .msg file, check to see how many redundant constraints exist in your model.
How many redundant constraints would you need to remove, in order to not have any?
2 Remove the redundant constraints created by two of the joints.
Replace the revolute joint between the pedal and the connecting rod with a spherical
joint.
Replace the translational joint between the cylinder and the ground with a cylindrical
joint.
3 Simulate the model and check for redundancies in the .msg file.
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103/111Brake System I 103
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1 What are the coordinates of the location exactly in between markers 1081 and 1082?
________________________________________________________________________
________________________________________________________________________
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2 What is length of the moment arm?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
3 Using the torque measurement, what is the equivalent steady-state force that could be
applied to the pedal?
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________________________________________________________________________
________________________________________________________________________
4 Does a motion remove DOF?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
5 If you were simulating a complex model and assuming you could get the same
information, would it be quicker to just ask for a request (.req) file or justask for a results(.res) file?
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