Working Model - MAELabs UCSD

WM52ProductGuide.fm Page 1 Tuesday, March 2, 2004 12:04 PM 

Working Model 

Version 5.2 

For Windows ® 95/98/ME/2000/XP/NT ® 4.0 and later 

Product Guide 

Contents: 

TM 

• What’s in This Package? 

• System Requirements 

• Installing and Launching Interactive Physics 

• Concurrent Network Licenses 

• Technical Support and Other Services 

• Troubleshooting and Helpful Suggestions 

• Limitations 

• New Features 

• Version Comparison 

1


2 

Information in this document is subject to change without notice and does not represent a commitment on the part of 

MSC.Software Corporation. The software described in this document is furnished under a license agreement or nondisclosure 

agreement. The software may be used or copied only in accordance with the terms of the agreement. It is 

against the law to copy the software on any medium except as specifically allowed in the license or non-disclosure 

agreement. No part of this manual may be reproduced or transmitted in any form or by any means, electronic or 

mechanical, including photocopying and recording, for any purpose without the express written permission of 

MSC.Software Corporation. 

© Copyright MSC.Software Corporation 2001. All rights reserved. Published and printed in the U.S.A. 

Portions © 1992-1995 Summit Software Company. 

Interactive Physics, Interactive Physics II, Interactive Physics Player, Smart Editor, Working Model, Working Model 

Basic and WM Basic are trademarks of MSC.Software Corporation. 

MSC, the MSC.Software logo, and Knowledge Revolution are registered trademarks of MSC.Software Corporation. 

Apple, Macintosh, Mac, and QuickTime are registered trademarks of Apple Computer, Incorporated. 

AppleGuide is a trademark of Apple Computer, Incorporated. 

Microsoft, Windows, and Windows NT are registered trademarks of Microsoft Corporation. 

WinHelp is a trademark of Microsoft Corporation. 

PowerPC, Lotus, and 1-2-3 are registered trademarks of International Business Machines Corporation. 

MATLAB is a registered trademark of the MathWorks, Incorporated. 

Quattro Pro is a registered trademark of Corel Corporation. 

AutoCAD is a registered trademark of AutoDesk, Incorporated. 

DXF is a trademark of AutoDesk, Incorporated. 

Claris and FileMaker are registered trademarks of Claris Corporation. 

MacroMind Three-D is a trademark of Macromedia, Inc. 

Wavefront Technology’s Advanced Visualizer is a trademark of Alias|Wavefront, a division of Silicon Graphics Limited. 

Electric Image is a trademark of Electric Image, Inc. 

All other brand or product names are trademarks or registered trademarks of their respective holders. 

http://www.workingmodel.com


Working Model Product Guide 

Congratulations on your purchase of Working Model! 

1. What’s in This Package? 3 

Working Model, the world’s most popular CAE tool, changes the way engineers 

design and develop mechanical systems. 

Please Register! 

Please make sure to either fax or mail the registration card enclosed. Once you have 

registered, we will notify you about periodic software updates. 

This Product Guide covers the following areas: 

• What’s in This Package? 

• System Requirements 

• Installing and Launching Working Model 

• Scripts 

• Technical Support and Other Services 

• Troubleshooting and Helpful Suggestions 

• Limitations 

• New Features 

1. What’s in This Package? 

This package contains the following: 

• Working Model CD-ROM for installation 

• Product Registration Card 

• MSC.Software Software License Agreement 

• Product Guide (this document, with new feature documentation) 

The Working Model CD-ROM contains: 

• Windows ® version 5.2 and MacOS version 4.0 of Working Model 

• Windows ® version 5.2 of Working Model in Japanese


4 

2. System Requirements 

Windows System Requirements 

• Windows 95/98/Me/2000/XP or Windows NT 4.0 (or later) 

• 64 MB of RAM 

• 60 MB of hard disk space for a full installation 

• CD-ROM drive (for installation) 

• Sound card (for audio effects) 

MacOS System Requirements 

• PowerPC-based systems 

• MacOS System 7.1 or above 

• 64 MB of RAM 

• 60 MB of hard disk space for a full installation 

• CD-ROM drive (for installation) 

3. Installing and Launching Working 

Model 

NOTE: If you are installing on Windows NT or Windows 2000, you must be logged 

in with administrator-level privilege. 

Insert the CD-ROM in your drive. If the Windows AutoRun utility is activated, the 

Installation Screen will automatically appear. If AutoRun is not activated, doubleclick 

the Setup.exe file located on the CD-ROM to launch the Installation Screen. 

Select the language you want. 

You will need a valid serial number to complete the installation. You may install a 

demo version of the software by typing Demo in the serial number box. The demo 

version does not permit saving, printing, or exporting of files. 

See “Concurrent Network Licenses” for network installation instructions.


3. Installing and Launching Working Model 5 

3.1 Attaching the Hardware Key (Professional 

Product) 

Before you launch Working Model, please make sure to attach the hardware key to the 

parallel port of your computer. You can attach the hardware key between your parallel 

port and printer cable. 

The following figure shows an example of the 25-pin parallel port. 

The hardware key needs to be attached at all times while running Working Model. If 

the hardware key is removed, Working Model prompts you to reattach the key or quit 

the application. (NOTE: The hardware key is NOT required during installation). 

If you do not have a hardware key, you can run Working Model in demo mode. All 

of the program’s features will be available, but you will not be able to save, print, or 

export 

If you have multiple parallel ports, attach the hardware key to LPT1. If Working 

Model does not find the key, restart your computer and try another port. In the 

unlikely event that you need to configure the hardware key driver, see the document 

Readme.txt located in the Install\Setup\Sysadmin\Sentinel\ folder of the Working 

Model CD-ROM. 

3.2 Launching Working Model 

After the installation: 

25- pin Parallel Port 

• On Windows 95/98/Me/2000/XP or Windows NT 4.0: Both the Windows 

Desktop and the Start->Programs menu provides access to the “WorkingModel” 

program icon. 

• On MacOS: Double-click the “Working Model 4.0” icon in the Working Model 

2D folder. Please enter the registration information and proceed. 

NOTE: Macintosh users installing Working Model 4.0 should use the serial number 

W2E40-9999-0A023510, instead of the serial number shown on the license 

agreement, registration card, or back cover of the User’s Manual.


6 

When Working Model launches, you will see a blank new document. 

A step-by-step introductory tutorial is available by clicking Start, then Programs, 

WorkingModel, WMIntroduction. Double-click on WMGetttingStarted.pdf. 

You are strongly encouraged to go over the introductory tutorial. The tutorial 

shows you useful tips and features that make your experience with Working Model 

more effortless and productive. 

4. Concurrent Network Licenses for 

Windows 

The Working Model executable can be installed anywhere on the network. The files 

need not be located on the NetSentinel server or a file server. The diagram below 

summarizes the operating principle of the network licensing with NetSentinel server. 

This section contains important information for network system administrators who 

wish to make Working Model accessible on a local area network (LAN). 

4.1 How does the Concurrent Network 

Licensing Work? 

Working Model employs the robust, versatile network licensing mechanism called 

NetSentinel, developed by Rainbow Technologies, Incorporated. The concurrent 

network licenses allow each copy of Working Model to poll your local area network 

to look for authorization to run. 

NetSentinel Server—Monitoring Agent for Your Network 

You need to assign one PC (in your network) to act as the NetSentinel server. This 

PC always runs a small software program to authorize any new request and to keep 

track of how many copies of Working Model are running concurrently. You can 

designate any PC on the network as the NetSentinel server by installing and running 

the necessary software. 

Note: The Working Model network licensing mechanism does not work 

over a subnet.


4. Concurrent Network Licenses for Windows 7 

How Concurrent Network Licensing Works 

Supported Network Protocols 

1 

File Server (Optional) 

PC Acting as NetSentinel Server 

(NetSentinel Hardware Key Attached) 

2 3 

PCs on which Working Model Runs 

Network protocols supported by Working Model include NetBEUI, IPX/SPX, and 

TCP/IP. See “Enabling and Disabling Network Protocols” for more information. 

What If I Already Have Stand-alone License(s)? 

Stand-alone licenses and concurrent network licenses can co-exist without interfering 

each other. For example, suppose you had a single stand-alone license in your office, 

and at a later time you purchased a 10-user network licences. Then you have a total 

of 11 licenses, where one copy can always run on the machine that has the Sentinel 

Pro hardware key attached, and 10 other copies can run anywhere on the network. 

NOTE: The hardware keys used in stand-alone licenses and network licenses are of 

different types. When you purchase the network licenses, you will receive the 

hardware key specifically designed to implement the network licenses. 

Can I Add More Concurrent Network Licenses? 

4 

1. The User runs the Working Model located on the File Server or on a local disk drive. 

2. Working Model is loaded from the server to the local machine. 

3. Working Model polls the network and asks for authorization from the NetSentinel server. 

4. NetSentinel server, keeping track of concurrent licenses, provides or denies authorization. 

You can install multiple NetSentinel servers, or increase the purchased licenses 

monitored by a single NetSentinel server. Please contact your sales agent or 

MSC.Software for more information. 

You cannot “cascade” or connect multiple NetSentinel hardware keys in sequence on 

a single parallel port. 

Once you upgrade the NetSentinel server(s) to increase the licenses, each copy of 

Working Model automatically polls your network until all the NetSentinel servers


8 

and licenses are exhausted. 

4.2 Installing the Hardware Key Driver 

The PC designated as a NetSentinel server must have the hardware key attached in 

order to run the server software. In addition, you need to install the driver for the 

hardware key on the PC. The Working Model CD-ROM has the installers located in 

the Install\Setup\Sysadmin\Sentinel\ folder. 

Installing the hardware key driver on Windows NT 

The Working Model CD-ROM provides separate hardware key driver installer for 

Windows NT systems based on 80x86, Alpha, MIPS, and PowerPC architectures. 

NOTE: Working Model only runs on 80x86 architecture, but the NetSentinel server 

software can run on any Windows NT system. 

1. Make sure you have the administrator-level privilege to your system. 

2. Locate the folder Install\Setup\Sysadmin\Sentinel\Win_nt\ on the 

CD-ROM. 

The folder contains separate applications for Windows NT architectures. 

3. Launch one of Setupx86.exe (for 80x86), Setupaxp (for Alpha), Setupmps 

(for MIPS), or Setupppc.exe (for PowerPC), depending on your CPU 

architecture. 

A window with the title bar “Sentinel Driver Setup Program” is 

displayed. 

4. Choose Install Sentinel Driver in the Function menu. 

A dialog box with the default path for the NT driver is displayed. 

5. Change the drive letter if necessary and click OK. 

Upon successful driver installation, a dialog with the message “Sentinel Driver 

Files Copied Successfully” is displayed, followed a dialog with the message 

“Driver Installed! Restart your system” is displayed. 

6. Click OK to terminate the installation program.


4. Concurrent Network Licenses for Windows 9 

7. Restart your computer. 

Installing the Hardware Key Driver on Windows 95 

To install the hardware key driver on a Windows 95 computer: 

1. Choose Run from the Start Menu and run the file 

Install\Setup\Sysadmin\Sentinel\win_95\SENTW95.EXE on the Working 

Model CD-ROM. 

The installation software launches and shows a blank window. 

2. Choose Install Sentinel Driver in the Functions menu. 

3. Click OK when the “Driver installed! Restart your system.” message 

appears. 

4. Restart Windows 95. 

Installing the Hardware Key Driver on Novell 

A Novell server communicates with the hardware key directly through the parallel 

port and does not require any driver software. 

Installing the Driver on Windows 3.11, DOS, OS/2 

Please refer to the document Install\Setup\Sysadmin\Sentinel\Readme.txt on the 

Working Model CD-ROM for instructions. 

4.3 Attaching the Hardware Key to NetSentinel 

Server 

If the PC designated as the NetSentinel server has multiple parallel ports, attach the 

hardware key to LPT1. Proceed to “Installing and Running the NetSentinel 

Server”, and if the server software does not find the key, try another port. In the 

unlikely event that you need to configure the hardware key driver, see the document 

README.TXT located in the Install\Setup\Sysadmin\Sentinel\ folder of the 

Working Model CD-ROM.


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4.4 Installing and Running the NetSentinel 

Server 

NetSentinel supports most of the many PC network platforms and protocols in use 

today. This section provides installation instructions for some of the most popular 

network platforms and protocols. For complete instructions on all supported 

platforms and protocols, see the document 

Install\Setup\Sysadmin\NetSenti\Ns_guide.doc on the CD-ROM. 

Windows NT 

Copy Install\Setup\Sysadmin\NetSenti\Server\Win32\Nsrvgx.exe located 

on the CD-ROM and launch it. Make sure to install the hardware key driver 

and attach the hardware key. 

Windows 95 

Copy Install\Setup\Sysadmin\NetSenti\Server\Win32\Nsrvgx.exe and 

launch it. Make sure to install the hardware key driver and attach the 

hardware key 

Currently, NetSentinel only supports the NetBIOS protocol on Windows 95. The 

NetBEUI protocol must be installed on the NetSentinel server, using the Network 

Control Panel item on Windows 95. 

Novell NetWare 

Copy and load the Novell Loadable Module NSRVNI.NLM located in 

Install\Setup\Sysadmin\NetSenti\Server\Nlm\. You do not need to restart the 

operating system 

If you are running NetWare on other operating systems, such as Windows NT/95, OS/ 

2, and Windows for Workgroups, see 

Install\Setup\Sysadmin\NetSenti\Ns_guide.doc for instructions. 

Windows 3.11, DOS, OS/2, and Other Network Configurations 

See Install\SetupSysadmin\NetSenti\Ns_guide.doc for instructions. 

4.5 Diagnostic Tools 

The Working Model CD-ROM contains several diagnostic tools to verify that the 

NetSentinel servers are functional. The tools are located in 

Install\Setup\Sysadmin\NetSenti\Tools\. See the document 

Install\Setup\Sysadmin\NetSenti\NS_guide.doc for more information.


5. Concurrent Network Licenses for MacOS 11 

4.6 Enabling and Disabling Network Protocols 

When Working Model launches on a client PC, the program polls the network 

in search of a NetSentinel server in the following order by default: 

• Local parallel port (to look for a stand-alone license hardware key) 

• IPX/SPX protocol 

• NetBIOS protocol 

• NetBEUI protocol 

• TCP/IP protocol 

This search order is given by the default setting in the file krevreg.ini. The 

file is located in the Program folder of Working Model installation and 

includes the following line: 

Network Protocols=XNBT 

This line specifies the search order of the network protocols (the local parallel 

port is always polled first). The alphabet letters on the right side of the equal 

sign are protocol designators, which include the following: 

• A:NetBIOS/ACSNETB protocol (OS/2 clients only) 

• B: NetBEUI protocol 

• P: Named Pipes protocol (OS/2 clients only) 

• N: NetBIOS/NETAPI protocol 

• T: TCP/IP protocol (for Windows 95 and NT clients only) 

• X: IPX/SPX protocol 

You could reorder or eliminate the protocol designators to match your 

network setup. For example: 

Network Protocols=X 

designates that Working Model searches for NetSentinel server only through 

IPX/SPX. 

5. Concurrent Network Licenses for 

MacOS 

Concurrent network licenses employed in the MacOS version of Working 

Model is fairly simple. Each running copy of Working Model polls the 

network, counts the number of running copies with the same serial number,


12 

and continues if the number of licenses has not reached the purchased limit. 

The mechanism runs on any AppleTalk network, including Open Transport 

(version 1.1 or above). 

Copies of Working Model can be installed anywhere on the network. 

However, you must launch and register each installed copy with your serial 

number first. 

Supporting Multiple Workstations with Different Processor Types 

If your network consists of multiple workstations with different processor types (such 

as PowerPC, 680x0 with floating point unit, and 680x0 without floating point unit), 

you can install the appropriate version of Working Model on each machine (Easy 

Install option is recommended), and register each copy with the given serial number. 

Regardless of the processor type, each copy of Working Model keeps track of the 

running copies. 

6. Scripts 

Working Model provides several scripts described below. In the future, we 

plan to make additional scripts available to further extend Working Model’s 

functionality. 

6.1 The Flexbeam Script 

Flexbeam enables users to simulate the behavior of flexible beams. 

Introduction 

Flexbeam replaces a selected rectangular body with a set of smaller rectangular elements 

attached with rotational springs. Flexbeam chooses values for the spring constants, 

which depend on the material and geometry of the selected rectangular beam, 

and creates an assembly that approximates a flexible beam. Figure 6-1 and Figure 6- 

2 show a sample document before and after running Flexbeam respectively. Notice 

that Flexbeam works on beams with an arbitrary orientation and maintains constraint 

relationships. An undo script, called Unflex, restores beams to their original rigid 

form.


Figure 6-1 

Before Running Flexbeam 

Figure 6-2 

After Running Flexbeam 

Unit Systems 

6. Scripts 13 

Flexbeam works with the SI and English unit systems only. Flexbeam automatically 

selects the mass and distance units to be consistent with the current force unit. If the 

user selects the force unit to be Newtons, the script selects meters for the distance 

unit and kilograms for the mass unit. If the user selects the force unit to be pounds, 

the script selects inches for the distance unit and pounds mass for the mass unit. If 

the user selects another unit for force, dynes for example, the user is notified that this 

system of units is unavailable and the program terminates. 

Running Flexbeam 

To use Flexbeam:


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Figure 6-3 

Dialog Provided by Flexbeam 

1. Select the rectangular body within your Working Model document 

which is to be modeled as a flexible beam. 

2. Choose Flexbeam from the Script menu. 

3. Enter the values for the structural stiffness of the beam (EI) and the 

number of elements (n) with which to model the beam. 

The structural stiffness can be chosen through either the highly stiff, minimally stiff, 

or custom option. The highly stiff and minimally stiff options provide a specified 

deflection for a load based on the weight of the beam. The highly stiff option specifies 

roughly a 3% deflection, while the minimally stiff option specifies roughly a 

10% deflection. 

The first input quantity, the structural stiffness, is the product of E, Young’s modulus 

of elasticity, and I, the area moment of inertia. I is a geometric property of the cross 

section of the beam and it is given by the equation: 

∫∫ 

I y 2 = dA 

where dA is a differential element of area and y is the distance of dA from the centroid 

axis (see Figure 6-4 for an example). Working Model is unable to calculate I because 

it simulates in the xy plane, while the beam cross section lies on the yz plane.


Figure 6-4 

Centroid Axis 

6. Scripts 15 

The second input quantity is n, the number of rectangular elements with which to 

approximate the flexible body. A larger value of n, produces a more accurate approximation 

to the flexible beam. However, as the warning message in Figure 6-3 indicates, 

the user should be careful to avoid using more elements than necessary. 

Assigning Values for the Rotational Spring Constants 

Flexbeam replaces the selected rigid rectangular body with a set of smaller rectangular 

elements attached by rotational springs. The spring constants are given by the 

formulas discussed in the technical paper, “Determination of Spring Constraints for 

Modeling Flexible Beams,” by Paul Mitiguy and Arun Banerjee. 

For all springs, other than those which model cantilever supports, the value of k is 

given by: 

where L is the length of the smaller rectangular element. 

Beam Constraints 

k 

= 

The constraints one can impose on a beam are termed fixed, pinned, roller and free. 

The fixed constraint confines a point on the beam to no translational movement in 

any direction, and it restricts the beam from rotating about that point. The pinned 

constraint imposes the same translational confinement but allows the body to rotate. 

The roller constraint confines a point to translational movement in only one direction. 

The roller can have either a fixed or a pinned attachment which would determine 

whether or not rotation of the beam about that point could occur. The free constraint, 

which really is no constraint at all, allows a point to move in any direction and there 

are no restrictions to the rotation of the body about that point. In the rest of this section, 

the construction of two of the more standard beam types is discussed. 

EI 

----- 

L


16 

Figure 6-5 

A Pinned-Roller Beam 

Figure 6-6 

Before Running Flexbeam 

Figure 6-7 

After Running Flexbeam 

The Pinned Roller Beam 

The left end of the pinned-roller beam shown in Figure 6-5 is pinned and the right end 

is attached to a pin-roller. To model the pinned-roller beam, use the circular pin for 

the pinned constraint and the slot joint to represent the end attached to the roller. 

The Fixed-Free (Cantilever) Beam 

The left end of the cantilever beam shown in Figure 6-8 is fixed and the right end is 

free. To model a cantilever beam, use a square pin to attach the beam to the 

background or to another body. As Figure 6-10 indicates, Flexbeam replaces the 

square-pin cantilever constraint with a rotational spring whose spring constant is 

defined by the equation: 

EI 

k ----- 

6n 

= ⎛-------------- ⎞ 

L ⎝3n– 1⎠


Figure 6-8 

A Cantilever Beam 

Figure 6-9 

A Cantilever Beam (before 

Flexbeam) 

6. Scripts 17 

This replacement accommodates the transition from the zero rotation constraint 

imposed by the square pin at the left end of the first element to the finite rotation at the 

right end. 

Notice that, in Figure 6-10, Flexbeam automatically replaces the square pin at the base 

of the beam with a rotational spring.


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Figure 6-10 

A Cantilever Beam (after 

Flexbeam) 

Restoring Flexible Bodies to Their Original Rigid 

Form 

The script Unflex undoes the alterations that Flexbeam made to the original document. 

To use Unflex on a single beam, select one or more of the elements of the beam and 

run Unflex to restore the beam to its original rigid form. If no beams are selected, 

Unflex will ask you whether you wish to simultaneously restore all the beams in your 

document. 

Name Convention For Beam Elements within the 

Working Model Document 

Unflex identifies the bodies modified by Flexbeam by examining the name of each 

body in the workspace. Flexbeam assigns a name to each of the rectangular elements 

of the following form: 

name = flexbeam[3 digit number][3 digit number]. 

The first 3 digit number refers to the identification number of the flexible body. The 

second 3 digit number expresses the identification number of a particular element in a 

particular flexible body. The fourth element of the second flexible body, therefore, 

would have the name flexbeam002004.


Sample Scripts and Documents 

Flexbeam includes the following sample scripts and documents. 

Type Filename Description 

References 

6. Scripts 19 

Sample Scripts flexbeam.wbs The Script which creates flexible 

representations of beams 

unflex.wbs The script which undoes the effect 

of Flexbeam 

flexbeam.hlp The help file for Flexbeam 

Documents bridge.wm Truck driving over a flexible bridge 

fixfree.wm Accuracy of a fixed-free (cantilever) 

beam 

fixroll.wm Accuracy of a fixed-roller beam 

pinroll.wm Accuracy of a pinned-roller beam 

The spring constants provided by Flexbeam are determined by the formulas in 

Determination of Spring Constants for Modeling Flexible Beams, by Paul Mitiguy 

and Arun Banerjee. 

The effectiveness of this formulation is discussed in MSC.Software’s technical 

document, Modeling Uniform Flexible Bodies in Working Model, by Keith 

Reckdahl. 

Copies of these documents may be obtained by sending e-mail to 

info@workingmodel.com or by contacting MSC.Software’s technical support at 

(800) 732-7284. 

6.2 Shear Force and Bending Moment 

Shear Force and Bending Moment creates shear force and bending moment diagrams 

for rectangular beams in Working Model simulations. These diagrams are useful for 

predicting structural failure in beams.


20 

Figure 6-11 

Shear & Bending Moment 

Example 

Introduction 

In general, the shear force and bending moment vary along the length of the beam and 

can be strongly affected by the beam’s motion. Using a graphics window as shown in 

Figure 6-11, this script displays shear force and bending moment versus the position 

along the length of the beam and updates these diagrams at each frame. This script 

also records and displays maximum and minimum values of both the shear force and 

bending moment over the history of the simulation. In addition, this script provides for 

the export of shear force and bending moment data to a text file for any time frame. 

Operation Instructions 

Before running the script, select the rectangular beam within your WM document to 

be analyzed. Invoke Shear & Bending Moment from the script menu. 

The script creates a window, like that shown below, which displays both shear force 

and bending moment diagrams. It shows the shear force diagram in red and the 

bending moment in blue and is updated each time frame. The numbers to the left of 

the diagrams are the maximum and minimum values of the shear force; the numbers 

to the right are the maximum and minimum values of the bending moment.


Figure 6-12 

Shear Force and Bending 

Moment Diagram 

Figure 6-13 

Maximum / Minimum Table 

6. Scripts 21 

There are six buttons which control various aspects of the simulation. The Run/Stop 

button starts and stops the simulation. While the simulation is running, this button has 

the word Stop on it, and only this button is enabled. The > and < buttons allow for 

forward or backward stepping through the simulation. The Max/Min button reports 

the maximum and minimum value of the shear force and bending moment over the 

entire history of the simulation. When the Max/Min button is selected, the diagrams 

are replaced by the dialogue box shown below. Selection of any of the other control 

buttons will bring back the shear-moment diagrams 

The Export button provides for the export of the shear force and bending moment data 

of the current time frame to a data file. With the > and < buttons, you can step forward 

and backward to any frame of interest. This may be used, for example, to record the 

profile associated with the maximum bending moment. The script automatically 

names the file according to the format Shear###.dta. The triple pound sign ### 

symbolizes the numeric characters between 001 and 999 and reflects the order in 

which this file was written. For example, the first profile exported is written to the file 

Shear001.dta. The files are written in the directory in which Working Model resides, 

e.g., C:\Program Files\Working Model.


22 

Figure 6-14 

Coordinate System and Sign 

Convention 

Unit Systems - (see previous Flexbeam script) 

Contact and Collision Forces Not Included 

This script creates the shear force and bending moment diagrams by identifying the 

kinematic state of the beam and the magnitude, direction, and point of application of 

the external loads applied to it. Working Model is designed primarily for rigid-body 

dynamic analysis. The construction of the shear force and bending moment diagrams 

requires a more detailed description of the location and distribution of contact loads 

than is available in a rigid body analysis. As a result, contact and collision loads are 

ignored. 

Coordinate System Assignment 

In calculating and presenting the shear force and bending moment diagrams, this script 

employs the coordinate system assigned to the rectangle by Working Model. Figure 

6-14 illustrates how this coordinate is assigned to a beam. The diagrams display the 

shear force and bending moment versus the rectangle’s x-coordinate shown below. 

The script calculates the bending moment value along the line, y = 0, which passes 

through the geometric center of the beam. 

Coordinate System 

Sign Convention 

(Forces and moments shown 

are acting in positive direction)


Figure 6-15 

Definition of the Area Moment of 

Inertia 

Sign Convention 

6. Scripts 23 

The bottom half of Figure 6-14 shows an exploded view of the beam element B. The 

shear force and bending moment are the internal loads which hold the beam together 

and ensure the rigid connection between the element B and the remainder of the beam, 

or the two elements A and C. 

Figure 6-14 also shows the sign convention for positive shear force and bending 

moment. As explained in the figure: 

• The shear force is positive when element A exerts a force in the positive ydirection 

on the element B and when element C exerts a force in the negative ydirection 

on the element B. 

• The bending moment is positive when element A exerts a moment in the positive 

z-direction (coming out of the page) on element B and when element C exerts a 

moment in the negative z-direction on element B. 

Normal Stress Induced by Bending Moment 

This choice of sign convention determines that a beam with a positive bending 

moment has its top surface in tension and its bottom surface in compression. The 

formula which relates σ, the stress, to the bending moment M, is: 

My 

σ = ----------- , 

I area 

where y is the distance from the beam’s neutral axis and I area, is the area moment of 

inertia of the beam cross section. I area, is defined and shown below: 

I area 

y 2 = ∫∫ 

dydz


24 

Figure 6-16 

Falling Smoke Stack 

Example: the Falling Smoke Stack 

The falling smoke stack is a well-known example where dynamic loads lead to a 

structural failure. A falling smoke stack is known to break in two before it hits the 

ground because of high tensile stresses caused by a bending moment during the fall. 

Figure 6-16 shows a simple representation of the falling smoke stack in Working 

Model. 

In Figure 6-17, we show both the static and dynamic analyses of this event. In the 

static beam analysis, the beam is rigidly attached to the background. In the dynamic 

analysis, the connection is made with a circular pin, which allows the beam to rotate. 

Figure 6-17 shows that the difference between the two analyses is substantial. Figure 

6-17 also highlights that in the dynamic analysis, the peak bending moment occurs in 

the middle of the beam which is consistent with the notion that a falling smoke stack 

breaks into two pieces before hitting the ground.


Figure 6-17 

Analysis of Static and Dynamic 

Beams 

6.3 The Optimize Script 

6. Scripts 25 

This script will adjust a user-specified parameter to minimize a user-specified cost. 

When invoked, choose the "Optimization Demo" option to see some example uses for 

this script. 

The script needs: 

Static Beam 

Dynamic Beam 

• An input parameter to vary, named "P0". 

• A meter named “COST” that measures the cost function to minimize. 

To inform Working Model of the length of your simulation run, add a pause control. 

If you need to stop the optimization at any time, use Ctrl-C. 

6.4 The Create Constraint Script 

Create Constraint allows you to create constraints between points. The type of 

constraint that you can create depends on the number of points selected: 

A. One point (Force, Torque)


26 

B. Two Points (Actuator, Damper, Pin, Rod, Rope, Separator, Spring, Spring/ 

Damper) 

C. Three or more points (Pin) 

Create and/or select the point(s) where you would like to add a constraint. Run the 

script and specify the desired constraint. 

6.5 The Document Model Script 

This script enables you to completely document a model. Running this script produces 

a text file that lists information (e.g., units, properties, bodies, constraints, integration 

settings, etc.) that describes the model. 

6.6 The Zoom to Extent Script 

Zoom to Extent adjusts the zoom so you can view your entire model in the simulation 

window. Simply select this script from the menu to run it. 

6.7 The Measure Between Points Script 

Running this script creates a meter that measures the distance between the two selected 

points. The distance is displayed once you run (or re-run) your model. 

6.8 The Flip Polygon Script 

Flip Polygon allows you to flip a polygon into a mirror-image position. Before 

running this script, create and select a polygon. Run the script, then specify whether 

you want to flip the polygon horizontally or vertically. 

6.9 The Pin Friction Script 

This script allows you to simulate friction on pin joints. Before running the script, 

create and select a pin joint. Run the script to create two input controls: one for the 

effective pin radius and the other for the coefficient of friction in the joint. Adjust the 

values and run your model to simulate the friction.


7. Technical Support and Other Services 27 

6.10 The Slot Friction Script 

The Slot Friction script allows you to model friction in your slot joints. Before 

running the script, create and select a slot joint. Run the script to create the applied 

forces that are programmed to model friction in the slot. An input control is created 

for you to assign the friction coefficient. 

6.11 The Slot Damping Script 

The Slot Damping script allows you to model damping in your slot joints. Before 

running the script, create and select a slot joint. Run the script to create the applied 

forces that are programmed to model damping in the slot. An input control is created 

for you to assign the damping coefficient. The units for the damping coefficient are 

consistent with those currently assigned to your simulation. For example, if you 

currently have selected force to be represented in lbf and velocity in feet/second, then 

the damping coefficient has units of lbf-second/foot. 

7. Technical Support and Other Services 

7.1 Technical Support 

Technical support for the use of Working Model is provided by Working Model 

agents, authorized dealers, and MSC.Software. Support for cducational customers is 

restricted to the first four months of ownership, and is limited to questions on 

installation and basic operations. 

If you purchased Working Model through a reseller, contact the reseller directly for 

technical support. 

If you purchased Working Model through MSC.Software, contact MSC.Software for 

technical support: 

• E-mail: wm.support@mscsoftware.com 

• Fax: (650) 574-7541, Attention: Working Model 2D Support. 

• Phone: (800) 732-7284, M-F 7 AM to 3 PM Pacific Standard Time.


28 

7.2 Contacting Technical Support 

Before contacting your technical support provider, please refer first to the Index, Table 

of Contents, and Appendix C in the Working Model User’s Manual. If you cannot find 

the answer to your question, please make sure to have the following information when 

contacting us or your sales agent: 

• Serial number of the product 

• Product name (e.g., Working Model version 5.2) 

• Operating system and version (e.g., Windows 95) 

• Hardware configuration (RAM and free hard disk space) 

• Specific descriptions of the problem and a way to reproduce it 

7.3 Consulting Services 

MSC.Software and its authorized dealers and agents provide consulting services on 

the construction, modeling, and analysis of mechanical systems using Working 

Model. For more information, call MSC.Software at (650) 574-7777. 

7.4 World Wide Web 

http://www.workingmodel.com/ 

The website features free demo files, technical notes, and periodic updates to the 

product. Also, please check the FAQ page of our website for answers to frequently 

asked questions. 

8. Troubleshooting and Helpful 

Suggestions 

8.1 Working Model Cannot Find Hardware Key 

Several issues can contribute to this error message. 

• If you have a Compaq Deskpro or Presario, and you are running Windows 95, 

the parallel ports are often hard-wired into “ECP Mode”. Currently, the hardware 

key does not support ECP Mode (Rainbow is working on drivers which 

allow ECP Mode, but at present time have given no release date.). In order to 

fix this problem, you must change the configuration of your computer via a 

jumper cable to Standard Mode. Please consult your computer owner’s manual.


9. Limitations 29 

Note: printer drivers that require ECP Mode will still work properly because the 

software is capable of switching the parallel port into ECP Mode. 

• If you are running Working Model with a stand-alone license, make sure you 

either have a hardware key attached to the parallel port (see “Attaching the 

Hardware Key (Professional Product)”). If you have concurrent network 

licenses, make sure the NetSentinel server is running (see “Installing and Running 

the NetSentinel Server”) and all the network functions are operational. 

• You may be running Working Model over the network and failed to install the 

appropriate hardware key driver on the local machine. See “Attaching the 

Hardware Key (Professional Product)” for more information. 

• If you have multiple parallel ports, try attaching the hardware key on a different 

port. 

• All the available network licenses for Working Model may be in use. Either 

wait for other users to exit Working Model, or contact MSC.Software to purchase 

more licenses. 

• If all else fails, restart your computer and try again. 

8.2 Simulation Generates Jaggy Plots 

Decrease the Positional Error and/or Animation Step (in Accuracy dialog) to increase 

accuracy. 

8.3 My AVI Export Does Not Work Well for RLE 

Compression (Windows only) 

Some systems may experience problems while exporting Video for Windows files 

from Interactive Physics with the RLE compression mode. Try using another 

compression mode, such as Microsoft ® Video 1. 

9. Limitations 

This section provides addenda to the documentation and known problems and 

incompatibilities. 

9.1 Working Model Basic 

Working Model Basic featured in Working Model 4.0 and 5.0 is slightly different 

from the previous version. If you encounter a script that ceases to compile or run 

under version 4.0 or 5.0, please refer to the following information.


30 

AppFileName 

The function AppFileName is no longer supported. 

Save As Binary 

The “Save As Binary” functionality, supported under the Script Editor with 

Working Model 3.0, is no longer supported. Scripts saved as binary under version 3.0 

are incompatible with version 4.0. Run all scripts as text. 

Double Precision 

Working Model 3.0 left unchecked small, fractional errors accumulated in double 

precision numbers. Therefore, the following script: 

Sub Main() 

end sub 

dim i as double 

for i = 0.5 to 1.0 step 0.1 

Msgbox i 

next 

ran up to “1.0” in version 3.0. In Working Model 4.0, the loop terminates after 

showing the value “0.9”. This new behavior is consistent with Microsoft 

Visual Basic ® . 

9.2 Curved Bodies 

For curved bodies, the snap points are available only at the frame of reference (FOR). 

However, you can find the snap points on a curved body by temporarily turning off the 

“Curved Body” checkbox in the Geometry window. 

The boundary of a curved body may appear “jaggy” when you zoom in, because 

Working Model approximates the splined boundary with linear segments for 

rendering purposes only. The simulation engine, on the other hand, treats each curved 

body’s boundary as a true NURB representation. 

9.3 Double Clicking on a .WM File Launches 

Windows Media Player 

Working Model files and Windows Media Player files share the same “.wm” 

file extension. Double-clicking on a file that has a “.wm” file extension 

prompts the Operating System to open the selected file with the default 

application, which is usually the Windows Media Player. To open Working


9. Limitations 31 

Model files with the “.wm” file extension you should launch the Working 

Model 2D 5.0 application and then use the File->Open command. Newer 

versions of Working Model will use the “.wm2” file extension. 

9.4 Dynamic Data Exchange (Windows Only) 

The filename of a Microsoft Excel file needs to match 8.3 format. This limitation does 

not apply to the directory path. For example, the pathname: 

C:\my folder\data files\project1.xls 

is acceptable, whereas: 

C:\my folder\data files\My_Project.xls 

is unacceptable, because the filename does not match the 8.3 format. 

9.5 Apple Guide Conflicts (Macintosh only) 

There is also an interaction between “7.0/7.1 Apple Guide Enabler” and “Dragging 

Enabler,” which prevents Apple Guide 2.0 from working properly if “Macintosh Drag 

and Drop” is installed by the user. The work-around is to remove “Dragging Enabler” 

from your System Extensions Folder. The “7.0/7.1 Apple Guide Enabler” contains the 

patches that “Macintosh Drag and Drop” needs to work properly; thus, “Dragging 

Enabler” is not needed. 

9.6 Degraded Redraw Speed on a Large 

Window 

You may experience a graphics speed loss if you have a very large document window 

(for example, a maximized window on a 1024-by-768 resolution screen). For 

optimum performance in playback, resize the window smaller


32 

10. New Features 

10.1 Script Button 

Working Model 2D allows you to create a button that invokes a script written in 

Working Model Basic. The script button serves as a flexible alternative to menu 

buttons, since it allows you to invoke a script file that could accomplish far more than 

a single menu command. For example, you can create a Working Model file that 

shows several script buttons that guide the user to different simulation scenarios. 

To create a script button: 

1. Choose Define->New Button->Script Button in the menu. 

File open dialog appears. 

2. Select the Working Model Basic script file in the dialog, and click Open. 

The script button appears in the Working Model document, with the file name (minus 

the.WBS suffix) as the default button name. You can change the button name in the 

Appearance window. 

For additional information, see “8.6. Running Scripts” in the Working Model 2D 

User's Manual. For details on Working Model Basic, see the Working Model Basic 

User's Manual (this can be found on the CD-ROM in 

\WM2D\Manuals\WMBasic.pdf). 

10.2 Rotating Pictures 

Attaching picture images to bodies is discussed in the Working Model User’s 

Manual, “7.6. Pictures,” page 7-27. In Section 7.6, a note indicates that 

pictures do not zoom or rotate with the body. Working Model now allows the 

following new functions: 

• Pictures attached to bodies may rotate with the body. 

• The frame of the picture may be offset and rotated from the frame of the body. 

NOTE: The imported picture will not zoom with the body. Therefore, attaching 

pictures to bodies is best accomplished by first zooming in or out to a view where the 

entire simulation can be seen and then attaching the image to the body. 

To create picture objects and attach them to bodies, follow the instructions listed on 

page 7-28 of the Working Model 2D User’s Manual.


Figure 10-1 

A body and a picture of an 

apple, unattached 

10. New Features 33 

Figure 10-1 of this document shows a polygonal body, a picture of an apple, and a 

wedge-shaped platform that is anchored to the ground. After the polygon and the 

apple are attached, they translate and rotate together, as shown in Figure 10-2. 

In Figure 10-2, the picture is attached to the body using the directions listed in the 

Working Model 2D User’s Manual, page 7-28. The picture is attached to the body so 

that the origin and orientation of the picture coincide with those of the body. This is 

the default behavior. 

Alternatively, the picture can be attached to the body so that it is offset and rotated 

away from the body. To offset and rotate the picture from the body: 

1. Select the picture (which also selects the body, since the picture is still 

attached to the body). 

The picture appears selected. 

2. Choose Geometry from the Window menu. 

The Geometry window appears, as shown in Figure 10-3. 

3. Choose Picture from the drop box in the Geometry window. 

4. Enter a 1.0 meter and 0.4 radian offset, as shown in Figure 10-3. 

5. Run the simulation.


34 

Figure 10-2 

The picture attached to the 

body, falling down a wedge 

Figure 10-3 

Geometry window for the 

body and the picture 

Because the picture is offset from the body, a gap between the wedge-shaped platform 

appears on the first bounce, as shown in Figure 10-4. This offset also causes the 

penetration of the picture into the platform on the second bounce.


Figure 10-4 

The attached picture with a 

1.0m and 0.4 radian offset 

Figure 10-5 

A body and picture, 

unattached, with a cyan 

background 

10. New Features 35 

10.3 Transparent or Non-Rectangular Pictures 

In Figure 10-2 and Figure 10-4, the picture includes the white, rectangular boundary 

around the apple. The simulation would look better if this boundary were transparent. 

To obtain a transparent boundary, color the boundary with cyan (red=0, green=255, 

blue=255), as shown in Figure 10-5.


36 

Figure 10-6 

Picture with transparent 

background attached to 

body 

Attach the picture to the body following the steps in the Working Model User’s 

Manual, page 7-28. Notice how the cyan background on the picture becomes 

transparent once the picture is attached to the body. The simulation appears in Figure 

10-6. Notice that only the apple is seen. The rectangular white background is now 

transparent. Compare the visual improvements present in Figure 10-6 to Figure 10-2. 

10.4 Showing and Hiding Text Objects 

The Appearance window for a Text Object now provides a means for showing the text 

only when a certain condition is met. Assuming the “Show” box in the Appearance 

window is checked, the Text Object will be shown only when the expression in the 

box labeled “Exists when:” evaluates to a non-zero value. Unchecking the “Show” 

box will still hide the text permanently, regardless of the expression in the “Exists 

when:” box. 

Note that entering the constant “0.0” for the expression will not permanently hide the 

text unless it is entered as “(0.0)”. This is necessary to create a Working Model 

formula out of the constant value of zero. 

For more documentation on the Text Object, see “7.5. Text” in the 

Working Model 2D User's Manual.


11. Version Comparison 

11. Version Comparison 37 

Upgrading from version 2.0 to version 5.2 

• Improved accuracy of calculations 

• Step-by-step introductory demonstration for first-time users 

• Vastly improved simulation speed 

• Improved interface that is more user-friendly 

• Runs on Windows 95, 98, ME, XP, NT, 2000 

• RunAllDemoFile script to help you evaluate Working Model 

• New and/or enhanced demo files 

• DXF import can now import more complex DXF models (i.e., models 

with much higher number of points/segments) 

• Audio sound has been added to the program 

• Sound files (.wav) included 

• Streamlined installer 

• New picture library with bitmap pictures 

• Rotating Pictures: Pictures attached to bodies rotate when the body 

rotates. 

• Non-Rectangular or Transparent Pictures 

• Showing and Hiding of Text Objects: Appearance window for a text 

object allows you to show text only when a certain condition is met. 

• Slot Friction: Script that allows you to model friction in your slot joints. 

• Slot Damping: Script that allows you to model damping in your slot 

joints. 

• Option to prevent a simulation from running faster than real time 

• Showing and hiding text objects 

• Available in Homework and Textbook editions 

• More ready-to-run simulations in a wider range of physics topics for your 

curriculum 

• Picture Library 

• New Tools: 

Curved Polygons 

Closed Curved Slot Joints 

Square Point element 

Slot elements 

Curved Slot elements


38 

Closed Curved Slot elements 

Join/Split Command 

• Zoom to Extent button 

• Script that measures the distance between points 

• Create a button that runs any of the scripts under the Script Menu 

• Specify overlap error, assembly error, and significant digits 

• Better organized two-column palette makes modeling tools more 

accessible 

• Resize and reshape objects while they are still joined 

• External Application Link to software packages such as Excel and 

Matlab 

• Measure the position, velocity, and acceleration of the center of mass 

• Geometry window: specify an object’s geometric properties 

• Export simulations to .avi video format for classroom presentations 

• Program translated into Japanese 

• Japanese user manual, tutorial, and Getting Started Guide are included on 

the CD 













• Script Button: Create a button that invokes a script. 

• Rotating Pictures: Pictures attached to bodies rotate when the body 

rotates. 

• Non-Rectangular or Transparent Pictures 

• Showing and Hiding of Text Objects: Appearance window for a text 

object allows you to show text only when a certain condition is met.


11. Version Comparison 39 

• Slot Friction: Script that allows you to model friction in your slot joints. 

• Slot Damping: Script that allows you to model damping in your slot 

joints. 



the CD 















the CD


40

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