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2009

By using an Annotation, you can display the weight of your assembly (or part) in the graphics window, which is awesome for when you are making design changes or optimizing it for weight.  Here is the procedure:

1. Insert > Annotations > Note
1.bmp

2. Drop the annotation on the screen where you want, and then over in the property manager, select the Link to property button.
2.bmp

3. Choose the File properties button.
3.bmp

4. "Weight" under Property Name, and "Mass" under Value / Text Expression, and then OK.
4.bmp

5. Back to the "Link to Property" dialog, use the pull down to select "Weight."
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6. Here is an example of the result (the 164.11).  You can add text around it and change the Font format as well.

6.bmp

 

Copyright © 2009 Dassault Systèmes SolidWorks Corp. All rights reserved.
Do not distribute or reproduce without the written consent of Dassault Systèmes SolidWorks Corp.

I'm looking for people to make comments about how they've been able to successfully relate analysis setup or results to people that don't have a solid background in FEA / simulation, let's just say the average lay person.


Here's some recent examples to help get the creative thinking in motion:


a) Did you know that people can blow about 2 psi.  Helps to explain pressure drop.


b) Supercritical fluids, like highly pressurized CO2, are used to extract substances like caffeine from coffee beans.  Just cool to know because before yesterday I didn't know how they decaffeinated coffee.


c) Changing the force on a linear static analysis just linearly scales the resulting values (as long as they stay below the yield strength are they valid) so all the colors on the model stay the same, no additional run/study is required.

How do you calculate the bolt preload for Bolt connectors in SW Simulation?

pre-load.bmp
I'm going  to try to make this super easy for you all.  Here is a link to two PDF  files, one for USA bolts and the other for Metric bolts, where the values of Ats (Tensile Stress Area, length^2) and Sp (Proof Load Strength, force/length^2) are  provided in one document.  These two parameters are even colored in the tables so that they can be found  more easily.

To calculate the  Axial Preload, Fi, use this equation:
For a permanent  connection: Fi = 0.90 * Ats * Sp
For a reusable  connection: Fi = 0.75 * Ats * Sp
For those  of you who want to input a torque, T, then it gets a little more complicated:
With a nut:  T = k * Fi * Dn
Without a nut: T = 1.2 * k * Fi * Dn
where k is the Friction Factor, and Dn is the nominal (major) diameter, which  can be found in the tables in the PDF files.

The friction factor, k, is difficult to estimate in a real world  application, so for practical usage recommended values are suggested  below:
Non-plated, k = 0.30
Zinc-plated, k = 0.20 - 0.28
Lubricated, k = 0.18
Cadmium-plated, k = 0.12 - 0.15
Default (No  information / not provided / unknown), k = 0.20
After  running the study, check the forces on the bolts by  right-clicking the Results folder and choosing the "List Pin/Bolt/Bearing Force"  item.  Typically the absolute value of the axial force on the bolt should be  about the value of the preload that was entered.  If the axial load on any of  the bolts is nearly zero, then that means that the bolt was not properly  preloaded and so the bolt is loose, which can cause real problems!

Here are two practical  examples:

(a) 1/4" -  20 UNC Bolt Grade 5

Ats = 0.031822 in^2 and Sp = 85000 psi

So, for a  permanent connection, the bolt preload is calculated be

  • Fi = 0.90 * 0.031822 in^2 * 85000 psi = 2430 lbf


(b) M10  x 1.25 x 40 - 9.8

Ats = 61.199 mm^2 and Sp = 650 MPa

So, for a reusable connection,  the bolt preload is calculated to be

  • Fi = 0.75 * 61.199 mm^2 * 650 MPa = 29800 N

Just one more thing before I finish this blog about Bolt Connectors...

A feature for the bolt connectors (for releases 2008 and greater) allows the bolt to go through more than two components.  If you have this case, then make sure that you open up the Advanced Option and turn on the "Bolt Series" flag and select the cylindrical faces of the holes for all the other parts that are sandwiched in between.

bolt_series.bmp

This meshing tech tip is perfect for when you really want to control the mesh through the whole volume or thickness of only a portion of a part.  Mesh controls on a surface may not propagate through the entire thickness of the part, which in some cases may be necessary for accuracy.  What you should do is use the Split feature!

You can create a multibody part from either a 2D sketch or a 3D surface as a "Trim Tool" for Insert > Features > Split.  If you've already created a Simulation study, make sure you right-click on the study name and choose Update Components.  This will update the component that you split with more than one body, and since they are probably the same material, you can just drag-and-drop the material from Body 1 to the rest of the bodies.

Apply a mesh control to one of the split bodies and you can control the mesh on that entire volume!  Here is an example of a mesh control on a portion of a cube, where on the left it shows a compatible mesh and on the right an incompatible mesh.  (Note: This example was not used for any real problem but just as a proof of concept for myself.)

 

Meshing - compatible & incompatible.gif

Joe Galliera

3GB switch question

Posted by Joe Galliera Employee Oct 8, 2009

Using more memory is definitely an advantage in Simulation. There seems to be a lot of confusion in the industry about what's commonly called the Windows “4GB memory limit.” When talking about performance tuning, people are quick to mention the fact that an application on a 32-bit Windows system can only access 4GB of memory. But what exactly does this mean?


By definition, a 32-bit processor uses 32 bits to refer to the location of each byte of memory. 2^32 = 4.2 billion, which means a memory address that's 32 bits long can only refer to 4.2 billion unique locations (i.e. 4GB).


In the 32-bit Windows world, each application has its own “virtual” 4GB memory space. (This means that each application functions as if it has a flat 4GB of memory, and the system's memory manager keeps track of memory mapping, which applications are using which memory, page file management, and so on.)


This 4GB space is evenly divided into two parts, with 2GB dedicated for kernel usage (i.e. used by Windows OS), and 2GB left for application usage. Each application gets its own 2GB, but all applications have to share the same 2GB kernel space.


To be able to extend this to 3GB for applications, such as SolidWorks Simulation, then here is how you do it:

 

Enable the 3GB switch on Windows  XP

  • Right-click My Computer. Click Properties.
  • In the System Properties dialog box, click the  Advanced tab.
  • On the Advanced tab, under Startup and Recovery,  click Settings.
  • In the Startup and Recovery dialog box, under  System startup, click Edit. The Windows boot.ini file will be opened in  Microsoft® Notepad.
  • Create a backup copy of the boot.ini file by doing a "Save As..." to a different  location. Note: Boot.ini files may vary from computer to computer. 
    Select the following line in the boot.ini file:

multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP  Professional 3GB" /noexecute=optin /fastdetect

  • Press Ctrl+C to copy the line and then press Ctrl+V  to paste it immediately above the original  line. This will be the default  selection, if you don't want to boot to the 3GB environment by default, then copy it below the original line instead.
    Note: Your text string may be different from the text  string in this solution, so be sure to copy the text string from your boot.ini  file, and not the text string included here.
  • Modify the copied line to  include "3GB" (you can change anything within the quotation  marks to be descriptive), as shown in the following example:

multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="WinXP  Pro 3GB" /noexecute=optin /fastdetect /3GB /userva=2900

 

Note: Do not overwrite any existing  lines. I set the timeout for my menu to be 8 seconds (instead of 30),  which is plenty enough to make a menu selection during the boot process.  To do this, just change the line to:  timeout=8

  • Save and close the boot.ini file.
  • Click OK to close each dialog box.
  • Restart your computer.
  • During startup, you be presented with a menu to have the option of which environment to boot.

Note: If problems occur during startup, you may need  to update some of your drivers.

Enable the  3GB switch on Windows Vista and Windows 7 (32-bit)

  • Right-click Command Prompt in the Accessories  program group of the Start menu. Click Run as Administrator.
  • At the command prompt, enter "bcdedit /set  IncreaseUserVa 3072"
  • Restart the computer.

Disable the 3GB switch on Windows  Vista and Windows 7 (32-bit)

  • Right-click on Command Prompt in the Accessories  program group of the Start menu. Click Run as Administrator.
  • At the command prompt, enter "bcdedit /deletevalue  IncreaseUserVa"
  • Restart the computer.

 

For more information on the 3GB switch,  refer to the following Microsoft MSDN article:

http://msdn2.microsoft.com/en-us/library/ms791558.aspxhttp://msdn2.microsoft.com/en-us/library/ms791558.aspx

 

More on BCDEdit at: http://www.windows7home.net/how-to-use-bcdedit-in-windows-7/