Archive for April, 2009

Summary of FEA 101 at COSSUG

Friday, April 24th, 2009

As promised, here is a summary of the FEA 101 session that Richard conducted at the COSSUG meeting in Westerville, OH this week:

The session involved a basic discussion of what the finite element method is, and why a user should opt for it. The fundamentals of finite elements were established as a process of breaking down a structure into smaller segments in order to capture its response to loading conditions. This breakdown relates to the process called meshing where the model now is made up of elements and nodes (corner points on elements). The roots of this process were traced back to the mathematics that governs stresses and strains.

eq11

Rearranging the terms,

eq21

In other words, it can be said that any structure behaves very similar to a spring mass system, where F is the external force, k is the stiffness of the structure (contributed by the material and the geometry), and x is the displacement response to the instigating force.

The above principles were extended to the displacements of the nodes created in the mesh, thus depicting the deflection of the structure to the applied loads. Once the resulting deflections are determined, the strains and subsequently the stresses are captured in the geometry.

The discussion moved on to understanding the different meshes that can be created inside Simulation, and how the nature of the geometry (solid structures v. sheetmetal v. weldments) dictates the type of mesh to be created. The topic of converged results crept into the picture here, and hence the topic of refining meshes progressively to study stress/energy norm convergence was brought up.

The different steps in setting up a finite element problem were discussed in good detail:

1. Definition of the study – determining the type of analysis to perform based on the desired results (static, non-linear, linear dynamics for stresses and deflection, thermal for temperature, frequency for resonant frequencies, etc.)

2. Material – determining the type of material to use, its underlying assumptions, and the required material properties for the type of study

3. Fixtures (Restraints) – specifying the locations in the geometry where the structure is constrained from freely moving

4. Connections (contacts/connectors) – locating areas of existing/potential contact and also connecting multiple bodies together with virtual fasteners

5. External Loads (forces/pressure etc.) – indicating regions where the load acts on the design, and the nature of the loads

6. Meshing, running the analysis and viewing the results

Finally, there was a good amount of time invested in understanding what SimulationXpress offers (the free FEA introductory tool inside every seat of SolidWorks), and what its limitations are.

The seminar ended on a summary of some neat tips and tricks shown at SolidWorks World this year. The discussion on the limitations of SimulationXpress will form the basis of the first part of FEA 201 next week, which will help lead into the full-blown Simulation Portfolio.

I will post some key take-aways from the session in my next post!!

Vikram Vedantham

Simulation Product Manager 3DVision Technologies

Central Ohio SolidWorks Simulation User Group

Thursday, April 23rd, 2009

Richard Wand at MJ Engineering is putting together a new format for the Central Ohio SolidWorks Simulation User Group (COSSUG) that begins this week. The new format includes two sessions, offered this Wednesday and next Wednesday at the MJ Engineering facility at Westerville, OH. Here is a brief description of what is to come on these two dates:

Wednesday, April 22nd, 2009

FEA 101: An Introduction to Finite Element Analysis - An introduction to the basics of running analyses, how to interpret results, how to ask educated questions of experienced FEA users, and other useful information.

Wednesday, April 29th, 2009

FEA 201: An Introduction to Finite Element Analysis – An introduction to SolidWorks Simulation, when and how to use certain aspects of the software to gain the best results possible with the shortest amount time consumed. Feel free to bring examples on USB drives for us to play with.

The location is at the MJ Engineering & Consulting Inc. facility (653 McCorkle Blvd. Unit F, Westerville, OH 43082). A quick note on the agenda:

5:30 pm – 6:00 pm Gathering/Pizza

6:00 pm — 7:30 pm Presentation

7:30 pm – 8:00 pm Questions/Answers

I apologize that this probably came a little late for the first session. I will summarize the first session in an upcoming post (so as to play catchup). The next session (FEA 201) is going to be the first time we are opening the software. The tentative agenda includes a quick preview of SimulationXpress and Simulation, and a whole bunch of Q&A, apart from what is mentioned in the note above. If you are interested in attending, please RSVP Richard at 614-891-6111, or at rwand@mjengineering.com. You can also let us get you registered by sending an email to Mark Hilty (mhilty@3dvision.com), or at 513-745-2700 x220.

I will see you there!!

Vikram Vedantham

Simulation Product Manager 3DVision Technologies

Explaining Catalyst EX build properties

Wednesday, April 8th, 2009

CatalystEX allows you to take full control of how to build your part. The Properties window is accessed from the General Tab.

properties_markedup.JPG

Layer resolution – height of each layer of material extruded to produce a part. Available resolutions are based on printer type.
.007 inch (.178 mm) Elite Only
.010 inch (.254 mm) Elite, 1200, and uPrint
.013 inch (.330 mm) 1200 Only

Resolution will effect build time and surface finish – A shorter height creates a smoother finish, but will take longer to build.

Model interior – establishes type of fill used for interior, solid areas of the part.

Solid - used when a stronger, more durable part is desirable. Build times will be longer and more material will be used.

solidfill.JPG

Sparse - high density (Elite, 1200es, uPrint 3D Printers only) – this is the default model interior style and it is highly recommended. Build times will be shorter, less material will be used, and the possibility of part curl for geometries with large mass will be greatly reduced.

sparse_high.JPG

Sparse -low density- the interior will be “honeycombed/hatched”. This style allows for the shortest build times and lowest material use.

sparse_low.JPG

Support fill – support material is used to brace the model material during the build process. It is removed when the part is complete. Support fill options will affect the support strength and build time of the print.

Basic - may be used for most parts. It uses a consistent spacing between the support raster tool paths.

Sparse - minimizes the amount of support material. Sparse uses a much larger spacing between raster tool paths than basic supports.

Minimal - is used for small parts that have small features in need of supports. It is designed to make support removal easier on these small parts. Do NOT use minimal supports on large parts or parts with tall columns of support.

Break-away – similar to sparse supports without a closed tool path-perimeter curve. They are easier to remove than other support styles but build slower than sparse supports (not available for all printers).

Surround - the entire model is surrounded by support material. Typically used for tall, thin (narrow) models (e.g., pencil).

Number of copies – select the number of copies you want to Print or Add to Pack. The number of possible copies will be limited by the size of the modeling platform. Multiple copies sent to Print will first be saved as a Pack_.cmb file. If using the Add to Pack button, each click will send the same number of copies to a Pack – if space allows. From the Pack Tab you can view the arrangement of the part(s) on the Modeling Platform.

STL units – select ‘inches’ or ‘millimeters’ units of measure for your STL file. STL files do not specify units of measure. You need to specify the units as either inches or millimeters.

Example: An STL file of a cube designed with a dimension of 100 X 100 X 100, opening with a unit of measure set to inches, will not fit within the build envelope. By changing the units of measure to ‘millimeters’, the part will be resized – and fit within the envelope.

STL scale – before you process a part for printing, you can change the size of the part within the build envelope. Every part has a pre-defined size within the STL file. After you have opened the file you can change the size of the part produced from the STL file by changing the scale. The Scale always relates to the ORIGINAL (or “Save As”) STL file size definition.

Brendon Breitenstein

Field Service Engineer 3DVision Technologies

3DVision Technologies Launches Engineering Stimulus Program

Wednesday, April 8th, 2009

How committed is 3DVision Technologies to the engineering community? On April 6 3DVision Technologies was one of a handful value-added resellers (VARs) in the United States to launch an Engineering Stimulus Program in partnership with SolidWorks Corp.

This past Monday, SolidWorks began offering unemployed engineers and designers a free, downloadable version of SolidWorks Standard 2009 and SolidWorks eDrawings for a period of 90 days.

Upon launch, 3DVision Technologies committed to offering free SolidWorks Essentials classroom training to assist these very same individuals as they work to better their CAD skills. While these classes are available on a first-come, first-served approach, it is our hope that this program will help many of our engineering friends find job placement and long-term satisfaction.

Applications for the 3DVision program will be accepted through June 30 and can be accessed through www.3dvision.com

To obtain a copy of the SolidWorks Engineering Stimulus Package visit http://www.solidworks.com/ESP

I am proud to work for an employer who is committed to supporting our fellow engineers and designers and I look forward to sharing their success stories as we move forward.

Carrie Patrick

Marketing Manager 3DVision Technologies

Free “SolidWorks Protection Plan”!

Tuesday, April 7th, 2009

I recently had an email come in from a customer in Cincinnati, OH. He got an error when opening a SolidWorks file. It seems that the file had some sort of corruption. This could have been due to network connectivity, over zealous anti-virus, or some other root problem. Either way, he needed a backup. Of course, you should be able to go to the IT or IS department and ask for the file off of yesterday’s tape :) ………Another option, if SolidWorks is setup correctly, is to go to your last saved iteration. SolidWorks has a couple tools that can help “cover our butts” when something goes wrong.

I introduce the “SolidWorks Protection Plan”:

BackupOptions

1. Auto-recover – If you enable this feature, SolidWorks will auto-save at set intervals to a temporary location. These auto-saves are used if SolidWorks crashes. After a crash, open SolidWorks, if there are files that SolidWorks can recover it will prompt you in the Task Pane. This works well if you had just a few documents open at the time of the crash. If you have a lot of documents open it is less effective. This is all automated and you have little control over it. One of the nice things is being able to set the auto-save interval to a set amount of changes (adding or editing features, adding or editing sketches, anything that causes SolidWorks to rebuild the model). This may better suit your needs than having it save at a set time interval.

2. Backup – If you enable this feature, SolidWorks will save a backup file in the backup folder every time you save the file. For example, if I save the file as “G:\Engineering\box.sldprt”, SolidWorks will also save “backup of box.sldprt” in my TempSWBackupDirectory above (this is triggered on the second save of every file, not the first). This would help if the original saved file became corrupted or didn’t save properly. However, the real power comes in setting a “Number of backup copies per document”. If you enable this and set the number to 3, SolidWorks will save up to 3 iterations of the file, one for each time you save the document. For example, if I save the file as “G:\Engineering\box.sldprt”, SolidWorks will also save “Backup (1) of box.sldprt” in my TempSWBackupDirectory (Again, this is triggered on the second save of every file, not the first). Then, when I save my box file again to “G:\Engineering\box.sldprt”, SolidWorks will save the second iteration, “Backup (2) of box.sldprt” in my TempSWBackupDirectory. Now I have control of how many iterations of my design are stored locally on my machine. Keep in mind, these aren’t to be confused with revisions. They are just iterative saves during the design process. If you use this feature, I suggest checking the box next to “Remove backups older than” and set the time for 7-15 days. You don’t want this function to fill up your hard drive (and it will, fast!) if you don’t put some controls on it.

Scott High

Technical Services Manager 3DVision Technologies

3DVision’s Famous

Friday, April 3rd, 2009

3DVision’s Famous!

I wanted to take a quick minute to point out the fact that 3DVision has officially become famous.  Being a former machine designer myself, I can’t imagine there’s an engineer out there that’s not subscribed to the Machine Design magazine.  Even if you’ve ignored the expiring subscription notices they attach to the cover with that gooey clear glue (the stuff I always ended up flinging somewhere into my neighboring cubicles), chances are – you’re still receiving the magazine on a monthly basis.  Nevertheless, if my notion is correct, approximately 1.5 million engineers read this article in last month’s edition of Machine Design magazine – making us famous.

I actually had the pleasure of spending the day with Leslie Gordon, and (for not having any past experience with 3D modeling) she made a lot of progress in just one day.  The thing she and I realized is that no matter how experienced you might be in 3D modeling, it is critical to have proper training.  Without fully understanding the best practices (i.e. when to use what tools), your chances of utilizing this powerful package to the fullest are slim.

Jordan Tadic

Certified Elite Application Engineer 3DVision Technologies

Calculating Stiffness for Impact in Motion Simulation

Thursday, April 2nd, 2009

One of the challenges when setting up impact problems in Simulation Motion is to input the impact parameters (Stiffness, Exponent, Damping and Penetration). Since Jordan Tadic, in his first post, came out with some goodies for the SolidWorks user, I figured it was my turn to dig up Santa’s sack a little early and give Simulation users a tool as well.

In particular, we will take a look at what Stiffness means from an impact perspective:

Stiffness is the parameter used to define the compression that occurs when parts contact each other. This is the equivalent of spring stiffness where the force generated is equal to the stiffness times the penetration between the parts. The other aspect of this value is that the stiffness is a function of geometry.

For example, theoretically, for a steel rod, the stiffness k = A*E / L

A is the cross-sectional area
E is the Young’s Modulus
L is the effective length which is free to deform

You can download and use this Excel Sheet for Stiffness Calculation.

Alternative method

An alternative approach would be to use FEA inside SolidWorks Simulation. You can setup a Gap/Contact problem of two blocks with the appropriate materials. Measure the contact force and the displacement at the interacting faces. Then, take an average stiffness = force/displacement and use that in the Impact model definition.

I definitely think it is time to put up the Christmas tree!!

Vikram Vedantham

Simulation Product Manager 3DVision Technologies

MVSWUG Meeting Announcement

Thursday, April 2nd, 2009

The next MIAMI VALLEY SOLID WORKS USER GROUP meeting is going to be on April 21, 2009 at Gander Mountain in
Huber Heights.

Agenda

5:30pm – 6:00pm Registration, food, and networking
6:00pm – 7:30pm Randy Simmons will do Surfacing Presentation
7:30pm – 7:45pm Break
7:45pm – 8:10pm Randy Adams will talk about SolidWorks World 2009
8:10pm – 8:20pm Discussion about next meeting date and what we would like to cover
8:20pm – 8:30pm Wrap-up, prize giveaways

Please RSVP to Randy Adams at ovapres@yahoo.com

PS: There might be a surprise hand out so come and see what you might get by just attending this meeting.

Randy Simmons

Application Engineer, CSWP 3DVision Technologies

Simplify Model for Meshing

Wednesday, April 1st, 2009

Driving home from work, it takes me a while to wind down after a day of mathematical puzzles (FEA = numbers!!). And more often than not, the talk shows on NPR are the ones that help me get off of work mode. Speaking of which, I sometimes wonder what I would be asked if I were interviewed on NPR on FEA using SolidWorks Simulation.

“Final question, Vik, as we are running out of time here!! What would be the one key piece of advice that you would give your customers working with SolidWorks Simulation before they start FEA on geometry? 30 seconds!!”

Well!! My answer really is not 30 seconds long, but is rather a three-word phrase that I re-iterate about 300 times in a 2-day training class – “Simplify the Geometry”.

In SolidWorks 2009, this task just became a whole lot simpler. The objective of simplifying geometry is clear cut – to reduce solve time by putting a simpler mesh on the model. To simplify the geometry, the user can now right click on the mesh folder, and choose the option “Simplify Model for Meshing”.

Mesh Menu
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Upon doing so, the task pane on the right side of the graphics window opens up the Find/Modify/Suppress/Simplify panel to scout the geometry and extract the filtered results. For example, the Simplify tab allows the user to simplify the geometry using a factor (0-1 scale). The Suppress tab is more robust, and allows the user to filter through the model and extract specific parameters (For example, specific categories like holes, hole wizard items, chamfers, drafts, ribs etc. that fall below a certain cut-off value).

Simplify model for meshing

What more, the user can ask SolidWorks to create a derived configuration of the simplified geometry, so that the original configuration is left undisturbed. A configuration for manufacturing and a derived configuration for FEA – how convenient?!!

The icing on the cake is the fact that a study can be linked to a derived configuration. All in all, the sequence of pre-processing should now include “Simplify Model for Meshing” right after defining a study!!

I believe my three-word answer would have left the next music on cue to be played for 28 seconds!!

Vikram Vedantham

Simulation Product Manager 3DVision Technologies

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