Archive for the ‘Training’ Category

Connections in Assembly Frequency Analysis

Tuesday, July 28th, 2009

If you have tried to run any type of frequency analysis on an assembly, you may have noticed that the only types of contact conditions available to you are Bonded and Free. The No Penetration contact condition is not available. The reason for this is that constant stiffness and mass matrices are a requirement for frequency analysis. No Penetration allows components to come together or to separate during the course of an analysis which would represent a change in the stiffness matrix. This also precludes the use of bolt connectors in an assembly frequency analysis as bolt connectors utilize No Penetration contact conditions.

There are two methods around this. The first is to replace the bolt connectors with bonded contacts at the necessary locations. The second option is to apply free contact between the connected components and utilizing pin connectors. The first method generally makes the model overly rigid resulting in higher than actual natural frequencies. The second method leans the other way. While these methods do not provide completely accurate results, they typically bound the true frequencies.

P.S. This is also the case for Modal Time History, Harmonic, and Random Vibration Linear Dynamic analysis. As stated above, Bonded and Free contacts are also typically suitable assumptions in these cases as well.

Seth Bischoff

Seth Bischoff
CAE Support Engineer
3DVision Technologies

Posted in COSMOSWorks, SolidWorks, Tips & Tricks, Training | No Comments »

Keeping up with the Joneses

Tuesday, May 19th, 2009

The following is an interview with Jimmy, our top gun designer from Friday’s upgrade zone episode.

Engineering Data Specialist Man: You have a reputation around here as the go to SolidWorks guy, yet we couldn’t help but notice you did not use any of the enhancements offered in the new upgrade what happened?

jonesesJimmy: I always try to attend the 3DVision “What’s new” presentations, but this year I wasn’t allowed to go. Isn’t it interesting that companies offer tuition reimbursement but won’t let you take a half day to attend a What’s New presentation? They’d pay for me to take a pottery class (as long as I get a “C” or better) but they won’t help me keep my SolidWorks skills current?

EDSM: [Sigh] Some companies don’t understand that there is a cost to maintaining talent. Do you remember if your job description mentions that one of your job responsibilities is to keep up with technology? I know that is a typical statement at most companies.

Jimmy: I think it does, I always figured that was just something they put in so they could fire me if they ever needed to.

EDSM: Ahh…they have you paranoid, looks like your boss is doing his job; however that little loop-hole statement is a good thing! It is your ticket to improving yourself on company time.

Jimmy: I suppose that is true, but if I miss the “What’s New” presentations how can I keep up?

EDSM: Yeah, it is difficult without being able to attend the “What’s New”s -I always think of them as the best continuing education opportunity around, but they aren’t the only tools at your disposal. SolidWorks World, Technical Summits, the SolidWorks forum, SolidWorks blogs, the “What’s New” document (found in the help section of SolidWorks), and even trade magazines are good tools at your disposal. Remember as fast as technology changes, if you don’t improve, you are falling behind. Try to set aside time each week to devote to “keeping up with technology”. At the very least ensure you go through the “What’s New” document, even if you don’t think a chapter directly will be used in your company. You might find a new approach to an age old issue in your company.

Jimmy: I’ve been thinking of attending one of the SolidWorks user group meetings do they help?

EDSM: I’ve never attended one where I didn’t at least learn something. Besides, you cannot go wrong with free pizza!

Jeff Sweeney

Jeff Sweeney
Engineering Data Specialist
3DVision Technologies

Posted in General, Training | No Comments »

The SolidWorks Upgrade Zone

Friday, May 15th, 2009

What you are about to read may surprise or even shock you. You are about to enter the SolidWorks Upgrade Zone.

spinyTake this man Jimmy. Jimmy is the top gun engineer at his company. Last night Jimmy’s IT department upgraded his SolidWorks installation from SolidWorks 2008 to 2009. Let’s watch to see how much faster Jimmy is with the new upgrade.

I see Jimmy is working with weldments, but not taking advantage of the new 2009 group feature. Interesting –I am sure it would have saved him quite a bit of time there. Let’s watch him as he works with sheet metal. Wow, he is still using the same techniques he learned when he took the sheet metal class four years ago! Now let’s watch as he works with some large assemblies, I am sure the new Speedpak technology will be a huge time saver! Wait! He isn’t even using it! Oh the calamity!

So here we are at the end of the day…let’s bring up the tote board to see how much time Jimmy saved with the upgrade! [Drum roll] Two minutes! Wait, only two minutes?! How could this be? Jimmy’s company has been paying maintenance for a full year to only gain two minutes? Granted that Engineering Data Specialist guy provides excellent support, but still -only two minutes? [Rod Sterling & Jerry Lee Lewis walk off the set shaking their heads.]

What you just saw here is going on all over the world right now. This is the time of year many companies upgrade their users to the new SolidWorks version. Sadly, for many, that is where the upgrade ends. If the users are not given an opportunity to learn how to use the new version, they will continue to use SolidWorks how they were originally taught.

An upgrade requires two steps. You need to upgrade the machine and the users. If you only upgrade one of the two your return on investment is not as good as it could be. Few users learn the new performance enhancements on their own.

Jeff Sweeney

Jeff Sweeney
Engineering Data Specialist
3DVision Technologies

Posted in SolidWorks, Training | 2 Comments »

COSMOSWorks Post-Processing Options – Part I

Tuesday, November 27th, 2007

Design Check Plot

The Design Check plot is a very useful tool for verifying the integrity of your design. COSMOSWorks provides a simple three step wizard for setting up a design check plot. The wizard interface guides the user through multiple options. Some of the available options are:

– Select entire assembly or specific components / bodies for FOS estimation

– Multiple failure criteria to select from including:

o Max von Mises Stress
o Max Shear Stress (Tresca)
o Mohr-Coulomb Stress
o Max Normal Stress

Search “Design Check” in COSMOS help for a complete description of each failure criterion and when each should be used.

– Multiple stress units. (The user can pick between N/m2, psi, kgf/cm2, and N/mm2 (MPa))

- Selection of property used to define stress limit including:

o Yield strength
o Ultimate strength
o User defined value

- Ability to enter stress limit multiplication factor. (Similar to a safety factor, this will multiply the stress values by this user specified value before calculating the design check results.)

There are also multiple result options available:

- Factor of safety distribution plot
- Non-dimensional stress distribution plot
- Areas below factor of safety plot

The factor of safety distribution plot is the standard factor of safety plot that everyone is accustomed to. The model is color coded based on the factor of safety at various locations. The non-dimensional stress distribution plot is basically the inverse of the factor of safety plot. For example, if the max von Mises criterion is used, the non-dimensional stress is the von Mises stress at a specific location divided by the yield strength of the material. If you enter a multiplication factor in Step 2 this factor will be applied to the stress before calculating the non-dimensional stress. The last option allows the user to specify a factor of safety. The plot will display all areas below the specified factor of safety in red.

Seth Bischoff

Seth Bischoff
CAE Support Engineer
3DVision Technologies

Posted in COSMOSWorks, Tips & Tricks, Training | No Comments »