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Ellipsis is the official blog of Autodesk's Technical Evangelist Team. We will discuss all things design and manufacturing related with a focus on industries such as automotive and transportation, consumer products, industrial machinery and building product manufacturing and fabrication. We also have resident experts who will blog about specific product developments in CAD, Simulation, Industrial Design and Data Management.
We look forward to providing you, our user community, with the most relevant and up to date developments in our industry, and hopefully with information that will assist you in doing your job better, faster, and more precisely.
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Weight Watchers...
September 16, 2009 12:27 PMby Jay TedeschiFor those of you who remember my post from last week you may recall that we had a small problem with vendor supplied library component data, namely it's construction did not allow for any type of mechanical functionality within the top level assembly. Fortunately, we were able to use Inventor's multi-body tools to break the caster chassis into several parts that we then reconstituted as a proper assembly, allowing for rotation around it's own spindle axis.
Well, that is just one of the problems that is encountered when working with data such as this. A larger problem from a physical standpoint, is that the property data for any part that is not modeled with 100% geometric accuracy is not going to be valid. If I take a look at a cross section view of the caster wheel assembly in question, it becomes quickly evident why this problem exists. Take a look at the image below...
As you can see, this caster has no internal structure whatsoever... it is quite simply a solid part whose exterior closely matches that of the actual component. From a mass properties standpoint, this is really bad. Fortunately, there is a way to correct for this, and it is incredibly easy. With the Caster Assembly open, I navigate to the browser and highlight the top level assembly... then right click and select iProperties.
Next I select the Physical tab and activate it. In the middle of this dialog box are the the General Properties for this assembly. Notice the calculated value for Mass...
A quick look at the product data sheet from the vendors web site shows the weight of this part to be .4536 Kg... less than half of what this is currently. By selecting the Mass field, I can highlight the current value and then overwrite with the value determined from the product sheet.
Notice that when I do this, the calculator symbol changes to a hand, indicating that the calculated value has been over-ridden. Any assembly that this caster wheel is placed into will now calculate the correct overall mass properties, as well as displaying a combination of the hand and calculator, to show that the data contains some Mass over-rides.
I have posted a video to my YouTube channel that shows this entire workflow, as well as a little bit more with regard to setting default BOM structure and adding BOM properties. I hope you find this useful, and as usual, if you have any questions at all, please let us konw and we will do our best to answer them or find someone who can.
0 Comment | Add CommentIn Ellipsis > Industry News, Links, Tips
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So... what now?
April 22, 2009 03:54 PMby Jay TedeschiYou've completed a single point stress analysis, discovered several areas of high stress in your assembly, but how best to deal with them? There are a dizzying number of model parameters that could be changed, all of which will no doubt have an effect upon, but which one(s) would yield the best results?
Well, fortunately, Inventor Professional 2010's Stress Analysis environment has a tool to help you determine just that! The technique is sometimes referred to as Parametric Optimization, but in the SA environment it is called Parametric Dimension. Essentially, it allows you to select a group of sketch and model parameters that will be used to build part/assembly iterations, and each of these interations, and all of the resultant combinations, will be analyzed and then the results measured against a set of design constraints in a process that it sometimes referred to as a sensitivity study.
Stick with me here... in the example below, you see that after we run the single point analysis we find that we have several high stress areas. These stresses, while not significant enough to exceed the yield strength of the material, are nonethless a concern because ultimately they could lead to fatigue failure of one of the parts in the assembly. The highest stresses are concentrated in the tab, so we can try a few different thicknesses for the tab itself and also for it's stiffening rib. Three different values for the tab, and two for the rib give us a combination of 6 different versions that will be analyzed. To save time in processing there is an option for running what is called a "Smart set" of configurations. If you arranged the versions in a table, you would see that we have 3 columns and 2 rows, or vice versa, of interations... 4 total with regard to the 1st column and 1st row, and a total of 6 different combinations.
In our case, the "Smart set" analyzes those 4 versions, and because we are performing linear analysis, is able to interpolate the results for the other two. Once the analysis is complete, we open up the Parametric Table once again and are now able to evaluate our results against specific design criteria... in our case, Mass, Stress and Factor of Safety. Once a version is found which meets our design requirements, we promote the parameter changes back to the model, whcih then changes all of the assoicated parts/assemblies/drawings.
It is a very powerful addition to what was already a powerful analysis tool. Check it out and let me know what you think.
1 Comment | Add CommentIn Ellipsis > Tips, Links
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August 2008 BAMUG...
August 22, 2008 07:11 PMby Jay TedeschiThe Bay Area Manufacturing User Group will be holding it’s August 2008 meeting on Monday the 25th at the San Jose Hilton. This is a great opportunity to meet with other manufacturing users and discuss what is important to you.
An added bonus this year is free admission for the nvision expo with your registration. There will be three days and over 77 hours of technical sessions at the nvision expo, plus a Keynote hosted by NVIDIA CEO Jen-Hsun Huang, an exclusive screening of 3D Film "Fly Me to the Moon" with special appearance by Buzz Aldrin, and appearances by other special guests including immersive display scientist and one of Time Magazine?s 2008 100 most influential people Jeff Han, Jamie and Adam of MythBusters fame, NASCAR driver Kyle Busch, actress Tricia Helfer from Battlestar Galactica and NASA astronaut and space shuttle commander Eileen Collins.For all the info, head on over to here and register now. -
Be heard...
March 5, 2008 01:41 PMby Jay TedeschiBe heard... before it’s too late. Here's your chance to help make Inventor the product you want it to be. There are only a few days left to make your contribution to the official AUGI Inventor Wish List. Simply follow this link... (http://www.augi.com/inventor/ballot.asp ) to the ballot page, select one of the feature categories and then vote for the improvements you feel are most needed.
Remember, you must be logged it to vote, so if you are not an AUGI member, you will have to register first. It only takes a minute or two, it’s free, they won’t bombard your inbox with emails, and best of all you can stay up to date with the largest Inventor community in existence.0 Comment | Add CommentIn Ellipsis > All, Links, Inventor 2008
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Free Stuff...
February 5, 2008 12:06 PMby Jay TedeschiFree Stuff... that should catch someone's attention. Like a sign that reads "Do not read the other side of this sign..." You know that you just have to have a look at the other side right? [grin]
Anyway, back to the free stuff... We are sponsoring a contest at http://mfgcommunity.autodesk.com/contest/ . You don't have to do anything other than enter to win. That's it.
You have to win it, but if you win, it's free, except of course for the taxes that the Federal Government is probably going to require you to pay... and of course any state or local taxes as well. But other than that, it's free. [grin]
2 Comments | Add CommentIn Ellipsis > Just for fun, Links, Tips
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Good engineering site
March 8, 2006 09:55 PMby Kevin SchneiderLooking for a site to start looking for new companies or equipment? Just interested in mechanical design and manufacturing? Take a look at http://www.engnetglobal.com it is a great site with lots of good technical information.
0 Comment | Add CommentIn Ellipsis > Links