Ellipsis

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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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  The same, but different...
  October 1, 2009 09:30 AMby Jay Tedeschi

  The same, but different... let me explain.  So, the same problem we were discussing for the last couple of weeks, namely, working with data from other sources.  If you recall, I had covered working with data from a vendor from whom I was buying components for our re-design.  This week, the problem is the same, but different in that in this case I am working not with a purchased component, but rather with an assembly that was created with a different design tool than the one I happen to use.

  In the best of conditions, this presents something of a challenge, but when we find ourselves needing to change the design in some way, the level of complexity quickly increases.  Autodesk Inventor Fusion was built from the ground up to facilitate the toughest of these type of design challenges.  In this, the first of several posts featuring Inventor Fusion, we will take a look at some basic assembly manipulation and modeling techniques.

  If you remember last week we finished up working on the Caster Wheel "Assembly" that we downloaded from our vendors web site.  Well now we are going to work on the brake assembly that attaches to two of those wheels... this was originally created in Pro/E, which is not a problem for us as we can open the .asm file natively.  Once open we can see that the existing torsion spring is not going to work in our new configuration, so we will select the body from the assembly, and then from the marking menu select "Isolate" to suppress all but the spring.

  

  I can now make several non feature based edits to this part, quickly and easily.  As these changes are symmetric, I will split the part, then correct for rotation and position with the Move command.  Here I am moving the body along its mount axis so that it fits correctly in the bearing block.

  

  Now we can address some of the feature lengths, but again, not via a feature edit, but rather with a direct manipulation of the feature face.  For example, as you can see in the figure above, the length of this element is a bit more than is required, so Press/Pull functionality is used to select the capping face and then press into the model, shortening the element.  As we split and then moved the entire body away from the center plane of symmetry, the split face is now short of the center plane by the amount of that first move.  Press/Pull is used here again, but in this instance I will select the symmetry plane after picking the capping face, and the pulled face "snaps" to that plane.

  

  Finally, the corrected spring is mirrored about the symmetry plane and the assembly saved for use back in the top level assembly.

  

  The thing that really hits you with Fusion is how absolutely easy it is to use.  The entire edit sequence shown above took no more than a couple of minutes... Don't take my word for it... check out the entire session for yourself in this video I shot.  As always, if you have any questions or suggestions I would love to hear them.

  Ciao'

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  Weight Watchers...
  September 16, 2009 12:27 PMby Jay Tedeschi

  For 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.

   

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  One is the loneliest number...
  September 8, 2009 04:17 PMby Jay Tedeschi

  One is the loneliest number... especially when we are dealing with assemblies.  Most of the assemblies that we find ourselves working on in the course of completing a design will require a number of purchased components... and depending on the type of product, that percentage can be pretty high.  In order to support a full digital mock-up or prototype of our designs, it is a frequent practice to model a geometrically accurate facsimile of those parts or assemblies or download from the vendors themselves, those models in some neutral format.  When we work with components such as these, often a single part file is used as a placeholder for what is actually an entire assembly.

  Consider this example... a caster wheel used on a piece of medical equipment.

  

  There is a locking mechanism which needs to pass through the slot in the top of the pivot axle of the caster wheel assembly, but unfortunately, this component, which was downloaded from the vendors site, is made up of only two parts, and therefore lacks the mobility to allow this type of movement in our model.  What we need to do is open this part, and using Inventor's new Multi-Body functionality, split this part into two new individual parts, and then save that split configuration to a new assembly document using the Make Components command.

  

  

  It would take far too long to explain this process right here in text, and you don't want to read that much, and I certainly don't want to type that much [grin]... so I created a video for you that will consume only about 4 minutes of time out of your busy day and will give you a really good idea on how to employ these new tools to your advantage.  I hope this sheds some light on what is otherwise possibly an obscure process, and please let me know if you have any specific questions that I can help you with...

   

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  Two Minute Tip - Direct Parameter Naming
  June 23, 2009 12:25 PMby Rob Cohee

  So I found it. My new favorite feature of Autodesk Inventor 2010. Direct Parameter Naming. Beautiful in its simplicity, it will drastically improve your productivity when dealing with parameters in Inventor. Believe it or not I was actually able to get a Two Minute Tip completed in under two minutes!

   

  Cheers,
  Rob

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  Simplify...
  June 19, 2009 02:38 PMby Jay Tedeschi

  Simplify... as defined by Websters...

  Function: Transitive Verb

  Inflected Form(s): sim.pli.fied; sim.pli.fy.ing

  Etymology: French simplifier, from Medieval Latin simplificare, from simplus simple, Date: 1759

  : to make simple or simpler: as a: to reduce to basic essentials b: to diminish in scope or complexity : streamline <was urged to simplify management procedures> c: to make more intelligible : clarify

  "Mmmmmm... that sounds good. I'll have that."  Wow, enough references in the first few lines to make Dennis Miller proud. [grin]  However, in all seriousness, when working with simulation, your goal should always be simplification.  Simplify.

  

  Ultimately, your goal is to analyze as accurate a representation of your assembly as possible.  But before you dive in with your top level file, think for a second as to what results you are trying to determine.  The assembly shown above is an excellent example... my goal was to determine the deflection of the welded chassis under load, therefore the rear trolley wheels and forward pivot mount are not required.  Their role in the analysis can be simulated with a constraint.  Ditto for all of the pylon mount points and the associated hardware located on the upper faces of the weldment.  These changes alone will save me an incredible amount of time in pre and post processing.

  There is however, more that I can do.  Take a look at the weldment assembly itself.  What one feature or characteristic do you notice almost immediately.  Right.  It has symmetry... and as long as the loads placed upon the trolley via the engine pylon are also symmetric, which they are, what assumption can I make with regard to the results?  Correct... they should also be symmetric about the center plane of the weldments.  So what can I do to simply this and still get accurate results?  Take a look at the following image...

   

  I am using a Level of Detail Representation, named "Simulation", for each of the Weldment sub-assemblies.  An LOD Rep in the top level assembly with the same name allows me to toggle back and forth.  Now in this situation, you have a lot of flexibility in how you create your simplified rep, but the easiest is to use a Shrinkwrap substitute and then drive a single extrude cut from the mid-plane out effectively removing half of each of the sub-assemblies.  The results are shown below...

  

  Sweet... right?  Okay, I am almost there... What?  You didn't think I was done did you?  Absolutely not.  What would happen if I was to load up this model the way it is now?  What do you think would happen to those unsupported elements that have all now been split?  Right... they do not effectively represent our full assembly any longer, precisely because I split them in half, and therefore I will not see the correct amount of deflection on those elements.  I can't use a Fixed constraint either, as it will leave me with a frame that is unnaturally stiff.

  The answer is the Frictionless constraint. 

  

  This constraint prevents a selected surface from moving or deforming in the normal direction relative to the surface selected.  It does however allow for rotation, movement and deformation in a tangential direction to the selected surface.

  

  So... applying the Frictionless constraint to all of the cut faces on the Weldment Sub-assemblies allows me to simulate symmetry, and I now have an much smaller model to have to pre and post process... these are all very desirable attributes when performing analysis.  Meshing is quicker, automatic contact detection is quicker, and best of all, the results are in-line with what I would expect to see if I had spent almost three times as long analyzing the full assembly.

  

  Simplification... "It's a good thing." 

  By the way, if you found this interesting, and are looking for a way to get better acquainted with Inventor Simulation, then you should head over to @adskcommunity on Twitter and send them a direct message to receive your copy of "Up and Running with Autodesk Inventor Simulation 2010".  Details are on the site.

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  All Mixed Up...
  June 11, 2009 03:01 PMby Jay Tedeschi

  If you frequently find yourself working in a "mixed geometry" environment then do we have a new tool for you... Up on //Labs today, the release of the Rhino Import Translator. http://tinyurl.com/nb8ul5

  

  This translator allows Inventor users to directly read Rhino surfaces, solids, wires and points, eliminating the need to intermediate file formats such as Iges or Step.  Check it out... !

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  So... what now?
  April 22, 2009 03:54 PMby Jay Tedeschi

  You'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.

   

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  Interoperability or Collaboration...
  April 10, 2009 01:08 PMby Jay Tedeschi

  Heres another post from Rob Cohee, our resident BPM expert... Enjoy!

   

  I’d like to expand upon a discussion thread that I saw on Facebook the other day. It had to do with which application should be applied toward a particular design challenge. Or to be specific, should I use Inventor, or Revit, or Maya, or MAX, or Navisworks, or Alias, or AutoCAD, etc. Yes – use them all, the key is how to determine which one to use. It’s simple really, ask yourself “what is my desired result.” The answer to that question will determine which application, or combination of applications to utilize on a project.

  Here’s an example – I want to build a new line of configurable office workspaces. Simple enough, sounds like I fire up Inventor and start creating iAssemblies, right? Well, what if you were working with an Architect to build out a project? Maybe starting with the Revit file to perform some early analysis of the project would be appropriate? Here is where we can start to talk about the difference between interoperability and collaboration. At this stage I want to collaborate with the Architect. I don’t want to, nor do I have any influence to change the design of the building, so I’m not looking for interoperability between Revit and Inventor. However, by utilizing the Revit model to bring in the information I need to perform my analysis on these workspaces I have saved myself a considerable amount of time compared to re-drawing or re-modeling the architectural space. I don’t in this case, require interoperability between the Revit files and Inventor – I just need some sort of collaboration between the two.
  Let me expand then on what I mean by interoperability. Interoperability, in this example, would be the ability to open a Revit project file natively in Inventor – AND be able to manipulate the native geometry through parametric or other methods. So if I wanted to move a wall, I could click on the wall and have Inventor recognize the Revit wall element and move, clean corners, adjust schedules, door position, window position – essentially all the things that Revit does, but do it within Inventor. That’s interoperability, and that’s not what you want.

  THUD! That’s the sound of someone hitting me on the back of the head with a bat. “What are you doing telling the customers that what they want isn’t exactly what they want?” Sorry guys, that’s the cold hard truth of it. Where is the control in the design process if everyone can edit anything whenever they want? Plus, when you create a single, monolithic application that is good at many things; they become average as a complete solution. Here’s my thought - apply the appropriate technology determined solely by the desired result allows you to determine which purpose built tool to apply to the design; with a higher degree of accuracy and unmatched ease of use. Any one of the Autodesk products previously mentioned is best in class at modeling, drafting, collaborating, and managing every aspect of a project throughout its lifecycle. Check out this example...

   

  This should get some blood pressure up... Bring on the comments!

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  DP and BIM: BFF
  March 26, 2009 07:33 PMby Jay Tedeschi

  Well, it's spring and there are a few changes around here that I have to let you know about.  First of all, I am no longer the sole evangelist for the Manufacturing Industry Group, I am now part of a team of evangelists that resembles the lineups of the great New York Yankee teams of the 60's, 70's and late 90's.  Powerhouse is the word that comes to mind, and we will deal with the introductions at a later date, but suffice it to say that it is a VERY strong team and I am proud to be part of it. Oh... the things we are going to show you...

  So, this is no longer my blog, but rather it is now "our blog", and without further ado, I will turn this post over to Rob Cohee, Industry Solution Evangelist specializing in Building Product Manufacturing... or BPM... the first of many new acronyms you are all about be innundated with... [grin]

  DP and BIM: BFF’s?

  Wouldn’t you know it, as soon as the industry begins to collaborate in ways that is challenging contractual agreements on building projects now all of the sudden everyone wants BIM content, aka Revit Families. And the exchange process has to be quick and easy and… Oh yeah, don’t give away the farm when you pass the design to an architectural firm, plus the architect isn’t necessarily looking for something they can create CNC code from anyway. And what about integrating the product into the buildings infrastructure, plugging in MEP elements so that the manufacturers model can participate in the BIM project?
  Sounds to me like architects are asking me to make a new lightweight version of the model that I have already exceeded my engineering budget for. I don’t even know if they can accept .SAT, .IGES, or the new one, the all popular .DMWISYUWBATRA (Doesn’t Matter What I Send You U Won’t Be Able to Read it Anyway) file type. Some people prefer the longer version of the new format which is the .DMWISYUWBATRA-YERA (You’ll End up Re-modeling it anyhow).
  That’s right, I just came up with the longest acronym in Autodesk history. I’m so proud…there are so many people to thank… tears are welling up… eh eh ehmm.
  Ok, sorry about that – very proud moment. SO, you don’t want to give away the farm when people ask for your designs and you don’t want to spend any time making a dummy version of your gazillion part assembly. Groovy, neither did I and now we have something that will make your day (insert dramatic pause and drum roll here..). We now have Shrinkwrap! Stay away from the Seinfeld references here guys… Seriously this is killer functionality that is not only going to allow you to collaborate with people that are asking to include your designs in with their projects; it’s an opportunity for BPE manufacturers (see another acronym – Building Product and Equipment) to drive new business opportunities. How impactful is it for architects to literally cut out one of your designs from a shop drawing and glue it down on to a drawing? (please, please tell me if anyone has heard of or has had to do this…)
  Here is how it works in the new AEC Exchange Environment click the option for Shrinkwrap. It’s a lot like Derived in an assembly – and should be used together when you need to get real specific on what gets packaged up, I’ll save that one for another post.

  Take a look at the detail here. Bolts, washers, nuts, welds – everything you could put into a model is typically in your Digital Prototype.

  

  You’ll want to play around a bit with the settings to give you the desired result for your company, but for the most part the interface is wicked easy to understand (just move to New Hampshire – had to work in a wicked reference). About 10% will do for me here, patch up the remaining holes and I now have a much more simplified version of this model.

  The preview shows me the areas where the parts were removed and the holes that will be filled in for me.

  

  Once I’m done with the shrinkwrap, hit Export Building Components, add the Component Type so that the design matches up with the appropriate SIC codes, include any relevant metadata and hit OK.

  

  It’s going to save out a .ADSK file. That .ADSK will be able to be read in Revit Architecture, Revit Structure, Revit MEP, AutoCAD MEP, and AutoCAD Architecture. The file is as native to those applications as a .RFA (Revit Family file) or a block in the AutoCAD applications.

  

  I’ll blog more on what is included in the file, how it can be integrated into a Revit project, and more in later posts. I’m getting a lot of questions about this new functionality which tells me that the paradigm is shifting so far beyond 2D shop drawings, and block libraries to a true collaboration within the design process. So no worries, I’ll get plenty of mileage out of blogging about AEC Exchange. Who said coming up with topics was hard…? (ask me in two years, right Jay?)
  Since I can’t think of a cool pen name…
  -Rob

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  Lights... Camera...
  January 23, 2009 04:08 PMby Jay Tedeschi

  Hmmm… I have a sneaking suspicion that I have named an entry this before, but a quick search of my archives came up with nothing so I will stick with it. In any case, this one is a quick tip that should help out all of you who use Inventor Studio for creating product imagery.

  The stock lighting styles that ship with Inventor assume a model of X cubic area or volume. You will more likely than not find that when applying a style to a model that is either significantly smaller or larger than the that default volume that the lights simply do not look “right”, either drowning out your model or highlighting a very small patch of it. Well, before you start moving the light origins there is a quick global change that you can make that may be just what you need.

  

  As you can see from this image, the model is a bit larger than the effectively lighted area defined by the default settings in this lighting style. As I already pointed out, this can be corrected without touching the position of either of these lights by simply adjusting the global scale.

  

  Upon opening the Lighting Styles dialog the last tab, named Position, has a Scale slider. Not surprisingly, by default it is set to 100%.

  

  If this setting is changed, as it is here to 300%, then the position of all of the lighting elements in the scene is changed and the result is more in line with what I wanted.

  

  Much better…
  Well, that is it for now, hope this helps.

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