We are pleased to introduce KAP’s Corner. This monthly column will provide an in depth look into a variety of CAD topics. It’s full of useful tips and tricks, the latest innovations from SolidWorks, shortcuts through the interface, best practices and ways to maximize your CAD experience.
KAP’s Corner is authored by Keith Pedersen, CAPINC’s resident technical guru and a SolidWorks Elite Applications Engineer. About KAP
“Keith Pedersen has the SolidWorks dexterity of a Chinese gymnast and the propensity for entertaining a crowd without the use of face paint. You will surely learn something new about SolidWorks after he’s done!”– Edson Gebo, Co-chair of the CMNC-SWUG
In the world of FEA, sometimes the answer has to be “Right” - and sometimes it has to be “Right Now”.
This month’s topic is about getting answers Right Now. Every example I’m going to cover here is a cheat of some kind. Purists, Beware! In each of these examples, the key to the method is to invent imaginary parts on which to apply loads or restraints, or imaginary material properties, or both. These materials will sometimes allow us to avoid computing real-world Gap/Contacts, or will turn a marginally unstable problem into a stable one, or will allow us to use a force-based load where a deflection-based boundary condition would be too confined.
I’ve written prior articles about the power of Envelope Parts in an assembly. And about ways to leverage the ability to build multiple solid Bodies in a part file. But now lets talk about a way that you can combine these two ideas, to work “Outside-In”. That is, to build detailed design work on welded tanks, sheet metal enclosures, furniture, cabinets, architectural, etc. – in a single part file. It’s a technique I’ve been using and teaching for about 4 years, but never could come up with a good name to describe it.
This article is a grab-bag of tips and background info having to do with the FEA Mesh. I started out intending only to review my previous article on "FEA Volume Meshing", to make sure it was up-to-date with Solidworks2008. But as I did so, I realized that first article was purely geometric - controlling the size, shape, and number of FEA elements.
As your use of FEA becomes more advanced, you start needing information that is more about Architecture - how does Cosmos represent remote loads, contact elements and gaps, convert CAD bodies into element groups, etc? Which element types are compatible across different types of studies, etc. If you've ever gotten an error message beginning with, "No Element Group has been assigned..." then this KAP's Corner is for you.
The Cosmos family of FEA tools features a user-interface that is so easy to learn, we sometimes have trouble convincing people of the necessity for formal training. I feel that sales literature and tutorial examples err on the side of over-simplifying the task of engineering analysis. Certainly, the friendly Cosmos interface makes the button-pushing aspect of FEA very easy to apprehend – but analysis is more than pushing software buttons. I sometimes get calls from frustrated analysis users who have fallen afoul of some foible that does not satisfy their intuition. One such recurring Hotline call is from users who are trying to extend their thermal analysis into the realm of non-linear material response, particularly the Coefficient of Thermal Expansion, (C-T-E).
My goal here is mercenary. In the future, I can shorten the duration of this type of hotline call by saying, “refer to the Kap’s Corner article”. But I also present this article in hopes it not only cure, but also prevent, you the user from experiencing thermally induced Stress and Strain. If you wish to extend your thermal studies into materials with non-linear thermal expansion, this KAP’s Corner is for you.
The size of your SolidWorks files are affected by a lot of factors. Although there are some good tips-n-tricks circulating out on the Web on this topic, the different file and session settings often interreact with each other. This can cause two users, with differently tuned systems, to report wide differences in the benefit of implementing the same tip. The past 6 versions of SolidWorks have also introduced changes to some of the options that were used to tune both performance and file size, so this topic has been something of a moving target.
When CAPINCruns a class on File Management, the discussion of how to reduce file sizes, especially for shipment via Email, consistently generates the most excitement. So for this installment of KAP’s Corner, we ’ll bring you up-to-date on factors that affect file size in 2007.
Mates are the “glue” that hold your assemblies together. One of the great strengths of Solidworks assemblies is that mates are independent objects which can be applied at any time, in any order. This makes assembly design easy for the CAD novice. It also means that a wide variety of mating strategies can be applied, based upon industry needs and user preference. As you become more expert at Solidworks, you discover that although Mates are relatively unconstrained, they are by no means unimportant.
The manner in which mates are applied have a strong impact on robustness – i.e., the survival of your mate scheme when changes are made. If you dread making changes to your parts or their mates, for fear that the Feature Tree will become festooned with those round, red error markers (I call that the ‘Cherry Tree’), then this article is for you.
Only a few years ago, the COSMOS integration with Solidworks was enhanced to support solid Part files that contained more than one Body. The most immediate obvious benefit is that you can now analyze a model with several different material regions, without having to create separate Part files, Assemblies, or positioning Mates. But my favorite reason for employing multiple-bodied Parts is that it enables us to employ a ‘trick’ that will enforce better control of the FEA Mesh. If you frequently perform Finite Element Analysis of thin-walled or slender parts, and wish that you could control surface mesh size independently of the thru-thickness mesh size, then this KAP’s Corner is for you.
Have you ever tried to open a coworker's assembly, only to find that all of the fasteners in his assembly have defaulted to some huge size? Have you ever taken work home over the weekend, and found that when you open an assembly on your home computer, some of the fasteners have become substituted for different, seemingly random sizes? These problems stem from sharing data that reference more than one Toolbox fastener library. This installment of KAP's Corner will show you why these problems occur, and how to avoid them in the future.
The Hole Wizard is probably the most popular "Macro Feature" inside SolidWorks. It eliminates a lot of the drudgery of sizing and locating holes: First, by incorporating a library of standards (a la Machinery's Handbook), and second, by positioning mutliple holes using a Sketch Driven Pattern. However, there are two subtle but important variations on how hole position is controlled. When I visit SolidWorks users, and review their geometry, I frequently discover that this nuance is not widely understood. If you've ever had trouble getting a drilled hole to stay-put, or fail to be fully-defined even when you've dimensioned the drill point, then this KAP's corner is for you.
The correct use of Assembly Templates can streamline your workflow and help you avoid problems when updating your configurations. Many users incorrectly assume that the software is “buggy” when unwanted parts keep popping up in other configs. Avoid unnecessary frustration by tuning your configuration settings in the default template. In this article, Keith sheds enlightenment on the nuances of past versions of SolidWorks, and the value of using mapped folders containing your company standards and templates.
There are several methods available for modeling mirror-image parts in SolidWorks. The selection of a technique is dependent on how you want changes to propagate. Should changes to the mirrored part be editable and automatically propagated between similar parts? Or should your mirrored part be independent of editing changes to the original part? Also, how will these part files be treated in your company document control system? To find out which method is best for you, download our first installment of KAP’s Corner.
Creating envelope components in SolidWorks can be one of the most powerful tools in your repertoire when working with assemblies. KAP invites you to expand your thinking about the use of envelopes any time you need hard geometry to design or mate against, but want the geometry treated as “phantom”. This discussion examines the way envelope components actually behave in an assembly. We show you how to maximize their use to build smarter, more robust assemblies, using interesting cases from the real world.
When we asked guest columnist Art Woodbury to review the new Step-by-Step guides, he jumped at the chance to cover some new ground. Although he's been running SolidWorks since 98 Plus, the only one of these add-ins that he uses is Toolbox, so he looked at the guides as a real beginner. This month, he reviews the CAD Productivity Tools volume that covers FeatureWorks, SolidWorks Utilities and PhotoWorks. "This guide costs less than a dinner for two and can save several hours on the learning curve. Using the restaurant analogy, I’d give the guide 4 out of 5 stars." - Art Woodbury
In the world of FEA, sometimes the answer has to be “Right” - and sometimes it has to be “Right Now”. 