Even with One Million SolidWorks licenses out there (Learn more here), many users find themselves dealing with imported data from time to time. This data usually comes to the designer in the format of IGES, STEP, Parasolid, or possibly native Pro/E, Inventor, and UG files. Fortunately, SolidWorks can import all of these data types, along with many others. Here are four tips for working with imported 3D data:
1. Get the right format
Is there a single-best format in which a user should request 3D CAD data? Yes, SolidWorks format of course! Seriously though, there are myriad formats out there. Some types are neutral, agreed-upon standards while some are proprietary and require licensing from a commercial entity. The best format depends on where the data is coming from.
Parasolid (.x_t or .x_b) is my usual recommendation, since SolidWorks is based on that kernel. Other software also licenses that technology, e.g. Unigraphics, SolidEdge, and MicroStation. Any software users with the ability to export parasolid should provide that format for import into SolidWorks. IGES and STEP files, both neutral formats, would be my second and third choices for data, respectively.
2. Say ‘Yes' to Import Diagnostics
Any time SolidWorks opens a non-native file type, the software first creates a SolidWorks document. SolidWorks uses the ‘Default Templates' system setting to determine which template to choose (or whether to prompt the user). The second thing to happen is the Import Diagnostics command is started:
Make it a habit to always answer ‘Yes' to this question. It will analyze the geometric data, and then allow for automated repair if issues are detected. Most of the time, it will find a few faulty faces or surface gaps, and most of the time these entities are repaired with one click. On some poor-quality imported data, the user will have to clean up via surfacing anything that is left behind. Pay attention to whether the data is solid or surface bodies, or possibly a mix. To become a solid, a surface must usually be patched until it is water-tight.
3. Use FeatureWorks
Imported files contain only geometric data, not the history of how it was made. FeatureWorks is a tool that allows imported solids to be transformed into an intelligent feature tree. It reverses a "dumb" imported part with only one feature (the imported body) into a full feature history. An example would be this IGES file with no history after being opened:
FeatureWorks has a few different recognition modes. Fore simple geometries, the automatic mode is pretty much turnkey. Alternatively, a user can proceed through manual interaction with the module to point out geometry that needs to be a certain feature type. After running the automatic recognition, 15 seconds later we see a fully-defined, parametric, SolidWorks part.
A complete feature history is invaluable when it comes time for complex design changes or creating a detailed drawing (it will also fully define the absorbed sketches). It is not always necessary to reverse a part that far. One tip is to use FeatureWorks on a feature-by-feature basis. With the add-in enabled, users can right-click on a feature in the graphics area (e.g. a fillet face, or fastener hole) and ‘Edit Feature' which will trigger background recognition of that specific geometry. This makes opening legacy data and making a few tweaks a painless process.
4. Get comfortable with Surfaces
All solids are really just surfaces in disguise. More precisely, solids are water-tight sets of surfaces that are ‘filled' up with volume. At the surface level, you can manipulate data even without having a part history. An example is the Delete Face command. Try the option ‘delete and patch' next time there's some feature (fillet, small hole) that you need to remove, or erase and re-create. Also tools such as Move Face and Replace Face come in handy to resize or manipulate imported geometry. As a final note: When you are stuck with a poor-quality imported surface and start to question how it can be turned into a solid, surfaces are the answer.
My hope is that these few tips help you transitioning legacy data from another CAD tool to SolidWorks easier and/or improve working with others who do not have the benefit of modeling in SolidWorks. If you continue to have issues, don't hesitate contacting your SolidWorks VAR Service Center. That's one of the many great reasons you pay for your Subscription renewal.
It's that time of year again when we at Alignex start to get excited: SolidWorks 2010 Beta is just around the corner. Every year we look forward to the hundreds of new pieces of functionality that SolidWorks has developed from customer suggestions as well as from their Reseller community. We have built a page on our website at Alignex with a preview of what should be included in
SolidWorks 2010. Much of this information came from SolidWorks World in February, but some of it has been updated since then. Keep that page bookmarked as we'll keep updating it as often as we are able to.
Prior to the official release of SolidWorks 2010 later this fall, SolidWorks offers a beta program which is open to all current subscription customers. This program typically lasts several weeks, and allows users a sneak peak at the latest version and the ability to weigh in on how well the enhanced features work.
Besides getting to see all the new functionality before anyone else, there are other great benefits to participation. SolidWorks allows Beta Testers to submit bug reports directly to them, and for a reward they offer a points program. Top point-earners are rewarded with prizes and recognition in the SolidWorks community. These prizes are not just SolidWorks mugs and posters, but typically high-end electronics and other similar toys.
One warning I always throw out about Beta is that it should not be mixed with a production environment. Just like all new releases, once files are saved in SolidWorks 2010, they can no longer be re-opened by an older version of the program. Always keep the Beta installed separately and work on copies of Parts and Assembly files. Beta releases contain software issues, which is why SolidWorks entices users to get involved and report them. If a user finds a bug or possible issue, he or she uses the SolidWorks RX tool to capture and describe the circumstances and issue and then post it to the Beta program via the customer portal. The more severe the issue, the more points the user gets! Everything is relevant, from a button that doesn't look right to a command that crashes on every click.
When I get the beta, the first thing I look at is the ‘What's New' PDF document. This is under the Help menu inside SolidWorks. Find the new things you want to try. Go through your largest assemblies and most complex parts and gauge performance changes. Ultimately, try anything that was causing pain in previous release versions.
We've heard beta will be out in the next week or two, but right now SolidWorks is allowing customers to register. Once the beta download is available, everyone who has signed up will receive email notification with download instructions. To get involved simply sign up through the Customer Portal. Click here for more information on the Beta Testing Program. And again, learn more about SolidWorks 2010 on the Alignex website, here.
Here's to successful SolidWorks 2010 testing!
Working our Alignex support hotline, I have received these SolidWorks questions on multiple occasions:
"I have some components that I want to show on my assembly drawing as hidden or reference. Additionally, I do NOT want them to show up in my Bill of Material. How do I do this?"
In an effort to provide the answer to a wider audience, I'm posting it here on our blog.
1. If you don't want Components to appear in your Bill of Material, select the component's properties in the assembly tree. You will find a checkbox in the lower right corner of the window that will allow you to "Exclude from bill of materials".
2. To show the component in a drawing view using a different font, Right click on the component in the drawing view of the drawing tree. Select component line font and uncheck the box to "Use Document Defaults". Choose Phantom (or other font) for ‘visible edges'.
3. To hide the component in your other drawing views, add the component to the list on the hide/show components tab of the drawing view properties by selecting them in the graphics window when this dialog box is displayed.
Tim Mika
SolidWorks and SolidCAM Application Engineer
Alignex, Inc.
tmik@alignex.com
In
Part One, I mentioned how important it was to keep an eye on your system resources, since those directly limit the size and scope of model that you can mesh and run. This blog will focus on how the Simulation mesh uses RAM. If you've seen my
blog about system resources in windows, then you'll already know the basics of the Performance Monitor tool in Windows.
The amount of system memory in your workstation will correlate directly into the number of nodes you can squeeze into your model. The more components you have, and the more complex their features, the more nodes required to capture that geometry properly. By properly I mean an element with an aspect ratio less than 3. As an example, let's take a 1" x 1" x 1" cube, and see how many high-quality tetrahedral nodes we can generate before running out of memory:
Notice that moving the slider from ‘default' to ‘fine' size will cut the global mesh size in half. You can input a smaller global size (or use mesh controls that are much smaller) as long as you have the RAM to complete that mesh. But, you can see the relationship is power-based between global size and nodes created. By cutting the mesh size in half, you more than double the number of nodes in the mesh. As a general reference, a 32-bit Windows XP machine with 4GB RAM, running a 3GB switch, can get about 1 million nodes out of a part while an 8GB RAM, x64 machine can get about 3.5 million.
In general, the mesh will use roughly one-third of the available memory before it gives the "Out of Memory" warnings. This is because the mesh needs to reserve the remaining RAM for other operations. Using a screen capture of Performance Monitor, here's how mesh RAM usage is broken down:
I run a 32-bit Dell laptop with 4GB RAM installed. In the above figure, I have about 2900 MB of RAM on my system when I boot up "clean" with the 3GB switch. I look at the ‘Available Mbytes' counter to see if it dips below about 1900 MB. At that point I will receive the out of memory warnings from the mesh, even though I'm not actually out of Windows memory yet.
So how can we maximize our available RAM to get the most nodes? I have several suggestions:
- Try a Fresh Reboot. This often goes over-looked. Rebooting your PC regularly clears out the memory. I've had models that would mesh after a clean reboot, but later would not due to lack of memory. When doing a great deal of Simulation, Windows needs to be refreshed regularly so the memory is clear.
- Fix meshing issues at the source instead of trying to use smaller element sizes. Use functions such as Tools > Check and SolidWorks Utilities > Geometry analysis. This will identify problem areas, and also allow you to see how many edges might be shorter than the smallest mesh size you can achieve. This will typically need to be resolved before meshing.
- Use proper modeling techniques; idealize and simplify as needed. Shells, de-featuring, mixed meshing, that is the first place to go to reduce the node count.
- Try the Curvature-based mesh. This is a new meshing technology introduced in SolidWorks Simulation 2008 that I believe is underutilized. You can switch to this mesh in the ‘Create Mesh' dialog. This works wonders for parts with varying magnitudes of feature sizes, such as castings or molds with very small fillets or faces that cannot be de-featured. It also appears capable of creating more nodes with the same amount of memory.
- For 32-bit systems with 4GB of RAM, use the 3GB switch. This is outlined in detail on Microsoft tech forums. Quite simply you add the parameter ‘/3GB' onto your boot.ini line item for Windows. What that accomplishes is to allow Windows to dip into your 3rd gigabyte of RAM (it can never access the fourth). Warning: If you use the stock ‘/3GB' this will sometimes lead to system instabilities, including graphics turning black in applications, sluggish behavior, and overall slowdown of the system. Check this link for some detailed information.
The best advice that I can give is using the USERVA modifier, so the boot.ini switch looks like: ‘/3GB /Userva=2400'. This allows applications to use 2400 MB, but not dip too much into Window's resources. Make this a second boot option, and only boot into this when you need that extra RAM.
- Try an MSCONFIG startup cleanup routine. From the Start menu, do a Run command and type in ‘msconfig'. This utility lets you choose what items are loaded next time you boot Windows. If you disable everything in the ‘Startup' tab you'll prevent most of the applications that show up in the system tray (far bottom right, near the clock on the Start menu) from loading. This saves me about 300 MB when I need that extra bit of memory.
- Finally, if you continue to have RAM issues, it may be time to consider upgrading to a x64-based computer. These have different architectures which allow the user to have 8, 12, 16, or even more gigabytes of RAM.
If you have not already done so, please take a look at my previous blog articles on Meshing in SolidWorks Simulation.
Meshing Advice in SolidWorks Simulation (Part 1 of 5)
Mixed Meshing in SolidWorks Simulation - (Part 2 of 5)
Mixed Meshing in SolidWorks Simulation - Contact Sets (Part 3 of 5)
- "If I didn't waste all my time quoting I could actually design something."
- "I wish I could find a better way to make each of these components longer, maybe a stretch all command."
- "If we could cut down on engineering lead time we could easily double maybe even triple production"
Do any of these sound familiar? If they do there is a tool just for you, in every seat of SolidWorks. It is called DriveWorksXpress and could very well be the Holy Grail of the Engineer-to-Order world.
What is Engineer-to-Order? Let us start with some simple questions.
- Are your products the same-as, but different?
- Do you have repetitive design tasks, such as making a particular product a little larger or smaller or adding standard options to an already designed product?
- Are your products defined by a set of rules? (e.g. We always have a 1/4 inch gap, unless the frame is over 4ft. wide, then we use 5/16 inch.)
If you answered yes to these questions or if this fits even a portion of your design, you have an Engineer-to-Order product.
DriveWorksXpress is an easy to use interface for automating your repetitive design tasks for that Engineer-to-Order environment. Amazing time savings and reduction in errors can be achieved with a simple implementation. DriveWorksXpress is also expandable into the upgraded versions of DriveWorks that allows for automating even further to integrate systems within the company, like ERP or CRM systems. Best of all, DriveWorksXpress is already built into every seat of SolidWorks since 2007. These abilities won't cost anything to implement, but your time.
Once you've implemented some simple time-saving features in DriveWorksXpress, you can begin to evaluate if a move to the full version of the product is warranted. There are documented case studies on the DriveWorks website that calculate the implementation of DriveWorks has:
- Taken simple 45 minute design cycles down to less than a minute.
- Eliminated 90% of repetitive task time freeing up engineers to design new and better products.
- Taking 80 hour design cycles down to an hour!
Some of these statistics are staggering and can be difficult to accept but the proof has been confirmed by the customers, themselves. Again, best of all, you have the tool at your fingertips to take the first step towards achieving results just like them.
Take a minute today in your SolidWorks window to click on Tools>DriveWorksXpress and then spend 20 Minutes on DriveWorksXpress.com and you could be saving hours next week. Our best advice is to start with one part within an assembly and create a DriveWorksXpress project out of it. Don't think you have to start with a full assembly. Once you're saving time on one part, reinvest the time savings into a second part, and so on. The process builds on itself and you're not having to reinvent the mousetrap from the ground up.
A very small investment for a big return. Yes, even in a down economy you can still get big returns on small investments.
Following on the first 2 parts of my SolidWorks Simulation topics, Meshing Advice in SolidWorks Simulation (Part 1 of 5) and Mixed Meshing in SolidWorks Simulation (Part 2 of 5), I'm going to present the new interface and functionality of contact sets in SolidWorks Simulation 2009. I'll also provide a refresher and description of what these are, and why they are important.
Any time we venture into assembly (or multi-body part) analysis, we have more than one component. Each possible interaction between components is described with a Simulation feature, such as contact set or connector. In Simulation Training, we treat in-depth three types of contact sets: bonded, no penetration, or free. It's easy to visualize these three types: components glued together, having a friction/contact interaction, or ignore each other completely.
An example is a dual-cantilever situation, with a downward point load on the free end of the upper beam. Remember we're dealing with small deformations, so we're working with just one possible contact set where the two bodies touch. I have setup a study with two pieces of half-inch plate (solid mesh). I ran this study with three contact options. The displacement contour plots below clearly demonstrate the difference:
Figures 1 & 2 - Setup and Displacement results - inches, true scale, front view
Since we're interested in moving into mixed meshing, let's expand our discussion. Treat both plates as shells - modeled as SolidWorks surface bodies:
Figure 3 - Surface model with same Simulation conditions
Global Contact does not apply with this model (as it did above with the solid mesh) as the surfaces are not coincident. For the un-initiated, Global conditions apply only to initially touching or overlapping faces. And now that we're on the same page: there are exceptions to this in 2009. Usually, if any gaps exist between components, then that interface will be treated as free unless a local contact set is defined.
Figure 4 - If you specify a local ‘no penetration' set with shells, Simulation will take the virtual thickness into account. With this type of contact the result is the same as the above solid mesh:
Moving on, there is some more new functionality with Sheet Metal (see Part 2). Even though the sheet metal component is meshed as a mid-plane shell, coincidence with the solid model is still respected, thus global contact applies. See the second example below:
The backing plate is a Sheet Metal plate, and is fixed on all edges. The brackets are regular solid bodies and have a 500lbf downward load applied each. They are mated coinciden
t in my assembly. Side view after meshing:
Global bonded will apply with these components. Check out page 130 of the SolidWorks Simulation 2009 What's New document for some more examples. I mention this every time because everyone should peruse this PDF at least once a year when upgrading. In 2009, this Global setting also extends to include mixed meshing: face/edge of shell to a solid or another shell, and face/edge of shell with a structural member (beam). However this technology is not perfect and I have found that many beam-to-shell interactions must still be defined with local contact sets.
It's easy to forget to define a local contact set, or sometimes global bonded isn't sticking, or we have gaps of which we are unaware. Any of these situations could result in rigid body motion which means a failed solve. Make it standard practice to enable ‘soft spring' when solving preliminary studies. If your model is a huge local-bonded model you can also use a Frequency study type to locate any ‘loose' components. Save time by running initial studies with draft-quality mesh.
Quick test: count how many unique interactions there are between the three components in the above model. Assuming small deformations, there will be two. It's pretty obvious based on the geometry this will be a bolted connection. When setting up an analysis, it's tempting to put in all the detail right away. In this case, I would need four bolt connectors and no-penetration contact. Remember anytime you use a pin or bolt connector, those components should not also be bonded.
Working with large models, I've found it's sometimes easier to start with everything bonded. Make sure everything is working and solving before complicating and severely elongating the solve with no-penetration sets. It's always easier to start simple and add features in a step-wise fashion (e.g. contact sets and bolt connectors).
The extension of this mindset applies to components that may or may not contact depending on deformation. No-penetration formulations take a substantial computational effort. So a typical workflow for me is to leave such an interaction as ‘free'. After solving, check the true scale displacement for interference or penetration between components, adding in no penetration as necessary and re-solving.
For you professionals out there, let me point out some key interface changes with Simulation 2009 contact sets. First, when defining local no-penetration contacts, the formulation type is not specified by default and the selection may even be hidden. All local sets are node-to-surface type by default, unless specified otherwise. Make sure and enable the option ‘Show advanced options for contact set definitions' under Simulation > Options > Default Options > Mesh. There is also an option to ‘Improve accuracy for contacting surfaces with incompatible mesh' which will force local sets to be surface-to-surface formulation.
If you are interested in SolidWorks Simulation Training, keep an eye on our Training Calendar for the next upcoming offering. I encourage everyone interested in getting started quickly to attend and learn about contacts and much more. Also, make sure and update to service pack 3.0 as soon as you are able since there are a few issues I've seen with earlier versions and mixed meshing. As always, if you are seeing any strange behavior or need support, give the Alignex Help Desk a call or contact us on our Support Webpage.
Have you ever considered a composite laminate as a design option? With the ever-increasing power of
SolidWorks, we now support composite laminate materials inside
SolidWorks Simulation to help create and test optimum designs. While we've had this capability inside COSMOS for awhile, this new module makes this tool accessible directly inside the
SolidWorks window.
Used for decades in the automotive and aerospace industries, composite materials are seeing widespread adoption by other industries concerned with creating optimal designs, lowering manufacturing and shipping costs, and providing increased quality to customers. Moving forward you can expect structures technology to adopt composite materials even more. They offer tremendous benefits, specifically in weight to stiffness cost, fatigue and corrosion resistance, and geometric flexibility. Not to mention the capability to embed secondary systems inside of primary structure (e.g. smart structures with embedded strain sensors/accelerometers).
With SolidWorks Simulation 2009, engineers and designers have the ability to immediately explore composite laminates as a material choice. The initial viability testing of such a material choice can be accomplished in a matter of minutes. It just might be the key to saving weight on your next design or expanding into composites as a material choice.
Traditionally, the setup of such composite simulation has been painful. Setup of ply orientation, local coordinate systems, and materials has been reserved for composite analysis specialists. In SolidWorks Simulation, the composite structure is based on a surface body. All the user needs is a surface body that represents the midplane of the laminate. Simulation can use that body to completely define the local coordinate systems.
As an example, below is a case study of a snow ski. Modern skis and snowboards are what we refer to as "sandwich" structures (I am getting hungry already). There is a ‘face' on both the top and bottom, respectively, and a middle core. The faces typically provide planar stiffness, while the core reacts out of plane bending. In this example, typical of modern design, the faces are made from composite laminate, and the core is wood (Balsa).
Figure 1 - SolidWorks model of snow ski
The ski is modeled in SolidWorks as three bodies: one solid to represent the wood, and one surface for each top and bottom laminate. Note that each surface body can represent many layers of laminate.
Figure 2 - Snow ski close up, with Simulation Interface
Figure 3 - definition of the layup
The angle is the ply orientation, and represents the direction of the fibers on a particular layer. These orientations can be arranged to create the optimal stiffness and strength for a given application. The complete visual feedback and automatic element orientation makes this software unique in the industry. Here a designer will easily be able to iterate layer choices: how many, what material, and what orientation. This is done until performance goals are met. Each layer can have a unique material and thickness.
Figure 4 - Displacement, 300 lbf static load
Figure 5 - Factor of safety, 300lbf static load
The results of a static test are displayed above. Besides the usual displacement and stress results, we also implement the Tsai-Hill, Tsai-Wu, and Max. Normal Stress failure criteria for plotting factor of safety. These are industry standards. Keep in mind that the mechanisms of failure for composites are many-fold. While this may predict stress failure, many factors ultimately contribute to composite material failures in the field: environment, damage, complex loading, etc. Our results indicate to the designer that the second play is the critical ply, with a minimum FOS of 2.4.
I encourage any designer who is concerned with weight, or interested in jumping into the next generation of structures, to explore composites. This functionality is included in the Simulation Premium package only.
Also remember that to fully exploit the capabilities of composites, you have to think outside the box. It's not about replacing every aluminum sheet with a composite sheet, it's more about rethinking the way you can manage your loads and join your structures together. And as always, remember that FEA is used to validate a concept, and physical testing should always be an integral part of any development process.
Brian Zias
Application Engineer
Alignex, Inc.
bzia@alignex.com
Often when the time of year rolls around to upgrade to
SolidWorks 2009 there are a couple key members of the family that are forgotten in the upgrade.
One item that is often overlooked is the Solid Network License (SNL) Manager. When in an SNL environment new version current SNL Manager software and a new license file must be installed for each version of SolidWorks. Each of these items can be obtained through the customer portal. As a side note licenses for previous versions can be managed with the latest version. For example the 2009 license manager will distribute a license to 2008 SolidWorks on the client PC. This makes upgrading the license manager software a great place to start your upgrade and also assures that it is not overlooked and downtime is very limited.
Another often forgotten, yet equally important piece to the puzzle is the Solidworks Workgroup PDM Vault. This must also be upgraded to match the current version of SolidWorks. A 2008 Vault will be unable to properly communicate with SolidWorks 2009 and vice versa. So it is critical to keep these items in sync. Planning ahead is important in a Workgroup environment to limit any down time. It is best to set aside a certain timeframe that will allow ample time for updating the vault and all client PC's with limited impact to the users. This is usually done overnight or during the weekend at many Alignex customer installations.
Remembering these two items can be the difference between a seamless, successful upgrade and a frustrating day of fire fighting. So make a note and don't forget the extras during your next upgrade!
Cole McLeod
Application Engineer
Alignex, Inc.
This is part two of a five-part series on meshing tips in
SolidWorks Simulation (formerly COSMOSWorks).
Part 1 can be viewed here. This time, I want to discuss some important improvements and changes made in the
SolidWorks 2009 interface with regards to meshing. I hope this will answer some lingering questions and also get you started more quickly with 2009.
If you have already made the jump to SolidWorks 2009, you've no doubt noticed some differences in the SolidWorks Simulation interface. The place to start is Chapter 10 of the What's New PDF (Help menu in SolidWorks, then What's New). In fact, each year I would recommend reading the germane sections of this document to see what has changed and also what new functionality should be implemented into your operations.
A big improvement has come our way in terms of mixed meshing. It changes the way we will work with SolidWorks Simulation. Check out this screen shot, showing the same assembly in both 2008 and 2009 after creating a new linear static study.
In 2008, one had to specify a ‘mixed mesh' when initializing the study. Once the study was created, every component was a solid type unless specified otherwise.
Starting with 2009 there is no longer an option to create a ‘mixed mesh' study. All studies are enabled to be mixed mesh always. Also, there is some automation with the default element type based on body type. By default, any surface bodies will be treated as shell elements, any structural members (weldment parts) will be treated as beam elements, and everything else will be treated as solid elements. This is illustrated in the 2009 screen shot above by the different icons for different element types. (Red Arrows) Let me elaborate on this:
Shells - If you have taken the Alignex version of COSMOSWorks or Simulation Training you have heard us preach about extracting mid-surfaces from thin-walled parts as the best way to use shell elements. For better or worse, SolidWorks now requires you to create a surface body before you can define a shell element type. There is no longer an option to define a shell based on the face of a solid. I think this is a brilliant idea, but requires us to actually do the right thing and create a mid-surface as a preliminary step. As I discussed in Part 1 of my meshing tips, there is a very nice tool (Mid Surface) in SW that will allow you to extract the mid-surface of any solid part. Be careful that after you create this surface body, you delete the solid body. If you don't do this, then you will have both a solid and a shell version of your part in your analysis! Of course when you delete a body from your part, it shows up as a feature on the Design Tree to facilitate easy use of configurations.
To make this process easier, SolidWorks will treat any sheet metal part (if you used SolidWorks sheet metal functionality to create the part) as a shell automatically, and it automatically creates the mid-surface. So you can ignore the above paragraph if all your thin-walled parts are SW sheet metal parts. Notice below the surface icon when I create a fresh study on this sheet metal part:
Similarly, if you use weldment functionality in SolidWorks, you'll notice that these solid bodies come in as beam elements by default.
Since sheet metal parts and weldment bodies come in as structural elements by default, you do have the option to return them to solid elements by right-clicking the body.
Another great enhancement is the ability to ‘Make Rigid' on a per-body basis. This will treat that body as non-deformable, thus you don't have mesh or solve strain in that body, but you can still include it in the analysis for contact and other interaction purposes. This only works in static and frequency studies so far. Right-click a body in the Simulation tree to access this option (it also toggles to ‘Make Deformable' which is standard). Of course you will be assuming an infinitely stiff component if you enable this, so take that into account.
Along the same lines, you can ‘Exclude from Analysis' on any body, which is similar to suppressing it in the assembly. This provides a way to use different studies with different components included without creating configurations.
While we're at it, the last new thing you'll see in this Right-click menu is ‘Fix'. This will anchor the entire body (which additionally makes it a rigid body). This is an alternative to applying fixed restraints to an anchor part on all its external faces, and much more efficient computationally. The opposite of Fix is Float, just the same as in a SolidWorks assembly.
In my next blog we'll visit contact sets and some helpful creation and performance tips.
Brian Zias
Application Engineer
Alignex, Inc.
Here at
Alignex, the
SolidWorks Simulation help desk gets a fair amount of calls regarding meshing. This is the first in a five-part series of meshing tips and tricks.
Quite frequently, the questions we receive deal with users running out of resources and the crashes that result from running out of those resources. Meshing is very memory (RAM) and processor (CPU) intensive. A slower processor simply means you will wait longer for the mesh generation to complete, and running out of RAM means you may get an application crash and be forced to begin again.
There is a finite number of elements that can be created given the amount of RAM on your system. The more RAM, the more elements you can create at one time. Think of your number of nodes as a good indicator of mesh size. This number is displayed during solve on the solver window, and also can be accessed by right-clicking the Mesh folder and choosing "Details."
A 32-bit system with 4 GB of RAM will let you get close to one million (1,000,000) nodes with a single part. As you increase the size of your assemblies, some of those resources are reserved for contact elements. You will find your own ceiling is between 700K and 900K nodes on a 4GB, 32-bit system. Many customers are choosing to outfit an "x64" machine as a dedicated Simulation machine. An x64 PC with 8GB RAM will raise that ceiling to roughly three million (3,000,000) nodes.
Most users running out of RAM are simply trying to mesh too many components. They neglect the de-featuring and idealization steps that are required for geometry preparation. Given enough elements, you can mesh anything. But here are some suggestions for creating the optimum mesh.
One technique that separates the casual user from expert is the mixed-mesh creation. Mixed-mesh refers to using solid, shell, and beam elements in the same study simultaneously. It allows the user to idealize structural members as beams, define thin-walled components as shells, and leave the remainder as solids in a large assembly.
Here in Part 1, we will discuss the best way to create geometry that is ready for a robust shell mesh. Once a few of the thin-walled sheets or plates are changed to shells, there is immediate relief. Shells are 2D elements which idealize the thickness direction, thus removing the need to mesh through the thickness. Meshing a thin plate with a solid is always going to require many, many more elements than idealizing it with shell elements.
Since a shell is a 2D element, it can be applied to pure surfaces in SolidWorks. In fact, it is more accurate to define a surface to represent the shell in the model itself than is it to select a face of the solid. The thicker the part, the more important it is to create this mid-surface. SolidWorks Simulation understands the surface you select to define the shell as the mid-surface of the part. Luckily, there is a command named "Mid-Surface" which allows us to create a surface from a solid part at the proper location. There is even an automatic selection of the faces (just set the threshold to be less than or equal to part thickness).
Fig 1. - Mid-Surface command in SolidWorks
You may want to knit these into a single surface. You can easily create these features as a separate configuration (hint: "FEA" configuration). The last feature in this configuration should be a Delete Body feature which removes the solid body and leaves only the surface.
Fig 2 - Knitting surfaces
Fig 3 - Idealized bracket in large assembly
After the surface configuration is created, it needs to be properly bonded to the rest of the assembly. Tune in next time for a primer on mixed-mesh contact creation.
By the way, there is some fantastic new functionality in SolidWorks Simulation 2009 along this same line. If you create a part with SolidWorks Sheetmetal, the Simulation will automatically extract the mid-surface and use that to mesh the part!
Part 2 - Mized Meshing in SolidWorks Simulation 2009
Brian Zias
Application Engineer
Alignex, Inc.
bzia@alignex.com