SolidWorks UK

Absolute or Relative. Which is best?

Last week I told you how to check your global mesh refinement by performing a number of simulations with a denser mesh and looking for convergence of your results. Have you given it a go yet?

This week we held a 2 day simulation training session covering the topics of motion and non-linear studies for our resellers and one of the surprising things for a lot of people was the sensitivity of the results to various parameters. The motion studies were highly sensitive to the contact settings and a non-linear buckling analysis we ran was very dependent on the mesh size chosen.

When discussing the implications of this it became clear to everyone that building a simulation, solving it and immediately believing the result can be a dangerous pastime. We call this ‘one-shot’ approach an Absolute Analysis, giving one absolute answer.

But what would you say if I asked how certain you are of your input loads? Could they be, say 5-10% out? Also, have you modelled all the boundary conditions accurately or used an approximation, perhaps fixing a face when in reality it is bolted to a plate? Have you chosen the true material data or an approximation from the database simply because it is there?

To mitigate these cumulative errors it is better to perform a Relative Analysis, a series of simulations where you change each parameter to see how it impacts the result.

If you are not sure that your loading is exactly 500N, try one at 450N and another at 550N. Is the direction of the loading really normal to the face of application? Perhaps you could check the result by running a couple of simulations with the load offset at 5 degrees each way to see how the induced moment affects your design. Using a bolt connection and a no penetration contact will give you a different result to a fixed restraint so try it to see just how different the results are. And finally perform a few studies with slightly varying material properties to see what impact this has.

The power of this approach is similar to the convergence check, you are making sure that your model is robust, i.e. not sensitive to variation, and if it is, you can begin to determine just how sensitive. This approach is also one way of building a real understanding of your product so you can appreciate how it behaves in the non-ideal world we actually live in.

Technorati Tags: SolidWorks Simulation,Simulation Tips & tricks,Relative Analysis

Design and sustainability- how making a difference through design also makes good business sense?

For those of you who are looking up and down the supply chain for ways to improve environmental performance – and save yourselves literally millions in the process, discover SustainabilityXpress.

Our new sustainability software package code-named “Sage” will be available with the release of SolidWorks 2010.

 

Have a look at the video on SolidWorks Lab. Be the first one to review the product.

Link: http://labs.solidworks.com/Products/Product.aspx?name=sustainability

 

 

 

Confused by all the buzzwords surrounding design and sustainability?

There are indeed a lot of buzzwords surrounding sustainable design today. Much of the debate surrounding environmentally friendly product design and manufacture hangs on the question of costs and profits: can I afford to go green?

As if reducing materials, designing more efficient manufacturing techniques and technologies, using less energy in production, spending less on raw materials and finding ways to reuse components and materials would actually cost more. What is Design and Manufacture all about? Isn’t it all about creating the maximum possible value with minimum resources?

 

 So, assuming as product designers and manufacturers we are already taking steps to make the best use of the resources we have, the question should be not: can I afford to go green? But rather: just how green is it possible for me to get?

 

See what people are saying about the issues on DesignTalks and add your voice to the debate.

 

 

How good is your mesh anyway?

This week I gave an overview of some simulation best practices to some of our Nordic partners, and I thought I’d share one of their tips with you this week.

How do you know if your mesh is sufficiently refined? There are a number of checks and balances that can be used to assess the quality of your mesh in particular areas, but what about the general level of mesh refinement? One under-utilised technique is the convergence check.

            

Firstly create an initial mesh on your model and plot the number of degrees of freedom (DoF) against a result of interest (e.g. max displacement). Then remesh with a finer mesh (try to at least double the DoF in your second attempt) and again plot the result of interest. Keep doing this until you see the resultant parameter converge to a solution. When you are happy you have a converged result, you will also have a suitable global mesh.

Two additional points to think of:

• if you choose stress as your function of interest ensure you don’t have a stress concentrating region in your model, otherwise you will find the value increasing indefinitely.
• if your ‘ideal’ mesh takes forever to solve, you can pick a courser mesh size from the graph that solves quicker and gives you an understanding of the error when compared to the converged solution. If 160,000 DoF takes too long but the result at 80,000 DoF is within 5% error, this may be sufficient.

Try it next time you develop your simulation.

Technorati Tags: SolidWorks simulation,Mesh,Mesh refinement,Convergence check

Interested in Wind Power?

Hear from some innovative companies, which are pushing the boundaries of wind turbine designs and expanding wind power's reach around the world.

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SolidWorks 2010 Beta... it's here... next week!

Repeat post from the SolidWorks Blog

Every year we give our customers a chance to preview the newest release of our software before it's made available to the public, and this year is no different. In the very near future, we'll be making the beta version of SolidWorks 2010 available for download to current subscription support customers in the SolidWorks Customer Portal.

You'll have all summer to play with the software, see what's new, and generally get an idea of what to expect when it's finally baked. If you want, you can even let us know if you find bugs or other problems. Find enough and submit them through the system and you can even win prizes. If you want to get a peek at what new features you can expect to see, click here to read the list Ricky Jordan posted on the last day of SolidWorks World 2009.

If you've already signed up to be notified when the beta program starts, be on the lookout for an email soon. If not, drop everything, click on this link, and sign up. We look forward to seeing you.

Filling the void

We all know that in simulation it is important to model as much of the relevant physics as possible, but there are some instances where things are commonly missed.

Take the example of fixing a heat sink to a CPU in your computer. We know that at a microscopic level the touching faces are not smooth but resemble something like this:

In practice electrical engineers use a thermally conductive gel to fill the gaps otherwise the interstitial air would form a barrier limiting heat removal away from the CPU. This is often overlooked in simulation models but I was recently reminded about such a solution in SolidWorks Flow.

It is possible to insert a ‘Contact Resistance’ feature that lets you define a) the resistance between two surfaces directly, or b) a material and its applied thickness. Just a quick tip though, you only need to pick one of the contacting faces when defining the contact resistance, otherwise it gets applied twice!

That got me thinking about SolidWorks Simulation Professional and the thermal module. A quick check and low and behold, there is a contact set here too that allows you to define a thermal resistance between two faces.

So whether you are using thermal or flow, you don’t have to fiddle around creating fake geometry to model these kinds of important physical features. Clever really!

Technorati Tags: SolidWorks Simulation,Flow,Thermal,Tips & tricks

SP4.0 Goodness!

SP4.0 Early Visibility (EV) was released last night… this means that the full release of SP4.0 is just around the corner!

If you want to know what has been added to this release make sure you check out the release notes. You don't need to download the EV to see what's coming, just take a look at the online version: From the SolidWorks window select: Help/Release Notes

A couple of highlights are:

• PhotoView 360 now imports decals applied using PhotoWorks™.
• Task Scheduler: You can now distribute file conversion tasks across multiple computers.

A full list of fixes is also available through the customer portal.

Technorati Tags: SolidWorks,Service Packs,Updates

Combining Multiple Properties

During the last couple of days I have been attending a SolidWorks workshop for Enterprise PDM implementation. The workshop has been very interesting and I’m sure all who attended have gained many ideas and and new concepts to use in future data management implementations.

During lunch one of the attendees (Simon Turner) got a phone call from one of his colleagues asking if custom properties can be combined?

First of all if you don’t know Simon let me fill you in… Simon is Technical Director of Solid Solutions Management, amongst his many roles he is a major part of the API team at Solid Solutions. We believe he played a part in programming the Matrix that we live in.

 

Back to the Question… It took a couple of minutes but Simon and SolidWorks stepped up to the plate and worked out a great and simple solution.

Example: You are doing design work for a client and you want a “Client Code” that comprises of part number (SW-Part Number), client name (Customer) and location (Location).

1. Add a Custom Property to your Part template

With the properties: “SW-Part Number”, “Customer” and “Location” already added to the template. Add another property called “Client Code”. For the value add the following:

$PRP:”SW-Part Number”-“$PRP:”Customer”-$PRP:”Location”

This works for any property and any number of properties with whatever separator you like!!

 

2. Add this to you Property Tab

Using the same properties and syntax as above you can create a new or add to an existing property tab.

If you haven’t used the new property tab and property tab builder, make sure you check out the SolidWorks 2009 What’s New Manual (found under the SolidWorks help menu)

Technorati Tags: Custom Properties,SolidWorks Tips and Tricks,SolidWorks

Are you achieving the full financial benefits of your product Development efforts?

 In today’s rapidly changing business environments, companies are constantly evaluating product development strategies on how to increase their competitive edge.

In this screencast we invited Dr Colin Mynott to share best practices on all aspects of product development, how it should be organised, its financial impact and management.

Dr Mynott has extensive hands-on experience of manufacturing systems and is one of the UK's leading experts in developing products.

Check this screencast for advice. Learn about

·      Key factors of the world's most successful products

• 7 steps to lean Product Development
• How to optimise products with fewer prototypes

Hope you find this informative.

Link: www.solidworks.com/screencastcm0609

Combining loadcases in SolidWorks Simulation

I was asked today about the use of a SolidWorks simulation product called Pressure Vessel Design, as the name suggests, a tool used regularly in the design of pressure vessels. Typically there are a number of different loadcases on a storage vessel, from internal gas or liquid pressures, self weight of the vessel, bending moments and forces exerted by the connecting pipes, and even temperature distributions.

As you would expect, all of these loadings might apply at the same time, and so a typical design code (like the ASME Boiler and Pressure Vessel Code supported by SolidWorks simulation) requires these separate loadcases to be combined in some way.

In fact, in SolidWorks Simulation you can factor the results from each separate loadcase and sum them linearly, or perform an SRSS (Square Root Sum of Squares) to combine them.

Having defined the combination method, simply run the study and hey bingo, you are ready to check your membrane and bending stresses against the limits set by your code.

But the neat thing about this tool is that you can apply this technique to any relevant model, it doesn’t have to be a pressure vessel. Whatever your model, if you want to create separate loadcases and superpose them at the end, just use the Pressure Vessel Design tool!

Technorati Tags: Simulation tips & tricks,loadcases,pressure vessel design