10 Replies Latest reply on Nov 1, 2010 11:16 AM by Ryan Werner

    Solidworks Simulation vs Simulation Express

    Glenn Parks

      We are new to using Solidworks Premium and have run into something that we cannot explain. We were designing a spring arm using Solidworks Simulation to develop a geometry that gave us a specific deflection based on a defined load. Once the design was created we then ran an ANSYS analysis and found that the ANSYS FEA program showed a deflection magnitude that was ten times greater than in the Solidworks Simulation analysis. While trying to find the cause of this deviation we found that running an analysis using Simulation Express gave us a deflection that was basically identical to what was found using the ANSY program. We have repeatedly run the analysis using both the Simulation Express option and the Simulation option with the same results. As near as we can find everything is the same except for which program is being used. The Simulation Express result for deflection is greater than the Simulation result by a factor of ten. Has anyone else run into this situation, or have any idea of what may be causing this?

       

      We have also found that running Simulation creates a folder for the new study but the program does not place the analysis files into the folder created?

        • Re: Solidworks Simulation vs Simulation Express
          Bill McEachern

          as a function of the depth of the member in the direction of deflection how far is the ansys/express deflection? If the arm is say 10 mm deep, so d=10mm what is the deflection .1d or 10d? If it is bigger than .5d the problem is on the threshold of non-linearity, if it is 5d then the Sim Premium is probably right and the other two programs are seriously in error. Or it could be finger trouble if it is less than 0.5d.

          • Re: Solidworks Simulation vs Simulation Express
            Ryan Werner

            Glenn,

             

            Simulation does create a folder in the same directory where the result files are saved and yes that folder remains empty.  I too am not sure why that folder is created but I usually just delete it once I am done running the analysis.  It will create the same folder though if you run the analysis again.

             

            As far as the deflection goes it is a little hard to trouble shoot without seeing the file and how the analysis is set up but a couple of things to look out for might be the material that is selected in the Simulation.  Usually it will try and default to what the material is in the part file but if it is a custom material Simualtion may not be getting that material correct.  Just a thought.  Also, Simulation has more options for restraints than Express so perhaps you have a different set of restraints in the Simulation.

             

            If you want to put the file here I can try and duplicate your different results between Express and Simulation.

             

            Ryan W.  

              • Re: Solidworks Simulation vs Simulation Express
                Glenn Parks

                Thanks, Ryan

                 

                I double checked and the material does show the Inconel 718 that was specified. Attached is the Solidworks part file and a couple of screenshots showing the displacement results from both Simulation and Simulation Express. The restraints used were simply fixing the three holes, and the load was 415 lbs applied normal to the flat surface shown on the end of the part as you can see from the screenshots.

                  • Re: Solidworks Simulation vs Simulation Express
                    Ryan Werner

                    Glenn,

                     

                    I can duplicate your results with the Express Displacement coming in at being 10 times higher than Simulation.  The reason you are getting those results is because for some reason the custom material for Inconel that Simulation is using has an Elastic Modulus 10 times larger than the custom material that is being used in the model itself (see pictures) and that is the material that Express uses.  If you fix that Modulus in Simulation you get the same results as in Express.

                     

                    Ryan W.

                      • Re: Solidworks Simulation vs Simulation Express
                        Glenn Parks

                        Ryan,

                         

                        Thanks so much for assistance, and we had figured that it could be a modulus issue early on but could not find any difference between the Simulation and the Simulation Express values since we were using the same material from the same library for both. We ran the analysis several times with the same results when both of the programs were showing the same modulus.

                         

                        We ran the study again this morning with the same results, but did see where there is a difference between the modulus value depending on where you look in the program. When you right-click on the part in the study, and select both the "Apply/Edit Material" and the "Details" option the modulus was different by the factor of 10 while all the other material properties are the same in both the windows. I have no idea why the value would show up differently in two areas of the same program.

                         

                        Thanks again for verifying that it was a modulus issue. Now we know for sure why the results were different between the two programs, but have no clue why the modulus would be different within the same program.

                         

                        Perhaps someone with Solidworks could explain the different values that are showing up? 

                    • Re: Solidworks Simulation vs Simulation Express
                      Dougal Hiscock

                      That folder solidworks creates is where any saved results plots go.  You can click on the tree and choose "save all" and that's the default location.

                       

                      Kind of off topic, but does anyone else think solidworks has chosen some terrible names for their FEA programs?  At least COSMOS sounded unique, "Solidworks Simulation" is a mouthful that tells people nothing.