15 Replies Latest reply on Jan 15, 2013 1:07 PM by Justin Strempke

    Not getting desired stress analysis simulation (Solidworks premium)

    Evan S

      Hi,

       

      I have Solidworks premium 2012 and I am using the simulation add-on to do a study. I was able to get rid of most of the issues I've had with meshing and mating (I had to treat most members as beams for analysis). Now, my issue is that when I simulate this structure, it gives me a very weird response and I'm not sure if I've done something wrong in the assembly or it is maybe my simulation settings. I have tried everything I can think of to try and analyze this structure. I would just like to add some forces on the cross beams and on the roof (seperate studies if necessary) and get a simple stress analysis that works (deformation, von mises stresses). Thank you very much in advance for your help, since I really need it!

       

      Also, let me know if my upload worked, because I uploaded only the assembly file and I'm not sure if I also have to upload all of the individual parts as well (there are quite a few). Thanks in advance for the help!

        • Re: Not getting desired stress analysis simulation (Solidworks premium)
          Jerry Steiger

          Evan,

           

          I didn't try downloading your file, but you do have to upload all of the individual parts as well as the assembly. Pack and Go is the easy way to make sure that you get all of the necessary files.

           

          Jerry S.

          • Re: Not getting desired stress analysis simulation (Solidworks premium)
            Justin Strempke

            I was able to take a quick look, and you had a few things incorrect in your setup.  The use of beams is the correct way to go on this, but you need to make sure to apply all your loads accordingly (your roof loading was set to surface face).

             

            Second, look closely at your joints.  You need to be sure all connections are pink, not gold.  You can click on a gold node and it will highlight the associated beam, from which you can click on additional beams to add to the connection and click 'Calculate', but be sure the 'Keep modified joint on update' box is checked.

             

            You also had 'Inertial relief' checked in your setup properties, but since your model had adequate fixtures this is unnecessary and was giving me errors.

             

            The sim ran well for me after changing these, give it a shot and let me know how it goes!

             

            P.S. - I assume you initially setup your sim for solids, but for beams you want to analyze your stress results accordingly (yours still had the solid's Von Mises used).  Adjust your stress charts' Definition to beams, using 'Upper bound axial and bending'.

              • Re: Not getting desired stress analysis simulation (Solidworks premium)
                Evan S

                Thank you VERY much for looking into this for me! I will make these changes and let you know how it goes! I may have a few small questions along the way. Again, thank you so much for helping me out! I am still learning the wonders of this software in terms of stress analysis.

                • Re: Not getting desired stress analysis simulation (Solidworks premium)
                  Evan S

                  Okay, my first question is, for the two gold joints, this beam is resting on two smaller beams which are "too short" to be modeled as beams. This may be why the joints are in gold? When I go into the joint option, I can only select the transverse beam, and when I try to select those two small, non-beams, it says I cannot edit joints with bodies that aren't beams. How did you get around this?  Thanks!

                    • Re: Not getting desired stress analysis simulation (Solidworks premium)
                      Justin Strempke

                      I changed these to beams, even though they're too short.  You should be fine with them as solids though, just be sure to add a bonded contact set between the beam (selected as such in the blue box) and solid face (in pink).  I believe SW should do this automatically, but I always just do it to be safe, and you only have four such connections.  Keep in mind you'll have to look at the stress in these using a seperate VM plot.

                       

                      I was referring to the overhung end, where the tapered beams attach to the end beam.

                        • Re: Not getting desired stress analysis simulation (Solidworks premium)
                          Evan S

                          Hi Justin, Sorry to bother you again. I'm having trouble getting the end bar (overhanging section) joints to turn from gold to pink. When I click on joint group, I select "all" then "calculate", and those nodes on the end stay gold. Then I select "select" then click on the far end beam as well as the two beams it is attached to, and still the joint nodes stay gold. How did you work around this? I'm not too sure how the joint group option works, but if you select all then select "select" and "calculate", does it override the last edit you made to all joint groups? I noticed it isn't like component contacts where you can have several different types/groups.

                            • Re: Not getting desired stress analysis simulation (Solidworks premium)
                              Justin Strempke

                              Here's the process:

                               

                              1. Select radio button 'All'

                              2. Click 'Calculate'

                              3. Verify 'Keep modified joint on update' is checked

                              4. On model, RMB on the gold node/connection you want to add beams to.

                              5. A pop-up window shows what beams are currently associated, and will highlight pink.  LMB other beams to add.  For future, these don't need to be end-end connections, they can be mid-beam.

                              6. Click 'Calculate' again - this will ADD your joint to the existing list and turn the joint pink.

                              7. Repeat 4-6 for additional connections.

                               

                              If you change the radio from 'All' to 'Select', you're defining which beams SW should try to connect.  Most often just leave it at All.  I found it helpful if you have stubborn joints or issues with them falling out of order (where the forces/fixtures are attached), you can choose Select and Calculate, then go back to All and Calculate to 'reset' them.  Keep in mind you'll have to redo and special connections you've made.