18 Replies Latest reply on Oct 2, 2013 11:52 PM by Atif Khan

    Simulations taking up too much memory space?

    Atif Khan

      I was running a modal time history analysis by running a shock test. I tried running the simulation for the different directions in which the shock pulse is applied. The problem is the result files are too big for my computers hard drive. Only 6 simulations have taken up around 211GB worth of space. Add that to the space already used and I do not have any more space left on my drive. I need to do more simulations too

       

      How can I address this issue? Is there any way to compress the files? Preferably it should not affect the accuracy of the simulation

        • Re: Simulations taking up too much memory space?
          Jared Conway

          Hi Atif, dynamic definitely does take up more file space. Not sure what version you're working with but later versions (2013 and 2014) do provide some improvements in storage and also the time in which it takes to open them.

           

          I'm also assuming that you've applied the standard practices to reduce the size of your problem by leveraging symmetry...etc. In the long run, the more elements, the larger the file size.

           

          If you want to reduce the size of the file, i would take a look at the results options in your tree. There you can turn results on and off to reduce the size of your file.

            • Re: Simulations taking up too much memory space?
              Atif Khan

              Thank you very much Jared. I am using Solidworks 2013 Premium with the latest service pack SP4.

               

              Just a few questions though. You mentioned leveraging symmetry. What exactly do you mean? I am relatively new to Solidworks Simulations just about 2 months into it. By more elements are you referring to the no of elements in the mesh??

               

              I looked at the result options like you said but I cannot figure out how to turn the results off? If I turn the results off and if I want to access the results at a later time can I switch the results back on?

                • Re: Simulations taking up too much memory space?
                  Jared Conway

                  symmetry means cutting the model in half and applying a symmetry boundary condition. there should be at least one example in the tutorials or the training that show this. now that i think of it, you're doing dynamic, probably isn't valid because of the need for frequency which usually shouldn't be done with symmetry.

                   

                  elements = mesh elements. building blocks of FEA.

                   

                  results options, there should be some examples in the tutorials. if not, it is well documented in the help and the solidworks kb. but in general for example you might choose some of the main locations you're intrested in and only save the results for those points. but as you've noted, if you don't run them, they won't be there when you go looking for them. you'd rerun to get that data. play around with it on a small model first because some options might be better than others. what we teach our customers is to run the model in draft quality with a coarse mesh first, find the hotspots, then you can come back and run with a finer high quality mesh but only save the locations that are of importance. in the long run, if you want smaller file sizes, these are your options.

                    • Re: Simulations taking up too much memory space?
                      Atif Khan

                      Thank you very much Jared! I guess that is workable for now.

                       

                      As far as the mesh is concerned I was using a curvature based mesh a little bit finer than the default value used by Solidworks. So it was not too coarse nor too fine.

                       

                      At the end I halved the time increment from the original value that I had used and used a shorter pulse duration (in accordance with our reuirements) which also reduces the no of steps by a lot. Turns out that I am now down to around 42GB of used space which is a significant improvement. The results seem to be okay too.

                        • Re: Simulations taking up too much memory space?
                          Jared Conway

                          reducing the number of time steps and the number of frequencies will definitely make the results file smaller, but similar to reducing the mesh quality or number of elements, you need to be careful that it doesn't affect the solution.

                            • Re: Simulations taking up too much memory space?
                              Atif Khan

                              From your experience is there a benchmark on the number of steps that are required to get accurate results? Or is it problem specific? I was using around 520 steps and ended up using 211GB but then by doing the above I got it down to around 144 steps which saved me a lot of space. How much will it affect the accuracy? 5% or 10% or more?? Mainly interested in stresses and displacements.

                                • Re: Simulations taking up too much memory space?
                                  Jared Conway

                                  problem specific, have you taken the dynamic class? in the manual there are several suggestions on how to choose a time step, they are based on things like the inputs, the response of the system, the elastic modulus, first natural frequency...etc. if you're not sure, really your best bet is to start with a value based on your understanding of the physics, run the analysis, then make it smaller and see if it changes the output. if it does, you haven't got a converged solution. kind of like mesh convergence. but in the long run, you have to ask yourself, it is still just a simulation, are you really looking for absolute results or relative results between designs. usually it is the latter, so whether it is 5% or 10%, it is likely affecting the solution the same but you narrow down your design to 2-3 versions instead of 10 that you have to physically test. then you go from there and refine your method in simulation based on the testing so you can finalize your design virtually or physically.

                      • Re: Simulations taking up too much memory space?
                        Atif Khan

                        No to be honest I have not taken any dynamics class. Our reseller provided some help for harmonic vibration simulations but the rest I have been working out on my own with help from manuals. I really require more study of the time step phenomenon. I will have to ask my reseller for additional training I guess.

                        • Re: Simulations taking up too much memory space?
                          Dave Laban

                          As another thing to check, have all of the temporary simulation files been cleared by the software properly?  I think it was when using SW2011, we were finding that some of the files SW uses during the runs weren't being deleted at the end of the study.  The .STE files can add up to a lot of space if they're left over at the end.