6 Replies Latest reply on Oct 23, 2014 10:56 AM by Sean Screws

    Solidworks simulation premium, how to simulate a "sine waveform vibration" test?

    Jing Liu

      A sine waveform vibration test has been done to a prototype. I want to simulate the test using the Solidworks simulation premium package.

       

      Question No. 1: I did the frequency study to the model and get 23 modes in the range of 0-2000 Hz. I wanted to copy the results to a new dynamic study, but the system told me like "Frequency studies with beam mesh, inplane loading effect due to applied loads or any type of remote loading cannot be copied to dynamic studies". I don't have any like beam mesh, inplane loading or remote loading in my model. How can I address this issue?

       

      Question No. 2: how to set up the simulation parameters to restore the real test which is described as the following?

                               (a) Frequency: Logarithmic Sweep from 10 Hz to 2000 Hz to 10 Hz

                               (b) Sweep Period: 20 minutes

                               (c) Displacement Limits: 1.5 mm from 10 Hz to 57.5 Hz

                               (d) Acceleration Limits: 69.3 m/sec2 RMS (10g peak) from 57.5 Hz to 2000 Hz

                               (e) Duration: 8 hours/axis

       

      Any input will be highly appreciated!

        • Re: Solidworks simulation premium, how to simulate a "sine waveform vibration" test?
          Jared Conway

          1, if you have checked, do the freq at the dynamic study level and report the issue to your var.

           

          2. Take the time aspect out and run 2 harmonic analyses. Or make a curve, run a time history and get some popcorn for a long simulation.

          • Re: Solidworks simulation premium, how to simulate a "sine waveform vibration" test?
            Mark Ankrom

            One of my major complaints about simulation is the model  is dependent on the study(statics, freq response, transient).  The copying model to each "study" is very inefficient from a modeling and updating perspective.

             

            As for the sine sweep simulation.  At that sweep rate (about 2 octaves/min), a lightly damped structure will hit steady state for each of the frequencies.  Just perform the harmonic analysis and use resonant frequencies plus some uniformly distributed points in between.  This will allow you to determine peak loading and make xy plots.

             

            Fatigue cycles can be determined by integrating the sweep function (usually logarithmic). If I remember correctly there are 22 cycles per hertz for 2 octaves/min. You can use this with the response plot to estimate the fatigue damage.

             

            Mark

              • Re: Solidworks simulation premium, how to simulate a "sine waveform vibration" test?
                Jing Liu

                I agree with you, the copying to the new study IS inefficient sometime. I got 23 modes from the frequency analysis between 10-2000 Hz. Do you suggest me to run the harmonic analysis for each of the mode? How to "plus some uniformly distributed points in between"?

                 

                Just began to do the simulation, feel like I have so much to learn

                  • Re: Solidworks simulation premium, how to simulate a "sine waveform vibration" test?
                    Mark Ankrom

                    Since you already have the test data you should have a collection of xy plots of response versus frequency.  your simulation objective should be to generate the same plots as the test.  The harmonic analysis requires user input specifying the frequencies for calculating the steady state response.

                     

                    if you only choose the natural frequencies you will only get some discontinues peaks.  To make a meaningful plot you need to add points before , between, and after the natural frequencies. Depending on the structure you may only need to analyze a much smaller freq range.  Analysis below the first mode will be rigid body and only requires a few points.  Analysis above your mode 23 will roll off in about an octave.  There is not much reason to analyze more than an octave above the last mode.

                • Re: Solidworks simulation premium, how to simulate a "sine waveform vibration" test?
                  Sean Screws

                  Looks like you have an idea of what your outputs should be. If you need RMS, then you'll need Random Vibe. If you need max value (i.e. max displacement), then you'll need Harmonic. If you need results based on time, Model Time History.

                   

                  A Harmonic analysis will look at X points around each frequency within a given bandwidth. If you assume that the transient effects are negligible (taking time out of the equation), then two harmonic analyses should give you two response plots that you can export to .csv and superimpose in excel,matlab,etc.