9 Replies Latest reply on Feb 8, 2019 5:14 PM by Ryan Dark

    assembly frequency simulation

    Seongwoo Oh

      The image below shows that I can run a frequency analysis for a single piece by specifying which surface comes in contact with noise/vibration under 'fixtures.'

      one body simulation.PNG

       

      I am trying to do something similar with a cylindrical shell hanging by springs from a metalic piece.

       

      The metalic piece is going to be the source of vibration and I want to know how that vibration will transmit through the springs and excite the cylindrical shell (assembly shown below).

       

      assembly simulation.PNG

       

      I would appreciate it if I could be provided with some guidance as to how best to do it.

       

      As can be seen below, I can run frequency simulations of assembly files with the cylindrical shell and top and bottom caps on.

       

      without screws and springs.PNG

      But if I attempt to do the same with the springs (cosmetic), screws, and the ceiling the springs hang from, I get an error message with the mesh for some reason.

        • Re: assembly frequency simulation
          Mohamed El Orche

          Hi,

           

          Can you please attach the model?

          You can use spring connectors instead of real springs in your simulation study.
          The frequency analysis will give you natural frequencies and their mode shapes. However, if you want to see how the structure behaves when it's excited by a dynamic load, you can perform a linear dynamic study.


          Regards

          Mohamed

            • Re: assembly frequency simulation
              Seongwoo Oh

              thanks for the response and offer to help.

               

              I've attached the assembly and its accompanying parts.

               

              I attempted to run a linear dynamic study.  I think I also attempted to use spring connectors.

               

              I get an error message saying "No excitation curve or initial condition are defined"

                • Re: assembly frequency simulation
                  Seongwoo Oh

                  I was able to arrive at the results shown in the image below

                   

                  what i got.PNG

                   

                  What I am interested in though is, given that there's noise, composed of many frequency components, coming from the ceiling (represented by the block with a clear hole in the middle), how does the cylindrical shell piece hanging by springs below respond to those different frequency components. 

                   

                  That's why I was looking at frequency analysis.

                   

                  Is there an analysis comparable to frequency analysis but starting with noise of many different frequency components at the ceiling and see how such frequency components excite the cylindrical shell below?

                    • Re: assembly frequency simulation
                      Ryan Dark

                      Hi Seongwoo,

                      I think you may be asking Frequency analysis to do something it is not designed to be doing.  Frequency analysis is just going to report back natural frequencies of the system.  In that way you would know what frequencies will set off violent vibrations in the design and change it accordingly.  So, if a frequency happens to vibrate any particular portion of the model you will get that listed as a resonant frequency.

                       

                      If you are looking for how a model might react to real life vibrations then you are exceeding the abilities of Frequency analysis and would need to move over to Linear Dynamic analysis.  Given what you are describing you would probably be doing a Harmonic sub-type analysis where you setup a Base Excitation (SOLIDWORKS Help - Uniform Base Excitation) that describes the vibration coming through the grounded plate and that would tell you how this model is going to react in a real physical situation.