General Mechanical

General Mechanical

Prestressed modal analysis

    • acakaca
      Subscriber

      Hello everyone,


      I wonder if someone could give me a hand with my project. I am currently working on modal analysis of an assembly with multiple parts and huge number of elements. 


      For the next step I would like to perform prestressed modal analysis. Is that possible without running static structural analysis first; is there another way to apply prestress directly in modal analysis?


      I am affraid that otherwise my computer will generate an error while solving the model and I wont't be able to get the solution.


      Have a nice day and stay healthy!

    • peteroznewman
      Subscriber

      Hello,


       You must run a Static Structural first and link the Solution cell of that to the Setup cell of the Modal analysis to run a Prestressed Modal analysis.


      Why do you think you need to prestress the structure before running the Modal analysis? Do you have long thin sections under high levels of tension like a guitar string or large thin plates under tension like a drum skin?  If not, you will not see much difference between the normal Modal result and the Prestressed Modal result.


      If your model has a huge number of elements, you should spend some time idealizing the model to reduce the number of elements. If your model is entirely made of solid bodies, here is a list of idealizations that greatly reduce the size of the model, in order of largest to smallest impact.



      • Replace a body with a point mass

      • Replace uniform cross-section long parts with beam elements on line bodies

      • Replace uniform thin-walled parts with shell elements on midsurfaced sheet bodies

      • Use Mesh Defeaturing to remove small details from the mesh

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