Pre-stressed modal / response spectrum analysis

- July 24, 2023 at 1:20 pm
  
  Chris David
  Subscriber
  
  Hello,
  
  I have been trying to learn to perform response spectrum analysis for preloaded structures using a simple cantilever beam model.
  
  To understand the affect of pre strees I have applied a point mass at the free end of the beam, which produces a 15mm deflection in a static structural analysis. Having performed modal and response spectrum the maximum deflection in the response spectrum analysis is 2mm. My question is what does this value tell me, is this a maximum displacement from the prestressed deflected position, or is my model setup incorrect?
  
  Many thanks
- July 25, 2023 at 8:38 am
  
  Surya Prakash
  Ansys Employee
  
  Hi Chris,
  The deformation that you get in Response Spectrum is the maximum response that you obtain when you provide the Spectrum load. The deformation in Static Structural Analysis is the normal state of the model (as per my understanding) - due to which the mode shapes will vary. We cannot compare these two deformation results.
  I would suggest you refer to this video on how to perform Response Spectrum Analysis -
  https://youtu.be/5DYMvfEUJNc
  
  Cheers,
  Surya