Finding Damping ratio theoretically

- March 16, 2020 at 9:07 am
  
  newuserdampingratio
  Subscriber
  
  I am trying to determine the material damping ratio(hysteretic) of a material using ANSYS. I already know its Young's modulus, Poisson's ratio, Shear modulus and its density; and the material is isotropic.
  
  I performed modal analysis on the material of a rectangular cross section(40mmx10mm), length 500mm and fixed at one end(cantilever) and found its first natural frequency.
  
  I came across the half power bandwidth method and hence I tried harmonic analysis by applying a force of 1000N at the free end.
  
  The amplitude goes to infinity(like 1000 meters) near and at the first natural frequency.
  
  How can I determine the structural damping ratio from these values from this harmonic frequency response curve?
- March 17, 2020 at 2:06 pm
  
  peteroznewman
  Subscriber
  
  You can't determine the structural damping ratio from an ANSYS structural simulation.
  
  Damping ratio is an input to the model.
  
  You have to find that value experimentally or use the best estimates available in the literature.
  
  Here is a document from the Regulatory Commission.