Reply To: How to calculate eigen frequencies using analytical approach?

[Rameez_ul_Haq]

,I couldn't understand what you mean by saying that Hooke's law is valid on local scale since the material remains linear. What do you mean by local scale? And you also said that for the global structure, Hooke's law is not valid if force-displacement curve is not linear when Large Deflection = ON. If is not valid on a global scale, then how can it be valid for a local scale?
So what does ANSYS consider? Does ANSYS consider a linear relation between stress-strain (i.e. Hooke's law) to calculate the stresses from strains within an element, or it does not and uses some other formulation to do so when Large Deflection is turned ON?