Learning Forum

[Emiliano Maldonado]

Hi everyone,

I'm modeling a foundation for a building subject to harmonic forces. I'd like to know how to simulate the supports' stiffness and damping to be frequency dependent. Thanks in advance for your help.

[BenjaminStarling]

There are a couple of ways, depending on how you would like to model the foundation.
Using springs on the bundaries
Using material properties, with or without infinite elements
Using springs, the spring properties can be parameterised against frequency using the *DIM command. Below is from the COMBIN14 help page. https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v212/en/ans_elem/Hlp_E_COMBIN14.html
Using material properties, you would need to model a layer(s) of elements that represent the soil/foundation, then apply a material model that can be defined as a function of frequency (or other nonlinear properties such as strain rate). The easiest is to add a frequency table to youngs modulus, possibly the second easiest is to use viscoelasticity that is defined in the frequency domain. As an example, in engineering data you can select the isotropic elasticity definition of any material, and in the top left field variables will appear, one of which is frequency.

[Emiliano Maldonado]

Crystal clear. Thank you very much indeed!