How to calculate stiffness from compliance ( *.out file of Optistruct)?

Yaseen_22346
Yaseen_22346 New Altair Community Member
edited December 2020 in Community Q&A

Hi there,

I want to validate stiffness of my dummy parts in assembly. Compliance and Epsilon is what we gets, in *.out file of Optistruct. Compliance is inverse of stiffness. So the value of compliance  i am getting is 3.384886e5  and if i inverse it (K=1/C) then I am getting   2.9543092 e-6 ( this stiffness value can't too small)!?

I would appreciate a response.

 

Regards,

Yaseen Khan

Answers

  • Adriano Koga_20259
    Adriano Koga_20259 New Altair Community Member
    edited December 2020

    Hi @Yaseen 

     

    Compliance is a measure that can be interpreted as a indirect measure of inverse stiffness.

    If you look at the OptiStruct documentation you will find the math behind compliance, and hopefully it will make it clear.

     

    For a fixed load vector F, Compliance can be calculated as a vector product of the forces applied, multiplied by the displacement vector (U) found under this loading. So:

    C = f'*U

    So, for a certain fixed load, the higher the displacements, the higher the compliance. Which can be understood as a indirect measure of stiffnes. If for the same load, your new structure presents a lower average displacement (with smaller compliace), them, your structure is stiffer, compared to the old one that presentts larger displacements (with larger compliance).

     

    If you take a look at OS help or any Topology Optimization theory you will find a detailed explanation about compliance.

    Hope this helps.

Welcome!

It looks like you're new here. Sign in or register to get started.

Welcome!

It looks like you're new here. Sign in or register to get started.