Learning Forum

[ReadyDieFurkan]

How can I do non-linear analysis with inertia relief turned on on Ansys?

[Ashish Khemka]

You can do a non-linear analysis with inertia relief turned on. Please refer to the link below:

14.2. Inertia Relief (ansys.com)

Regards Ashish Khemka

[ReadyDieFurkan]

I'm looking

[ReadyDieFurkan]

,I actually checked out the 14.2 section for inertia relief but the topic is very lengthy. There were some points present there which said that these are the limitations for inertia relief to be used in ANSYS, and one of them was that non-linear analysis cannot be used with inertia relief turned ON. Other than that, I couldn't find anything which said that still inertia relief turned ON can be used together with non-linear analysis. If you can write down that specific section from 14.2 here, that could help :)

[Ashish Khemka]

14.2.2.2. Nonlinear Static Analysis
For a nonlinear static analysis, the first step is to calculateinertia reliefacceleration (Equation14ÔÇô27) on the original geometry based on structural density at the beginning of the substep of a load step byEquation14ÔÇô8. The nonlinear equation to be solved (similar toEquation14ÔÇô16) is:

The nonlinearEquation14ÔÇô28is solved by Newton-Raphson iterative procedure as previously described. The nonlinearity can be material or large deformation (NLGEOM,ON) nonlinearity. In the case ofNLGEOM,ON, the inertia force term
is re-calculated at every substep to reflect the effects of updated geometry by:
Regards Ashish Khemka

[ReadyDieFurkan]

I don't quite understand, can you explain in more detail? I beg you

[Ashish Khemka]

My apologies, if the previous post did not help you. But you can have two types of non-linearities one is material non-linearity (i.e. having non-linear material models defined under Engineering Data) and other is geometrical non-linearity with Large Deflections turned on and the stiffness matrix is updated during the solution.

Regards Ashish Khemka

[ReadyDieFurkan]

I couldn't understand the previous post. Could you explain your previous post in more detail and solve an example?

[peteroznewman]

When I tested Inertia Relief in ANSYS 2021 R2, I got an error when I turned on Large Deflection.

[ReadyDieFurkan]

Yes, don't work. I'm looking for another method

[Ashish Khemka]

,
Let me check the same.

Regards Ashish Khemka

[ReadyDieFurkan]

Please help if there is another solution?

[Ashish Khemka]

Both cannot be used simultaneously (NLGEOM,ON) and Inertia Relief.
14.2. Inertia Relief (ansys.com)
Regards Ashish Khemka

[peteroznewman]

Here is a model setup for Inertia Relief:
Here is the solution for that model:
I can look up the Acceleration computed by model J above
and apply it as a load in model K below and turn off inertia relief and get the same result.
In this model, I am free to turn on Large Deflection as shown below:

[Rameez_ul_Haq]

,can you also show what the force reactions are when you turn ON the Inertia Relief, and then OFF? Since the forces are getting balanced by the inertia forces of the body, I don't think that we should be expecting any reaction forces in the case when Inertia relief is turned OFF.

[peteroznewman]

The reaction forces are numerically zero in all three models compared to the applied force of 314 N.
J: Inertia Relief On Reaction, Force (X) = 1.279e-13 N
K: Inertia Relief Off Reaction, Force (X) = 1.2079e-13 N

[Akhilesh Agarthade]

In model J, remote displacement is used along with inertia relief. What DOF it is constrained? But we should not use any constraints for inertia relief, right?
In model K, all 3 that is Acceleration, Force, and remote displacement used then how it is comparable with model J?