Learning Forum

[CarlosGN]

Hi there, 

I am new in ANSYS, and I would like to obtain the energy strain in a thin disc at different resonance frequencies. For that, I have obtained successfully the eigenfrequencies of the disc using the Modal analysis. However, in that analysis I the energy tab is disabled, hindering the calculation of the strain energy. Do you know how could I calculate the strain energy for each resonant mode detected in the disc?

 

Many thanks in advance. 

 

Kind regards, 

 

Carlos

[peteroznewman]

Hi Carlos,

You need to drop a Harmonic Response analysis onto the Solution cell of the Modal analysis.

How are you supporting the thin disc?  If you have a fixed support, then you could put an Acceleration load to vibrate the thin disc in a direction normal to the disk at a range of frequencies above and below the resonance frequency found in Modal. This simulates the disk being mounted on a shaker table.

You also must define Damping under Analysis Settings in the Harmonic Response because the magnitude of damping has a large influence on the peak response at resonance.

[Sandeep Medikonda]

Strain Energy is calculated from stress and strains...so first go to Analysis Settings>Output Controls and turn on all relevant outputs.

Once your analysis is completed, click on Solution and the on Worksheet. This should give you access to all the results that are available from a modal analysis.

In general, this is often of less significance. Please see peters explanation on this.

 

[CarlosGN]

Hi peteroznewman, 

Thanks for your prompt response. Currently, in the Modal analysis, I am not supporting the disc. The analysis is able to determine the deformation of the disc and the corresponding resonant modes without using any support.

Do you mean that I have to create a second analysis right after the Modal analysis? 

Kind regards, 

Carlos 

[CarlosGN]

Thanks SandeepMedikonda, 

I have followed the steps that you suggest and now I can see some energies from the Modal analysis. The energies I can see in the worksheet are as follows:

ENERGYPOTENTIAL

ENERGYKINETIC

STEN

SERR

Now, I would need to SUM the total energy stored in the disc for each specific resonant frequency. Do you have any idea how to do that?

Thanks in advance

 

Kind regards 

 

Carlos

[CarlosGN]

Hi Peter, 

 

I managed to create a Harmonic Response analysis showing similar results to those obtained by the Modal analysis, applying an Acceleration load on one of the disc edges. However, in the solution/strain tab the energy option is disabled which means I can not obtain the energy stored at each resonant mode. Any clue? 

 

Thanks in advance

 

Carlos

[CarlosGN]

One of my colleagues told me that in Classic ANSYS there is an option namely

Elcalc

Element calculation key:

 

 

NO

 — 

Do not calculate element results, reaction forces, and energies (default).

YES

 — 

Calculate element results, reaction forces, energies, and the nodal degree of freedom solution.

That you can enable (i.e. YES) and that will allow you to determine the energy of each resonant mode. However, in ANSYS Workbench, I cannot find that option. 

 

Kind regards, 

 

Carlos

 

[peteroznewman]

It's what Sandeep said, click on Analysis Settings under Harmonic Response, and under Output Controls, set everything to Yes.

[peteroznewman]

STEN is zero and SERR is not defined in results.

Here are the two energy results and a simple sum created by putting a + sign in the expression.

 

 

[CarlosGN]

Thanks Peter for the response.

Actually, the energy that I need to obtain is known as SENE, i.e. the "stiffness" energy or thermal heat dissipation (applies to all elements where meaningful). This parameter is available in classic ANSYS but I don't know why in ANSYS Workbench I can find it! SENE is not in the Available Solutions Quantities in my simulation, which indicates that my file is not calculating that parameter.?

Any idea how can I make the software to calculate SENE in Modal analysis? Is this available in the student version of ANSYS?

Thanks in advance

Kind regards, 

Carlos

[peteroznewman]

I don't know Carlos, I hope someone from ANSYS will reply.

Kind regards,
Peter

[shkiefer]

A bit late but check this Medium post out. May be helpful.nn