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# Prony series from flexural DMA for use in Abaqus/Explicit

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Topic starter
(@j0shuamerkley2)
New Member
Joined: 7 years ago

Hi.

I cant find a clear answer on this, so Im asking in this forum and would be very happy for any insight.

Im trying to evaluate linear viscoelasticity in ABAQUS using Prony series. I dont know exactly which data to generate, and hence this question.

I have the possibility to generate loss modulus, storage modulus (and tan delta) at different frequencies and temperatures using flexural DMA. In the ABAQUS help I see they are asking for g and possibly k, which would be the shear (loss and elastic) moduli. Can I use the data from my flexural test and evaluate the shear moduli using some equation such as G=E/(2(1+v))? Is this correlation valid for not only the complex modulus bu also for the storage and loss moduli?

Or, do I have to find an external sourcing for my tests, going for a rotary oscillating test to immediately get the shear modulus?

Also, in the documentation I find it quite complicated to understand what is actually needed in ABAQUS input. In ABAQUS CAE the input should be:
Omega g* real
Omega g* imag

From what I see in the help, this would correspond to:
Omega g* real = G_loss/G_inf
Omega g* imag = 1-(G_storage/G_inf)

where G_inf is then calculated from the long term Youngs modulus of the material using G_inf=E/(2(1+v)) where v = poissons ratio.

So, to summarize this long post:
Can I use flexural DMA to evaluate the Prony-series in ABAQUS?
Have I understood correctly that I should not input the raw data, but re-calculate those before input into the software.
Frequency is measured in Hz (periods/s).

Thank you in advance for any insight on this.
Best regards

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(@jorgen)
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Joined: 5 years ago

You are correct. You can use that data to generate a Prony Series. I will need to convert your DMA data to a Prony Series, which is what Abaqus ultimately will need. Abaqus has a built-in tool for doing this, but it does not always work too well.

I always use MCalibration for that purpose. MCalibration can take your data and calibrate the Prony Series directly.

-Jorgen

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Posts: 2
Topic starter
(@j0shuamerkley2)
New Member
Joined: 7 years ago

[QUOTE=Jorgen,n25487]You are correct. You can use that data to generate a Prony Series. I will need to convert your DMA data to a Prony Series, which is what Abaqus ultimately will need. Abaqus has a built-in tool for doing this, but it does not always work too well.

I always use MCalibration for that purpose. MCalibration can take your data and calibrate the Prony Series directly.

-Jorgen

Thank you Jrgen.

Best regards
Oskar

Posts: 1
(@jiaxin qi)
New Member
Joined: 7 years ago

[QUOTE=Jorgen,n25487]You are correct. You can use that data to generate a Prony Series. I will need to convert your DMA data to a Prony Series, which is what Abaqus ultimately will need. Abaqus has a built-in tool for doing this, but it does not always work too well.

I always use MCalibration for that purpose. MCalibration can take your data and calibrate the Prony Series directly.

-Jorgen

Jorgen,
I am trying to use MCalibration to define correct material parameters of mine.
However, I do not know how I can use MCalibartion to define Prony Coefficients. I have generated master curves of storage and loss modulus. How can I import them to MCalibration to define the right Prony coefficients?

Cheers, Ben

Posts: 21
(@msuhairil04)
Eminent Member
Joined: 7 years ago

[QUOTE=Jorgen,n25487]You are correct. You can use that data to generate a Prony Series. I will need to convert your DMA data to a Prony Series, which is what Abaqus ultimately will need. Abaqus has a built-in tool for doing this, but it does not always work too well.

I always use MCalibration for that purpose. MCalibration can take your data and calibrate the Prony Series directly.