Increasing element temperature as strain increases? Used to incorporate Soil shear modulus reduction

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Increasing element temperature as strain increases? Used to incorporate Soil shear modulus reduction

melsawy
Hi everyone,

I am trying to incorporate the Shear modulus reduction curve. This is basically a curve that shows the relationship of the modulus with changing strain (modulus of soil decreases as strain increases).
First of all, is there a way to incorporate this without defining a umat? And if the only way is umat, where can I learn how to write a umat code?
I know there is a way to change the properties of elements for different temperatures, so I was thinking of checking there is a way to automatically make elements get hotter(increase temperature) as their strain increases? And then for each value of strain they will have different properties?

I am simulating soil-pile interaction of a pile embedded in soil (dry sand with 100% relative density) under dynamic loading (earthquake). During the time-history of the earthquake certain elements face high strain therefore, their properties (shear modulus) should decreased based on their strain.

Thanks in advance.
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Re: Increasing element temperature as strain increases? Used to incorporate Soil shear modulus reduction

melsawy
I figured, I have to use USDFLD. I have one question though, USDFLD is used for material points? I want to be able to control material properties for individual elements. Is it possible to do it through it?
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Re: Increasing element temperature as strain increases? Used to incorporate Soil shear modulus reduction

Abaqus Users mailing list
In reply to this post by melsawy
You can probably do this using the routines USDFLD/UFIELD to define a
field variable that governs the property change of your materials.


Material properties have to depend on this (with *DEPVAR)


> Hi everyone,
>
>
> I am trying to incorporate the Shear modulus reduction curve. This is
> basically a curve that shows the relationship of the modulus with changing
> strain (modulus of soil decreases as strain increases).
> First of all, is there a way to incorporate this without defining a umat?
> And if the only way is umat, where can I learn how to write a umat code?
> I know there is a way to change the properties of elements for different
> temperatures, so I was thinking of checking there is a way to automatically
> make elements get hotter(increase temperature) as their strain increases?
> And then for each value of strain they will have different properties?
>
>
> I am simulating soil-pile interaction of a pile embedded in soil (dry sand
> with 100% relative density) under dynamic loading (earthquake). During the
> time-history of the earthquake certain elements face high strain therefore,
> their properties (shear modulus) should decreased based on their strain.
>
>
> Thanks in advance.
>
>
>
>
>
>
> --
> View this message in context: http://abaqus-users.1086179.n5.nabble.com/Increasing-element-temperature-as-strain-increases-Used-to-incorporate-Soil-shear-modulus-reduction-tp25038.html
> Sent from the Abaqus Users mailing list archive at Nabble.com.
>
>
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Re: Increasing element temperature as strain increases? Used to incorporate Soil shear modulus reduction

melsawy
Hi,

Could you please provide an example where my modulus changes with strain?
Modulus     Strain
50 MPa          0
45 Mpa           0.01
40  Mpa           0.005
Or provide anything I can build on as I am fairly new to abaqus.
Thanks in advance.
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Re: Increasing element temperature as strainincreases? Used to incorporate Soil shear modulus reduction

Abaqus Users mailing list
In reply to this post by melsawy
The integration points are unique to each element, so yes, your changes will be applied on an element-by-element basis.  Note that if you’re using fully integrated elements (i.e., elements with more than one integration point), that there could be a gradient within the element (i.e., since there’s a strain gradient, you will have a temperature/material property gradient).

Regards,

Dave Lindeman
Lead Research Specialist
SEMS Research Laboratory
3M Center 235-3G-08
St. Paul, MN 55144
651-733-6383

From: [hidden email] [mailto:[hidden email]]
Sent: Tuesday, February 14, 2017 9:15 PM
To: [hidden email]
Subject: [EXTERNAL] [Abaqus] Re: Increasing element temperature as strain increases? Used to incorporate Soil shear modulus reduction



I figured, I have to use USDFLD. I have one question though, USDFLD is used for material points? I want to be able to control material properties for individual elements. Is it possible to do it through it? -





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Johnson-Cook parameters AFTER recrystallization temperature

Abaqus Users mailing list
Dear Sir David Lindeman


Wanted to confirm,whether John-Cook parameters work well after recrystallization temperature too or they are applicable BELOW recrystallization temperature only?Any reference material may be highly appreciable.Thanks.
Best Regards