Setting the materials properties as variables

Submitted by davidf on Mon, 05/16/2011 - 19:04

Hello all !

I tried to define a variable function for youngs modulus , poisson ratio and the 2 coefficients as temperature dependent, but encountered an error telling me the values must be floating point.

Is there any way of defining the materials properties in liggghts as dependent on temperature or timestep for example ?

If so, what's the easiest way of doing so ? (I assume it involves the modification of some code)

Thanks !

Forums:

ckloss's picture

ckloss | Mon, 05/16/2011 - 19:27

>>Is there any way of defining the materials properties in liggghts as dependent on temperature or timestep for example ?
out of the box ... no

>>If so, what's the easiest way of doing so ? (I assume it involves the modification of some code)
Depends on what exactly you want to do... but have a look at the pair style code, e.g. pair_gran_hooke_history.cpp
You need to get yourself a pointer to the per-particle temperature, then you can code something

Christoph

davidf | Mon, 05/16/2011 - 19:34

Hi Christoph !

What i'm trying to do is to simulate a non-isothermal process where there are particles involved and the temperature varies relatively greatly.
In such a case it would be incorrect to use the same material properties all over the temp range, so i'm trying to modify those properties each timestep according to some function of the temperature.

Thanks for your quick reply !

ckloss's picture

ckloss | Tue, 05/17/2011 - 16:16

What you can do is write yourself a pair style like e.g. hertz/history/tempvariable, that, additionally to the two flags, reads a reference temperature T0, gets itself a reference to per-particle temperature T and changes the material parameters as a function of (T-T0).

Christoph

40044600's picture

40044600 | Mon, 12/09/2019 - 22:31

Hello, I've came across this post from 2011 which is relevant to what I am trying to do at the minute. Has there been any updates to LIGGGHTS since this in regards to defining temperature dependant variables.

In my case I want to assign a cohesionEnergyDensity value to atoms once they have reach a specific temperature. Any guidance on how I could achieve this would be greatly appreciated.

Thanks,
Jon Adams