17 votes

How to find Young's Modulus using stress strain curve using Python?

I designed the Python program a few years back but haven't looked at it in some time. The __init__.py line can be commented out for your usage. That "model" was for my team's use case, and ...
Enusi's user avatar
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16 votes
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How to find Young's Modulus using stress strain curve using Python?

I was able to run the code on your data and got a Young's Modulus of $2.08236\times10^{-5}$. This clearly doesn't seem right for an aluminum system, though I don't know the units you are using. To get ...
Tyberius's user avatar
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12 votes
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How does a complete basis set remove Pulay forces/stress?

I think a good way to see this is to simplify the stage a little. Imagine we want to solve the Schrödinger equation for a Hamiltonian $H$. For this we take a very simple basis, namely just two real-...
Michael F. Herbst's user avatar
10 votes
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Mathematical models for the plastic region in the tensile test

Plasticity is still an actively researched area. The Ludwik-Hollomon equation is one model that is used for the strain-hardening region since it captures the convex shape of the curve using a power ...
Mythreyi's user avatar
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6 votes
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How to find the Cauchy stress tensor in solids using ab-initio methods?

A useful reference for this is [1], which describes how to compute the energy, forces, and stress tensor efficiently when performing PBC calculations using Gaussian atomic orbitals. Assuming you can ...
Tyberius's user avatar
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5 votes

Mathematical models for the plastic region in the tensile test

The other answer is great and comes from a viewpoint of macroscopic plasticity. I'd just like to note that another perspective on plasticity exists, a multiscale view based on following atomistic ...
s47's user avatar
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5 votes

How to find Young's Modulus using stress strain curve using Python?

Unfortunately, due to my reputation, I cannot comment yet. However, to the surprise of Tyberius, I would like to note that the function young_modulus does not return the Young's modulus, but the ...
Noco's user avatar
  • 121
4 votes

How to perform Strain induced properties in Quantum ESPRESSO?

"Do I have to do it manually by increasing/decreasing cell parameters?" The answer is yes, you need to change the simulation box vector based on strain. You can use the following logic: $$a'...
Pranav kumar's user avatar
  • 4,083
3 votes

How does a complete basis set remove Pulay forces/stress?

To complement Michael's answer, Pulay forces can actually be dampened by a suitable design of the basis set, as noted by Pulay in 1977. We have recently shown in arXiv:2207.03587 that accurate ...
Susi Lehtola's user avatar
  • 19.1k
2 votes

Why is strain rate used instead of absolute strain for modelling stress relaxation of a viscoelastic material using the Maxwell model?

If we integrate both sides of: $$\frac{d\epsilon}{dt} = \frac{d\sigma}{dt} \cdot \frac{1}{E} + \frac{\sigma}{\eta} \tag{1}$$ with respect to time, we get: $$\int_0^t \frac{d\epsilon}{dt^\prime} dt^\...
I have no free time anymore's user avatar
2 votes

How to calculate 2D elastic constants of boron nitride monolayers from uniaxial strains?

I think you should take a rectangular unit cell instead of the hexagonal unit cell depending on this article (The response of mechanical and electronic properties of graphene to the elastic strain M. ...
2 votes

Is it possible to define a property like strain to characterize the structural change?

I would select a group of atoms and calculate the relative deviation along the 3 dimensions. So I would take the initial (xi, yi, zi) and final (xf, yf, zf) coordinates and then calculate the 3N-...
cbornes's user avatar
  • 91
2 votes

Build supercell in ASE with forces and stress

Here is a simple Python script that can read forces and stress and store in atoms.arrays. Note that you cannot do get_stress() ...
Shaun Han's user avatar
  • 1,845
1 vote

Supercell Elastic Constant

In the undoped case, when considering a cubic crystal structure and using a tetragonal supercell not changes point symmetry, Hence number of independent elastic constants remains three. If you rotate ...
Pranav kumar's user avatar
  • 4,083
1 vote
Accepted

Print full stress tensor in ASE to calculate Green Kubo viscosity

Thank to all the comments and parallel discussions, I realised that to calculate Green Kubo viscosity one has to use the stress tensor. From Allen Tildesley, p61: These quantities [the stress tensor] ...
Marco Di Gennaro's user avatar

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