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LAMMPS : The Irreversible mechanical deformation – Viscosity

Viewed : 175 times,  2021-10-26 01:59:33

Plastic deformation occurs when external stress is applied to the material that exceeds its elastic limit. In the case of amorphous materials, plastic deformation occurs in a similar way to the flow of liquids. Therefore, this can be explained by the viscous flow mechanism.

In particular, the quantity of viscosity (η) is a fundamental factor in determining such viscous flow. Viscosity is a time-dependent characteristic.

For more Information on this topic, please refer to the “ Viscoelastic properties of polymers" article.

 

This module tip aims to find the viscosity of a certain polymer system as a function of temperature using the LAMMPS (Viscosity) module.

 

 

Calculation Procedure

We need the successfully finished ‘LAMMPS (Thermalization)’ module to calculate the viscosity .

You can perform the thermalization calculation by referring to the following posts.

  1. Modeling: How to perform the polymer simulation – Polymer MD Modeling
  2. Structure optimization (Thermalization): The Essential Step for Polymer Simulation – Thermalization

 

The calculation is conducted via the Green-Kubo method, an equilibrium molecular dynamics calculation. Therefore, we cannot adjust the strain rate. The average viscosity of the material can therefore be calculated in this way.

 

 

Calculation Results

 

 

👉 View the example work

 

Following the calculation, you can check the resulting viscosity data as a function of temperature and time, as shown in the example above.

 

 

Example Video

 

 

 

🍀  Need more Information?

>Docs
[Modules] Molecule Builder

>Blog
[MatSQ Tip] Molecule Modeling in Materials Square
[MatSQ Tip] How to Model Complicated Molecule
[MatSQ Tip] How to Model Polymer in 3D: Molecule Builder
[MatSQ Tip] PolymRize: Predict polymer properties
LAMMPS : Molecular Dynamics Simulation for Polymer – Polymer MD
LAMMPS: How to perform the polymer simulation – Polymer MD Modeling
LAMMPS: The Essential Step for Polymer Simulation – Thermalization
LAMMPS: The Property of Polymer - Glass Transition Temperature
LAMMPS : Special mechanical properties of Polymers – Elastic properties
LAMMPS : The Electrical Properties of Polymers – Dielectric Constant

 

 


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