Linear Spring Dashpot Model

The linear spring dashpot model in MercuryDPM referred to as LinearViscoelasticNormalModel (LinearViscoelasticNormalSpecies, LinearViscoelasticInteraction).

A very simple interaction law was presented by Cundall and Strack in 1971 for spherical particles, and remains the most commonly used law in DPM simulations. This is the linear spring dashpot model, which quantifies the normal force \( \vec{f}_{ij}^{n} = f_{ij}^{n} \vec{n}_{ij} \), with

\( f_{ij}^{n} = \begin{cases} k_n \delta_{ij}^{n} + \gamma_n v_{ij}^{n} & \quad \text{if} \quad \delta_{ij}^{n} > 0 \\ 0 & \quad \text{else} \end{cases} \)

where, \( k \) is the particle stiffness, \( \gamma \) is the dissipation coefficient, \( \delta^{n} \) is the normal overlap, and \( v^{n} \) is the relative velocity.

Header:

#include <Species/LinearViscoelasticSpecies.h>

Interaction function:

void LinearViscoelasticInteraction::computeNormalForce() 

Unit Test: LinearViscoelasticUnitTest.cpp

Contact behaviour: