rolling_friction model epsd2

Purpose

The elasto-plastic spring-dashpot model with a single parameter, a widely used rolling friction model.

Note

This command is supported by Aspherix GPU.

Syntax

rolling_friction epsd2 [other model_type/model_name pairs as described here ] settings keyword values

zero or one keyword/value pair may be appended after the keyword settings (after all models are specified)

torsionTorque values = 'on' or 'off'
  on = also the normal, relative rotation (torsion) contributes to the resulting torque
  off = only the tangential, relative rotation contributes to the resulting torque

Associated material properties

Material interaction properties

coefficientRollingFriction ( $\mu_r$ ): Coefficient of rolling friction [–]

Description

This model can be used in the rolling_friction argument of both particle_contact_model and wall_contact_model.

The alternative elasto-plastic spring-dashpot (EPSD2) model is similar to the EPSD model, but in contrast to the original model the rolling stiffness $k_r$ [Nm] is defined as (Iwashita and Oda 1998)

$k_r = k_t (r^*)^2$

where $k_t$ [N/m] is the tangential stiffness of the tangential force model . Furthermore, the viscous damping torque $M_{rd}$ [Nm] is disabled completely (Wensrichi et al. 2012).

Torque information:

By default the relative, normal rotation (torsion) is subtracted and does not contribute to the resulting torque. By setting the torsionTorque keyword to ‘on’, the full relative rotation contributes to the rolling friction torque.

Coarse-graining information:

Using coarsegraining in combination with this command might lead to different dynamics or system state and thus to inconsistencies.

Default

torsionTorque = ‘off’

References

Iwashita, M. Oda, Rolling Resistance at Contacts in Simulation of Shear Band Development by DEM. J. Eng. Mech. 124, 285–292 (1998).

1. Wensrich, A. Katterfeld, Rolling friction as a technique for modelling particle shape in DEM., Powder Technology, 217, 409–417 (2012).