rolling_friction model epsd3

Purpose

Elasto-plastic spring-dashpot model with an additional torque contribution.

Syntax

rolling_friction epsd3 [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 [–]
coefficientRollingViscousDamping ( $\eta_r$ ): viscous damping coefficient for the rolling friction model [–]

Global scalars

coeffRollingStiffness ( $C_k$ ): Stiffness of the rolling friction model [–]

Description

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

The third alternative elasto-plastic spring-dashpot (EPSD3) model is similar to the EPSD model, but in contrast to the original model the rolling stiffness $k_r$ [Nm] is defined as

$k_r = C_k k_n \mu_r \mu_r {r^*}^2,$

where the non-dimensioanl scaling prefactor $C_k$ [–] is defined by the user by setting the global scalar coeffRollingStiffness, $k_n$ [N/m] is the spring stiffness of the normal contact model, $\mu_r$ [–] is the coefficient of rolling friction and $r^*$ [m] is the effective radius (see e.g. here). The viscous damping component of the rolling friction torque is calculated as in the EPSD model but the rollFrictionFactor is always set to zero ( $f=0$ ) and can not be modified by the user.

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

Jun Ai, Jian-Fei Chen, J. Michael Rotter, Jin Y. Ooi, Powder Technology, 206 (3), p 269-282 (2011).