Force frictional sliding contact behavior in RBD ?

- October 4, 2017 at 12:20 pm
  
  pgl
  Ansys Employee
  
  How does force frictional sliding contact behave in Rigid Body Dynamics (RBD)?
- October 11, 2017 at 8:59 pm
  
  pgl
  Ansys Employee
  
  Force Frictional Sliding contact is not designed to model sticking situation.It works well for sliding contact where the friction leads to a resisting force (opposed to the sliding velocity) which is directly proportional to the normal contact force Ft=muFn.
  
  In order to avoid integration difficulty with low sliding velocities (basically when the contact would ideally be sticking or close to sticking), the friction factor varies linearly between 0 and its nominal values if the sliding velocity is lower than a given velocity.
  
  In summary, If ||v||>=v_tol, Ft=muFn If ||v||tol, Ft=mu*(||v||/vtol)*Fn This velocity tolerance is internally computed from the contact radius among many other parameters.
  
  Unfortunately, this tolerance cannot be get or set by the user. However, there is a command that affects its computation. options=CS_SolverOptions() options.VelocityToleranceFactor=1.0 The default value is 100. It allows to improve the behavior to be "closer" to a sticking contact but it won't ever be perfectly sticking.
  
  With a factor=1 (a lower velocity tolerance), it will be possible to have lower sliding velocities, like an "almost sticking" contact status.