EnginSoft - Conference Abstracts

EnginSoft International Conference 2009
CAE Technologies for Industry

Modelling and Simulation of contacts in Multi-Body Simulation with SIMPACK

Mulski Steve - INTEC GmbH (Germany)
Mauer Lutz - INTEC GmbH (Germany)

Abstract

When we consider the course of a normal day in our lives we quickly realize that contact mechanics plays an integral and indispensable role in essentially everything we do. From simply laying a pencil on a desk top, walking down the street, all the way to guiding a railway vehicle through switches and crosses, contact mechanics is omniprevalent. A brief overview of some industrial sectors where contact mechanics plays a significant role gives insight into just how diversified and encompassing contact mechanics is.

• Drivetrains – bearings, gearwheels, shift mechanisms, belts, clutches synchromeshes, etc.
  
• Rail – wheel/rail contact, buffers, bump stops
  
• Wind Turbines – similar to drivetrains, (Aerodynamics is not covered in this paper since air is not modelled as individual bodies but as applied forces and moments)
  
• Automotive – tires, bump stops, jounce bumpers, roll over manoeuvre
  
• Engine – timing mechanisms (chains, gear wheels), cam roller contact, valve contact with valve seat and fingerfollower, valve springs (between windings)
  
• Biomechanics – joints (e.g. “rolling” of knee joint), sport equipment, pedestrian and passenger safety
  
• Automation / Robotics – material handling

The number of applications and modelling fidelity of contact mechanics is virtually limitless and is therefore perhaps the most diversified and demanding field of multi-body simulation. Not only do the modelling elements have to cover an extensive range of applications but additionally the solvers used have to be robust enough to handle the extreme non-linear “shocks” resulting from the contact mechanics. Furthermore, there is no one “best” method suitable for all applications. A decision must be made based upon the tradeoff between accuracy and the effort required for modelling, validation and simulation (i.e. CPU time).
The simulation of contact mechanics can be essentially divided into two distinct tasks: One; calculating the contact kinematics (position and velocity) and two; calculating the contact forces (normal and tangential).
This paper begins with an overview of the standard contact force laws used, along with advantageous solver functionality, before moving on to describe different methods for solving the contact kinematics, both general and application specific.