The CONTACT add-on to Universal Mechanism

The CONTACT add-on for UM is a version of CONTACT that is integrated seamlessly into Universal Mechanism. This provides the option to simulate vehicle dynamics using CONTACTs detailed contact algorithms. Including the full non-Hertzian geometry instead of relying on Hertzian theory or the Kik-Piotrowski algorithm, and using full linear elasticity instead of FASTSIMs simplified theory.

In contrast to the SIMPACK add-on, where CONTACT is used only for post-processing, the UM add-on is integrated in the dynamic integration loop. It completely replaces the simplified algorithms. This way, one may study derailments using the full CONTACT model and compare with simplified algorithms. The calculation time is controlled effectively by varying the discretization accuracy.

You build your model first using simplified algorithms. When this is done and initial simulations are running, switch the algorithms to CONTACT and off you go. You may start with for instance 15 times 15 elements and play around with the model. Then run one simulation with 25 times 25 elements to get a feeling for robustness of the results.

results of CONTACT add-on

Main benefits

  • fully integrated in the vehicle dynamic simulation;
  • easy access to Kalker's full non-Hertzian theory;
  • validation of results of simplified theories;
  • assessing the contact area and peak stresses causing damage phenomena.


The add-on takes care of all the preparations that are required:

  • determining the initial contact point(s) between wheel and rail;
  • defining a local coordinate system;
  • computing the initial penetration of the undeformed profiles;
  • computing the creepages.
The contact results then include:

  • the location of the contact patch(es) w.r.t. the wheel and the rail;
  • the contact angle and creepages;
  • the size of the contact, adhesion and slip areas;
  • the contact forces, normal and tangential, according to Kalker's theories;
  • the maximum pressure, maximum shear stress and the wear number.
More features will be implemented in consecutive releases. This concerns the integration with UMs wear and RCF prediction, exporting of the detailed results and creating an input file for CONTACT as well.

More information

If you're interested in finding out more, fill in your questions in the following form. We will then contact you on the e-mail address as indicated below.

Distribution of tangential forces:

results of CONTACT add-on

Longitudinal creep force Fx:

results of CONTACT add-on

Lateral creep force Fy:

results of CONTACT add-on

(* required fields).