Module Stress

Computation of stress in contact patches of a simulation run. Data of patches are written into a file and anlysed by module STRESS.

Surface stress in contact patch

 subsurface stresses to the patch

The method used is a “Boundary Element Method”   based on the algorithm developed by Kalker and published in  (Kalker, 1990) and  (Hashemi & Paul, 1979).

During a dynamic simulation at defined sites, output for this case is written into a file. This output is used as input for the ACStress tool which computes surface stresses in wheel/rail contact and subsurface stresses in the body of wheel and rail.

Theory of stress computation

BEM-method developed by Kalker and described in (Kalker, 1990) allows solving numerically general rolling contact problems for linear-elastic bodies. If elastic properties of the contacting bodies are very similar normal contact problem and tangential contact problem are independent from each other. Solution is found in a so called Johnson procedure. This is the case for contact problems between wheel and rail of railway systems. The algorithm works with rectangular elements for surface stress computation and computes subsurface stresses in defined nodes.

Discretization of surface, which means length of elements, influences results on surface. Quality of subsurface stresses is independent of the number of subsurface nodes. It is also independent of mesh size on surface.