Residual Stresses in Passenger Car Wheels

The purpose of this paper is to present the extension of previous studies aimed at understanding the residual stress distribution in as-manufactured railroad wheels. In order to address loading conditions which are not axially symmetric, a manufacturing simulation has been conducted with a 3-dimensional model. Results from the 2- and 3-dimensional models have been shown to be comparable. This agreement allows the manufacturing model to be integrated with other loading conditions such as contact. Manufacturing simulations using the 2D, axisymmetric model execute in about 50 minutes on a 2.8 GHz PC. Contact load simulations with the 3D model ran for about 60 hours on the same machine. An analysis methodology to estimate residual stresses in the wheel rim due to simulated wheel/rail contact was illustrated with a prototype calculation. A deformable representation of a portion of the rail was needed to capture the contact pressure distribution and patch size of the contact zone. The indenting rail was modeled with two regions. Load is applied to a rigid part. The second region is deformable. It acts to distribute the load as it forms a contact zone interacting with the surface of the wheel model. Initial manufacturing stresses were not considered in order to confirm the validity of the contact model. Previous work which attempted to develop residual stress estimates in wheels due to manufacturing and service conditions relied on a very simplified material model and crude means of accounting for contact pressure. An investigation of more realistic material models has also been conducted. While the as-manufactured residual stresses have not been included in the development work presented here, future efforts will concentrate on integrating the manufacturing, contact and thermal effects in a single model. Such a model is envisioned to form the basis for an analysis procedure for consideration as a replacement for the current AAR S-660 wheel design standard.