Papers by Author: Roman Bogacz

Abstract: Certain analytical elastic solution for curvilinear track section under uniform thermal loading has been proposed. Track section is composed of circular arc, transition curves and straight lines. Next step is the analysis of two-dimensional model of the track structure (stress plane, without vertical direction). The rails and the sleepers are assumed as elastic bodies. The fasteners and ballast are modeled as elastic-plastic elements. Non-linear properties of these elements are determined by comparison of numerical data with experimental results. Cyclic uniform thermal field is applied as the load of the system. Pre-buckling analysis is the basic part of the considerations. Certain remarks on the track stability, based on the previous author analyses, are also presented. It is shown that track structure with Y-shaped steel sleepers gives the possibility to use of continuous welded rail (CWR) track practically in any radius of curvature.

Abstract: We discuss the dynamic behavior of stepped columns subjected to follower forces. In particular, limit cases which correspond to columns with hinges or cracks and concentrated lateral supports are studied for the stability limit. Typically, solutions suffer jumps in certain derivatives, which have to satisfy compatibility conditions. The influence of these interface conditions on the critical force is investigated. The aim is to optimize the location of such singularities and thus to obtain maximum critical loads, respectively worst case estimates for the loss of stability.

Abstract: We studied several cases of dynamical problems, where the motion is driven by a concentrated force or distributed load applied at a moving position. The velocity of motion is assumed as constant. In particular, we studied interactions with periodic structure of the medium. Earlier results on one-dimensional structuresare extended to the case of an array of plates.