ANALYSIS OF STRENGTH CHARACTERISTICS IN RAILROAD DOWELS PRODUCED BY VARIOUS MANUFACTURERS

The article describes operating conditions of the railroad dowel used in ZhBR 65 resilient rail fasteners. Requirements for railroad dowel tests in terms of their expediency, possibility to perform such tests and conformity with the actual operating conditions are analyzed. The initiative of the authors, arisen during an analysis of regulatory documents, served as a basis for the studies. Stresses in a dowel and its safety factor in operation and tests were determined analytically by the finite element method, using the APM FEM library, the system of strength analysis for KOMPAS-3D, certified within the GOST-R system. Railroad dowels manufactured by OOO NTT, ZAO Polimer ZAO and Vossloh Fastening Systems GmbH were used as study objects. For the purposes of simulation, 3D models of the corresponding dowels and their mating parts (sleeper, railroad screw, tension clamp, etc.) were built. According to the studies, in tensile tests of dowels, conducted according to Clause 4.6 of Specifications TsP 369 ТU-7, stresses of 85...100 MPa occur in the bodies of all dowels under consideration, which considerably exceed stresses appearing in dowels during operation, and the nature and distribution of such stresses do not correspond to those of operating stresses, the maximum value of which does not exceed 10 MPa. The analysis of stresses arising in sleepers with dowels by the manufacturers under consideration has shown that their limit value is 75 MPa. Besides, in sleepers with dowels by OOO NTT and Vossloh Fastening Systems GmbH, the maximum stresses are in the sleeper body, which allows for their redistribution and prevents dowel pulling-out from a sleeper. Sleepers with dowels made by ZAO Polimer have maximum stresses in the upper face of a sleeper coaxially with the dowel axis, which significantly increases the probability of dowel pulling-out in case of extreme loads.