Evaluation of Strain-Stress State of the Rails in the Production

Abstract

High values of residual stresses is one of the most common reason of breaking lots of metal constructions, including rails. These stresses can reach values of flow limit, especially in the area of faults. Estimation of residual stresses values allows to get information about technical condition of the rail and also allow to avoid abnormal situations So, the aim of the research is creating the model of stress-strain state of the rail, which was hardened in its top and bottom, and to compare modeling results with experimental measurements of stresses and discrepancy of the housing.For creating the model and making evaluations by finite element method we used a program COMSOL. Forces on the top and bottom of the rail cause tension stresses, forces on the web of the rail cause tensile stresses. We compared calculated values of stresses with discrepancy of the housing. The discrepancy of the housing is informative characteristic for estimating the residual stresses according to standards. For experimental measurements we used an acoustic structuroscope SEMA. This structuroscope uses the acoustoelastic phenomenon for measurements. We made measurements of the five rails.According to the calculation results of the model, critical discrepancy of the housing in 2 mm corresponded to the following values of maximum stresses: –54 MPa in the top of the rail, 86 MPa in the web and –62 MPa in the bottom of the rail. Experimental measurements are the following: from –48 MPa to – 64 MPa in the top of the rail, 54 MPa to 93 MPa in the web of the rail, and –59 MPA to –74 MPa in the bottom of the rail. Absolute error was ±5 MPa.Thus we created the model, which allowed to analyze strain-stress state and compare real values of stresses with discrepancy of the housing. Results of the modeling showed coincidence with structure of distribution of residual stresses in five probes of rails.

Measurement of Residual Stresses of Locomotive Wheel Treads During the Manufacturing Technological Cycle

“…The insufficiently high accuracy of techniques and the necessity of standard sample usage set bounds to their application. One of the approaches to solving problems of the stress-strain behavior and structure of metals is application of electromagnetic-acoustic (EMA) technique of ultrasound pulse excitation and registration [14,15,16,17,18,19,22,25]. Contactless EMA method of excitation-receipt does not require application of the contact liquid, thus giving the possibility to perform control procedures for rough and contaminated surfaces of objects, at high and low temperatures and for objects moving at high speeds.…”

Information and measuring complex for studying the influence of mechanical stresses in metal on the parameters of electromagnetic-acoustic transformation

“…[10], [11], Muravyova V.V. [13], [14] and their colleagues made it possible to create electromagnetic-acoustic devices -structuroscopes, mechanical stress meters, flaw detectors, thickness gauges, which are used to solve specific problems in real production conditions. But, despite the results achieved in the field of creating electromagnetic-acoustic means of non-destructive testing and diagnostics, we have to admit that in terms of their main technical and metrological characteristics they are inferior to similar indicators of traditional ultrasonic testing means with contact piezoelectric transducers.…”