Approach of Pavement Surface Layer Degradation Caused by Tire Contact Using Semi-Analytical Model

New methods of degradations on the pavement’s surface, such as top-down cracking and delamination, caused by the repeated passage of heavy vehicles led to questions about the impact of the contact between the tire and the pavement. In fact, to increase the service life of the structures, future road design methods must have a precise knowledge of the consequences of the contact parameters on the state of stress and deformation in the pavement. In this paper, tractive rolling contact under the effect of friction is modeled by Kalker’s theory using a semi-analytical method (SAM). A tire profile is performed thanks to a digitization by fringes or a photogrammetry technique. The effect of rolling on the main surface extension deformations is then highlighted to study top cracking. At the end of the SAM calculation, contact areas are closed to 200 μdef, exceeding the allowable micro-deformation limit for the initiation of cracking. In addition, results on the main strain directions also give information on the direction of cracking (initiation of longitudinal or transverse cracks). The cracking then becomes evident, leading to a reduced service life.

Determination of main requirements for reporting forms of complex for contactless catenary diagnostics

Catenary of the electrified railways is unprotected and therefore defenseless element of a traction power supply system. Samara State Transport University has developed a complex for contactless catenary diagnostics. The complex can be installed on special diagnostic rolling stock units and on regular units of tractive and non-tractive rolling stock. The paper determines main requirements to reporting forms of the complex for contactless catenary diagnostics, provides scheme of operation, presents the results of measurements gained during real trips and shows their assessment.

Assessment of possibility to use KS-400 high-speed catenary suspension for direct current traction systems with increased voltage

The paper considers the possibility to use KS-400 high-speed catenary suspension for direct current traction systems with increased voltage of 12, 18 and 24 kV. It also presents the temperature of catenary wires at tractive rolling stock passing with maximum possible current. It is established that the passage of a current collector under the worst conditions of heat release is insignificant for catenary wires even at a voltage of 12 kV. According to the results of calculations at voltage of 12 kV and 18 kV, the current collector is the limiting element in the standby and traction modes with maximum current.

Application of Selected Multiaxial High-Cycle Fatigue Criteria to Rolling Contact Problems

The risk of fatigue failure of elements working in rolling contact conditions (such as railway wheels, rolling bearings, etc.) is a significant issue with respect to safety and economy. In this case the complex and non-proportional stress state with pulsating three dimensional compression occurs. Therefore, the analysis of fatigue life of structures working in rolling contact conditions can be performed using recently proposed multiaxial high-cycle fatigue criteria. However, there is no hypothesis that could be universally accepted for calculations of fatigue strength. Furthermore, not all criteria proposed in literature for rolling contact fatigue (RCF) analysis can predict it. In the paper, the most popular criteria based on different theories are investigated in the application to RCF problem. Moreover, modification of the popular Dang Van hypothesis is proposed. The problem of free and tractive rolling contact fatigue is analysed on the example of a cylindrical crane wheel and spherical thrust roller bearing.

Incipient Slip Conditions in the Rolling Contact of Tyred Wheels

The contact problem of a driving tyred wheel, pressed and rolling over an elastically similar half-plane, is considered. Although applicable to a wide range of shrink-fitted assemblies, the simplified model is solved to study the practical case of an elastically similar steel tyre mounted on a locomotive steel wheel subjected to tractive rolling. The behaviour of the system at the tyre—substrate interface is studied using closed-form solutions to calculate the state of stress within the tyre. Conditions leading to incipient slip and/or plasticity are identified and mapped for different loads and geometries.