Abstract Summary
The railway track is subject to the spatial stresses imposed by the vehicle and to the stresses generated by the typical temperature ranges of the seasons, increased by the running away actions of the waters that undermine the roadbed below the rail. The imposed stresses are static and dynamic. The higher the speed of transit of the trainsets and the worse the dynamics of the vehicle, the higher the intensity of dynamic loads. The vehicle’s dynamic aggressiveness is measured primarily by the axle weight. Secondly, by the high rigidities of the primary suspension and the more or less high unsprung masses of the engines, bridges, brake discs, and bushings. The thermal stresses are measured by the temperature differences between those imposed by the seasons and those of laying the railway track. Static stresses, dynamic stresses on the rolling stock, and the stresses imposed by the seasons affect the roadbed. The work of undermining is favored by the action of water that increases the free length of inflection of the rails and varies the stiffness of the railway. These stresses cause stresses on the rail that can affect fatigue and wear and therefore line maintenance. Both parameters, due to fatigue and wear and tear, are related to average operating speeds and therefore to traffic intensity. As the speeds and intensities of traffic affect stress and fatigue cycles, the abrasive action of the wheels on the rail, and the misalignment of the complex rail sleepers concerning the underlying ballast, a comprehensive investigation of these phenomena affecting the work of the railway line is useful, to define the parameters that limit the life of the railway track. The railway track is represented by a beam resting of infinite length on an elastic ground such that at each point its reaction is proportional to the failure that the beam undergoes inflection. This hypothesis is verified experimentally because at each passage of an axis the sleepers sink into the roadbed and then rise as soon as the line is discharged. On the elasticity of the soil, there are experimental tests such as the remote transmission of sound waves and seismic waves. In the case of the railway track which is a beam resting on several points, the above considerations are valid with sufficient approximation, since the distance between the sleepers is small about the length of the rail inflection. The loads that cause high sagging close to the action and then decrease as the burdened point of the axis moves away. The wheelbase can be an influencing element. Where the wavelength interacts with a geometric dimension of the rolling stock, the concept of overlapping effects shall be used to determine the total stresses acting on the rail. The rail in addition to the vertical plane is stressed laterally in the curve for these considerations introducing the overall lateral stiffness of the railway track obtained experimentally. In the straight and in the curve, the railway track and the ground are stressed to torsion.
