Simulation of Energy Absorption Performance of the Couplers in Urban Railway Vehicles during a Heavy Collision

Railway vehicles are generally operated by connecting several vehicles in a row. Mechanisms connecting railway vehicles must also absorb front and rear shock loads that occur during a train’s operation. To minimize damage, rail car couplers are equipped with a buffer system that absorbs the impact of energy. It is difficult to perform a crash test and evaluate performance by applying a buffer to an actual railway vehicle. In this study, a simulation technique using a mathematical buffer model was introduced to overcome these difficulties. For this, a model of each element of the buffer was built based on the experimental data for each element of the coupling buffer system and a collision simulation program was developed. The buffering characteristics of a 10-car train colliding at 25 km/h were analyzed using a developed simulator. The results of the heavy collision simulation showed that the rubber buffer was directly connected to the hydraulic shock absorber in a solid contact state, and displacement of the hydraulic buffer hardly occurred despite the increase in reaction force due to the high impact speed. Since the impact force is concentrated on the vehicle to which the collision is applied, it may be appropriate to apply a deformation tube with different characteristics depending on the vehicle location.

Analysis of Damping Characteristics of a Hydraulic Shock Absorber

In the present study, a hydraulic shock absorber is proposed. Since the damper is mainly used in suspension energy recovery system, the damping characteristics of the damper under no-load state are studied in this paper. Structural design is conducted so that the unidirectional flow of the oil drives the hydraulic motor to generate electricity. Meanwhile, an asymmetrical extension/compression damping force is obtained. A mathematical model of the shock absorber is established, and the main characteristics of the inherent damping force are obtained. Based on the established model, effects of the accumulator volume, accumulator preinflation pressure, hydraulic motor displacement, check valve inner diameter, and spring stiffness, hydraulic line length and inner diameter on the indicator characteristics are analyzed. Moreover, a series of experiments are conducted on the designed damper to evaluate the characteristics of the inherent damping force and analyze the effect of the accumulator volume and preinflation pressure on the damping characteristics.

Numerical substantiation of the parameters of the air-hydraulic hood by a diaphragm

The article is about calculating the main parameters of air - hydraulic hoods with a diaphragm to reduce the emergency consequences of a water hammer, possible in the pressure pipelines of an irrigation pumping station. Based on the results of numerical studies by the method of finite differences of the proposed hydraulic shock absorber, dependencies were obtained based on a certain air in the absorbers, the total capacity of the cylindrical cap was determined to determine the main dimensions of the absorbers. Based on the results of numerical studies by the method of finite differences of the proposed hydraulic shock absorber, dependencies were obtained based on a certain air in the absorbers, the total capacity of the cylindrical cap was determined to determine the main dimensions of the absorbers. To determine the economic dimensions of the proposed cap design, comparative calculations of numerical experiments with experimental data prove the reliability of the proposed dependencies using the finite difference method.

Application of the Signal Change Tracking Algorithm in the Hydraulic Shock Absorber Monitoring System

During nuclear power plant (NPP) operation, the reactor plant main equipment can show displacements when subjected to the effect of various external and internal loads. These displacements are mainly caused by thermal expansion of the metal and seismic loads. To cope with these phenomena, the reactor plant components that are most susceptible to these types of loads are fastened with hydraulic shock absorbers (HSAs) to limit their displacements under the effect of seismic or accident dynamic loads, as well as to ensure thermal displacements in increasing or decreasing the power unit output. For monitoring the HSA operation and indirectly monitoring the displacements of the reactor plant equipment items fastened with hydraulic shock absorbers, the dedicated hydraulic shock absorber monitoring system (HSAMS) is used, which is equipped with linear displacement sensors installed directly on the HSAs. If the displacements go beyond the predetermined limits, the HSAMs algorithms produce an appropriate alarm. The information from the HSAMS is also used by the automated residual lifetime monitoring system (ARLMS) to calculate the steam generator connection pipe displacement criteria parameters. However, during the operation of a number of NPP power units, a problem associated with numerous failures of the HSAMS linear displacement sensors has been faced. These failures manifested themselves in that the sensor signals went beyond the valid range or frozen under the effect of external influencing factors. As a result, the HSAMS and ARLMS operation was complicated by a large number of unreliable measurements and the functions of these systems were not performed in a proper way. To solve this problem, it has been proposed to use an algorithm for tracking signal changes, which can improve the credibility of HSAMS indications by determining unreliable data in the online mode and by performing statistical processing of the already available array of indications.