The paper investigates the heat-affected zone (HAZ) of several rail joints executed by thermite rail welding (TW). The examined rail profile was 54E1 (UIC54). The rail steel categories were different: R260 and R400HT. The welding portions of the TWs fitted R350HT and R260 rail categories with normal welding gaps. The rail pieces were brand new, i.e., without any usage in the railway track. The authors executed Vickers-hardness tests (HV10) and material texture tests on the running surface of the rail head, as well as on slices cut from the rail head. The cutting was performed by the water jet method, five longitudinal direction slices with vertical cutting lines. The considered specimen lengths were 2×70 mm (i.e., 70 mm from the mid-point of the rail joint), however, the depths were 20 mm from the running surface. Therefore, the measuring spaces were 5 mm lengthwise and 2 mm in depth. The variation of the hardness values was determined considering the microstructures of the base steel material and the TW. For comparison, previously measured Elektrothermit SoW-5 and earlier own research were taken into consideration.

The deterioration of the sleeper support on the ballasted track begins with the accumulation of sleeper voids. The increased dynamic loading in the voided zone and the ballast contact conditions cause the accelerated growth of the settlements in the voided zones, which results in the appearance of local instabilities like ballast breakdown, white spots, subgrade defects, etc. The recent detection and quantification of the sleeper voids with track-side and onboard monitoring can help to avoid or delay the development of local instabilities. The present paper is devoted to the study of the dynamic behavior of railway track with sleeper voids in the ballast breakdown zone. The result of the experimental track-side measurements of rail acceleration and deflection is presented. The analysis shows the existence of the dynamic impact during wheel entry in the voided zone. However, the measured dynamic impact is subjected to the bias of the track-side measurement method. Both the mechanism of the impact and the measurement aspects are explained by using the one-beam model on viscoelastic foundation. The void features in the dynamic behavior are analyzed for the purpose of track-side and onboard monitoring. A practical method of the void parameter quantification is proposed.

The ballasted track superstructure is characterized by a relative quick deterioration of track geometry due to ballast settlements and the accumulation of sleeper voids. The track zones with the sleeper voids differ from the geometrical irregularities with increased dynamic loading, high vibration, and unfavorable ballast-bed and sleeper contact conditions. This causes the accelerated growth of the inhomogeneous settlements, resulting in maintenance-expensive local instabilities that influence transportation reliability and availability. The recent identification and evaluation of the sleeper support conditions using track-side and on-board monitoring methods can help planning prevention activities to avoid or delay the development of local instabilities such as ballast breakdown, white spots, subgrade defects, etc. The paper presents theoretical and experimental studies that are directed at the development of the methods for sleeper support identification. The distinctive features of the dynamic behavior in the void zone compared to the equivalent geometrical irregularity are identified by numeric simulation using a three-beam dynamic model, taking into account superstructure and rolling stock dynamic interaction. The spectral features in time domain in scalograms and scattergrams are analyzed. Additionally, the theoretical research enabled to determine the similarities and differences of the dynamic interaction from the viewpoint of track-side and on-board measurements. The method of experimental investigation is presented by multipoint track-side measurements of rail-dynamic displacements using high-speed video records and digital imaging correlation (DIC) methods. The method is used to collect the statistical information from different-extent voided zones and the corresponding reference zones without voids. The applied machine learning methods enable the exact recent void identification using the wavelet scattering feature extraction from track-side measurements. A case study of the method application for an on-board measurement shows the moderate results of the recent void identification as well as the potential ways of its improvement.

Unsupported sleepers or void zones in ballasted tracks are one of the most recent and frequent track failures. The void failures have the property of intensive development that, without timely maintenance measures, can cause the appearance of cost-expensive local instabilities such as subgrade damages. The reason for the intensive void development lies in the mechanics of the sleeper and ballast bed interaction. The particularity of the interaction is a dynamic impact that occurs due to void closure. Additionally, void zones cause inhomogeneous ballast pressure distribution between the void zone and fully supported neighbour zones. The present paper is devoted to studying the mechanism of the sleeper–ballast dynamic impact in the void zone. The results of experimental in situ measurements of rail deflections showed the significant impact accelerations in the zone even for lightweight slow vehicles. A simple three-beam numerical model of track and rolling stock interaction has shown dynamic interaction similar to the experimental measurements. Moreover, the model shows that the sleeper accelerations are more than 3 times higher than the corresponding wheel accelerations and the impact point appears before the wheel enters the impact point. The analysis of ballast loadings shows the specific impact behaviour in combination with the quasistatic part that is different for void and neighbour zones, which are characterised by high ballast pre-stressed conditions. The analysis of void size influence demonstrates that the maximal impact loadings and maximal wheel and sleeper accelerations appear at a certain void depth, after which the values decrease. The ballast quasistatic loading analysis indicates an increase of more than 2 times in the ballast loading in neighbour zones for long voids and almost full quasistatic unloading for short-length voids. However, the used imitation model cannot explain the nature of the dynamic impact. The mechanism of the void impact is clearly explained by the analytic solution using a simple clamped beam. A simplified analytical expression of the void impact velocity shows that it is linearly related to the wheel speed and loading. The comparison to the numerically simulated impact velocities shows a good agreement and the existence of the void depth with the maximal impact. An estimation of the long-term influences for the cases of normal sleeper loading, high ballast pre-stress and quasistatic loading in the neighbour zones and high impact inside the void is performed.

This paper investigates the usability of touch screens used in mass production road vehicles. Our goal is to provide a detailed comparison of conventional physical buttons and capacitive touch screens taking the human factor into account. The pilot test focuses on a specific Non-driving Related Task (NDRT): the control of the on-board climate system using a touch screen panel versus rotating knobs and push buttons. Psychological parameters, functionality, usability and, the ergonomics of In-Vehicle Information Systems (IVIS) were evaluated using a specific questionnaire, a system usability scale (SUS), workload assessment (NASA-TLX), and a physiological sensor system. The measurements are based on a wearable eye-tracker that provides fixation points of the driver’s gaze in order to detect distraction. The closed road used for the naturalistic driving study was provided by the ZalaZONE Test Track, Zalaegerszeg, Hungary. Objective and subjective results of the pilot study indicate that the control of touch screen panels causes higher visual, manual, and cognitive distraction than the use of physical buttons. The statistical analysis demonstrated that conventional techniques need to be complemented in order to better represent human behavior differences.

The main objective of this research is to identify optimal printing strategies and PLA (polylactic acid) filament materials to produce rapid prototype deep drawing tools. Additive 3D printing technologies have been applied for a long time to produce tools, but the research is unique in that it uses conventional and various reinforced PLA materials with conventional FDM (Fused Deposition Modeling) printers. The advantage of this method is that PLA is easy to print and recycle and does not require expensive or special printers, this also gives the article its novelty. A further aim was to produce the tools using commercially available low-end printers. DX53D 0.8 mm thick body steel and AlMg3 2.5 mm thick sheet were the materials to be molded for the tests. The test tool was an Erichsen deep drawing punch. Tool wear was tested using the GOM ATOS measuring system, an optical coordinate measuring machine based on the DIC (Digital Image Correlation) principle, which is also popular in the automotive industry. The study aims to determine the 3D printing and material parameters that can safely produce a minimum batch of 100 parts.