•A lab test method to evaluate dynamic performances of track inspection wagons (TIWs) is proposed.•Dynamic performances of a new TIW are revealed through extensive measurements.•Safety of the new TIW ...under different rail misalignments and defects is validated.•The new TIW can withstand a certain degree of impacts due to track irregularities.
A new type of track inspection wagons (TIWs) for damage detection in urban rail transit systems is proposed to overcome the problems existing in traditional track inspection and ensure efficient and safe detection. Research on the dynamic testing and evaluation of TIWs is inadequate, which is not conducive to the design and improvement of similar products. Considering this, extensive dynamic performance tests and safety assessments under different running speeds were carried out on a new intelligent TIW. In this study, the rail misalignment and harmonic defects were designed to simulate the local irregularities in actual track lines. The accelerations of the axle-box, frames, vision modules, and wheel–rail forces were measured and analysed. Since the vision modules are the most critical components in the inspection system, the experiments focused on the evaluation of the safety of the visual module subjected to various track impacts. The experimental results indicate that the new intelligent TIW shows outstanding dynamic performance in the lab tests. Within the normal working range of the vision module, the vision modules of the wagon can withstand certain impacts from local rail local irregularities owing to its suspension design. Rail harmonic irregularity has a higher impact on wagon vibration than rail misalignment irregularity.
The rationalization of logistics activities and processes is very important in the business and efficiency of every company. In this respect, transportation as a subsystem of logistics, whether ...internal or external, is potentially a huge area for achieving significant savings. In this paper, the emphasis is placed upon the internal transport logistics of a paper manufacturing company. It is necessary to rationalize the movement of vehicles in the company’s internal transport, that is, for the majority of the transport to be transferred to rail transport, because the company already has an industrial track installed in its premises. To do this, it is necessary to purchase at least two used wagons. The problem is formulated as a multi-criteria decision model with eight criteria and eight alternatives. The paper presents a new approach based on a combination of the Simple Additive Weighting (SAW) method and rough numbers, which is used for ranking the potential solutions and selecting the most suitable one. The rough Best–Worst Method (BWM) was used to determine the weight values of the criteria. The results obtained using a combination of these two methods in their rough form were verified by means of a sensitivity analysis consisting of a change in the weight criteria and comparison with the following methods in their conventional and rough forms: the Analytic Hierarchy Process (AHP), Technique for Ordering Preference by Similarity to Ideal Solution (TOPSIS) and MultiAttributive Border Approximation area Comparison (MABAC). The results show very high stability of the model and ranks that are the same or similar in different scenarios.
The research is concerned with the use of double walls filled with aluminium foam for an open wagon in order to decrease the dynamic stresses during the operational modes. The research presents the ...strength calculation for the bearing structure of an open wagon with consideration of the engineering solutions proposed. It was found that the maximum equivalent stresses appeared in the bottom section of the centre sill behind the back support; they amounted to about 315 MPa and did not exceed the allowable values. The maximum displacements were detected in the middle section of the centre sill and amounted to 9.6 mm. The maximum deformations were 1.17 × 10−2. The research also presents the strength calculation for a weld joint in the maximum loaded zones of the bearing structure of an open wagon and gives the results of a modal analysis of the bearing structure of the improved open wagon. It was found that the critical oscillation frequencies did not exceed the allowable values. The results of the research may be useful for those who are concerned about designing innovative rolling stock units and improving the operational efficiency of railway transport.
This paper presents an analysis of loaded freight wagon dynamics in curve alignments. We investigate the effects of the combined centre of gravity (CCOG) on the running safety of freight wagons and ...examine proper position of the CCOG. A simple wagon-rail model is implemented using the multibody dynamics software ADAMS/Rail. The simulation model is operated on curve tracks with various radii and velocities and the curving performances are evaluated. The results indicate that the CCOG can be located within a flexible and accurate range. The longitudinal offset is good for the curving performance and the permissible lateral offset should be assessed based on the curve radius and cant deficiency.
Due to super elevation and centrifugal force, close attention is needed to lateral stability of cargo when the train negotiates curves. To guarantee the security of cargo on wagons, proper blocking, ...bracing and lashing are essential. In this study, we implement a cargo-wagon-rail coupling model that adopts diagonal lashing to restrain cargo movement. A preliminary dynamic simulation analysis demonstrates that the selected cargo tilts when the wagon negotiates curves. The quasi-static analysis reveals the cargo force condition and the key role of lashing stiffness. Coupling models are endowed with various lashing stiffness values. The curving performance of each model is evaluated considering different running conditions. The results indicate that increasing lashing stiffness reduces lateral cargo vibration and increases lashing tension force until the stable state. The cargo movement in this study is proved to have no significant effect on the wheel-rail interaction. Based on simulation results, this paper determines the diagonal lashing. It is demonstrated that the use of dynamic simulation to calculate the diagonal lashing force will improve cargo stability and avoid unnecessary expenditure on load restraint assemblies. Finally, it is proved that the promotion of pre-tension force is not necessary for diagonal lashings.
A special case study of a rail transport consist comprised of 11 wagons on three-piece bogies was carried out using advanced multi-body vehicle simulations to evaluate if the safety and stability of ...the wagons would be compromised by loading 39 continuous welded rails on the wagon decks. Each rail was 139 m long and laterally fastened to the wagon decks. The wagon model components, including a car body, two bolsters, 4 sideframes and 4 wheelsets, were connected by non-linear spring and damping elements. A non-linear coupler was used to connect the adjacent wagon models. A twist simulation for a single wagon model was conducted and the results were compared with experimental data for validation. The lateral stability analysis found that the lowest critical hunting speed was 90 km/h for the empty wagon model, which satisfies the current operational speed range from 0 to 70 km/h. Safety simulations were conducted on the curved track geometry modelled from the actual track alignment and included FRA Class 4 track irregularities. The safety simulation results indicated that the 11-wagon consist performed within the maximum safety criteria limits as stipulated in the AS7509:2017 standard.
In this correspondence, useful measurement results of the propagation channel characteristics in an intra-wagon environment at millimeter wave (mmWave) frequencies are presented. The measurements ...were collected inside an underground convoy from 25 to 40 GHz in the frequency domain. A broadband radio over fiber (RoF) link was used in order to avoid the high losses introduced by cables at these frequencies, thus allowing long distances between the transmitter and receiver antennas. Values of the path loss exponent and delay spread are reported at the potential 26, 28 and 38 GHz bands to deploy the future fifth-generation (5G) systems. These results allow us to have a better knowledge of the path loss and time dispersion characteristics of the propagation channel in this particular environment, characterized by rich-scattering with long delays.
A multibody dynamic model of railway wagon is established by Simpack software, and the derailment coefficient, wheel load reduction rate, impact angle and wear index of freight car are calculated ...under different gravity center offsets and different curve conditions. The simulation results show that the lateral and longitudinal offsets of cargo gravity center have a great influence on the derailment coefficient, wheel unloading rate, impact angle and wear index of the vehicle. The larger the offset of the cargo gravity center is, the worse the operation performance of the wagon is, the more serious the wheel-rail wear is, and the shorter the transport life of the wagon is. The smaller the radius of the curve is, the greater the impact is.
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