Braking dynamics plays an essential role in ensuring the comfort and running safety of trains. Due to the complexity of the phenomena involved and the presence of dry friction, studies have been carried out by numerical methods using smoothening. Based on the non-smooth dynamics framework, in the present paper, an efficient and comprehensive alternative model is defined. Set-valued friction of Coulomb's law type is accounted for and motion equations are formulated as a differential inclusion. Some of the fundamental issues of contact dynamics are briefly reviewed. Static friction forces which arise in buffers are computed in a very intuitive and efficient manner, using an original method involving generalised inverses of matrices. The corresponding algorithm is described. Numerical integration is done by an event-driven algorithm. Indeterminate system configurations can be appropriately handled. The number of vehicles on which tests have been carried out ranged from 5 to 50. Comparison with the smoothening method reveals significant differences. Computational efficiency is dramatically improved. Computation speed can rise by a few orders of magnitude. Specific phenomena such as stick–slip or persistent longitudinal forces can be evidenced. Computed values of the system states differ substantially. In addition to this, any wagon connection model can be embedded.

The pneumatic elastic elements are widely used in the secondary suspension of modern railway vehicles due to their important advantages compared to the conventional ones. In the present paper, the modelling and analysis of the pneumatic suspension is approached, taking into account the main elements, pneumatic enclosures and rubber elements. The analysis performed investigates the influence of relevant parameters on suspension stiffness and on its dynamic response.

A solar driven cooling system consisting of a single effect H₂O-LiBr absorbtion cooling module (ACS), a parabolic trough collector (PTC), and a storage tank (ST) module is analyzed during one full day operation. The pressurized water is used to transfer heat from PTC to ST and to feed the ACS desorber. The system is constrained to operate at the maximum ACS exergetic efficiency, under a time dependent cooling load computed on 15 July for a one storey house located near Bucharest, Romania. To set up the solar assembly, two commercial PTCs were selected, namely PT1-IST and PTC 1800 Solitem, and a single unit ST was initially considered. The mathematical model, relying on the energy balance equations, was coded under Engineering Equation Solver (EES) environment. The solar data were obtained from the Meteonorm database. The numerical simulations proved that the system cannot cover the imposed cooling load all day long, due to the large variation of water temperature inside the ST. By splitting the ST into two units, the results revealed that the PT1-IST collector only drives the ACS between 9 am and 4:30 pm, while the PTC 1800 one covers the entire cooling period (9 am–6 pm) for optimum ST capacities of 90 kg/90 kg and 90 kg/140 kg, respectively.

In the present paper is investigated the influence of wheel flat on wheel-rail dynamic interaction, considering various parameters of the vehicle, track and wheel defect. The analysis shows that wheel-rail dynamic forces have very large magnitudes, even for low speeds. Over a certain speed, the maximum wheel-rail force is increasing with the vehicle speed. In the lower speed domain, it was noticed a maximum, depending on the flat length, corresponding to the natural frequency of the system. It is found that wheel-rail interaction maximum forces are higher for flats with larger ratio a/L. The maximum dynamic forces are also influenced by the track parameters especially by track stiffness while among the vehicle parameters only the wheelset mass have a perceivable influence.

The aim of this paper is to analyze the reliability of freight wagon wheelset on the basis on real field data, observed and collected in actual operations of freight wagons. The failure modes and their associated occurrence absolute frequencies are identified and a Pareto analysis is carried out.The Weibull probability distribution is used to determine the reliability mathematical model for railway wheelset. The probability law is linearized, allowing the use of linear regression to estimate, on the basis of empirical data, the˰̸̵̱̓̀˰̵̵̱̱̀͂̽̈́͂˰ڂ˰̴̱̾˰̸̵̈́˰̵̳̱̼̓˰̵̵̱̱̀͂̽̈́͂˰ڇ of Weibull distribution. The estimated reliability model is close to an exponential one, assuming a failure rate almost constant.The estimated reliability probabilistic model i̓˰̴̵̴̱̼̹̱͆̈́˰̲͉˰̵̶̷̹̀͂̿͂̽̾˰̱˰ڗ² test to verify that the estimated theoretical reliability mathematical model fits the the empirical distribution.