Braking forces occurring during emergency brake applications of passenger trains are generated by disc brake units. The acting friction forces depend on the frictional properties between disc and brake pad and are influenced by relative velocity, temperatures and normal pressure of the contacting surfaces. In this work a mathematical model is developed which aims to link these influencing variables to the instantaneous acting friction coefficient in order to include the characteristic behavior of friction forces in the calculation of longitudinal dynamics of railway vehicles. The model is identified by the use of data recorded on a full-scale dynamometer test rig and verified regarding the estimation of the brake distance.
To achieve the climate protection targets despite the increasing transport demand, the shift from carbon-intensive to more environmentally friendly modes, such as rail, is indispensable in the field of freight transport. The Next Generation Train CARGO concept is intended to improve the competitiveness of rail freight, especially for lowdensity high value goods. However, the corresponding transshipment infrastructure has not yet been analyzed in detail. In this work, we introduce a Model-Based Systems Engineering approach for the closer analysis and specification of an intermodal freight terminal for this high-speed freight train concept. This includes the elaboration of the system idea and context, the most important stakeholders and their requirements as well as the identification of the essential system functions. The systematic approach reveals a broad diversity of stakeholders and points out the complexity of the procedures taking place at the terminal. The chosen approach applied in this work has proven to be promising for the holistic system analysis of an intermodal transport node
The rules and standards that define the requirements and methods for the layout of friction brake systems for railway vehicles still demand extensive experimental surveys since the general confidence in the theoretical predictability of the brake pad friction behaviour is limited. In fact, a review of numerous measurements from dynamometer test rigs exposes a large variation of the friction characteristics. Nevertheless, these measurements could be exploited to develop an elaborate friction modelling approach that includes deterministic and stochastic influences. The comparison of vehicle measurements from field tests with simulation results reveals that a significant improvement of the theoretical predictability of braking distances is within reach. Consequently, this applies as well for a more virtual layout and acceptance procedure for railway vehicle brake systems in the future.
The newly released commercial DLR RailwayDynamics Library is intended to support the design, optimization and control development as well as hardware-and software-inthe-loop testing of railway vehicles mainly on the system level. To this aim, it provides the capability to consider vehicle dynamics issues such as traction, comfort and safety in multi-domain engineering tasks by preparation of vehicle, track, wheel-rail contact models and roller rig scenarios on different levels of detail. Exploiting several precursor papers on specific railway modeling topics, their models have been collected and reorganized in order to propose a sound modeling framework dedicated to railway dynamics. The paper gives an overview on particular concepts and ideas of the library, presents several application examples and discusses two approaches to organize multi-domain modeling.
Since rail traffic is the mode of mass transport with minimal transportation-related greenhouse gas emissions, it plays a key role in achieving the sustainability targets of the transportation sector. To enable a modal shift from road to rail the German Aerospace Center has developed the Next Generation Train CARGO, a high-speed freight train concept targeted to ship so-called Low-Density High Value goods on existing railway infrastructure. Studies have revealed that an intermodal transshipment terminal is key to a successful integration of the concept in current logistics networks. Driven by high requirements regarding handling, reliability, and time, the terminal is a complex intralogistics system strongly depending on the particular good that shall be handled. This work uses the principles and methods of Model-Based Systems Engineering in a tailored modeling approach to specify a generic terminal system architecture. Based on this generic architecture an exemplary good-specific variant of the terminal is derived with focus on intralogistics freight handling. The chosen design approach is further evaluated regarding its suitability in context of intralogistics system design. The results of this work demonstrate that Model-Based Systems Engineering is capable of successfully guiding architecture specification in the novel application domain of complex intralogistics facilities and further contributes to a consistent and comprehensive terminal design.
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