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Organisationseinheit der BAM
Eingeladener Vortrag
- nein (34)
A methodology is proposed for the experimental analysis of the liquid cargo effect under combined orthogonal accelerations. To simultaneously subject the vehicle-cargo system to longitudinal and lateral accelerations, the vehicle is set obliquely on a tilt table. The experimental outputs suggest that there is a significant effect of the liquid cargo on the lateral load transfer ratio (LTR), on the order of 20%, which is attributable to the resulting shifting of the liquid cargo’s centre of gravity. That is, the peak LTR values due exclusively to sloshing were not significant, in such a way that the liquid cargo would only pose a safety risk under a steady acceleration input.
Also, the inverse of the product of the magnitude of the acceleration times the free surface length, correlates with the liquid cargo effect. That is, the magnitude of the input acceleration is not fully determinant for greater load transfers.
This paper presents a method for processing acceleration data registered on a train and determining the health condition of a subway’s substructure. The acceleration data was converted into a dynamic deformation by applying a transfer function defined using the Empirical Mode Decomposition Method.
The transfer function was constructed using data produced on an experimental rig, and it was scaled to an existing subway system. The equivalent deformation improved the analysis of the dynamic loads that affect the substructure of the subway tracks because it is considered the primary load that acts on the track and substructure. The acceleration data and the estimated deformations were analyzed with the Continues Wavelet Transform. The equivalent deformation data facilitated the application of a health monitoring system and simplified the development of predictive maintenance programs for the subway or railroad operators. This method better identified cracks in the substructure than using the acceleration data.
Die Vorhersage der Beanspruchung bei plastischem Versagen von zylindrischen Druckbehältern wird häufig mittels Finite Elemente Berechnungen durchgeführt. Die Berechnung der zulässigen Beanspruchung erfordert ein elastisch-plastisches Werkstoffmodell und die Berücksichtigung von nichtlinearen geometrischen Effekten. Das plastische Versagen verursacht eine gesamte Strukturinstabilität und kann nicht direkt aus der Finite Elemente Analyse bestimmt werden. In dem vorliegenden Beitrag wird die Beanspruchung für plastisches Versagen eines zylindrischen Druckbehälters mittels eines analytischen Verfahrens basierend auf einem linear elastischen ideal-plastischen Materialmodell bestimmt. Wenn Plastizität auftritt, wird zum einen der Werkstoff als inkompressibel und zum anderen der Tensor der plastischen Dehnungen als parallel zum Spannungsabweichungstensor angenommen. In diesem Fall kann die Spannungs-Dehnungs-Beziehung von Henkel angewendet werden, um den Druck zu berechnen, bei dem plastisches Fließen und Versagen eintritt. Die analytischen Ergebnisse werden von den Finite Elemente Berechnungen vollkommen bestätigt.
Nondestructive Testing (NDT) and fracture mechanics are two different disciplines in applied engineering science. Both areas are very important for the evaluation of the component integrity. Unfortunately the technical understanding in both disciplines is not identically, what lead to misunderstandings. In the present paper, the basic ideas about fracture mechanics and the input parameters coming from the NDT side are explained, concerning the integrity evaluation of the components. The widely used NDT methods are magnetic particle, dye penetrant, electrical eddy currents, radiography and ultrasonics. But not all of these common NDT methods can deliver parameters satisfy the fracture mechanics requirements. The first two can detect only surface-breaking or immediately sub-surface defects. Eddy current can also find defects in deeper sub-surface layers, while radiography and ultrasonics can also find embedded, remote defects. These three methods have furthermore a high potential for defect sizing and are therefore predestined to provide fracture mechanics input parameters. At the example of steam generator tube inspection the interplay of eddy current and fracture mechanics as related to tube integrity will be explained.
Pressure Vessel Fire Test
(2014)
Ermittlung explosionsfähiger Gemische beim Gefahrguttransport unter normalen Beförderungsbedingungen
(2009)
Für die Bewertung der Integrität von Tanks ist die detaillierte Kenntnis der belastungsrelevanten Parameter unabdingbar. Die Wärmeübergangszahl a ist eine derartige Größe. Die Wärmeübergangszahl bestimmt direkt die Größe der vorhandenen Beanspruchungen im Tank. Insofern sollte die Wärmeübergangszahl bekannt sein. Aus diesem Grund wurden experimentelle Untersuchungen durchgeführt. Für einen sich im Feuer befindlichen Tank ergibt sich die Wärmeübergangszahl zu 50 W/m2K. Auf dieser Basis konnten die bereits durchgeführten experimentellen Untersuchungen mithilfe der Methode der finiten Elemente nachgerechnet werden. Die dabei erzielten Ergebnisse sind infolge der getroffenen modelltechnischen sowie thermodynamischen Vereinfachungen als zufriedenstellend zu bezeichnen. In einem nächsten Schritt wird an einer verbesserten Modellierung sowie thermodynamischen Beschreibung der Verhältnisse im Tank gearbeitet.
In einem von der BAM Bundesanstalt für Materialforschung und -prüfung durchgeführten Forschungsvorhaben wurde untersucht, inwieweit bei Gefahrguttanks im Brandfall ein 'BLEVE', d. h. ein Versagen der Umschließung mit anschließender Freisetzung der Flüssigkeit bzw. des verflüssigten Gases, verzögert bzw. verhindert werden kann.
Pressurisation of full-containment pressure vessels in fire is known to be driven by thermal stratification. The predominant mode of heat transfer to the contents (convection from the shell to the liquid phase) results in formation of „hot“ boundary layers. Sub-cooled boiling may also be present. The warm layer rises to the surface through buoyancy and bubble flow, increasing the surface of the liquid above that of the bulk temperature, and hence driving a pressure rise.
For reliable prediction of the complex effects governing vessel pressurization a three-dimensional numerical model is required. Work is being undertaken on such a model by other institutions in cooperation with this project.
A new tank design for Hazmat
(2016)
Initial studies have shown pre-deformed honeycomb structure
pressure vessels to have comparable burst pressure to straight steel vessels.
It was shown that honeycomp structured tanks have a higher energy absorption than straight steel tanks.
Future studies will investigate optimization of the deformed plate, to determine if increased payloads or a reduced wall thickness can be achieved.
The outputs from a simplified mathematical designed to simulate the liquid cargo-vehicle interaction during an emergency braking maneuver, have been compared with full scale data regarding the sloshing pressure on one of the vehicle chambers. While the specific dimensions and fill level of the fluid within the chamber in the full scale testing, have been considered for the simulation model, the vehicle has been simplified to a straight truck instead of an articulated truck. Nevertheless, the pressure within the chamber is realistically modelled, concerning the maximum and minimum pressures attained, with differences lower than 10% between the simulation and the experimental data. Consequently, these results suggest that the articulation pertaining to the articulated vehicle, does not affect in a significant manner the maximum and minimum values of the pressure within the chamber. A nonlinear model for the suspension, however, could improve the model performance. On the other hand, simulation results suggest that the effect of sloshing could cause a loss of braking efficiency on the order of 7%, when such performance is measured in terms of the stopping time.
Simplified cargo-vehicle interaction: linear pendulum, rigid multibody linear dynamics, straight, instead of articulated vehicle.
Realistic results about the pressure developed on the sensor, with differences lower than 10% between the simulation and the experimental data.
Sloshing could affect the braking efficiency in 7%, approximately, corresponds with other sources.
The arrangement of the measuring sensors allowed the
capture of air flow induced temperatures and material
temperatures on various points of the cylinder body. Four
significant temperature levels could be observed: Inside the cylinder (far from the wall, close to the wall), inside the aluminium liner and outer surface. Figure 5 shows the temperature distribution after a regular filling process with a filling time of ten minutes. The temperature sensors T1 - T9 are marked with different colors. The corresponding measurement points are shown in Figure 4. Due to the high thermal conductivity of the aluminum liner the induced temperature peaks are quickly derived. A flow-induced exceeding of the maximum approval temperature is not expected. Regarding the safety assessement the results show that the pressure and temperature profilesmustbe taken into account.
The US Department of Transportation, Federal Railroad Administration (FRA) current regulations for rail tank cars in the United States stipulate that, for certain hazardous materials, tank cars shall have a thermal protection system capable of preventing rupture of the tank for 100 minutes when exposed to an engulfing fire with a blackbody equivalent flame temperature of 871 °C (+/- 56°C), and that tanks shall have a pressure relief device set at an appropriate level (depending on the type of tank car and contents). Pressure relief devices are a source of non-accident releases, and hence may cause serious incidents when tanks are transporting hazardous materials. Industry in North America would therefore benefit from removal of pressure relief devices on tanks transporting certain hazardous materials. Such an approach is known as full Containment, and is standard practice in Europe. In 2014 the FRA commissioned an experimental study to investigate the ability of a specific design of rail tank to resist rupture without incorporating a pressure release valve. As a precursor to tests on tanks there was a need to develop and characterise a simulated pool fire capable of reliably exposing large-scale tanks to repeatable, uniform conditions. This paper describes such a fire test setup, developed using a burner array system fuelled by liquid propane and designed to produce luminous, low velocity flames representative of those found in large hydrocarbon pool fires. The experimental set-up is described, along with the Instrumentation (directional flame thermometers, infra-red camera, and thermally massive calorimeter) and methodology used to characterise the fire. Comparisons are made against previous fire tests on vessels to assess the suitability of the experimental set-up for future vessel testing.
Limit load analysis is a well known method to calculate the allowable design pressure of container components. A limit load of a pressurized container is achieved, when the stress of a wall and the flow stress are equal. In the following paper the transferability of limit load analysis from small scale tank containers up to large scale containers (railway tank) are investigated. Finite element calculations are carried out and compared with experimental results. It can be concluded that the limit load analysis works very well. Furthermore, the yield strength of the material should be used as flow stress.
The prediction of the plastic collapse load of cylindrical pressure vessels is very often made by using expensive Finite Element Computations. The calculation of the collapse load requires an elastic-plastic material model and the consideration of non-linear geometry effects. The plastic collapse load causes overalls structural instability and cannot be determined directly from a finite element analysis. The ASME (2007) code recommends that the collapse load should be the load for which the numerical solution does not converge. This load can be only determined approximately if a expensive nonlinear analysis consisting of a very large number of sub steps is done. The last load sub step leading to a convergent solution will be taken as the critical load for the structure. In the instability regime no standard finite element solution can be found because of the lack of convergence of the numerical procedure. Other methods for the calculation of the allowable pressure proposed by the ASME code are the elastic stress analysis and the limit load analysis. In the present paper the plastic collapse load for a cylindrical pressure vessel is determined by an analytical method based on a linear elastic perfectly plastic material model. When plasticity occurs the material is considered as incompressible and the tensor of plastic strains is parallel to the stress deviator tensor. In that case the finite stress-strain relationships of Henkel can be used for calculating the pressure for which plastic flow occurs at the inside of the vessel wall or in the case of full plasticity in the wall. The analytical results are fully confirmed by finite element predictions both for axisymmetric and high costs three dimensional models. The analytical model can be used for fast predictions of the allowable load for the design of a large variety of pressure vessels under safety considerations. The accuracy of the predicted collapse load largely depends on the quality of the temperature dependent wall material data used both in the analytical and numerical calculations.
The vessel wall response shows a good agreement between the numerical predictions of and experimental data using the limit load approach. Further work is continuing to understand the thermohydraulic response and the boundary conditions for material modelling. As shown in figure 2 there was one BLEVE of a bare tank containing a PRV, highlighting the risk of serious consequences if models are inaccurate. The behavior of partly coated tanks were similar to the bare tank.
Parameter study for CFD in the bottle – grid resolution plays an important role on the temperature at the specific positions, 2D axi-symetrical calculation is a sufficient solution strategy in regards to the examined particular Problem. The intensity of filling process can be controlled by pressure “User defined function” provided by experiments. Numerical simulation demonstrated feasibility to predict temperature progress during the filling process successfully validated by experiments. The turbulent model k-w SST is the best strategy for the turbulent property calculations. The most intensive turbulent kinetic energy appeared in the middle region of the pressure bottle, the impact of the eddy viscosity on the wall was mostly in the wall region.
Die BAM – Bundesanstalt für Materialforschung und -prüfung führt schon seit vielen Jahren auf zwei Brand- prüfständen Brandprüfungen z.B. an Transport- und Lagerbehältern für radioaktive Stoffe oder zur Prüfung von Brandschutzbeschichtungen durch. Als Brandmedium wird auf diesen Prüfständen Flüssiggas (Propan- Butan-Gemisch C) eingesetzt, mit dem die Prüfobjekte simulierten Unfallfeuern ausgesetzt werden. Mit dem neuen Jetfire – Prüfstand der BAM können seit Anfang 2018 diverse Belastungsszenarien nach den Anforde- rungen der ISO22899-1:2007 [1] simuliert werden.
A testing rig for the measurement of the dynamic loads on the rails due to cargo sloshing,has been proposedin this paper. The system represents a scale-down approach that simulates astraightening maneuver of the railway car after negotiating a turn. As part of the experimental effort, a mathematical model was developed that, oncevalidated, will provide more insights about the potential effect of many other cardesign factors, on the level of stress developed in the raildue to the sloshing cargo.A fundamental output from the testing, will be the objective comparison between the railloads due toa sloshing and a non-sloshing cargo, together with a validated model that wouldallow parametric studies in relation withthe potential effect,of several track and carproperties,on the magnitude of the sloshing forces on the rail.
Wasserdruckprüfung kann entfallen: Schutzziel definieren, Qualitätssichernde Maßnahmen während der Herstellung, Nachweise der vorhandenen Qualität muss stetig erfolgen mittels: Betriebsüberwachung, zfP Bewertung des Standes der Technik: Zustandsorientierte Instandhaltung/Inspektion, Reduzierung von Ausfallzeiten durch optimierten Betrieb
Effective assessment and management of railway infrastructure for competitiveness and sustainability
(2018)
In this chapter the challenges facing railways have been illustrated through the description of two important events occurring in different geographical areas. While the explosion in Quebec, Canada, points out the importance of taking away the transportation infrastructure from highly populated areas; the disruption of the European railway network in Rastatt, Germany, describes the importance of designing alternative routes to critical railway segments, together with the need to have contingency plans to face extraordinary situations regarding the connectivity in a given transport network.
Future research efforts are recognized in relation with the railway car – track interaction, as the dynamic loads derived from such interaction could be reducing the life of such infrastructure. It is particularly important for infrastructures dedicated to the transportation of liquid hazardous substances.
Wheel forces generate stresses in the rail as a function of several vehicle and infrastructure characteristics and operating conditions. The different components of the wheel forces develop strains in the rail which contain an elastic and hysteretic (irreversible) components. The irreversible deformations of the rail would be associated with locomotive energy losses. In this paper, a testing facility is proposed to indirectly characterize the level of stresses in the rail, in terms of the energy that is lost during tuming maneuvers. Different potentially influential factors are considered, including the friction at the Center plate, the wheelbase length, the distance between bogies and the radius of the curved track. The change
in the potential energy during a U-turn displacement is measured. In this respect, an experimental model under this operating principle, aimed at validating such a principle of Operation, reveals a significant effect of the friction at the center plate on the energy lost during turning maneuvers, and consequently, on the level of stresses in the rail.
Exposure of pressure vessels to fire can result in catastrophic explosion and escalation of accidents. The safe transportation of cargo in pressure vessels therefore requires knowledge of what will happen to the cargo in the event of a vehicle derailment or rollover resulting in fire exposure. The chapter presents an overview of selected testing and modelling work undertaken to understand the thermohydraulic processes within a vessel that drive pressurization during fire. A series of experiments highlighting the importance of adequate design and selection of protection systems are summarized. It is concluded that pressure relief alone is typically insufficient to prevent vessel rupture, but the combination of relief and thermal coatings can be effective.
An overview of test standards and regulations relevant to the fire testing of pressure vessels
(2021)
Fire exposure of storage and transportation vessels of hazardous materials (including pressure liquefied gases) can result in BLEVEs and other high-consequence incidents with large societal and economic impacts. To reduce risk most countries have numerous regulations, codes of practice and guidance notes covering the design, operation and maintenance of vessels and thermal protection systems. Yet despite such regulations there remains no internationally accepted fire test procedure for pressure vessel and accompanying thermal protection systems that is capable of meeting a range of regulatory requirements. This paper considers some of the regulations in place in the western world and considers the origin of these based on large and medium-scale testing conducted to date. It examines conditions found in these tests to propose a set of recommendations on which to base a standard method of test. These recommendations are proposed as being representative of a credible large pool fire scenario that may occur.
In spite that transport activities do not represent the biggest contributor of pollutants emissions, their reduction has been a priority as some other externalities are associated to such emissions and to the transport itself. A crucial element to characterize the behavior of the vehicles against the environment are the losses that such vehicles exhibit in a passive way, that is, without any involvement of power conditions. The energy loses due to the rolling, the drag and to the friction in mechanical components, have been assessed so far in terms of the stopping acceleration when the vehicle idles on a ramp. However, such a testing procedure produces some uncertainties due to the dynamic conditions that are considered. To avoid such critical limitations, in this paper a testing procedure and facility are proposed, which are based on static conditions of the vehicle at the initiation and at the ending of the test, which are assumed to provide a better reliability to the testing. Some preliminary theoretical analysis should be made in order to validate the operational principles proposed herein for such testing facility.
Different approaches have been attempted so far to reduce fuel consumption and linked pollutants, including vehicle equipment and design, with rational driving style being recognized as a potential source of fuel savings. However, no specific methodology had been suggested so far to assess fuel economy of driving other than the fuel consumed itself. In this paper, the Standard deviation of driving acceleration has been found to be directly associated to fuel consumption, so that the less dispersion of the driving acceleration, produces the lower fuel consumptions and emissions. Such metric could be thus used to assess driving style.
Turning maneuvers originate higher forces exerted on the rail and the loss of locomotive energy, at a rate that is function of several parameters that influence the magnitude of the developed horizontal wheel-rail forces, including the friction at the centre plate and the bogie´s yaw stiffness. However, such a friction at the contact surfaces of the centre plate is needed to mitigate the Hunting phenomenon when the train moves on straight track segments. In this paper, a self-centering centre plate is proposed, consisting of a lubricated centre plate, equipped with a spring- and damper-based self-centering mechanism. Simulation results of the proposed mechanism suggest that the energy performance in turns of a train car equipped with such self-centering centre plate is comparatively better, as the peak friction forces linked to the dry friction at the contact surfaces of current centre plate designs, are avoided. The assessment of the hunting performance of the proposed device in straight track segments is proposed as the continuation of this work.
A facility is proposed in this paper to apply a selective carburizing process to the lateral faces of a railways´ head, aiming to increase its carbon content and to decrease the friction coefficient in case that the flange of the railway car wheel gets in contact with the rail during turning. Such a treatment would reduce the energy that is lost during the turning maneuvers performed by the vehicle, further improving the energy efficiency of the railway car. The facility consists of a furnace, which should be set next to the rails´ hot-rolling facility, in order to use the available enthalpy. The proposed furnace is equipped with what is necessary to avoid the decarbonization of the remaining rail material, based upon batteries of oxy-acetylene burners that are installed at the bottom of the furnace, on the opposite side to the carburizing surface. An experimental facility is necessary to validate the operational principles for the equipment proposed in this paper. On the other hand, a study should also be carried out to assess the effect of any rail welding process on the carburized surfaces.
Gefahrguttanks werden primär gegen betriebliche Belastungen dimensioniert. Unfallbelastungen spielen hierbei keine Rolle. In der Vergangenheit gab es immer wieder einige katastrophale Unfälle, die nicht nur materielle Schäden zur Folge hatten sondern bei denen auch Todesopfer zu beklagen waren. Zur Ermittlung möglicher Sicherheitsreserven werden Untersuchungen zum Abtrag auslegungsüberschreitender Belastungen durchgeführt. Mit dem Grenzlasttragverfahren steht ein leistungsfähiges Analysewerkzeug zur Verfügung, mit dem nichtlineare Beanspruchungsszenarien bewertet werden können. Der Vergleich der numerischen mit den experimentellen Ergebnissen zeigt dies eindeutig.
Gefahrguttanks
(2016)
Given the frequent incidences of Non-Accident Releases (NARs) of hazardous materials from tank cars, there in an increasing interest in transporting hazardous materials in total containment conditions (i.e., no pressure relief devices). However, the ability of tank cars to meet thermal protection requirements provided in the Code of Federal Regulations under conditions of total containment has not been established. Also, the modeling tool commonly used by industry to evaluate thermal protection, AFFTAC, has not been validated under these conditions. The intent of this effort was to evaluate through a series of third-scale fire tests, the ability of tank cars to meet the thermal protection requirements under total containment conditions, and also, to validate AFFTAC for such conditions.
This paper describes the test design and planning effort associated with this research, including the design and evaluation of a fire test setup to simulate a credible, fully engulfing, pool fire that is consistent and repeatable, and the design and hydro-static testing of a third-scale tank specimen. The fire design includes controls on the spatial distribution and temperature variation of the flame temperature, the heat flux, and the radiative balance, to best reflect large liquid hydrocarbon pool fire conditions that may be experienced during derailment scenarios.
Using plastic jerrycans or plastic containers, dangerous goods are transported as air freight in commercial aircrafts. Liquids or gases can escape by leakage or permeation effects from these plastic containers. The German Federal Institute for Materials Research and Testing (BAM) conducted prior research which showed that the lower explosion limit can be reached when transporting dangerous goods in sea-freight containers under normal transportation situations. The presented study is motivated based on these findings. The research objective of this study is to analyze the transportation situation of dangerous goods in cargo compartments of commercial airplanes. The scope of this paper is to present the experimental method used for validating a numerical model for CFD (Computational Fluid Dynamics) simulations and to present some simulation results of the mass transport of dangerous goods in the cargo compartment.
The velocity profiles and the mass transport is calculated using numerical simulations and measured by Laser-Doppler-Anemometry (LDA) experiments. The mock-up is a generic model of a wide-body aircraft lower deck cargo compartment in a 1: 10 scale. Geometry, air exchange rates and inlet as well as outlet flow conditions in the cargo compartment are modeled using realistic boundary conditions. The commercial CFD (Computational Fluid Dynamics) code ANSYS CFX 14 is used for numerical flow simulations applying RANS (Reynolds-Averaged-Navier-Stokes) equations and turbulence models. The turbulence models studied are the renormalization group k-e-model (RNG), the BSL-Reynolds-Stress model (BSL) and the SST-k-co-model by Menter (SST).
The flow measurement with LDA in the mock-up of a cargo compartment proves to be a feasible method for producing data to validate CFD simulations. Qualitative evaluation of the results shows a good overall agreement between numerical and experimental results. The experimental validation indicates that the implemented CFD model is capable of reproducing the flow situation in the model mock-up
This paper describes the testing methods used to determine the thermal properties of insulation materials and mechanical properties of materials used for the load-bearing structure for pressure tanks (up to 4 bar, relative) and cryogenic liquids (LNG, −166 °C to -157 °C at atmospheric pressure). Goal is to design a transportation tank that does not exceed 4 bars (relative) within 10 h, starting at atmospheric pressure. PUR-foam is a suitable material for the insulation. A 12,5 l small scale tank prototype reached 4 bar (relative) within 87 minutes, which is, regarding the influence of the size, a satisfying result. The mechanical properties change significantly at cryogenic temperatures. The bending modulus is similar at first, but decreases at a certain point by appr. 50 %. However, the maximum stress is much higher and could not be reached within this testing setup.
A simplified formulation is proposed in this paper to assess the proximity of the earthquake-related Perturbation frequencies to the natural sloshing frequencies of the liquid contained in vertical cylindrical tanks. The methodology is based upon an existing gravity-waves approach, which was developed for rectangular cross-section reservoirs, and is extended in this paper to analyze circular cross-section tanks.
The experimental outputs of this paper show that the existing methodology correlates at 100% with experimental data in the case of rectangular containers; while the corresponding average error in the case of a conical container and a cylindrical container is 7% and 9.1 %, respectively. The full diameter of the cross section was considered. The use of sovalidated methodology to full scale tanks, suggests that cylindrical vertical tanks with a capacity lower than 700 m3, could be exposed to a resonance excitation when subjected to
earthquake motions, regardless of the fill level.
Tanks with capacity larger than 700 m3, could be exposed to a resonance excitation when subjected to earthquake motions, regardless of the fill level. Further studies to assess the dynamic forces linked to such resonance and close-to-resonance situations, in a context of a standard overloading situation due to sloshing forces.
To reduce the emission of carbondyoxide (CO2) of combustion engines, liquefied natural gas (LNG) is used as an alternative fuel. LNG is transported via truck, ship or railway for long distances. Double walled stainless steel tanks are used for transportation, which are heavy and expensive. The vacuum insulation between the two walled structure ensures that the LNG stays liquid over the transportation time (boiling point of LNG: -162 ◦C). This causes a high temperature difference between the transported good and the ambient air.
A simplified tank construction is used to reduce the weight and price of the tank. Instead of stainless steel, glass fiber reinforced plastic (GFRP) is used. The design is changed to a single walled construction with a solid insulation material outside on the GFRP structure.
Goal of this work is the characterization of a suitable insulation material and configuration as well as the analysis of the mechanical properties of GFRP under cryogenic conditions. Several experiments are carried out. Numerical models of these experiments can then be used for parameter studies.
The efficiency and safety of railway transportation depends on many factors and operating conditions, associated to the vehicle, the infrastructure, the operator and the environment. From the vehicle-infrastracture perspective, some influential factors include the dynamics of the vehicle and infrastructure interaction when the vehicle operates on curved tracks. Düring such changes of direction, the vehicle dynamically responds to the lateral perturbation, producing a lateral load transfer that represents an increase of the wheel forces on one side of the track, as a function of the train operating conditions and track design, including track's geometry and over-elevation, and vehicle's operating speed as well as its inertial properties and dimensions. In this context, the lateral load transfer superimposes to tangential steering forces, which are developed when the vehicle enters the curved track, and stabilize once a steady state is attained if the vehicle travels along a constant radius track at constant speed. The magnitude of such tangential forces depends on a variety of factors, including the yaw stiffness of the bogie, and the friction at the centre plate. While the friction at the
centre plate generates higher tangential forces on the track and a consequential greater rail wearing and lose of locomotive energy, such friction is also crucial to avoid the hunting phenomenon when the vehicle travels along tangents.
In this paper, a mechanically active centre plate is proposed, which increases the friction torque at the centre plate when the vehicle travels along tangents, and reduces such a friction torque when the vehicle negotiates curved portions of the track. Such conceptual design includes the principles of Operation and a needed preliminary
experimental model to assess the potential benefits as well as the feasibility of such equipment.