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Eingeladener Vortrag
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The transportation of liquids involves several situations derived from the curved shape of the cargo containers, including a comparatively high center of gravity, which negatively shifts when the container is partially loaded, and the vehicle is subjected to steering or braking accelerations. Aiming at reducing these effects several experimental approaches have been applied, involving different tank shapes and the use of baffles, tested under laboratory or field conditions, at full scale or at a down-scale. However, the scope of such approaches has been limited, mainly because the potential effect of other components of the vehicle on the road tanker behavior, has been neglected. In this paper, a critical review is presented of the experimental approaches considered so far, identifying specific experimental needs to improve the performance of the vehicles, from both the road safety and the environmental perspective.
Externalities of the road transportation are multidimensional in nature and involve the road-vehicle interaction under different environmental conditions. Estimating the pavement and vehicle damage potentials as a function of the condition sunder which such interaction takes place, is important to avoid accelerated or catastrophic damages in these systems. Such an assessing is crucial from the perspective of pricing the effects of the vehicle on the infrastructure and vice versa. The existing models for pricing such interaction, critically depends on gross average statistical models. In this paper, it is proposed a deterministic approach to realize such an assessment, based upon validated approaches for the pavement damage. The simulation scheme considers different degrees-of-freedom vehicle models, and a discrete asphalt pavement, that make possible the simulation of massive traffic situations on realistic road lengths.
A testing methodology has been proposed in this paper, to compare the load transfer derived from solid and liquid cargoes when the carrying vehicle is subjected to a lateral acceleration in a tilt table. Besides the type of cargo, the other factors
(a) One-quarter fill level
(b) One-half fill level
(c) Three-quarter fill level
(d) Fast input
considered are the fill level and the rate at which the considered are the fill level and the rate at which the acceleration input is acceleration input is exerted on the vehicleexerted on the vehicle. The acceleration The acceleration input can represent the entering of the carrying vehicle into a input can represent the entering of the carrying vehicle into a curved portion curved portion of of aa road.
The testing device integrates the needed components to measure the fourmeasure the four--wheel loads of the wheel loads of the carrying vehicle, while carrying vehicle, while providing different times to attain providing different times to attain aa 10°10° angle angle for the tilt table. for the tilt table.
The performance measure selected is significant to assess the rollover trend of a vehicle, on the basis of the wheel loads at both sides of the vehicle. both sides of the vehicle.
The outputs from the experiments suggest that the sloshing suggest that the sloshing cargo transfercargo transferss the greater loads, the greater loads, regardless of the fill level and regardless of the fill level and acceleration rate inputacceleration rate input, as a result , as a result of the shifting of the center of of the shifting of the center of gravitygravity of the liquidof the liquid, and of of the the dynamic vibration at the end of dynamic vibration at the end of the perturbation input. In this respect, while the solid cargo the perturbation input. In this respect, while the solid cargo exhibits an initial peak and decay, the exhibits an initial peak and decay, the sloshing cargo exhibits sloshing cargo exhibits several oscillations of the saseveral oscillations of the same magnitude, which is attributed me magnitude, which is attributed to the to the liquid inertia and liquid inertia and to the to the reflection of the surface waves. reflection of the surface waves.
A further analysis could supplement this research, to assess supplement this research, to assess the effect of some other factors on the dynamic the effect of some other factors on the dynamic behavior of the behavior of the liquid cargoliquid cargo-vehicle system. Fvehicle system. For example, to analyze the effect or example, to analyze the effect of longitudinal baffles, and to validate theoretical models.of longitudinal baffles, and to validate theoretical models.
Avoiding road crashes has been the purpose behind many specialized software and hardware systems, involving both active and passive safety principles. Global Positioning technologies were incorporated into the transportation systems with the main purpose of acquiring the position of the vehicle under a continuous basis, for security and economy purposes. However, the GPS data can also be used for assessing the level of safety at which the vehicle is driven. On the basis of the essential data available from commercial GPS devices, in this paper we propose a combined performance measurement to assess the road safety level at which the vehicle is being driven. Such performance measure uses GPS data of the vehicle displacement, including the speed and the acceleration, as well as the course (latitude and longitude coordinates), in an integral driving assessment formulation that can run in real time. Results from the experimental use of this formulation suggest that the level of safety in the driving is time dependent, and that there are risky situations when different factors converge.
GPS-data based calculation scheme for assessing, in real-time, the level of safety exerted during driving, has been described and used. The several variables involved considered the main factors that lead to road mishaps, including the speed, the acceleration and the effects that these variables have on the vehicle when it is negotiating a turn. The performance measure combines three individual performance outputs: speed, acceleration and a hybrid performance measure considering the speed, the acceleration and the change in latitude/longitude. The measures are designed in such a way that weighting factors can be calibrated in order to establish certain critical parameters. On the other hand, the terms in the equations preclude any division by zero of the involved ratios. On the other hand, the simplicity of the equations makes it possible to carry out the assessment in real time. The use of the resultant performance measure to a relatively long path, together with its current average value, indicates that the safe performance of the driving changes with time, and that, for the selected values of the calibration constants, the traveling speed dominates the overall safety performance of the driving. Furthermore, the different calibration constants provide the possibility of considering different types of hazmat carrying vehicles. While many other formulation components could be integrated into the performance measure, this three-component performance measure could be used to assess the driving of a hazmat-carrying vehicle, in order to detect and to prevent dangerous conditions, such as driver fatigue.
Finally, the implementation of the different performance measure formulations in a system such as the one described in the introduction of this paper, could be straightforward.
A simplified methodology is proposed to estimate the dynamic pressures developed within partially filled cylindrical vertical tanks when subjected to earthquake-related horizontal accelerations. The total pressure at the bottom of the tank is calculated as the superposition of vertical and horizontal pressures. While the magnitude of the vertical pressure depends on the free surface height of the liquid, the horizontal pressure depends on the magnitude of the horizontal acceleration and on the diameter of the tank. The liquid free surface oscillation angle is simulated based upon the principles of the simple pendulum analogy for sloshing. The length of the pendulum, however, is set on the basis of a methodology to calculate the free sloshing frequency of partially filled containers. Such a methodology is experimentally verified in this work. The outputs of the model for full scale situations, suggest that the lateral perturbation - sloshing phenomenon (earthquake effect) can generate an increase in the total pressure of 56% above the no lateral perturbation situation, further suggesting that such an overpressure should be taken into account when designing tanks that could be potentially subjected to earthquake-related perturbations.
Simulation of liquid cargo – vehicle interaction under lateral and longitudinal accelerations
(2018)
Amongst the vehicle parameters influencing road safety, the carried cargo plays a critical role in the case of a liquid cargo, posing rollover risk and affecting the available friction forces for braking. While the lateral sloshing of the cargo within the vehicle´s compartments, can be excited when the vehicle negotiates a turn, the longitudinal motion of the cargo derives from changes of speed. The combination of both types of perturbations occurs when the vehicle brakes while negotiating a turn. In this paper, a two-pendulum formulation is used to simulate the lateral and longitudinal behavior of a vehicle when negotiating a braking in a turn maneuver. The suspension forces are thus calculated as the linear superposition of both models. Results suggest that the vehicle roll stability is affected by the cargo sloshing, with increments on the order of 100% in the lateral load transfer, for a 50% filled tank. On the other hand, the dispersion of the travelling speed also affects the lateral stability of such type of vehicles, as a function of the dispersion of the vehicle´s travelling speed.
The use of railway transportation for satisfying the transport needs of goods in Mexico is less intense than in developed countries, such as Germany. Mexican performance measures based upon the railway length per capita (intensity), or the railway length per square km of the country surface (density), are well behind from corresponding indicators for Germany, in such a way that the length of the railway infrastructure of Mexico should be, at least, doubled in order to reach a comparable intensity rate as that of Germany. In this paper, the benefits from transferring the whole transportation of goods from road to railway, is discussed. The benefits include a remarkable reduction in energy consumption and CO2 emissions. The feasibility for the electrical infrastructure to provide the necessary energy is further shown, while the economic feasibility of such situation is analyzed on the basis of the federal budget of Mexico. According to these estimations, the investment in railway infrastructure is feasible, while the electrical installed capacity is enough to satisfy an all-electric system.
This paper describes a theoretical model to simulate the effects of a sloshing cargo on the safety performance of a vehicle that performs a braking-in-a-turn maneuver when travels at a partial fill level. The fundamental assumption of the model consists of the superposition of the effects of two simplified mechanical-analogy models that represent a liquid cargo on a vehicle, including one for the roll motion and another one for the pitch motion. The distinctive characteristics of the mechanical models, however, is that they are based upon a validated formulation to establish the properties of the pendulum (length).
The results suggest a small effect of the sloshing cargo on the braking efficiency of the cargo, while the load transfer is moderately affected. However, such results should be put into a perspective, according to which such small variations can represent the avoidance of a rear-end crash or a rollover. In this respect, a specialized ABS system could be considered to improve the performance of such kind of vehicles when performing such maneuvers.
Validation of the proposed methodology should be performed as a continuation of this research effort.
Seit zehn Jahren führt die Bundesanstalt für Materialforschung und -prüfung (kurz: BAM) auf zwei Prüfständen Brandprüfungen z. B. an Transport-und Lagerbehältern für radioaktive Stoffe oder zur Prüfung von Brandschutzbeschichtungen durch. Als Brandmedium wird Flüssiggas (Propan-Butan-Gemisch C) eingesetzt, mit dem die Prüfobjekte simulierten Unfallfeuern ausgesetzt werden. Seit Anfang 2018 verfügt die BAM darüber hinaus auch über einen Jetfire-Prüfstand, der die Anforderungen der ISO 22899-1:2007 1) erfüllt.
Commodities and rail damage
(2018)
The normalized contact-mechanics fourth-power law approach for the
dynamic loads, suggest: worst railway use situation (double deck at 65 km/h) is 350 times that of the less rail damage situation (flat car at 45 km/h).
The normalized dispersion approach for the dynamic loads (Dynamic Load Coefficient), suggest that the worst railway use situation (double deck at 65 km/h) is about 4 times that of the less rail damage Situation (flat car at 45 km/h).
The potential effect of the different types of cars on the railway fatigue life could be significant, as a function of the vehicle speed.
The experimental validation of these outputs will be carried out as a continuation of this research effort. In addition to that, it should be mentioned that the associated simplified model could be used to analyze some other situations, related with the transport safety of different products.
Transport safety depends in great extent of what happens to the cargo once the carrying vehicle derails or rollovers. The exposure of tanks to direct fire is a condition that potentially involves catastrophic consequences. Studying the behavior of the contained fluid under these drastic circumstances, is critical to develop methods and techniques to mitigate the serious consequences of many mishaps. In this paper, the experimental potentials of a Particle Image Velocimetry data acquisition system are described, for providing experimental data that could be used to calibrate mathematical models. As an example of the situations that need to be modelled, an experiment is described concerning the effect of the boundary conditions and protecting devices, on the rate of variation of pressure and temperature of the fluid in a tank exposed to a direct fire. In this regard, the results emphasize the importance of equipping the vessels with both thermal insulation and safety valves.
There was a need to validate the longitudinal performance required for the cargo securement, as current standards exhibit differences.
A model has been proposed in this paper, to simulate the effect of a shifting cargo on the braking efficiency of the vehicle. Results suggest that the braking efficiency can be greater in the case of a shifting cargo, as a result of the uncoupling of the cargo-vehicle systems, implying that similar braking forces are exerted on a reduced mass. The shifting of the cargo can occur as a result of the vibration of the vehicle, that leads to having a diminished friction force to prevent the shifting of the cargo.
A filling process of the pressure bottle used for the air storage was investigated by numerical simulations. During the filling process, the temperature was rising up to maximal value and after that started to decline. The good match was found between experimental and numerical results. In order to reproduce the experimental conditions, the process of the filling bottle was controlled by the pressure which varied in time. This filling strategy influenced furthermore the mass flow rate and the air flow velocity. Because of the geometrical symmetry, the simulation was calculated as an axisymmetric problem.
Transport safety depends in great extent of what happens to the cargo once the carrying vehicle derails or rollovers. The exposure of tanks to direct fire is a condition that potentially involves catastrophic consequences. Studying the behavior of the contained fluid under these drastic circumstances, is critical to develop methods and techniques to mitigate the serious consequences of many mishaps. In this paper, the experimental potentials of a Particle Image Velocimetry data acquisition system are described, for providing experimental data that could be used to calibrate mathematical models. As an example of the situations that need to be modelled, an experiment is described concerning the effect of the boundary conditions and protecting devices, on the rate of variation of pressure and temperature of the fluid in a tank exposed to a direct fire. In this regard, the results emphasize the importance of equipping the vessels with both thermal insulation and safety valves.
Small and large-scale tests have been carried out Pressure vessel – to improve numerical modelling Different types of fire must be distinguished Modelling of vessels were discussed Test configuration has been developed to see what happens in the vessel First results encourage us to continue the Research Thermohydraulics needs further work (boundary layers).
There was a need to validate the longitudinal performance required for the cargo securement, as current standards exhibit differences. A model has been proposed in this paper, to simulate the effect of a shifting cargo on the braking efficiency of the vehicle. Results suggest that the braking efficiency can be greater in the case of a shifting cargo, as a result of the uncoupling of the cargo-vehicle systems, implying that similar braking forces are exerted on a reduced mass. The shifting of the cargo can occur as a result of the vibration of the vehicle, that leads to having a diminished friction force to prevent the shifting of the cargo.
The safety of any transport system depends on a multitude of conditions, parameters and circumstances. In this regard, the interaction of the carried Cargo with the carrying vehicle represents a factor influencing the overall safety of any transport. The effects of cargo on the vehicle have to do with the vibration or shifting of the cargo, affecting the lateral stability of the vehicles and the braking performance.
Such interaction has been associated to road crashes and maritime vehicles capsizing. Simulation of cargo-vehicle interaction thus represents an interesting Topic when a reduction in transport accidents is pursued. In this paper, the fundamentals principles for simulating the interaction of the liquid cargo and the carrying vehicle, is presented. In the case of a road transportation, the proposed simplified Simulation methodologies, show good agreement with a full-scale test.
Biofuels, particularly biodiesel, have gained significant attention as an alternative to traditional fossil fuels in recent years. Unlike diesel, which contains hundreds of compounds, biodiesel only contains a few compounds in the C16-C18 carbon chain. However, the use of biodiesel in automobile and transportation applications can result in problems of degradation or even damage in materials. Among the commonly used polymer materials, fluorocarbon (FKM) shows excellent performance and high stability and compatibility towards oil, diesel, ethanol, and other chemicals. FKM is a family of fluorocarbon-based fluoroelastomer materials, which provide excellent high-temperature and chemical stability compared to other elastomers. As a result, FKM is widely used in chemical processes such as petroleum refining, where it is used for sealings, pumps, and other components.