3.2 Gefahrguttanks und Unfallmechanik
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- Zeitschriftenartikel (21) (entfernen)
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- Fire (3)
- Experimental methods (2)
- Experimental modelling (2)
- GFRP (2)
- LNG (2)
- Lightweight design (2)
- Liquid cargo (2)
- Load transfer (2)
- Road tankers (2)
- Simulation (2)
- Sloshing (2)
- ABS (1)
- BLEVE (1)
- Bogie´s yaw friction (1)
- Bogie´s yaw stiffness (1)
- Braking in a turn manoeuvre (1)
- Braking-in-a-turn maneuver (1)
- Carburizing (1)
- Cargo shifting (1)
- Cargo sloshing (1)
- Centre plate (1)
- Continuous wavelet transform (1)
- Cryogenic Vessels (1)
- Decarbonization (1)
- Drag resistance (1)
- Driving style (1)
- Dry friction (1)
- Dynamic loads (1)
- Empirical mode decomposition (1)
- Energy efficiency (1)
- Energy losses in transportation (1)
- Environmental assessment (1)
- Filling procedere (1)
- Finite element method (1)
- Fire safety composite tanks (1)
- Frequency analysis (1)
- Friction energy (1)
- Fuel consumption (1)
- Furnace design (1)
- GPS data (1)
- Gravity response (1)
- Health monitoring (1)
- Hunting phenomenon (1)
- JetFire (1)
- Jetfire (1)
- LH2 (1)
- LPG (1)
- Lateral load transfer (1)
- Liquefied Hydrogen (1)
- Liquefied Natural Gas (1)
- MLI (1)
- Mechanical fatigue (1)
- Mechanical modelling (1)
- Mechanical prtoperties (1)
- Multilayer Insulation (1)
- Particle emissions (1)
- Pendulum analogy (1)
- Pendulum-analogy (1)
- Pressure vessel (1)
- Prüfstand (1)
- Prüftstand (1)
- Rail damage (1)
- Rail tankers (1)
- Rail vibrations (1)
- Railroad (1)
- Railway braking forces (1)
- Railway vibration measurements (1)
- Receptacle (1)
- Roll reactions (1)
- Rolling resistance (1)
- Safety (1)
- Selective carburizing (1)
- Self-centering mechanism (1)
- Stored energy (1)
- Substructure failures (1)
- Tank (1)
- Test (1)
- Thermal properties (1)
- Tiefkalt (1)
- Transfer function (1)
- Transport efficiency (1)
- Transport safety (1)
- Transportation energy (1)
- Turning (1)
- Turning forces (1)
- Turning maneuvers (1)
- Vibration signal analysis (1)
- Wheel forces (1)
- Wheel-rail friction coefficient (1)
- Wheel-rail tangential forces (1)
Organisationseinheit der BAM
- 3 Gefahrgutumschließungen; Energiespeicher (21) (entfernen)
Multilayer Insulation (MLI) is frequently used in vacuum conditions for the thermal insulation of cryogenic storage tanks. The severe consequences of the degradation of such materials in engulfing fire scenarios were recently evidenced by several large-scale experimental tests. In the present study, an innovative modelling approach was developed to assess the performance of heat transfer in polyester-based MLI materials for cryogenic applications under fire conditions. A specific layer-by-layer approach was integrated with an apparent kinetic thermal degradation model based on thermogravimetric analysis results. The modeling results provided a realistic simulation of the experimental data obtained by High-Temperature Thermal Vacuum Chamber tests reproducing fire exposure conditions. The model was then applied to assess the behavior of MLI systems for liquid hydrogen tanks in realistic fire scenarios. The results show that in intense fire scenarios degradation occurs rapidly, compromising the thermal insulation performances of the system within a few minutes.
The interest in hydrogen-based green energy is increasing worldwide, and the same is true for hydrogen-powered vehicles. Among the possible solutions to store hydrogen in such vehicles, cryogenic tanks equipped with multi-layer insulation (MLI) are the most promising to increase the amount of energy stored per unit volume. However, MLI is affected by severe deterioration when exposed to an external source of heat such as a fire following a car accident, leaving the tank unprotected and leading to failure in a relatively short time. In this work, a one-dimensional model to evaluate MLI thermal degradation when a liquid hydrogen tank is exposed to fire is presented. The relevance of taking MLI degradation into account when simulating the pressure increase due to external fire exposure is here demonstrated through the analysis of several case studies. The results show that MLI systems performance depletes within a few minutes of exposure to hydrocarbon poolfire.
The dynamic response of a vehicle during braking is influenced by the tangential forces developed at the wheel-rail’s contact surface. The friction coefficient affects the load transfer from the wheel’s tread to the vehicle. In this work, the vibrations of a scale-down railway vehicle are monitored during braking and their relationship with the friction coefficient between wheel and rail is found out. The vehicle is instrumented with encoders, accelerometers, and is controlled via Bluetooth.
The tests are carried out with clean and friction-modified rails. The tangential forces transmitted from the wheel to the railcar’s body are visualized in time and frequency using a proposed correlation algorithm based on the outputs of the ContinuousWavelet Transform (CWT). The results demonstrate
that tangential forces have a significant impact on railway vehicles under conditions of high friction coefficients and large creep values.
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.
Hunting is a potentially dangerous phenomenon related to the lateral oscillation of the wheels that impacts the rails and causes the wear of the infrastructure’s components. Therefore, the analysis and timely detection of hunting can lead to the application of corrective maintenance tasks, reducing damages, and costs and even derailments as a result. In this work, the vibration response of a finite element model of a rail with hunting-induced loads by a single wheel is analyzed in three directions: longitudinal, lateral, and vertical. The contact patch forces are calculated by means of Simpack® using the Kalker linear theory and the contact Hertz theory. The system is solved by using the Newmark-_ approach. The results of the deflection and vibration analysis, following the proposed methodology, show how the different characteristics of the loads impact the rail.
The objective of this paper is to describe and to validate a simplified pendulum-analogy model to simulate the interaction of a liquid cargo with ist carrying vehicle. The resulting testing rig consists of a rectangular container, spring supported on a two wheelset-bogie having a scale down of 1/10 with respect to a full-size equipment. The testing rig is used to validate a simple pendulum-based, simplified three degree-of-freedom mathematical model of the response of a partially filled container to lateral accelerations. The length of the pendulum is set according to validated methodologies. The resulting mathematical scheme reveals a high correlation with the experimental output, on the order of 99%, while some other performance measures, related to the peak forces and the range of variation of the wheel-rail forces, also show good concordance with the experimental results.
Vehicle’s components damage
(2020)
The failure of vehicle’s suspension components has contributed to road crashes, while their defective operation can deteriorate the fuel efficiency of the vehicles. In this context, and when compared with solid cargo transporters, the road tankers would tend to produce larger roll forces during turning, as the curved shape of the liquid cargo container, shifts upwards the centre of gravity of the cargo. With reference to a rectangular cargo container representing the solid cargo situation, the increase in the position due to elliptical and circular tank shapes, can attain a value of 17% (100% fill, circular tank). In this study, experimental results comparing the lateral load transfer due to solid and liquid cargoes, indicate that the average force increase on the vehicle’s load-receiver side due to a liquid cargo, is 4.3%. To analyse the fullscale situation of both situations, that is, the higher position of the centre of gravity and the shifting of the liquid cargo, a simplified model is developed. The outputs from such a model when subjected to realistic operating conditions (speed
and turning radius), suggest that the higher position of the centre of gravity due to using a non-rectangular cargo container generates an average force increase of 4.9% on the side receiving the load transfer. The incorporation of the effect of the liquid cargo, through the simple pendulum analogy, suggests that such an average increases to 6.76%, with a maximum of 8.35% in the case of the elliptical tank at 75% fill level. It is found that the average liquid cargo effect is 5.44%, which should be compared with the 4.3% of the experiments. Road tankers components would thus have a relatively shorter load cycle life than those of the solid cargo trucks.
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.
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.