Tank Cars

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Christopher P. L. Barkan - One of the best experts on this subject based on the ideXlab platform.

  • napl source zone depletion model and its application to railroad Tank car spills
    Ground Water, 2012
    Co-Authors: Amanda Marruffo, Mohd Rapik Saat, Christopher P. L. Barkan, Hongkyu Yoon, David J Schaeffer, Charles J Werth
    Abstract:

    We developed a new semi-analytical source zone depletion model (SZDM) for multicomponent light nonaqueous phase liquids (LNAPLs) and incorporated this into an existing screening model for estimating cleanup times for chemical spills from railroad Tank Cars that previously considered only single-component LNAPLs. Results from the SZDM compare favorably to those from a three-dimensional numerical model, and from another semi-analytical model that does not consider source zone depletion. The model was used to evaluate groundwater contamination and cleanup times for four complex mixtures of concern in the railroad industry. Among the petroleum hydrocarbon mixtures considered, the cleanup time of diesel fuel was much longer than E95, gasoline, and crude oil. This is mainly due to the high fraction of low solubility components in diesel fuel. The results demonstrate that the updated screening model with the newly developed SZDM is computationally efficient, and provides valuable comparisons of cleanup times that can be used in assessing the health and financial risk associated with chemical mixture spills from railroad-Tank-car accidents.

  • generalized railway Tank car safety design optimization for hazardous materials transport addressing the trade off between transportation efficiency and safety
    Journal of Hazardous Materials, 2011
    Co-Authors: Mohd Rapik Saat, Christopher P. L. Barkan
    Abstract:

    North America railways offer safe and generally the most economical means of long distance transport of hazardous materials. Nevertheless, in the event of a train accident releases of these materials can pose substantial risk to human health, property or the environment. The majority of railway shipments of hazardous materials are in Tank Cars. Improving the safety design of these Cars to make them more robust in accidents generally increases their weight thereby reducing their capacity and consequent transportation efficiency. This paper presents a generalized Tank car safety design optimization model that addresses this tradeoff. The optimization model enables evaluation of each element of Tank car safety design, independently and in combination with one another. We present the optimization model by identifying a set of Pareto-optimal solutions for a baseline Tank car design in a bicriteria decision problem. This model provides a quantitative framework for a rational decision-making process involving Tank car safety design enhancements to reduce the risk of transporting hazardous materials.

  • an environmental screening model to assess the consequences to soil and groundwater from railroad Tank car spills of light non aqueous phase liquids
    Journal of Hazardous Materials, 2009
    Co-Authors: Hongkyu Yoon, Christopher P. L. Barkan, David J Schaeffer, Charles J Werth, Pooja Anand
    Abstract:

    North American railroads transport a wide variety of chemicals, chemical mixtures and solutions in railroad Tank Cars. In the event of an accident, these materials may be spilled and impact the environment. Among the chemicals commonly transported are a number of light non-aqueous phase liquids (LNAPLs). If these are spilled they can contaminate soil and groundwater and result in costly cleanups. Railroads need a means of objectively assessing the relative risk to the environment due to spills of these different materials. Environmental models are often used to determine the extent of contamination, and the associated environmental risks. For LNAPL spills, these models must account for NAPL infiltration and redistribution, NAPL dissolution and volatilization, and remediation systems such as pump and treat. This study presents the development and application of an environmental screening model to assess NAPL infiltration and redistribution in soils and groundwater, and to assess groundwater cleanup time using a pumping system. Model simulations use parameters and conditions representing LNAPL releases from railroad Tank Cars. To take into account unique features of railroad-Tank-car spill sites, the hydrocarbon spill screening model (HSSM), which assumes a circular surface spill area and a circular NAPL lens, was modified to account for a rectangular spill area and corresponding lens shape at the groundwater table, as well as the effects of excavation and NAPL evaporation to the atmosphere. The modified HSSM was first used to simulate NAPL infiltration and redistribution. A NAPL dissolution and groundwater transport module, and a pumping system module were then implemented and used to simulate the effects of chemical properties, excavation, and free NAPL removal on NAPL redistribution and cleanup time. The amount of NAPL that reached the groundwater table was greater in coarse sand with high permeability than in fine sand or silt with lower permeabilities. Excavation can reduce the amount of NAPL that reaches the groundwater more effectively in lower permeability soils. The effect of chemical properties including vapor pressure and the ratio of density to viscosity become more important in fine sand and silt soil due to slow NAPL movement in the vadose zone. As expected, a pumping system was effective for high solubility chemicals, but it was not effective for low solubility chemicals due to rate-limited mass transfer by transverse dispersion and flow bypassing. Free NAPL removal can improve the removal efficiency for moderately low solubility chemicals like benzene, but cleanup times even after free NAPL removal can be prolonged for very low solubility chemicals like cyclohexane and styrene.

  • improving the design of higher capacity railway Tank Cars for hazardous materials transport optimizing the trade off between weight and safety
    Journal of Hazardous Materials, 2008
    Co-Authors: Christopher P. L. Barkan
    Abstract:

    As with many aspects of modern industrial society, decision-makers face trade-offs in considering hazardous materials transportation equipment and practices. Tank Cars used for transport of hazardous materials can be made more resistant to damage in accidents through use of a thicker steel Tank and other protective features. However, the additional weight of these features reduces the car's capacity and thus its efficiency as a transportation vehicle. In this paper the problem of Tank car safety versus weight is developed as a multi-attribute decision problem. North American railroads recently developed specifications for higher capacity Tank Cars for transportation of hazardous materials including enhanced safety design features. A group of Tank car safety design features or "risk reduction options" (RROs) were analyzed with regard to their effect on the conditional probability of release in an accident, and their incremental effect on Tank car weight. All possible combinations of these RROs were then analyzed in terms of the reduced release probability per unit of weight increase and the Pareto optimal set of options identified. This set included the combinations of RROs that provided the greatest improvement in safety with the least amount of additional weight for any desired level of Tank car weight increase. The analysis was conducted for both non-insulated and insulated Tank Cars and used two objective functions, minimization of conditional probability of release, and minimization of expected quantity lost, given that a car was derailed in an accident. Sensitivity analyses of the effect of Tank car size and use of different objective functions were conducted and the optimality results were found to be robust. The results of this analysis were used by the Association of American Railroads Tank Car Committee to develop new specifications for higher capacity non-insulated and insulated, non-pressure Tank Cars resulting in an estimated 32% and 24% respective improvement in safety.

  • optimizing the design of railway Tank Cars to minimize accident caused releases
    Computers & Operations Research, 2007
    Co-Authors: Christopher P. L. Barkan, Satish V Ukkusuri, Travis S Waller
    Abstract:

    The design of vehicles transporting hazardous materials has important public safety and economic implications. Conventional wisdom among industry and government has held that a thicker Tank on railroad Tank Cars and trucks reduces risk. However, a thicker Tank increases vehicle weight and thus leads to an increase in the number of shipments required to transport the same amount of product and consequently greater exposure to accidents. In this research we develop a model that analyzes the tradeoff between increased damage resistance and greater exposure to accidents in which the objective function is minimization of the probability of release. The model accounts for the reduction in Tank car release probability as a function of Tank thickness, and the increased exposure to accidents that occurs due to the increased number of shipments needed for the heavier car. Three variables affecting this optimal thickness are considered in this paper: the volumetric capacity of the Tank, the probability of release from other, non-Tank sources, and the weight capacity of the car. Sensitivity analyses using the model indicate that for any particular configuration of Tank car there is an optimal thickness. This optimal thickness is affected by several factors and there is no single optimum for all Tank Cars.

Guangxue Yang - One of the best experts on this subject based on the ideXlab platform.

  • a finite element analysis on mechanical behavior of al al mg composites for the design of Tank Cars under actual measuring loads
    Engineering Failure Analysis, 2019
    Co-Authors: Guangxue Yang, Zhiming Liu
    Abstract:

    Abstract The transportation safety of Tank Cars carrying concentrated nitric acids under conditions of heavy loads has attracted the increasing attention. The use of Aluminum/Aluminum-Magnesium(Al/Al-Mg) alloys to form laminated composites can solve the problems associated with the low corrosion resistance and strength of Tank car bodies. In this work, a finite element analysis was used to simulate the tensile tests of the Al/Al-Mg laminated composites. In particular, the stress and strain behavior of the composites under tensile loads was investigated, and the corresponding mechanical properties of the composites were determined, which was verified by the tension test results. Furthermore, the effective load time history was obtained by processing the measuring data of C70E type gondola car body on three typical general railway line. Load spectra of car body were compiled using the rain-flow count method, which was applied to do the fatigue design for 70 t Al/Al-Mg Tank body. Most importantly, in conjunction with the S N curve of the base materials and the lap-welded joint, based on the Tank car finite element analysis results under various load cases, the fatigue life of the 70 t Al/Al-Mg Tank body was calculated based on Miner's linear accumulative damage theory. The results showed a very promising application of such composite materials to meet the safety requirements.

  • fatigue properties of al al mg alloy laminated materials for the applications to railway Tank Cars
    International Journal of Fatigue, 2019
    Co-Authors: Guangxue Yang
    Abstract:

    Abstract In this study, Al/Al-Mg alloy laminated plates were developed, and such composite materials are applied in a 70 t Tank car for transporting concentrated nitric acids. The fatigue tests of the base materials and the lap-welded joint of the Al/Al-Mg alloy laminated plate were conducted, and the stress-cycle (S-N) curve with a survival rate of 97.7% was obtained. The fatigue failure mode was analyzed, and its fracture mechanism of the laminated plates was determined. Furthmore, the mechanical behavior of Al/Al-Mg alloy laminated plate was investigated using the finite element analysis (FEA). Based on the load spectrum of 100 t Tank car described in the Association of American Railroads (AAR) standard, in conjunction with the S-N curve of the base materials and the lap-welded joints, the fatigue life of the 70 t Tank body was calculated based on the Miner’s linear accumulative damage theory. The results showed that the 70 t Tank car constructed with such materials can meet the safety requirements of operating for 2.5 million km.

David Y. Jeong - One of the best experts on this subject based on the ideXlab platform.

  • SEMI-ANALYTICAL APPROACH TO ESTIMATE RAILROAD Tank CAR SHELL PUNCTURE
    2020
    Co-Authors: David Y. Jeong, Yim H Tang, Benjamin A Perlman
    Abstract:

    ABSTRACT This paper describes the development of engineeringbased equations to estimate the puncture resistance of railroad Tank Cars under a generalized shell or side impact scenario. Resistance to puncture is considered in terms of puncture velocity, which is defined as the impact velocity at which puncture is expected to occur. In this context, puncture velocity represents a theoretical threshold limit. A given object striking the side of a Tank car at an impact speed below the threshold velocity is not expected to penetrate the commodity-carrying Tank. This definition for puncture velocity is similar to that for ballistic limit velocity, which is used to measure a target's ability to withstand projectile impact in military applications The term "semi-analytical" is used to characterize the current approach in developing equations for shell puncture in order to distinguish the present work from the semi-empirical approach used previously to develop equations corresponding to head puncture. While several tests have been conducted to study Tank car head puncture, only a limited number of tests have been performed to study Tank car shell puncture. The semi-analytical approach employs a combination of three tactics to deal with the paucity of test data. The first tactic applies collision dynamics to derive an idealized relationship between impact speed and maximum force for a generalized Tank car shell impact scenario. Specifically, the principle of conservation of energy is applied. The second tactic applies computational methods to simulate Tank car shell impacts in greater detail. Specifically, finite element analysis is used to examine the force-deformation behavior of different Tank car configurations under different loading conditions. Regression analyses are performed on the results of the detailed finite element results to develop best-fit curves to account for the effects of various factors such as shell thickness, Tank diameter, internal pressure and indenter size. The third tactic is empirical, in which various factors are related to puncture force using empirical formulas that have been developed in research to examine impact resistance in pipeline applications. Results from applying the semi-analytical method to estimate shell puncture velocity are presented. Similarities and differences between the current method for shell puncture and the semi-empirical method for head puncture are discussed. In addition, results from sensitivity studies are presented to show the relative effect of different factors on estimated puncture velocity. These studies indicate that indenter size and internal pressure have the most significant effect on shell puncture velocity. Conversely, these studies indicate that Tank diameter and ram car weight have a relatively weak effect on shell puncture velocity

  • impact dynamics and puncture failure of pressurized Tank Cars with fluid structure interaction a multiphase modeling approach
    International Journal of Impact Engineering, 2016
    Co-Authors: David Y. Jeong
    Abstract:

    Abstract This paper presents a computational framework that analyzes the effect of fluid–structure interaction (FSI) on the impact dynamics and puncture failure of pressurized commodity Tank Cars carrying hazardous materials. Shell (side) impact tests have been conducted on full scale Tank Cars resulting in deformed or punctured Tank Cars. A finite element (FE) modeling method is applied that explicitly simulates the three distinct phases in a Tank car loaded with a liquefied substance: pressurized gas, pressurized liquid and solid structure. Furthermore, an equivalent plastic strain based fracture initiation criterion expressed as a function of stress triaxiality is adopted to depict the fracture behavior of the Tank car steel material. The fracture initiation is implemented for ductile, shear and mixed fracture modes and followed by further material deterioration governed by a strain softening law. The force, displacement and impact energy results obtained from the FE analysis show good agreement with the corresponding shell impact test data. The simulations demonstrate that FSI plays a critical role in predicting the correct dynamics of Tank car impact. The puncture resistance of a Tank car, characterized as limit impact conditions in terms of puncture energy or puncture velocity, is further analyzed in shell impact scenarios. The puncture energy is shown to increase as the initial fluid pressure decreases, the Tank car thickness increases or the effective impactor size increases. Quantitative correlations between puncture energy/velocity and each of these factors are obtained using the FE analysis method developed in this paper.

  • application of a stress triaxiality dependent fracture criterion in the finite element analysis of unnotched charpy specimens
    Theoretical and Applied Fracture Mechanics, 2010
    Co-Authors: H L Yu, David Y. Jeong
    Abstract:

    Abstract Nonlinear dynamic finite element analysis (FEA) is conducted to simulate the fracture of unnotched Charpy specimens of steel under pendulum impact loading by a dedicated, oversized and nonstandard Bulk Fracture Charpy Machine (BFCM). The impact energy needed to fracture an unnotched Charpy specimen in a BFCM test can be two orders of magnitude higher than the typical impact energy of a Charpy V-notch specimen. To predict material failure, a phenomenological, stress triaxiality dependent fracture initiation criterion and a fracture evolution law in the form of strain softening are incorporated in the constitutive relations. The BFCM impact energy results obtained from the FEA simulations compare favorably with the corresponding experimental data. In particular, the FEA predicts accurately the correlations of the BFCM impact energy with such factors as specimen geometry, impactor tup width and material type. The analyses show that a specimen’s progressive deterioration through the thickness dimension displays a range of shear to ductile fracture modes, demonstrating the necessity of applying a stress state dependent fracture initiation criterion. Modeling the strain softening behavior helps to capture the residual load carrying capability of a ductile metal or alloy beyond the onset of damage. The total impact energy can be significantly under predicted if a softening branch is not included in the stress–strain curve. This research supports a study of the puncture failure of railroad Tank Cars under dynamic impact loading. Applications of the presented fracture model in failure analyses of other structures are further discussed.

  • finite element analysis of fluid structure interaction in pressurized Tank Cars subjected to dynamic impact loading
    2009
    Co-Authors: Yim H Tang, Jeff Gordon, David Y. Jeong
    Abstract:

    This paper presents a computational study of the fluid-structure interaction (FSI) mechanism in pressurized commodity Tank Cars in railroad application. Within the Lagrangian framework of Abaqus/Explicit, finite element analysis (FEA) is conducted to predict the structural response of Tank Cars under dynamic impact loading. A three-phase approach is adopted that explicitly models pressurized gas, pressurized liquid and Tank car structure with three distinct sets of governing equations, and available contact options are investigated for modeling the interactions among different phases. To characterize the elastic-plastic behavior of a Tank car structure, shell element formulation provides accurate solutions at relatively low costs. To capture the progressive fracture behavior of an impact zone, however, solid element formulation must be employed. The solid-to-shell coupling technique is employed in the latter case to avoid the high cost of an all-solid-element structural model. With small to moderate amounts of fluid sloshing in an impacted Tank car, the general contact option is successful in simulating the FSI when the structural model involves only shell elements, whereas combined general contact and contact pair definitions are necessary if the structural model includes both shell and solid elements and solid-to-shell coupling. The force-displacement results from FEA show good correlations with the available shell (or side) impact test data.

  • modeling the effect of fluid structure interaction on the impact dynamics of pressurized Tank Cars
    Volume 13: New Developments in Simulation Methods and Software for Engineering Applications; Safety Engineering Risk Analysis and Reliability Methods;, 2009
    Co-Authors: Yim H Tang, Jeff Gordon, David Y. Jeong
    Abstract:

    This paper presents a computational framework that analyzes the effect of fluid-structure interaction (FSI) on the impact dynamics of pressurized commodity Tank Cars using the nonlinear dynamic finite element code ABAQUS/Explicit. There exist three distinct phases for a Tank car loaded with a liquefied substance: pressurized gas, pressurized liquid and the solid structure. When a Tank car comes under dynamic impact with an external object, contact is often concentrated in a small zone with sizes comparable to that of the impacting object. While the majority of the Tank car structure undergoes elasticplastic deformations, materials in the impact zone can experience large plastic deformations and be stretched to a state of failure, resulting in the loss of structural integrity. Moreover, the structural deformation changes the volume that the fluids (gas and liquid) occupy and consequently the fluid pressure, which in turn affects the structural response including the potential initiation and evolution of fracture in the Tank car structure. For an event in which the impact severity is low and the Tank car maintains its structural integrity, shell elements following elastic-plastic constitutive relations can be employed for the entire Tank car domain. For events in which the impact severity is higher and the Tank car is expected to be punctured, an equivalent plastic strain based fracture initiation criterion expressed as a function of stress triaxiality is adopted for the material in the Tank car’s impact zone. The fracture initiation is implemented for ductile, shear and mixed fracture modes and followed by further material deterioration governed by a strain softening law. Multi-layered solid elements are employed in the impact zone to capture this progressive fracture behavior. The liquid phase is modeled with a linear Us–Up Hugoniot form of the Mie-Gruneisen equation of state, and the gas phase is modeled with the ideal gas equation of state. Small to moderate amounts of fluid sloshing are assumed for an impacted Tank car in this study. As such, the FSI problem can be solved with the Lagrangian formulation of ABAQUS, and appropriate contact algorithms are employed to model the multi-phase interactions. The force, displacement and impact energy results from the finite element analysis show good correlations with the available shell (side) impact test data. The puncture energy of a Tank car in a shell impact scenario is further analyzed. It is demonstrated that the FSI effect needs to be adequately addressed in an analysis to avoid overestimating the puncture resistance of a Tank car in an impact event.

Douglas J. Bammann - One of the best experts on this subject based on the ideXlab platform.

  • modeling the dynamic failure of railroad Tank Cars using a physically motivated internal state variable plasticity damage nonlocal model
    Modelling and Simulation in Engineering, 2013
    Co-Authors: Fazle R. Ahad, Yustianto Tjiptowidjojo, Koffi Enakoutsa, Kiran Solanki, Douglas J. Bammann
    Abstract:

    We used a physically motivated internal state variable plasticity/damage model containing a mathematical length scale to idealize the material response in finite element simulations of a large-scale boundary value problem. The problem consists of a moving striker colliding against a stationary hazmat Tank car. The motivations are (1) to reproduce with high fidelity finite deformation and temperature histories, damage, and high rate phenomena that may arise during the impact accident and (2) to address the material postbifurcation regime pathological mesh size issues. We introduce the mathematical length scale in the model by adopting a nonlocal evolution equation for the damage, as suggested by Pijaudier-Cabot and Bazant in the context of concrete. We implement this evolution equation into existing finite element subroutines of the plasticity/failure model. The results of the simulations, carried out with the aid of Abaqus/Explicit finite element code, show that the material model, accounting for temperature histories and nonlocal damage effects, satisfactorily predicts the damage progression during the Tank car impact accident and significantly reduces the pathological mesh size effects.

  • a physically motivated internal state variable plasticity damage model embedded with a length scale for hazmat Tank Cars structural integrity applications
    ASME ASCE IEEE 2011 Joint Rail Conference (JRC2011)American Society of Mechanical EngineersAmerican Society of Civil EngineersInstitute of Electrical , 2011
    Co-Authors: Fazle R. Ahad, Koffi Enakoutsa, Kiran Solanki, Yustianto Tjipowidjojo, Douglas J. Bammann
    Abstract:

    In this study, we use a physically-motivated internal state variable model containing a mathematical length scale to re present the material behavior in finite element (FE) simulation s of hazmat Tank car shell impacts. Two goals motivated the curre nt study: (1) to reproduce with high fidelity finite deformationand temperature histories, damage, and high rate phenomena whi ch arise during the impact, as well as (2) to investigate numeri cal aspects associated with post-bifurcation mesh-dependenc y of the finite element solution. We add the mathematical length scal e to the model by adopting a nonlocal evolution equation for th e damage, as suggested by Pijaudier-Cabot and Bazant (1987) i n a slightly different context. The FE simulations consist ofa moving striker colliding against a stationary hazmat Tank car a nd are carried out with the aid of ABAQUS/Explicit. The results of t hese simulations show that accounting for temperature historie s and nonlocal damage effects in the material model satisfactori ly predicts, independently of the mesh size, the failure process o the Tank car impact accident.

G. W. Widell - One of the best experts on this subject based on the ideXlab platform.

  • Reducing Hazardous Materials Releases from Railroad Tank Car Safety Vents
    Transportation Research Record, 2000
    Co-Authors: Christopher P. L. Barkan, Todd T. Treichel, G. W. Widell
    Abstract:

    The leading cause of hazardous materials releases in railroad transportation over the 5 years prior to this research was burst frangible disks on Tank Cars. These burst disks occur as a result of pressure surges in the Tank car safety vent during transportation. More than a dozen different surge pressure reduction devices (SPRDs) have been developed to protect the frangible disk from these surges. A statistical analysis of Tank Cars in service indicated that Cars equipped with SPRDs experienced a lower rate of leakage due to burst frangible disks than similar Cars without SPRDs. This analysis, however, did not provide sufficient resolution to determine the relative effectiveness of the different SPRD designs. A series of controlled experiments was conducted to determine the surge reduction effectiveness and the flow performance of different SPRDs. These tests showed that there were significant differences in the performance of the various surge pressure reduction devices in both surge reduction and flow r...