Finite Element Analyses of Railroad Tank Car Head Impacts

Tang, Yim H.; Yu, Hailing; Gordon, Jeff; Jeong, David Y.

doi:10.1115/rtdf2008-74022

Cited by 12 publications

(8 citation statements)

References 6 publications

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“…The dimensions of the tank car and the jacket are the same as in the works of Tang et al [25] and Tang et al [26]. The tank is a 0.777-inch-thick cylinder and is closed at its two ends with elliptical caps of aspect ratio 2.…”

Section: Fe Model Of the Problemmentioning

confidence: 88%

Modeling the Dynamic Failure of Railroad Tank Cars Using a Physically Motivated Internal State Variable Plasticity/Damage Nonlocal Model

Ahad

Enakoutsa

Solanki³

et al. 2013

Modelling and Simulation in Engineering

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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.

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Section: Fe Model Of the Problemmentioning

confidence: 88%

Modeling the Dynamic Failure of Railroad Tank Cars Using a Physically Motivated Internal State Variable Plasticity/Damage Nonlocal Model

Ahad

Enakoutsa

Solanki³

et al. 2013

Modelling and Simulation in Engineering

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“…This method, used by Tang, et al [10], in the tank car impact study, allows for the use of solid elements in the area around the failure location and shell elements away from the failure location. With the interface of the solidmeshed and shell-meshed regions of the structure properly defined, appropriate kinematic constraints are automatically applied.…”

Section: Model Developmentmentioning

confidence: 99%

“…Material failure models were recently used with great success to model the impact of a railroad tank car with a rigid punch [7][8][9][10]. These failure models employ the BaoWierzbicki fracture criterion [3], which features a specific stress triaxiality dependence on the plastic strain for initiation of failure.…”

Section: Introductionmentioning

confidence: 99%

Modeling Material Failure During Cab Car End Frame Impact

Stringfellow¹,

Paetsch²

2009

2009 Joint Rail Conference

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New standards have been proposed to increase the strength requirements for cab car end structures and impose further requirements on their ability to absorb energy during a grade-crossing collision [1,2]. To aid in the development of these new standards, the Federal Railroad Administration (FRA) and the Volpe Center recently completed a set of fullscale tests aimed at assessing the quasi-static and dynamic crush behavior of these end structures.In support of this testing program, end frames designed to meet the new standards were fabricated and retrofitted onto the forward end of an existing cab car. A series of largedeformation quasi-static and explicit dynamic finite element analyses (FEAs) were performed to evaluate the performance of the design.Based on the results of a 2002 full-scale test in which a heavy steel coil impacted the corner post of an end frame built to these new standards, some fracture was expected in certain key end frame components during the tests. For this reason, a material failure model, based on the Bao-Wierzbicki fracture criterion [3], was implemented in the FEA model of the cab car end frame using ABAQUS/Explicit. The FEA model with material failure was used to assess the effect of fracture on the deformation behavior of cab car end structures during quasistatic loading and dynamic impact and, in particular, the ability of such structures to absorb energy.The failure model was implemented in ABAQUS/Explicit for use with shell elements. A series of preliminary calculations were first conducted to assess the effects of element type and mesh refinement on the deformation and fracture behavior of structures similar to those found on cab car end frames, and to demonstrate that the Bao-Wierzbicki failure model can be effectively applied using shell elements.Model parameters were validated through comparison to the results of the 2002 test. Material strength and failure parameters were derived from test data for A710 steel. The model was then used to simulate the three full-scale tests that were conducted during 2008 as part of the FRA program: a collision post impact, and quasi-static loading of both a collision post and a corner post. Analysis of the results of the two collision post tests revealed the need for revisions to both the design of some key end frame components and to key material failure parameters. Using the revised model, pre-test predictions for the outcome of the corner post test were found to be in very good agreement with test results.

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“…Therefore, in a higher speed impact, the tank will have a greater capacity to absorb kinetic energy than if no sacrificial structure were present. The energy to puncture the conventional chlorine tank car is calculated from finite element analyses that include the effect of fluid-structure interaction by modeling the fluid lading with a Lagrangian mesh [14]. In addition, material failure is included in the analyses by assuming that failure initiates when the effective plastic strain exceeds a critical value for a given state of stress or stress triaxiality [25].…”

Section: Refined Analysismentioning

confidence: 99%

“…The analyses must account for the key physical aspects of collisions which include: (1) quantifying forces and deformations as functions of time which define the forcedeformation or force-indentation characteristic, (2) elasticplastic stress-strain behavior with large deformations, (3) fluidstructure interaction, and (4) material failure. For example, detailed finite element analysis modeling of a conventional chlorine tank car under generalized head [14] and shell [15] impacts have been conducted. Full-scale shell impact testing of the conventional chlorine tank car [16] was funded and conducted by the NGRTC project to validate the detailed FEA model.…”

Section: Evaluate Structural Behavior Of Current Designsmentioning

confidence: 99%

Improved Tank Car Design Development: Ongoing Studies on Sandwich Structures

Jeong

Tyrell

Carolan

et al. 2009

2009 Joint Rail Conference

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The Government and industry have a common interest in improving the safety performance of railroad tank cars carrying hazardous materials. Research is ongoing to develop strategies to maintain the structural integrity of railroad tank cars carrying hazardous materials (hazmat) during collisions.This paper describes engineering studies on improved tank car concepts. The process used to formulate these concepts is based on a traditional mechanical engineering design approach. This approach includes initially defining the desired performance, developing strategies that are effective in meeting this performance, and developing the tactics for implementing the strategies. The tactics are embodied in the concept. The tactics and concept evolve through engineering design studies, until a design satisfying all of the design requirements is developed.Design requirements include service, manufacturing, maintenance, repair, and inspection requirements, as well as crashworthiness performance requirements.One of the concepts under development encases the pressurized commodity-carrying tank in a separate carbody. Moreover, this improved tank car concept treats the pressurized commodity-carrying tank as a protected entity. Welded steel sandwich structures are examined as a means to offer protection of the commodity tank against penetrations from impacting objects in the event of a collision. Sandwich structures can provide greater strength than solid plates of equal weight. Protection of the tank is realized through blunting of the impacting object and absorption of the collision energy. Blunting distributes impact loads over a larger area of the tank. Energy absorption reduces the demands on the commodity tank in the event of an impact. In addition, the exterior carbody structure made from sandwich panels is designed to take all of the in-service loads, removing the commodity tank from the load path during normal operations.Design studies described in this paper focus on the protection aspect of using sandwich structures. Studies are conducted to investigate the influence of different parameters, such as sandwich height and core geometry, on the forcedeformation behavior of sandwich structures. Calculations are carried out numerically using nonlinear finite element analysis. These analyses are used to examine the crashworthiness performance of the conceptual design under generalized impact scenarios.

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Finite Element Analyses of Railroad Tank Car Head Impacts

Cited by 12 publications

References 6 publications

Modeling the Dynamic Failure of Railroad Tank Cars Using a Physically Motivated Internal State Variable Plasticity/Damage Nonlocal Model

Modeling the Dynamic Failure of Railroad Tank Cars Using a Physically Motivated Internal State Variable Plasticity/Damage Nonlocal Model

Modeling Material Failure During Cab Car End Frame Impact

Improved Tank Car Design Development: Ongoing Studies on Sandwich Structures

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