Engineering Analyses for Railroad Tank Car Head Puncture Resistance

IEEE/ASME/ASCE 2008 Joint Rail Conference

et al. 2008

Self Cite

This paper examines impacts to the side of railroad tank cars by a ram car with a rigid indenter using dynamic, nonlinear finite element analysis (FEA). Such impacts are referred to as shell impacts. Here, nonlinear means elasticplastic material behavior with large deformations. Several computational issues are addressed. The dynamic response of the shell structure coupled with the sloshing response of fluid inside the tank is characterized through various mesh formulations. Puncture of the tank is calculated using a material failure criterion based on the general state of stress in the shell structure in terms of stress triaxiality. The FEA models were verified and validated in previous work. In the present work, the verified and validated FEA framework is applied to examine the effect of various factors on the structural response of the tank. These factors include shell thickness and indenter geometry.

Section: Appendixmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Analysis of Railroad Tank Car Shell Impacts Using Finite Element Method

Jeong

Gordon

IEEE/ASME/ASCE 2008 Joint Rail Conference

et al. 2008

Self Cite

“…The comparisons indicated that the estimates for puncture velocity tend to be conservative [6][7]. In this context, conservative means that puncture is expected to occur at velocities greater than the calculated value.…”

Section: Figure 1: Generalized Tank Car Head Impact Scenariomentioning

confidence: 99%

Semi-Analytical Approach to Estimate Railroad Tank Car Shell Puncture

Jeong

2011 Joint Rail Conference

Perlman

2011

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 [1].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.

“…Results from FEA models were presented previously in reference [5], but the effects of This material is declared a work of the U.S. Government and is not subject to copyright protection in the United States. Approved for public release; distribution is unlimited.…”

Section: Introductionmentioning

confidence: 99%

“…More recently, the focus of the research has shifted to also maintain tank integrity under rare and extreme circumstances such as impact loading during accidents. Previous research has been conducted by the Volpe Center to examine tank car impacts to the head [5] and the side or shell [6,7] of tank cars. Such failures occur from collisions with objects such as couplers and wheels from adjacent cars, broken rails, etc.…”

Section: Introductionmentioning

confidence: 99%

Finite Element Analyses of Railroad Tank Car Head Impacts

ASME 2008 Rail Transportation Division Fall Technical Conference

Yu²,

Gordon

et al. 2008

Self Cite

This paper describes engineering analyses of a railroad tank car impacted at its head by a rigid punch. This type of collision, referred to as a head impact, is examined using dynamic, nonlinear finite element analysis (FEA). Commercial software packages ABAQUS and LS-DYNA are used to carry out the nonlinear FEA. The sloshing response of fluid and coupled dynamic behavior between the fluid inside the tank car and the tank structure are characterized in the model using both Lagrangian and Eulerian mesh formulations. The analyses are applied to examine the structural behavior of railroad tank cars under a generalized head impact scenario. Structural behavior is calculated in terms of forces, deformations, and puncture resistance. Results from the two finite element codes are compared to verify this methodology for head impacts. In addition, FEA results are compared to those from a semi-empirical method.