Fuel Tank Crashworthiness: Loading Scenarios

2014 Joint Rail Conference

Perlman

2014

Self Cite

The Federal Railroad Administration's Office of Research and Development is conducting research into fuel tank crashworthiness. A series of impact tests are planned to measure fuel tank deformation under two types of dynamic loading conditions -blunt and raking impacts. This paper describes the results of the first set of blunt impact tests for two retired EMD F-40 locomotive fuel tanks, Tank 232 and Tank 202.On October 8, 2013 and October 9, 2013, the FRA performed impact tests on two conventional passenger locomotive fuel tanks at the Transportation Technology Center (TTC) in Pueblo, Colorado. Each fuel tank was emptied of fluid and mounted on a crash wall with the bottom surface exposed. A rail cart modified with a "rigid" indenter was released to impact the center of the bottom of each fuel tank at about 6 mph. A center-impact on Tank 232 was chosen to impact between two baffles. A center-impact on Tank 202 was chosen to impact on a baffle.In the first test, Tank 232 was impacted by the indenter at 4.5 mph. The maximum residual indentation on the bottom of the tank measured approximately 5 inches. The tank deformed across the middle longitudinal span of the tank forming a diamond-shaped indention. In the second test, Tank 202 was impacted by the indenter at 6.2 mph. The maximum residual indentation on the bottom of the tank measured approximately 1.5 inches. The bottom of the tank deformed with an "X" shape spanning out from the location of square indenter at the center of the tank.Post-test autopsies revealed the deformation of the interior structures, i.e. baffles and attachments. There was no damage to the baffles in Tank 232. Deformation to the interior structure of Tank 202 was limited to the baffle directly beneath the impact location, which folded in the area near the impact location. Material coupons were cut and tensile testing performed to determine the properties of the materials used in each tank.Prior to the test, computer models were developed from measurements taken on the test articles. Material properties were estimated based on Brinell hardness measurements. Computer analyses were conducted to determine the conditions for the test, i.e. instrumentation, location of impact, target impact speeds and to predict the deformation behavior of the tank. Post-test, the resulting stress-strain relationships for the bottom sheets and baffles of both tanks were used to update the finite element models of the two tanks. The models were also updated to reflect the actual geometry of the tanks as confirmed by measurements of the tank interiors. The results of the finite element (FE) models run at the test conditions with the updated tank details are compared with the results from the test itself. Specifically, the deformation progression and the residual dent depth are compared between the tests and the models.In accidents, fuel tanks are subjected to dynamic loading, often including a blunt or raking impact from various components of the rolling stock or trackbed. Current design practice requires...

Section: Figure 1 Flow Diagram Of Crashworthiness Research Methodologymentioning

confidence: 99%

Conventional Fuel Tank Blunt Impact Tests: Test and Analysis Results

2014 Joint Rail Conference

Perlman

2014

Self Cite

“…To develop scenarios for the fuel tank research, FRA conducted a survey of accidents and derailments in the U.S. over the last two decades [1]. Two key findings should be noted from the results of this survey.…”

Section: Figure 1 Flow Diagram Of Crashworthiness Research Methodologymentioning

confidence: 99%

Results of a Conventional Fuel Tank Blunt Impact Test

2015 Joint Rail Conference

2015

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The Federal Railroad Administration's Office of Research and Development is conducting research into passenger locomotive fuel tank crashworthiness. A series of impact tests is being conducted to measure fuel tank deformation under two types of dynamic loading conditions -blunt and raking impacts. This program is intended to result in a better understanding of design features that improve the puncture resistance of passenger locomotive fuel tanks. One reason for performing this program is to aid in development of appropriate standards for puncture resistance to be applied to alternativelydesigned fuel tanks, such as on diesel multiple unit (DMU) passenger rail equipment. This paper describes the results of the third blunt impact test of retired F-40 locomotive fuel tanks.The test setup was designed for the Transportation Technology Center (TTC) in Pueblo, Colorado, to impart blunt impacts to the bottom of each fuel tank specimen. The specimens tested to date are from FRA-owned retired F-40 passenger locomotives. To conduct the test, each tank was emptied of fluid and mounted on a crash wall with the bottom surface exposed. A rail cart modified with a "rigid" indenter measuring 12 inches by 12 inches, was released to impact the bottom of fuel tank at a target impact speed. The first two tests, conducted on October 8 and 9, 2013, were designed to impact the center of two different tank designs. Tests were conducted at impact speeds of 4.5 and 6.2 mph and caused maximum residual dents of 5 inches and 1.5 inches, respectively. On August 20, 2014 the test of fuel tank 234 was conducted to impact the tank off-center between two baffles. Forcedeformation measurements were collected for each tank during the three tests. The series of tests provide information regarding the influence of tank design on puncture resistance.In the test of tank 234, the target impact speed was 12.5 mph, and the actual impact occurred at 11.2 mph. The test resulted in a residual dent depth of approximately 9 inches, and buckling of several internal baffles. The impact did not result in puncture of the tank. Following the test, the tank was cut open to permit examination of the baffles. This examination revealed a different baffle geometry than was modeled based on pre-test measurements.Finite element analysis (FEA) was used to predict the behavior of the tank during the test. The FE model of the tank required several material properties to be defined in order to capture puncture behavior. The combination of metal plasticity, ductile failure, and element removal would permit the model to simulate puncture for this tank. Following the test, the tank was cut open, revealing a different baffle arrangement than had been initially thought. The post-test FE model was then updated to include the actual baffle arrangement of tank 234. With the actual baffle arrangement included in the model, the FE results are in fairly good agreement with the test. Additional changes to the ductile failure criterion were also made in the post-test model.The o...

“…To develop scenarios for the fuel tank research, FRA conducted a survey of accidents and derailments in the U.S. over the last two decades [1]. The survey was conducted using the FRA accident database and includes freight and passenger train fuel tanks that reported a fuel tank rupture during a collision or derailment.…”

Section: Figure 1 Flow Diagram Of Crashworthiness Research Methodologymentioning

confidence: 99%

“…This paper describes and discusses the test setup, pre-test modeling, test and model results, and planned next steps for this DMU fuel tank. Discussion of the previous tests and analyses on conventional locomotive fuel tanks can be found in References [1] through [5].…”

Section: Test Scenario -Blunt Impactmentioning

confidence: 99%

Results of a Diesel Multiple Unit Fuel Tank Blunt Impact Test

2017 Joint Rail Conference

2017

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The Federal Railroad Administration's Office of Research and Development is conducting research into passenger locomotive fuel tank crashworthiness. A series of impact tests is being conducted to measure fuel tank deformation under two types of dynamic loading conditions -blunt and raking impacts. The results of this research program assist in development of appropriate standards for puncture resistance requirements to be applied to alternatively-designed fuel tanks, such as on diesel multiple unit (DMU) passenger rail equipment. This paper describes the results of the first blunt impact test performed on a DMU fuel tank.On June 28, 2016, FRA performed a dynamic impact test of a fuel tank from a DMU rail vehicle. The test was performed at the Transportation Technology Center (TTC) in Pueblo, Colorado. An impact vehicle weighing approximately 14,000 pounds and equipped with a 12-inch by 12-inch impactor head struck the bottom surface of a DMU fuel tank mounted vertically on an impact wall. The impact occurred on the bottom of the fuel tank at a location centered on two baffles within the fuel tank. The target impact speed was 11.5 mph, and the measured impact speed 11.1 mph. The test resulted in a maximum indentation of approximately 8 inches, the bottom of the tank bending away from the wall, and buckling of several internal baffles. Following the test, the tank was cut open to inspect the damage to the internal structure. This revealed that the buckling behavior of the baffles was isolated to the baffles immediately adjacent the impact location, each one buckling as the tank deformed inward.Prior to the test, finite element analysis (FEA) was used to predict the behavior of the tank during the test. The FE model of the tank required material properties to be defined in order to capture plastic deformation. The combination of metal plasticity, ductile failure, and element removal would permit the model to simulate puncture for this tank at sufficiently-high impact speeds. The pre-test FE model results compared very favorably with the test measurements, and both the pre-test model and the test resulted in similar modes of deformation to the DMU fuel tank. Following the test, material coupons were cut from undamaged areas of the fuel tank and subjected to tensile testing. The post-test FE model was updated with the material behaviors from the post-test material testing.This test is part of a research program investigating puncture resistance of passenger locomotive fuel tanks. The objective of this research program is to establish the baseline puncture resistance of current locomotive fuel tanks under dynamic impact conditions and to develop performance requirements for an appropriate level of puncture resistance in alternative fuel tank designs, such as DMU fuel tanks.Future tests are planned within this research program. The lessons learned during the series of tests support finite element (FE) modeling of impact conditions beyond what was tested. Additional tests investigating the puncture resistance of...