scholarly journals Collision safety comparison of conventional and crash energy management passenger rail car designs

2003 ◽  
Author(s):  
K.J. Severson ◽  
D.C. Tyrell ◽  
A.B. Perlman
Keyword(s):  
Energy Management ◽  
Passenger Rail ◽  
Collision Safety

scholarly journals Train-to-Train Impact Test of Crash Energy Management Passenger Rail Equipment: Structural Results

2006 ◽  
Author(s):  
David Tyrell ◽  
Karina Jacobsen ◽  
Eloy Martinez ◽  
A. Benjamin Perlman
Keyword(s):  
Energy Management ◽  
Large Scale ◽  
Equal Mass ◽  
Full Scale ◽  
Full Scale Test ◽  
Design Strategies ◽  
Alternative Design ◽  
Passenger Rail ◽  
Scale Test ◽  
Crush Zone

On March 23, 2006, a full-scale test was conducted on a passenger rail train retrofitted with newly developed cab end and non-cab end crush zone designs. This test was conducted as part of a larger testing program to establish the degree of enhanced performance of alternative design strategies for passenger rail crashworthiness. The alternative design strategy is referred to as crash energy management (CEM), where the collision energy is absorbed in defined unoccupied locations throughout the train in a controlled progressive manner. By controlling the deformations at critical locations the CEM train is able to protect against two dangerous modes of deformation: override and large-scale lateral buckling. The CEM train impacted a standing locomotive-led train of equal mass at 31 mph on tangent track. The interactions at the colliding in Interface and between coupled interfaces performed as expected. Crush was pushed back to subsequent crush zones and the moving passenger train remained in-line and upright on the tracks with minimal vertical and lateral motions. The added complexity associated with this test over previous full-scale tests of the CEM design was the need to control the interactions at the colliding interface. between the two very different engaging geometries. The cab end crush zone performed as intended because the locomotive coupler pushed underneath the cab car buffer beam, and the deformable anti-climber engaged the uneven geometry of the locomotive anti-climber and short hood. Space was preserved for the operator as the cab end crush zone collapsed. The coupled interfaces performed as predicted by the analysis and previous testing. The conventional interlocking anti-climbers engaged after the pushback couplers triggered and absorbed the prescribed amount of energy. Load was transferred through the integrated end frame, and progressive controlled collapsed was contained to the energy absorbers at the roof and floor level. The results of this full-scale test have clearly demonstrated the significant enhancement in safety for passengers and crew members involved in a push mode collision with a standing locomotive train.

scholarly journals Development of Crash Energy Management Designs for Existing Passenger Rail Vehicles

2004 ◽  
Author(s):  
Eloy Martinez ◽  
David Tyrell ◽  
Benjamin Perlman
Keyword(s):  
Energy Management ◽  
Full Scale ◽  
Lateral Buckling ◽  
Passenger Rail ◽  
Rail Vehicles ◽  
Used Car ◽  
Baseline Levels ◽  
Full Scale Tests ◽  
Prototype Design ◽  
Crush Zone

As part of the passenger equipment crashworthiness research, sponsored by the Federal Railroad Administration and supported by the Volpe Center, passenger coach and cab cars have been tested in inline collision conditions. The purpose of these tests was to establish baseline levels of crashworthiness performance for the conventional equipment and demonstrate the minimum achievable levels of enhancement using performance based alternatives. The alternative strategy pursued is the application of the crash energy management design philosophy. The goal is to provide a survivable volume where no intrusion occurs so that passengers can safely ride out the collision or derailment. In addition, lateral buckling and override modes of deformation are prevented from occurring. This behavior is contrasted with that observed from both full scale tests recently conducted and historical accidents where both lateral buckling and/or override occurs for conventionally designed equipment. A prototype crash energy management coach car design has been developed and successfully tested in two full-scale tests. The design showed significant improvements over the conventional equipment similarly tested. The prototype design had to meet several key requirements including: it had to fit within the same operational volume of a conventional car, it had to be retrofitted onto a previously used car, and it had to be able to absorb a prescribed amount of energy within a maximum allowable crush distance. To achieve the last requirement, the shape of the force crush characteristic had to have tiered force plateaus over prescribed crush distances to allow for crush to be passed back from one crush zone to another. The distribution of crush along the consist length allows for significantly higher controlled energy absorption which results in higher safe closing speeds.

Development of Crash Energy Management Specification for Passenger Rail Equipment

2007 ◽  
Vol 2006 (1) ◽  
pp. 76-83 ◽  
Author(s):  
Jo Strang ◽  
Ron Hynes ◽  
Tom Peacock ◽  
Bill Lydon ◽  
Cliff Woodbury ◽  
...  
Keyword(s):  
Energy Management ◽  
Passenger Rail

scholarly journals Collision Safety Comparison of Conventional and Crash Energy Management Passenger Rail Car Designs

Joint Rail ◽  
2003 ◽  
Author(s):  
Kristine J. Severson ◽  
David C. Tyrell ◽  
A. Benjamin Perlman
Keyword(s):  
Energy Management ◽  
Impact Velocity ◽  
Structural Damage ◽  
Rigid Wall ◽  
Collision Dynamics ◽  
Average Force ◽  
Secondary Impact ◽  
Passenger Rail ◽  
Conventional Design ◽  
The One

In conjunction with full-scale equipment tests, collision dynamics models of passenger rail cars have been developed to investigate the benefits provided by incorporating energy-absorbing crush zones at the ends of the cars. In a collision, the majority of the structural damage is generally focused at the point of impact for cars of conventional design. In contrast, cars with crush zones, or crash energy management (CEM), can better preserve occupied areas by distributing crush to the ends of cars. Impact tests of conventional equipment have already been conducted, which consisted of a single car and two coupled cars colliding with a rigid wall. Corresponding tests are planned using CEM equipment. This paper presents preliminary predictions of the one- and two-car CEM tests, and compares them to the results of the respective conventional equipment tests. The comparison will focus on loss of occupant volume, secondary impact velocity (SIV), and lateral buckling, as measures of occupant protection. The modeling results indicate that the occupant volume can be preserved in both the one-car and two-car tests of the CEM equipment, while 2 1/2 and 3 feet of occupant volume were crushed in the respective tests of conventional equipment. In the two-car model, the CEM design is able to distribute the crush between both cars, whereas the conventional design incurs nearly all the crush at the point of impact. The CEM design can absorb more energy without crushing the occupied area because it requires a higher average force per foot of crush at the vehicle ends. The trade-off associated with this higher crush force is generally a higher SIV for occupants in the CEM cars. Secondary impact velocity refers to the velocity at which an occupant strikes some part of the interior, in this analysis the back of the seat ahead of the occupant. The greatest SIV penalty is in the impacting car. The difference between the SIV for cars in a conventional and a CEM consist decreases in each trailing car. That is, the SIV generally decreases in each trailing car of a CEM consist, while the SIV remains approximately the same in each trailing car of a conventional consist.

Analysis of Collision Safety Associated With Conventional and Crash Energy Management Cars Mixed Within a Consist

2003 ◽  
Author(s):  
Kristine J. Severson ◽  
David C. Tyrell ◽  
A. Benjamin Perlman
Keyword(s):  
Energy Absorption ◽  
Energy Management ◽  
Significant Benefit ◽  
Collision Dynamics ◽  
Dynamics Model ◽  
Safety Hazards ◽  
Passenger Train ◽  
Occupant Protection ◽  
Potential Safety ◽  
Collision Safety

A collision dynamics model of a passenger train-to-passenger train collision has been developed to simulate the potential safety hazards and benefits associated with mixing conventional and crash energy management (CEM) cars within a consist. This paper presents a comparison of estimated injuries and fatalities for seven collision scenarios based upon the variable mix of conventional and CEM cars. Based on the analysis results, recommended car placement when mixing cars within a consist is identified. The model includes a 6 car cab car-led consist colliding with a 6 car locomotive-led stationary consist. The stationary consist is made up of all conventional cars. The moving consist has a variable mix of conventional and CEM cars. For comparison, the bounding scenarios are: - a moving consist with all conventional cars, and - a moving consist with all CEM cars. The collision speed ranges from 15 to 35 mph. Since the two car designs behave differently under impact conditions, there is a concern that there may be hazards associated with mixing the two designs in the same consist. In none of the cases evaluated is the mixed consist less crashworthy than the conventional consist. The modeling results indicate that the least crashworthy consists are ones in which a conventional cab car is leading any combination of vehicles. The conventional cab car incurs nearly all the damage and prevents trailing cars from participating in energy absorption, whether they are conventional or CEM. The most crashworthy consists are ones in which a CEM cab is leading. The CEM cab can absorb a significant amount of energy without intruding into the occupied volume. The CEM cab also allows trailing cars to participate in energy absorption, which provides further occupant protection. The recommended strategy for car placement is to put the CEM car(s) at the leading end(s) and the conventional car(s) at the trailing end or in the middle of the consist in push-pull operation. There is also significant benefit to placing the seats in the leading CEM car or two so they are rear-facing. Rear-facing seats can reduce the severity of secondary impact injuries because the occupant is already in contact with the seat in the direction of travel and does not develop a significant velocity relative to the seat.

scholarly journals Impact Test of a Crash-Energy Management Passenger Rail Car

Joint Rail ◽  
2004 ◽  
Author(s):  
Karina Jacobsen ◽  
David Tyrell ◽  
Benjamin Perlman
Keyword(s):  
Energy Management ◽  
Impact Test ◽  
Test Results ◽  
Structural Components ◽  
Passenger Car ◽  
Dynamic Component ◽  
Car Body ◽  
Passenger Rail ◽  
The Impact ◽  
Crush Zone

On December 3, 2003, a single-car impact test was conducted to assess the crashworthiness performance of a modified passenger rail car. A coach car retrofitted with a Crash Energy Management (CEM) end structure impacted a fixed barrier at approximately 35 mph. This speed is just beyond the capabilities of current equipment to protect the occupants. The test vehicle was instrumented with accelerometers, string potentiometers, and strain gages to measure the gross motions of the car body in three dimensions, the deformation of specific structural components, and the force/crush characteristic of the impacted end of the vehicle. The CEM crush zone is characterized by three structural components: a pushback coupler, a sliding sill (triggering the primary energy absorbers), and roof absorbers. These structural mechanisms guide the impact load and consequent crush through the end structure in a prescribed sequence. Pre-test activities included quasi-static and dynamic component testing, development of finite element and collision dynamics models and quasi-static strength tests of the end frame. These tests helped verify the predicted structural deformation of each component, estimate a force-crush curve for the crush zone, predict the gross motions of the car body, and determine instrumentation and test conditions for the impact test. During the test, the passenger car sustained approximately three feet of crush. In contrast to the test of the conventional passenger equipment, the crush imparted on the CEM vehicle did not intrude into the passenger compartment. However, as anticipated the car experienced higher accelerations than the conventional passenger car. Overall, the test results for the gross motions of the car are in close agreement. The measurements made from both tests show that the CEM design has improved crashworthiness performance over the conventional design. A two-car test will be performed to study the coupled interaction of CEM vehicles as well as the occupant environment. The train-to-train test results are expected to show that the crush is passed sequentially down the interfaces of the cars, consequently preserving occupant volume.

scholarly journals The Influence of Manufacturing Variations on a Crash Energy Management System

2008 ◽  
Author(s):  
Philip Mallon ◽  
Benjamin Perlman ◽  
David Tyrell
Keyword(s):  
Energy Management ◽  
Energy Levels ◽  
Primary Energy ◽  
Coupling Mechanism ◽  
Lumped Mass ◽  
Mass Model ◽  
Average Force ◽  
Energy Absorber ◽  
Passenger Rail ◽  
Manufacturing Tolerances

Crash Energy Management (CEM) systems protect passengers in the event of a train collision. A CEM system distributes crush throughout designated unoccupied crush zones of a passenger rail consist. This paper examines the influence of manufacturing variations in the CEM system on the crashworthiness of CEM passenger rail equipment. To perform effectively, a CEM system must have certain features. A coupling mechanism allows coupled cars to come together in a controlled fashion and absorb energy. A load transfer mechanism ensures that the car ends mate and maintain contact. A principal energy absorber mechanism is responsible for absorbing the vast majority of crash energy. These components function by providing an increasing force-crush characteristic when they are overloaded. The force-crush behavior can vary due to manufacturing tolerances. For the purposes of this research, the pushback coupler, the deformable anticlimber, and the primary energy absorber were the devices that performed these functions. It was confirmed in this study that the force-crush characteristic of the pushback coupler and the primary energy absorber have the greatest influence on crashworthiness performance. To represent the influence of these parameters, the average force of the pushback coupler and the average force of the primary energy absorber were examined. A cab-led passenger train impacting a standing freight consist was represented as a one-dimensional lumped-mass model. The force-crush characteristic for each coach car end was adjusted to examine the effects of variation in manufacturing. Each car end was modified independently while holding all other car ends constant. The model used in this study was designed to be comparable with a 30 mph, full-scale, train-to-train CEM test. Using crush distribution and secondary impact velocity as measures of crashworthiness, the standard CEM consist performance has a maximum crashworthiness speed limit of 40 mph. Percent total energy absorbed was used as a means of comparison between cars for each consist configuration. When energy absorption levels are decreased at any particular car end, crush tends to be drawn towards this car end. Correspondingly, when available energy levels are increased at a car end, crush is drawn away from this car end. For both cases, the overall distribution of crush has more of an effect locally and less of an effect at other coupled interfaces. This paper shows that moderate variations in crush behavior may occur due to manufacturing tolerances and have little influence on the crashworthiness performance of CEM systems.

Overview of a Crash Energy Management Specification for Passenger Rail Equipment

2006 ◽  
Author(s):  
David Tyrell ◽  
Eloy Martinez ◽  
Kristine Severson ◽  
Karina Jacobsen ◽  
Daniel Parent ◽  
...  
Keyword(s):  
Energy Management ◽  
Passenger Rail

scholarly journals Train-to-Train Impact Test of Crash Energy Management Passenger Rail Equipment: Occupant Experiments

2006 ◽  
Author(s):  
Kristine J. Severson ◽  
Daniel P. Parent
Keyword(s):  
Energy Management ◽  
Injury Risk ◽  
Impact Test ◽  
Full Scale ◽  
Passenger Cars ◽  
Occupant Protection ◽  
Injury Threshold ◽  
Passenger Rail ◽  
Upper Abdominal ◽  
Head And Neck Injury

As part of an ongoing passenger rail crashworthiness effort, a full-scale impact test of a train with crash energy management (CEM) passenger cars was conducted on March 23, 2006. In this test, a train made up of a CEM cab car, four CEM coach cars, and a locomotive impacted a stationary train of similar mass at 30.8 mph. This test included five occupant experiments on the cab car and the first coach car to evaluate occupant injury risk and seat/table performance during the collision using anthropomorphic devices (ATDs). Three occupant protection strategies were evaluated in these occupant experiments. Forward-facing intercity seats were modified to reduce the high head injury risk observed in a previous test. Prototype commuter seats, included in both forward-facing and rear-facing orientations, were designed to mitigate the consequences of higher decelerations in the lead two CEM cars. Improved workstation tables, tested with two different advanced ATDs, were designed to compartmentalize the occupants and reduce the upper abdominal injury risk to the occupants. Similar experiments were also conducted on the two-car impact test of CEM equipment [1]. The experiments described in this paper were conducted to evaluate the level of occupant protection provided by seats and tables that were specifically designed to improve crashworthiness. Pre-test analyses indicated that the occupant environment would be more severe for the CEM test than for the comparable test of conventional equipment. The environment in the leading cab car was predicted to be similar to a 12g, 250 millisecond triangular crash pulse. The environment in the first coach was predicted to be comparable to an 8g, 250 millisecond crash pulse. To aid the design of the occupant experiments, occupant response models were developed for each of the occupant experiments using MADYMO. These models were developed for the previous two-car CEM full-scale test and adapted to the newly designed commuter seats and tables. Predictions of the occupant response during the CEM train-to-train test were developed before the test. The models were subsequently fine-tuned to better agree with the test data, so that many different collision scenarios may be simulated. Most of the test results were similar to the pre-test predictions. The modified intercity seats successfully compartmentalized the occupants. The risk of both head and neck injury, however, were above the respective injury threshold values. In the forward-facing commuter seat experiment the impacted seat experienced a partial failure of the seat pedestal attachment, resulting in loss of compartmentalization. The attachment failures occurred because the seats weren't fabricated as designed. However, the occupants were still compartmentalized, and the injury criteria were within survivable levels. The rear-facing commuter seat experiment experienced a more significant failure of the seat pedestal attachment, resulting in a loss of compartmentalization. The attachment failures likely occurred because the seats were not fabricated as designed and the collision was slightly more severe than predicted. To assure that this failure mode is prevented in the future, a more robust attachment is currently being developed. It will be tested quasi-statically and dynamically to demonstrate its effectiveness. The improved workstation tables successfully compartmentalized the occupants while limiting the injury risk to acceptable levels.

scholarly journals Impact Tests of Crash Energy Management Passenger Rail Cars: Analysis and Structural Measurements

2004 ◽  
Author(s):  
Karina Jacobsen ◽  
David Tyrell ◽  
Benjamin Perlman
Keyword(s):  
Energy Management ◽  
Three Dimensions ◽  
Test Results ◽  
Strain Gages ◽  
Collision Dynamics ◽  
Passenger Cars ◽  
Impact Tests ◽  
Passenger Rail ◽  
Conventional Tests ◽  
Dynamics Models

Two full-scale impact tests were conducted to measure the crashworthiness performance of Crash Energy Management (CEM) passenger rail cars. On December 3, 2003 a single car impacted a fixed barrier at approximately 35 mph and on February 26, 2004, two-coupled passenger cars impacted a fixed barrier at approximately 29 mph. Coach cars retrofitted with CEM end structures, which are designed to crush in a controlled manner were used in the test. These test vehicles were instrumented with accelerometers, string potentiometers, and strain gages to measure the gross motions of each car body in three dimensions, the deformation of specific structural components, and the force-crush characteristic of the CEM end structure. Collision dynamics models were developed to predict the gross motions of the test vehicle. Crush estimates as a function of test speed were used to guide test conditions. This paper describes the results of the CEM single-car and two-car tests and provides results of the structural test. The single-car test demonstrated that the CEM design successfully prevented intrusion into the occupied volume, under similar conditions as the conventional test. During both CEM tests, the leading passenger car crushed approximately three feet, preserving the occupant compartment. In the two-car test, energy dissipation was transferred to the coupled interface, with crush totaling two feet between the two CEM end structures. The pushback of the couplers kept the cars in-line, limiting the vertical and lateral accelerations. In both the conventional tests there was intrusion into the occupant compartment. In the conventional two-car test sawtooth lateral buckling occurred at the coupled connection. Overall, the test results and model show close agreement of the gross motions. The measurements made from both tests demonstrate that the CEM design has improved crashworthiness performance over the conventional design.

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