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.

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.

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.

Study on Light Induced Leakage Current Related to Amorphous Silicon TFT Design

2007 ◽  
Vol 124-126 ◽  
pp. 259-262
Author(s):  
Jae Hong Jeon ◽  
Kang Woong Lee
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Leakage Current ◽  
Thin Film Transistor ◽  
Silicon Layer ◽  
Gate Electrode ◽  
Silicon Thin Film ◽  
Pattern Design ◽  
Conventional Design ◽  
The One

We investigated the effect of amorphous silicon pattern design regarding to light induced leakage current in amorphous silicon thin film transistor. In addition to conventional design, where amorphous silicon layer is protruding outside the gate electrode, we designed and fabricated amorphous silicon thin film transistors in another two types of bottom gated structure. The one is that the amorphous silicon layer is located completely inside the gate electrode and the other is that the amorphous silicon layer is protruding outside the gate electrode but covered completely by the source and drain electrode. Measurement of the light induced leakage current caused by backlight revealed that the design where the amorphous silicon is located inside the gate electrode was the most effective however the last design was also effective in reducing the leakage current about one order lower than that of the conventional design.

scholarly journals Passenger Car Energy Demand Assessment: a New Approach Based on Road Traffic Data

2020 ◽  
Vol 197 ◽  
pp. 05006
Author(s):  
Umberto Previti ◽  
Sebastian Brusca ◽  
Antonio Galvagno
Keyword(s):  
Energy Management ◽  
Energy Demand ◽  
Electric Propulsion ◽  
Road Traffic ◽  
Driving Cycle ◽  
City Centre ◽  
Automotive Market ◽  
Driving Cycles ◽  
Traffic Level ◽  
The One

Nowadays the automotive market is oriented to the production of hybrid or electric propulsion vehicle equipped with Energy Management System that aims to minimize the consumption of fossil fuel. The EMS, generally, performs a local and not global optimization of energy management due to the impossibility of predicting the user’s energy demand and driving conditions. The aim of this research is to define a driving cycle (speed time) knowing only the starting and the arrival point defined by the driver, considering satellite data and previous experiences. To achieve this goal, the data relating to the energy expenditure of a car (e.g. speed, acceleration, road inclination) will be acquired, using on-board acquisition system, during road sections in the city of Messina. At the same time, the traffic level counterplot and others information provided, for these specific sections, from GPS acquisition software will be collected. On-board and GPS data will be compared and, after considering an adequate number of acquisitions, each value of the traffic level will be associated with a driving cycle obtained by processing the acquired data. After that, the numerical model of a car will be created which will be used to compare the energy demand of two driving cycles. The first one acquired on a section with a random starting and destination point inside the historic city centre of Messina. The second is the one assigned, for that same section, considering only the value of the traffic level counterplot.

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.

Shock compression of a perfect gas

1956 ◽  
Vol 1 (4) ◽  
pp. 399-408 ◽  
Author(s):  
Cerda Evans ◽  
Foster Evans
Keyword(s):  
Shock Compression ◽  
Entropy Change ◽  
Rigid Wall ◽  
Adiabatic Process ◽  
Perfect Gas ◽  
Compression Process ◽  
Specific Heats ◽  
Initial Shock ◽  
The One ◽  
Shock Reflections

The compression of a perfect gas between a uniformaly moving piston and a rigid wall is discussed in the one-dimensional case. If the piston moves with a finite speed, it will initiate a shock in the gas which will reflect successively from rigid wall and piston and cause the compression process to deviate from a reversible adiabatic process. Expressions are derived for the relative changes in pressure and density at each shock reflection. Then values of density and pressure after any number of shock reflections are computed relative to their initial values, and, in terms of these, the corresponding values of temperature and entropy, as well as shock speeds, are determined. The limiting value of the entropy change, as the number of reflections goes to infinity, is obtained as a function of the ratio of specific heats of the gas and the strength of the initial shock. Hence it is possible to estimate an upper limit to the deviation of the shock compression process from a reversible adiabatic process. Some illustrative numerical examples are given.

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.

scholarly journals Crashworthiness Requirements for Commuter Rail Passenger Seats

2005 ◽  
Author(s):  
Kristine J. Severson ◽  
David C. Tyrell ◽  
Robert Rancatore
Keyword(s):  
Analytical Models ◽  
Crash Test ◽  
Collision Dynamics ◽  
Element Analysis ◽  
Secondary Impact ◽  
Impact Surface ◽  
Commuter Rail ◽  
Crashworthiness Design ◽  
Occupant Injury ◽  
Design Requirements

Occupant experiments using instrumented crash test dummies seated in commuter rail seats have been conducted on board full-scale impact tests of rail cars. The tests have been conducted using both conventional cars and cars modified to incorporate crash energy management (CEM). Test results indicate that an improved commuter seat design could significantly reduce occupant injuries associated with collisions of CEM railcars. Commuter seats built to specific crashworthiness design requirements can mitigate the increased severity of secondary impacts associated with CEM equipment. In a collision, the leading car or two in a CEM consist may have a more severe longitudinal crash pulse than the leading car in a conventional consist. The crash pulse associated with a leading CEM cab car results in a higher secondary impact velocity between the unrestrained occupant and the seat, when compared to a conventional cab car. This conclusion applies to both rear- and forward-facing occupants. As a result, the seat must absorb more energy, which may cause significant deformation of the seat back, preventing occupant compartmentalization. Compartmentalization is an occupant protection strategy that aims to: contain occupants between rows of seats, provide a ‘friendly’ impact surface, and prevent tertiary impacts with other objects. To compartmentalize occupants during a collision, seats must be relatively stiff. To limit the forces and accelerations associated with occupant injury, the seat must be compliant, absorbing the occupant’s kinetic energy as it deforms. The objective of seat design crashworthiness requirements is to strike a balance between the competing objectives of compartmentalization and minimizing occupant injury. Work is currently on-going to design, build and test a prototype 3-passenger commuter rail seat that will improve interior crashworthiness. The first step is to develop the design requirements, which are based on a head-on collision between a CEM cab car-led train and a CEM locomotive-led train. The seat design will be evaluated using quasi-static and dynamic finite element analysis. The occupant response will be evaluated using a collision dynamics model two rows of seats and three Hybrid III 50th percentile anthropomorphic test devices (ATDs). The seat design will be modified until the analytical models demonstrate that it meets the design requirements. Finally the prototype seat will be fabricated and tested quasi-statically and dynamically to ensure that the seat meets the design requirements. This paper describes the performance-based requirements that the prototype commuter rail seat must meet. Performance-based requirements include occupant compartmentalization, maximum allowable injury criteria, and maximum allowable permanent seat deformations. The paper also provides strategies for designing commuter seats that are better able to manage and dissipate the energy during a secondary impact. The paper describes computer models used to determine if the seats meet the design requirements.

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

Impact Crushing and Rebound of Thin-Walled Hollow Spheres

2013 ◽  
Vol 535-536 ◽  
pp. 40-43 ◽  
Author(s):  
Rong Hao Bao ◽  
T.X. Yu
Keyword(s):  
Impact Velocity ◽  
Analytical Modeling ◽  
Hollow Spheres ◽  
Rigid Wall ◽  
Coefficient Of Restitution ◽  
Dynamic Responses ◽  
Relative Thickness ◽  
Thin Walled ◽  
Impact Crushing ◽  
The Impact

The dynamic behavior of a thin-walled hollow sphere colliding onto a rigid wall has been studied by experiments, numerical simulation and analytical modeling, as reported in our previous papers. In the present paper, the impact crushing of metallic thin-walled hollow spheres onto rigid plates and the subsequent rebound are analyzed using finite element method. The effects of hollow sphere’s thickness-to-radius ratio, the material properties and the impact velocity on the dynamic responses are systematically investigated. The transition from axisymmetric dimpling to non-axisymmetric lobing is found to depend on the relative thickness of spheres and impact velocity; while the coefficient of restitution almost merely depends on impact velocity.

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