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.

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 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 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.

Using Conventional Articulation Tests With Highly Unintelligible Children

1992 ◽  
Vol 23 (1) ◽  
pp. 52-60 ◽  
Author(s):  
Pamela G. Garn-Nunn ◽  
Vicki Martin
Keyword(s):  
Test Results ◽  
Phonological Processes ◽  
Rule Based ◽  
Severity Level ◽  
Error Sensitivity ◽  
Conventional Tests ◽  
Severity Levels ◽  
Conventional Test ◽  
Impaired Children

This study explored whether or not standard administration and scoring of conventional articulation tests accurately identified children as phonologically disordered and whether or not information from these tests established severity level and programming needs. Results of standard scoring procedures from the Assessment of Phonological Processes-Revised, the Goldman-Fristoe Test of Articulation, the Photo Articulation Test, and the Weiss Comprehensive Articulation Test were compared for 20 phonologically impaired children. All tests identified the children as phonologically delayed/disordered, but the conventional tests failed to clearly and consistently differentiate varying severity levels. Conventional test results also showed limitations in error sensitivity, ease of computation for scoring procedures, and implications for remediation programming. The use of some type of rule-based analysis for phonologically impaired children is highly recommended.

scholarly journals Development Instruments Through Confirmatory Factor Analysis (CFA) in Appropriate Intensity Assessment

2017 ◽  
Vol 12 (1) ◽  
pp. 13-19
Author(s):  
Ari Saptono
Keyword(s):  
Factor Analysis ◽  
Confirmatory Factor Analysis ◽  
Three Dimensions ◽  
Likelihood Method ◽  
Test Results ◽  
Validity And Reliability ◽  
Measurement Instruments ◽  
School Students ◽  
Multi Stage ◽  
Confirmatory Factor

The research aims to develop the valid and reliable measurement instruments of entrepreneurship intention in vocational secondary school students. Multi stage random sampling was used as the technique to determine sample (300 respondents). The research method used research and development with confirmatory factor analysis (CFA). Result of confirmatory factor analysis (CFA) at the second order with robust maximum likelihood method shows that valid and reliable instrument with the acquisition value of loading factor is more than 0.5 (> 0,5) and a significance value of t is more than 1,96 (> 1,96). Reliability test results shows that the value of the combined construct reliability (CR) of 0.97and a variance value extract (VE) to 0.52 is greater than the limit of acceptance CR ? 0.70 and VE ? 0.50. The conclusion of the measurement instruments of entrepreneurship intention with three dimensions and 31 items met the standards of validity and reliability in accordance with the instrument development process.

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.

PREDICTION OF A MODIFIED PTW MODEL FOR VARIOUS TAYLOR IMPACT TESTS OF TANTALUM

2008 ◽  
Vol 22 (31n32) ◽  
pp. 6247-6252 ◽  
Author(s):  
JONG-BONG KIM ◽  
HYUNHO SHIN
Keyword(s):  
Strain Rate ◽  
Strain Hardening ◽  
Impact Test ◽  
Constitutive Behavior ◽  
Test Results ◽  
Impact Tests ◽  
Different Temperatures ◽  
Taylor Impact ◽  
Prediction Capability ◽  
Voce Equation

The strain hardening part of the Preston-Tonks-Wallace (PTW) model, developed for the description of the plastic constitutive behavior of materials at wide ranges of strain, strain rate, and temperature, has been modified by employing the Voce equation. The prediction capability of the modified PTW (MPTW) has been investigated with reference to Taylor impact test results in the literature, and comparison has been made with the models of Johnson-Cook (JC), Steiberg-Guinan (SG), Zerilli-Armstrong (ZA), and PTW. Of the compared existing models, no model was appropriate for describing the results of various Taylor impact tests. However, the modified PTW is shown to predict fairly accurate results in terms of the length, diameter, and shape of the deformed specimen tested at different temperatures and impact velocity.

A rapid method for planning paths in three dimensions for a small aerial robot

Robotica ◽  
2001 ◽  
Vol 19 (2) ◽  
pp. 125-135 ◽  
Author(s):  
M. Williams ◽  
D.I. Jones
Keyword(s):  
Path Planning ◽  
Computational Algorithm ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Computer Memory ◽  
Test Results ◽  
Effective Operation ◽  
Execution Speed ◽  
Aerial Vehicle ◽  
Electricity Power

This paper describes a path planning method for a small autonomous aerial vehicle to be used for inspecting overhead electricity power lines. A computational algorithm is described which converts a standard three dimensional array representation of one or more obstacles in the vehicle's environment into an octree and a connectivity graph. This achieves a significant reduction in computer memory usage and an increase in execution speed when the graph is searched. Path planning is based on a three-dimensional extension of the distance transform. Test results demonstrate rapid and effective operation of the planner within different workspaces.

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