scholarly journals Modeling Tire Blow-Out in Roadside Hardware Simulations Using LS-DYNA

2003 ◽  
Author(s):  
Fabio Orengo ◽  
Malcolm H. Ray ◽  
Chuck A. Plaxico
Keyword(s):  
Real World ◽  
Full Scale ◽  
Strongly Coupled ◽  
Rubber Tire ◽  
Improved Model ◽  
Roadside Hardware ◽  
Crash Tests

Often when vehicles interact with roadside hardware like guardrails, bridge rails and curbs, the interaction between the roadside hardware and the tire causes the tire to lose its air seal and “blow-out”. Once the seal between the rim and rubber tire is lost, the tire deflates. The behavior of the deflated tire is much different than the behavior of an inflated tire such that when this behavior is observed in real world crashes or in full-scale crash tests, the vehicle kinematics are strongly coupled to the behavior of the deflated tire. Accounting for this behavior in LS-DYNA models is crucial in many types of roadside hardware simulations since the forces generated by the deflated tire often introduce instability into the vehicle that can cause rollover or spinout. This paper will present a method for accounting for tire deflation during LS-DYNA simulations and will present examples of the use of this type of improved model.

Vertical Boilerplate

2017 ◽  
Author(s):  
James Gibson
Keyword(s):  
Market Power ◽  
Real World ◽  
Empirical Work ◽  
Full Scale ◽  
Market Mechanism ◽  
Law School ◽  
Information Cost ◽  
Information Costs ◽  
Policy Proposals ◽  
Radical Solution

Despite what we learn in law school about the “meeting of the minds,” most contracts are merely boilerplate—take-it-or-leave-it propositions. Negotiation is nonexistent; we rely on our collective market power as consumers to regulate contracts’ content. But boilerplate imposes certain information costs because it often arrives late in the transaction and is hard to understand. If those costs get too high, then the market mechanism fails. So how high are boilerplate’s information costs? A few studies have attempted to measure them, but they all use a “horizontal” approach—i.e., they sample a single stratum of boilerplate and assume that it represents the whole transaction. Yet real-world transactions often involve multiple layers of contracts, each with its own information costs. What is needed, then, is a “vertical” analysis, a study that examines fewer contracts of any one kind but tracks all the contracts the consumer encounters, soup to nuts. This Article presents the first vertical study of boilerplate. It casts serious doubt on the market mechanism and shows that existing scholarship fails to appreciate the full scale of the information cost problem. It then offers two regulatory solutions. The first works within contract law’s unconscionability doctrine, tweaking what the parties need to prove and who bears the burden of proving it. The second, more radical solution involves forcing both sellers and consumers to confront and minimize boilerplate’s information costs—an approach I call “forced salience.” In the end, the boilerplate experience is as deep as it is wide. Our empirical work should reflect that fact, and our policy proposals should too.

scholarly journals Is Acceleration a Valid Proxy for Injury Risk in Minimal Damage Traffic Crashes? A Comparative Review of Volunteer, ADL and Real-World Studies

2021 ◽  
Vol 18 (6) ◽  
pp. 2901
Author(s):  
Paul S. Nolet ◽  
Larry Nordhoff ◽  
Vicki L. Kristman ◽  
Arthur C. Croft ◽  
Maurice P. Zeegers ◽  
...  
Keyword(s):  
Real World ◽  
Injury Risk ◽  
Angular Acceleration ◽  
Traffic Crashes ◽  
Rear Impact ◽  
Comparative Review ◽  
Minimal Damage ◽  
Injury Causation ◽  
Crash Tests ◽  
Biomechanical Approach

Injury claims associated with minimal damage rear impact traffic crashes are often defended using a “biomechanical approach,” in which the occupant forces of the crash are compared to the forces of activities of daily living (ADLs), resulting in the conclusion that the risk of injury from the crash is the same as for ADLs. The purpose of the present investigation is to evaluate the scientific validity of the central operating premise of the biomechanical approach to injury causation; that occupant acceleration is a scientifically valid proxy for injury risk. Data were abstracted, pooled, and compared from three categories of published literature: (1) volunteer rear impact crash testing studies, (2) ADL studies, and (3) observational studies of real-world rear impacts. We compared the occupant accelerations of minimal or no damage (i.e., 3 to 11 kph speed change or “delta V”) rear impact crash tests to the accelerations described in 6 of the most commonly reported ADLs in the reviewed studies. As a final step, the injury risk observed in real world crashes was compared to the results of the pooled crash test and ADL analyses, controlling for delta V. The results of the analyses indicated that average peak linear and angular acceleration forces observed at the head during rear impact crash tests were typically at least several times greater than average forces observed during ADLs. In contrast, the injury risk of real-world minimal damage rear impact crashes was estimated to be at least 2000 times greater than for any ADL. The results of our analysis indicate that the principle underlying the biomechanical injury causation approach, that occupant acceleration is a proxy for injury risk, is scientifically invalid. The biomechanical approach to injury causation in minimal damage crashes invariably results in the vast underestimation of the actual risk of such crashes, and should be discontinued as it is a scientifically invalid practice.

scholarly journals An improved holographic nodal line semimetal

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Yan Liu ◽  
Xin-Meng Wu
Keyword(s):  
Mass Term ◽  
Nodal Line ◽  
Duality Relation ◽  
Strongly Coupled ◽  
Nodal Lines ◽  
Form Field ◽  
Improved Model ◽  
Fermionic Spectrum ◽  
Chern Simons ◽  
Tensor Operators

Abstract We study an improved holographic model for the strongly coupled nodal line semimetal which satisfies the duality relation between the rank two tensor operators $$ \overline{\psi}{\gamma}^{\mu v}\psi $$ ψ ¯ γ μv ψ and $$ \overline{\psi}{\gamma}^{\mu v}{\gamma}^5\psi $$ ψ ¯ γ μv γ 5 ψ . We introduce a Chern-Simons term and a mass term in the bulk for a complex two form field which is dual to the above tensor operators and the duality relation is automatically satisfied from holography. We find that there exists a quantum phase transition from a topological nodal line semimetal phase to a trivial phase. In the topological phase, there exist multiple nodal lines in the fermionic spectrum which are topologically nontrivial. The bulk geometries are different from the previous model without the duality constraint, while the resulting properties are qualitatively similar to those in that model. This improved model provides a more natural ground to analyze transports or other properties of strongly coupled nodal line semimetals.

Component and Full Scale Tests for Suspension Model Validation

2009 ◽  
Author(s):  
Pradeep Mohan ◽  
Dhafer Marzougui ◽  
Cing-Dao Kan ◽  
Kenneth Opiela
Keyword(s):  
Full Scale ◽  
Transportation Safety ◽  
Fe Model ◽  
George Washington ◽  
Model Library ◽  
Safety Research ◽  
Oblique Impacts ◽  
Full Scale Tests ◽  
Suspension Model ◽  
Roadside Hardware

The National Crash Analysis Center (NCAC) at the George Washington University (GWU) has been developing and maintaining a public domain library of LS-DYNA finite element (FE) vehicle models for use in transportation safety research. The recent addition to the FE model library is the 2007 Chevrolet Silverado FE model. This FE model will be extensively used in roadside hardware safety research. The representation of the suspension components and its response in oblique impacts into roadside hardware are critical factors influencing the predictive capability of the FE model. To improve the FE model fidelity and applicability to the roadside hardware impact scenarios it is important to validate and verify the model to multitude of component and full scale tests. This paper provides detailed description of the various component and full scale tests that were performed, specifically, to validate the suspension model of the 2007 Chevrolet Silverado FE model.

A Sub-System Test Methodology for Simulating EEVC Side Impact

2000 ◽  
Author(s):  
Krishnakanth Aekbote ◽  
Srinivasan Sundararajan ◽  
Joseph A. Prater ◽  
Joe E. Abramczyk
Keyword(s):  
Full Scale ◽  
Test Method ◽  
Side Impact ◽  
Vehicle Body ◽  
Crash Test ◽  
Vehicle Performance ◽  
Test Methodology ◽  
Supporting Frame ◽  
The Impact ◽  
Crash Tests

Abstract A sled based test method for simulating full-scale EEVC (European) side impact crash test is described in this paper. Both the dummy (Eurosid-1) and vehicle structural responses were simulated, and validated with the full-scale crash tests. The effect of various structural configurations such as foam filled structures, material changes, rocker and b-pillar reinforcements, advanced door design concepts, on vehicle performance can be evaluated using this methodology at the early stages of design. In this approach, an actual EEVC honeycomb barrier and a vehicle body-in-white with doors were used. The under-hood components (engine, transmission, radiator, etc.), tires, and the front/rear suspensions were not included in the vehicle assembly, but they were replaced by lumped masses (by adding weight) in the front and rear of the vehicle, to maintain the overall vehicle weight. The vehicle was mounted on the sled by means of a supporting frame at the front/rear suspension attachments, and was allowed to translate in the impact direction only. At the start of the simulation, an instrumented Eurosid-1 dummy was seated inside the vehicle, while maintaining the same h-point location, chest angle, and door-to-dummy lateral distance, as in a full-scale crash test. The EEVC honeycomb barrier was mounted on another sled, and care was taken to ensure that weight, and the relative impact location to the vehicle, was maintained the same as in full-scale crash test. The Barrier impacted the stationary vehicle at an initial velocity of approx. 30 mph. The MDB and the vehicle were allowed to slide for about 20 inches from contact, before they were brought to rest. Accelerometers were mounted on the door inner sheet metal and b-pillar, rocker, seat cross-members, seats, and non-struck side rocker. The Barrier was instrumented with six load cells to monitor the impact force at different sections, and an accelerometer for deceleration measurement. The dummy, vehicle, and the Barrier responses showed good correlation when compared to full-scale crash tests. The test methodology was also used in assessing the performance/crashworthiness of various sub-system designs of the side structure (A-pillar, B-pillar, door, rocker, seat cross-members, etc.) of a passenger car. This paper concerns itself with the development and validation of the test methodology only, as the study of various side structure designs and evaluations are beyond the scope of this paper.

scholarly journals The influence of position of the post or its absence on the performance of the cable barrier system

2018 ◽  
Vol 219 ◽  
pp. 02012
Author(s):  
Dawid Bruski ◽  
Stanisław Burzyński ◽  
Jacek Chróścielewski ◽  
Łukasz Pachocki ◽  
Krzysztof Wilde ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Road Safety ◽  
Numerical Study ◽  
Full Scale ◽  
The Road ◽  
Safety Barriers ◽  
Study Results ◽  
Crash Tests

Road safety barriers are used to increase safety in potentially dangerous places on the roads. They are designed and installed on the roads to prevent any vehicle from getting outside the travelled way or from entering the opposite lane of the road. Barriers, which are used on European roads, have to undergo full scale crash tests according to the EN 1317 standards. Nowadays as a supplement to real crash tests, numerical simulations are commonly used. The work concerns the influence of position of the post or its absence on the crashworthiness of the cable barrier based on numerical study results.

Development of a 34-in. Tall Thrie-Beam Guardrail Transition to Accommodate Future Roadway Overlays

2019 ◽  
Vol 2673 (2) ◽  
pp. 489-501
Author(s):  
Scott K. Rosenbaugh ◽  
Ronald K. Faller ◽  
Jennifer D. Schmidt ◽  
Robert W. Bielenberg
Keyword(s):  
Full Scale ◽  
Safety Performance ◽  
Performance Criteria ◽  
Concrete Barriers ◽  
Before And After ◽  
Level 3 ◽  
Crash Tests ◽  
Test Level

Roadway resurfacing and overlay projects effectively reduce the height of roadside barriers placed adjacent to the roadway, which can negatively affect their crashworthiness. More recently, bridge rails and concrete barriers have been installed with slightly increased heights to account for future overlays. However, adjacent guardrails and approach transitions have not yet been modified to account for overlays. The objective of this project was to develop an increased-height approach guardrail transition (AGT) to be crashworthy both before and after roadway overlays of up to 3 in. The 34-in. tall, thrie-beam transition detailed here was designed such that the system would be at its nominal 31-in. height following a 3-in. roadway overlay. Additionally, the upstream end of the AGT incorporated a symmetric W-to-thrie transition segment that would be replaced by an asymmetric transition segment after an overlay to keep the W-beam guardrail upstream from the transition at its nominal 31-in. height. The 34-in. tall AGT was connected to a modified version of the standardized buttress to mitigate the risk of vehicle snag below the rail. The barrier system was evaluated through two full-scale crash tests in accordance with Test Level 3 (TL-3) of AASHTO’s Manual for Assessing Safety Hardware (MASH) and satisfied all safety performance criteria. Thus, the 34-in. tall AGT with modified transition buttress was determined to be crashworthy to MASH TL-3 standards. Finally, implementation guidance was provided for the 34-in. tall AGT and its crashworthy variations.

Development of Universal Breakaway Steel Post for Bullnose Median Barrier

2012 ◽  
Vol 2309 (1) ◽  
pp. 94-104
Author(s):  
Robert W. Bielenberg ◽  
Karla A. Lechtenberg ◽  
Dean L. Sicking ◽  
Steve Arens ◽  
Ronald K. Faller ◽  
...  
Keyword(s):  
Controlled Release ◽  
Full Scale ◽  
Successful Completion ◽  
Safe Alternative ◽  
Long Span ◽  
Level 3 ◽  
Crash Tests ◽  
Test Level ◽  
Bolt Steel ◽  
Satisfactory Manner

A new fracturing-bolt universal breakaway steel post (UBSP) was developed and evaluated for use as a replacement for the controlled-release terminal (CRT) wood post currently used in the Thrie beam bullnose system. After numerous steel post concepts were investigated, a fracturing-bolt steel post was selected as the most promising design. The fracturing-bolt steel post successfully matched the strength and dynamic behavior of the CRT wood post in three impact orientations. The UBSP was incorporated into the Thrie beam bullnose barrier system and subjected to three full-scale vehicle crash tests according to the Test Level 3 guidelines provided in NCHRP Report 350. Test Designations 3–30, 3–31, and 3–38 were chosen to evaluate the performance of the Thrie beam bullnose system with UBSPs. All three full-scale crash tests demonstrated that the UBSP performed in a satisfactory manner in the bullnose system, as the vehicle was captured and safely brought to a controlled stop. On the basis of the successful completion of the three full-scale crash tests, it is recommended that the UBSP be considered a safe alternative to CRT posts in the original Thrie beam bullnose median barrier system. It is also noted that the performance of the UBSP suggests that it may have additional applications, including in long-span guardrail, end terminals, and guardrail in mow strips or encased in pavement.

The Reconstruction Scheme Design and Experiment of the Height-Adjustable W-Beam Guardrail

2012 ◽  
Vol 490-495 ◽  
pp. 2676-2680
Author(s):  
Hong Jun Cui ◽  
Xiao Jing Shen ◽  
Yu Liu ◽  
Xi Xin Sun
Keyword(s):  
Computer Simulation ◽  
Full Scale ◽  
Scheme Design ◽  
Roadside Safety ◽  
Reconstruction Scheme ◽  
Crash Tests

Pave overlay to the freeway repeatedly causes the guardrail’s height lower and lower, which seriously influences its performance in protection and safety. The paper aims to work out a height-adjustable W-beam guardrail which is economic, feasible and safe to solve the shortage in barrier’s height causes from paving overlays by computer simulation tests and full-scale crash tests, which will improve the roadside safety of the guardrail and save the reconstruction cost.

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