System-Based Energy and Momentum Analysis of Collisions

Schmidt, Bruno; Haight, W. R. “Rusty”; Szabo, Thomas J.; Welcher, Judson

doi:10.4271/980026

Cited by 10 publications

(7 citation statements)

References 6 publications

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“…Of the remaining 34 studies, one was excluded as the authors reported barrier equivalent velocity (BEV) rather than delta V [ 18 ]. Among the 33 remaining studies there were data from 408 individual crash tests that could be abstracted for description and analysis [ 16 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 ]. The number of unique test subjects could not be determined from the studies, as multiple studies were performed by the same authors who also included themselves as test subjects, and most papers described two or more crash tests per subject (making the likely number of unique subjects in the included studies between 100 and 200).…”

Section: Resultsmentioning

confidence: 99%

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

Nolet

Nordhoff

Kristman

et al. 2021

IJERPH

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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.

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Section: Resultsmentioning

confidence: 99%

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

Nolet

Nordhoff

Kristman

et al. 2021

IJERPH

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“…relative velocity of the centres of mass respectively of the unsprung mass without FKESS, sprung mass and FKESS to translational moving reference frame starting at the centre of mass of the mechanical system. The kinetic moment of the unsprung mass without the FKESS to its centre of mass in its relative motion around it in the projections of the coordinate axes permanently connected to the unsprung mass is of the kind , (17) where:…”

Section: Dynamic Analysis Of Post Impact Motion Of Vehiclesmentioning

confidence: 99%

“…Dynamic crash tests are main tasks for expert assessment of road traffic accidents. As a result, the velocity of the centres of mass of the two vehicles is obtained (Schmidt et al, 1998;Sharma et al, 2007;Daily et al, 2006;Prasad, 1990;Stucki, 1998;Hight et al, 1985;Mchenry R. and Mchenry G., 1986;Wach, 2003). There are different methods of dynamic analysis, each with certain inaccuracy of the results obtained.…”

Section: Introductionmentioning

confidence: 99%

Identifying Vehicle and Collision Impact by Applying the Principle of Conservation of Mechanical Energy

Karapetkov

Dimitrov

Uzunov

et al. 2019

Transport and Telecommunication Journal

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Various methodologies and tools applied to identification of vehicle and collision impact seek to present more and more accurate solutions to reproduce, restore, recreate and investigate the casualty. Modern computer technology and software provide the tools to solve specific problems developing mathematical modelling of complex mechanical systems involving vehicles and other objects in a road accident. Scientists generally utilize the Standard Test Method for Impact Testing calculating the energy of deformation of both vehicles, however, one of its limitations is the evaluation of the kinetic energy of the vehicles in post-collision taking into consideration vehicle rotation and linear displacement. To improve the analysis, dynamic traffic simulation is used, taking into account the variations in the coefficient of friction, suspension elasticity and damping. The proposed method is based on a system of two equations derived from two principles: the Principle of Conservation of Mechanical Energy and the Principle of Conservation of Momentum in the impact phase. The new approach is conducted on mathematical modelling and computer simulation of vehicle motion after the impact, wherefrom the linear and angular velocities are analysed. This is achieved by the numerical solution of the differential equations of motion of the cars after the impact, and the given initial conditions that satisfy the solution are used to solve the system of equations. The main findings of the study can be grouped as follows: 1) The positions of the vehicles prior to the moment of first impact and the post-impact orientation of velocity vectors are more precise. 2) The variability of the tire-road friction coefficient is taken into consideration. 3) The value of coefficient of restitution according to Newton’s theory of impact is unnecessarily determined.

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“…where Δ E is the collision energy dissipated within the vehicle body structures; in this case, it amounts to 53.3 kJ. It is known that the ratio of absorption of energy from a collision is proportional to the change in the vehicle velocities, 5 denoted Δ V a and Δ V b , where…”

Section: Vehicle Body Structure Legislation Issuesmentioning

confidence: 99%

Active Buckling Control for Future Lightweight Vehicle Body Structures

Trollope

Burnham

2013

Measurement and Control

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This paper provides a premise and the motivation for making a case for lightweight vehicle body structures, with embedded functionality, using actively controlled materials. Such active materials have the ability to change the structural properties in the event of varying conditions, including dynamic loading and vibrations, with the extreme scenario being that of a collision. Prompted by ever stringent legislation concerning crashworthiness and CO2 emissions, coupled with the fact that all new vehicles in the future will be fully equipped with advanced driver-assisted systems, including on-board active safety systems, the paper proposes a strategy for actively controlling the energy absorption of the vehicle body structure. The concept of an active buckling control approach, while still in its early development stage, is described. Encouraging results have been obtained via simulation, and the potential control approach for specifying a buckling load, related to the smallest positive buckling eigenvalue, hence onset of energy absorption, is discussed. It is conjectured that an active buckling control approach may become part of future legislation for testing vehicle body structures, where the issues of compatibility and reduced aggressivity are deemed to become compulsory.

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System-Based Energy and Momentum Analysis of Collisions

Cited by 10 publications

References 6 publications

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

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

Identifying Vehicle and Collision Impact by Applying the Principle of Conservation of Mechanical Energy

Active Buckling Control for Future Lightweight Vehicle Body Structures

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