An Examination of the CRASH3 Effective Mass Concept

Rose, Nathan A.; Fenton, Stephen J.; Ziernicki, Richard M.

doi:10.4271/2004-01-1181

Cited by 7 publications

(8 citation statements)

References 6 publications

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“…It complements the result of Rose et al [9]. This formula gives this component in terms of Δv and so includes the effects of restitution via equation (16).…”

Section: Closing Speedssupporting

confidence: 58%

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The Determination of Vehicle Speeds from Delta-V in Two Vehicle Planar Collisions

Neades¹,

Smith

2010

Proceedings of the Institution of Mechanical Engineers, Part D:

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The change of a vehicle's velocity, delta-V ( v), due to an impact is often calculated and used in the scientific investigation of road traffic collisions. In isolation however, this figure does not yield any information concerning the actual velocities of the vehicles and such information is often of prime concern to those investigating collisions. In this paper a method is developed which uses the change in velocity sustained by a vehicle in a planar collision to estimate the velocities of the vehicle before and after a collision. The key equations are derived from conservation of momentum, conservation of energy and restitution. As with the calculation of delta-V, the method requires an initial estimate of the principal directions of force. The pre and post impact angles of the vehicles' velocities can be used to obtain better estimates of the principal directions of force and of the coefficient of restitution. In collisions where it is difficult to analyse the vehicles' post-impact motion, this method provides a way to estimate the actual speeds of vehicles. To demonstrate the method, it is used to analyse one of the RICSAC collisions. The results of an analysis of other staged collisions illustrate the accuracy of the method.

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“…It complements the result of Rose et al [9]. This formula gives this component in terms of Δv and so includes the effects of restitution via equation (16).…”

Section: Closing Speedssupporting

confidence: 58%

“…Rose et al [9] use a heuristic method based on McHenry's spring model [4] to obtain some interesting and helpful results for collisions. In this section, Smith's [8] analysis is extended along the lines of Rose et al to provide expressions for the change in velocity of the vehicles along the line of action of the impulse.…”

Section: Planar Collisionsmentioning

confidence: 99%

The Determination of Vehicle Speeds from Delta-V in Two Vehicle Planar Collisions

Neades¹,

Smith

2010

Proceedings of the Institution of Mechanical Engineers, Part D:

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“…Equation (4) is valid for a two-vehicle planar impact as long as the dominant mechanism of energy loss during the impact is plastic deformation of the vehicle structure. While Equation (4) is generally considered valid only for central collisions, the effective mass concept that is used within crush analysis and to derive Equations (2) and (3) renders Equation (4) a valid definition of the coefficient of restitution for non-central impacts, as well [17].…”

Section: Defining the Coefficient Of Restitutionmentioning

confidence: 99%

“…Equation (20) provides a relationship between the dynamic crush stiffness coefficient K 1 and the residual crush stiffness coefficient B. Substitution of Equation (20) into (17) yields an expression for the dynamic crush, which can then be substituted into Equation 15to yield the following equation:…”

Section: Restitution and Ebsmentioning

confidence: 99%

Restitution Modeling for Crush Analysis: Theory and Validation

Rose¹,

Fenton²,

Beauchamp³

2006

SAE Technical Paper Series

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This paper describes, demonstrates and validates a method for incorporating the effects of restitution into crush analysis. The paper first defines the impact coefficient of restitution in a manner consistent with the assumptions of crush analysis. Second, modified equations of crush analysis are presented that incorporate this coefficient of restitution. Next, the paper develops equations that model restitution response on a vehicle-specific basis. These equations utilize physically meaningful empirical constants and thus improve on restitution modeling equations already in the literature of accident reconstruction. Finally, the paper presents analysis of four vehicle-to-vehicle crash tests, demonstrating that the application of the restitution model derived in this paper results in crush analysis yielding more accurate ΔV calculations.

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“…The accuracy of PDOF estimates derived from EDR data has not been investigated, however. In full engagement collisions, PDOF is relatively constant through the crash (Rose et al, 2004). However, real-world collisions often are not full engagement collisions and may involve sliding (e.g.…”

Section: Introductionmentioning

confidence: 97%