Factors Influencing Roof-to-Ground Impact Severity: Video Analysis and Analytical Modeling

Abstract

This paper explores the dynamics of rollover crashes and examines factors that influence the severity of the roof-to-ground impacts that occur during these crashes. The paper first reports analysis of 12 real-world rollover accidents that were captured on video. Roll rate time histories for the vehicles in these accidents are reported and the characteristics of these curves are analyzed. Next, the paper uses analytical modeling to explore the influence that the trip phase characteristics may have on the severity of roof-to-ground impacts that occur during the roll phase. Finally, the principle of impulse and momentum is used to derive an analytical impact model for examining the mechanics of a roof-to-ground impact. This modeling is used to identify the influence of various impact conditions on the severity of a roof-to-ground impact.

The Influence of Vehicle-to-Ground Impact Conditions on Rollover Dynamics and Severity

“…6 6 This point in the discussion is also an ideal point to observe that one of our conclusions in Ref. 25 The Deceleration Rate for a Rolling Vehicle Next, it can be observed that the rate at which a rolling vehicle decelerates will be determined by the accumulation of the ground plane velocity changes that occur during the rollover. Thus, any factor that influences the ground surface velocity changes will also influence the deceleration rate that the vehicle experiences.…”

“…In a previous paper [25], the authors presented a planar, vehicle-to-ground impact model derived using the principle of impulse and momentum and based on the idealized vehicle-to-ground impact shown in Figure 1.…”

“…Application of the principle of impulse and momentum for the idealized impact of Figure 2 results in the following equations, which yield the vehicle's upward and ground plane CoM velocity changes and the vehicle's change in roll velocity [25]. 1 A full derivation of these equations is provided in Appendix A.…”

“…Table 1 lists the factors that influence the behavior of Equations (1) through (9) along with the method that will be used to establish a range for each factor. [25]. The characteristics of these crashes provide a basis on which to establish a range for several of the factors listed in the table above.…”