This study compared utilized coefficient of friction (COF) measured during nonslip pedestrian gait to estimated utilized COF values calculated using anthropometric (i.e., leg length) and stride characteristic data (i.e., impact angle, step length). Twenty healthy adults walked at slow, medium, and fast speeds with kinematic and kinetic data recorded simultaneously. Estimated and measured impact angle varied with walking speed, with greater angles evident with faster speeds (p < 0.001 and p < 0.05, respectively). The estimated impact angle was greater than the mea-sured impact angle (p < 0.05). Estimated and measured peak utilized COF values varied with walking speed, with higher utilized COF values evident with faster speeds (p < 0.001 and p = 0.001, respectively). Estimated utilized COF values were 86, 118, and 131% greater than measured peak utilized COF values for slow, medium, and fast speeds, respectively (p < 0.001). Higher estimated utilized COF values varied moderately with increased measured peak utilized COF values (r = 0.522; p < 0.001). These data suggest that impact angle and step length alone cannot be used to accurately assess the utilized COF on level walking surfaces.

No abstract

No abstract

The CRASH3 computer program increasingly is being used by engineers as a tool to reconstruct automobile accidents. The damage analysis portion of CRASH3 provides a useful means for quantifying the change of velocity, ∆V , that was experienced by a vehicle during the collision phase of a traffic accident. The degree of usefulness of the damage analysis portion of the program, however, is dependent upon the availability of valid crush stiffness coefficients. Published crush stiffness coefficients are available for a large number of vehicles * [1] & [2]. These publications, however, contain only a limited number of coefficients that describe the stiffness characteristics of the side structure of vehicles. Engineers are often asked to perform an accident reconstruction when there are neither published stiffness coefficients for the side structure of an involved vehicle nor crash test data from which to determine the stiffness. Such a collision usually involves the front end structure of a striking "bullet" vehicle and the side structure of a left turning "target" vehicle. If stiffness coefficients are available for the bullet vehicle, then it may be possible to determine accident-specific stiffness coefficients for the target vehicle. A method is presented in this paper that will allow a determination of accident-specific crush stiffness coefficients for target vehicles. The method is based in theory on the CRASH3 damage algorithm. Intrinsic to * The numbers in the brackets refer to references listed at the end of the paper. different accidents may not be based on a common and/or constant set of parameters. These stiffness coefficients, therefore, should be considered valid only for the specific accident.

CRASH3 based computer programs model a vehicle structure as a homogeneous body. Crush stiffness coefficients determined from full-overlap crash tests, when used in these computer programs allow for an accurate reconstruction of collisions where the accident damage profiles are full-overlap. The structures of vehicles, however, might not be purely homogeneous in their crush response. How accurately do crush stiffness coefficients that were determined from full-overlap crash tests represent the crush response of that same vehicle in a partial-overlap/offset frontal collision? Before this question can be answered a method needs to be developed for determining crush stiffness coefficients from partial-overlap/offset frontal test collisions. These crush stiffness coefficients then could be used in a comparative analysis of the crush response of vehicles tested in both full-overlap and partial-overlap/offset frontal collisions. A method is set forth that allows for the determination of crush stiffness coefficients from tests involving partial-overlap/offset frontal collisions with a fixed deformable barrier. This method is extended to tests involving side impacts with movable barriers.