Motorcycle-to-car and scooter-to-car collisions: speed estimation from permanent deformation

Abstract

This paper proposes from fundamental mechanics that the specific energy ( E/ M) absorption characteristics of motorcycles and scooters in frontal impacts are similar where the primary load path is through the front wheel and fork assembly. Examination of 43 barrier test results for 14 different model types of motorcycle and scooter over the impact speed range from 10km/h to 76km/h shows that the specific energy versus wheelbase shortening characteristics are similar and that a single specific collision energy ( E/ M) regression equation with its associated statistical distribution ( r2=0.845) can be used to represent the motorcycle and scooter populations in frontal impact for wheelbase shortening up to 0.45m where the front-fork and front-wheel assemblies remain intact, albeit deformed. Data from 31 staged tests where motorcycles or scooters impacted stationary cars at 90° are used to obtain the energy absorption characteristics of the sides of cars subject to frontal motorcycle or scooter impact. These two regressions are used to estimate collision energy Eca from the permanent deformation or penetration depth of the collision partners, which, when substituted into the standard impact energy loss equation with the appropriate collision partner masses, yields an estimation of collision speed Vccs. This procedure for calculating collision closing speed Vccs is validated against 13 staged tests (six 90° impacts against stationary cars and seven angled impacts at angles up to 45° from the normal, four of which were against moving cars) and shows that the predicted Vccs speeds bound the actual speeds with a standard deviation of 11.2km/h for collision closing speeds up to 122km/h.

Physical and empirical models for motorcycle speed estimation from crush

“…This concept, originally proposed by Pugsley and Macaulay [16] in relation to railway coaches, has been shown by Wood [22,23] to apply to the frontal crush properties of cars. This paper extends previous work by Wood [24,25] with the introduction of a 'ForceÀBalance' approach between the motorcycle and car to estimate the proportion of the collision energy absorbed by the struck car. This 'ForceÀBalance' model is compared to the original Wood model [25] which uses an empirical estimate of the collision energy absorbed by the car, Searle's [18] linear force model and an empirical model derived by Schmidt [17].…”

“…This paper extends previous work by Wood [24,25] with the introduction of a 'ForceÀBalance' approach between the motorcycle and car to estimate the proportion of the collision energy absorbed by the struck car. This 'ForceÀBalance' model is compared to the original Wood model [25] which uses an empirical estimate of the collision energy absorbed by the car, Searle's [18] linear force model and an empirical model derived by Schmidt [17]. The comparison uses the results of 107 published staged tests where motorcycles and scooters are impacted against stationary (N ¼ 100) and moving (N ¼ 7) cars.…”

“…From analysis of barrier impact tests (N ¼ 43) of motorcycles (N ¼ 18) and scooters (N ¼ 25), Wood [25] has shown that…”

“…Since then a number of researchers, including Limpert [12] and Schmidt [17] have proposed empirical relations between impact speed and either motorcycle wheelbase shortening or the combination of wheelbase shortening and the crush depth of the car. More recently, Wood [24,25] and Searle [18] proposed physical models based on the proposition that structural deformation and energy absorption behaviour of motorcycles are proportional to the motorcycle mass. This concept, originally proposed by Pugsley and Macaulay [16] in relation to railway coaches, has been shown by Wood [22,23] to apply to the frontal crush properties of cars.…”

“…The comparison uses the results of 107 published staged tests where motorcycles and scooters are impacted against stationary (N ¼ 100) and moving (N ¼ 7) cars. In the original Wood [25], Searle [18] and Schmidt [17] models a number of the staged tests were used for model derivation and hence not available for validation/comparison purposes.…”