Effect of acceleration pulse shape on the safety of unbelted motorcoach passengers in frontal collision under uncertainty of their seating posture

Abstract

Crashworthiness design of motorcoaches is a new research area driven by the constantly upgrading crash safety regulations. One important parameter to be considered during the crashworthiness design is the shape of acceleration profile experienced by the vehicle’s occupants. The paper presents the results of the analysis of the influence of the pulse shape on the safety of motorcoach passengers in a frontal collision. Owing to a large number of uncertainties involved in a real-world crash, a probabilistic approach is undertaken for the parametric study. For each considered acceleration pulse, several random occupant postures are generated and used in the numerical sled test. The influence of the pulse shape on occupants’ injury criteria is then evaluated and compared to the amount of scatter introduced by the random postures. The results indicate the effect of the uncertainty in the seating posture overcomes the effect of the pulse shape changes. The coefficient of variation (CV) in the Head Injury Criterion (HIC) across stochastic postures is found to be from 11% to 34% while the average total change in the HIC values between different acceleration profiles is only 8%. Overall, the research demonstrates the significance of the consideration of the posture variation in the parametric crash test studies.