Translating Cadaveric Injury Risk to Dummy Injury Risk at Iso-energy.

Abstract

Injury risk assessment based on cadaver data is essential for informing safety standards. The common 'matched-pair' method matches energy-based inputs to translate human response to anthropometric test devices (ATDs). However, this method can result in less conservative human injury risk curves due to intrinsic differences between human and ATDs. Generally, dummies are stiffer than cadavers, so force and displacement cannot be matched simultaneously. Differences in fracture tolerance further influence the dummy risk curve to be less conservative under matched-pair. For example, translating a human lumbar injury risk curve to a dummy of equivalent stiffness using matched-pair resulted in a dummy injury risk over 80% greater than the cadaver at 50% fracture risk. This inevitable increase arises because the dummy continues loading without fracture to attenuate energy beyond the 'matched' cadaver input selected. Human injury response should be translated using an iso-energy approach, as strain energy is well associated with failure in biological tissues. Until cadaver failure, dummy force is related to cadaver force at iso-energy. Beyond cadaver failure, dummy force is related to cadaver force through failure energy. This method does not require perfect cadaver/dummy biofidelity and ensures that energy beyond cadaver failure does not influence the injury risk function.