Design of human surrogates for the study of biomechanical injury: a review

Human surrogates are representations of living human structures employed to replicate “real-life” injurious scenarios in artificial environments. They are used primarily to evaluate personal protective equipment (PPE) or integrated safety systems (e.g., seat belts) in a wide range of industry sectors (e.g., automotive, military, security service, and sports equipment). Surrogates are commonly considered in five major categories relative to their form and functionality: human volunteers, postmortem human surrogates, animal surrogates, anthropomorphic test devices, and computational models. Each surrogate has its relative merits. Surrogates have been extensively employed in scenarios concerning “life-threatening” impacts (e.g., penetrating bullets or automotive accidents). However, more frequently occurring nonlethal injuries (e.g., fractures, tears, lacerations, contusions) often result in full or partial debilitation in contexts where optimal human performance is crucial (e.g., military, sports). Detailed study of these injuries requires human surrogates with superior biofidelity to those currently available if PPE designs are to improve. The opportunities afforded by new technologies, materials, instrumentation, and processing capabilities should be exploited to develop a new generation of more sophisticated human surrogates. This paper presents a review of the current state of the art in human surrogate construction, highlighting weaknesses and opportunities, to promote research into improved surrogates for PPE development

Initial validation of a relaxed human soft tissue simulant for sports impact surrogates

Impact injuries are a common occurrence in sport such that personal protective equipment (PPE) is often mandatory to ensure participant safety. Current tests to assess PPE effectiveness often use unrepresentative human surrogates, insufficient to accurately assess human impact response. More refined surrogates typically use “off the shelf” silicone elastomers to better represent human tissue, however using a single simulant material for all soft tissues means some phenomena associated with injury are not adequately represented. This study presents an evaluation of the effectiveness of a bespoke muscular tissue simulant using a proprietary blend of additive cure silicones. The mechanical response has been compared and validated with porcine tissue properties and provides improved behaviour when compared with a previously used silicone elastomer, Silastic 3481. The material has also been modelled computationally using a two-term Ogden model and exhibits a significantly different response to Silastic 3481 under a low-speed knee-strike loading condition