Characterisation of Surrogate Ribs with Variation of the Anterior-Posterior Load Angle: A New Test Methodology

In this study, an innovative setup was employed to test rib surrogates using a drop tower with an adaptable carriage guidance system at dynamic loads up to 1500 mm/s. A new rib model was created using fused filament fabrication (FFF) with P-PLA™ material, aiming to investigate failure mechanisms under varying test angles and comparing them to specific, male post-mortem human subjects (PMHS) data from the literature. The primary objective was to understand fracture dynamics resulting from different load orientation and filament printing directions. Horizontal printing increased fracture resistance, while vertical printing facilitated better control over internal supports, achieving desired fracture behaviour. The experiments involved varying the force application angle (αPH), demonstrating its significant impact on deformation and strain distribution within the specimens. Results included detailed analysis of force-time curves and strain distribution using 3D digital image correlation (3D-DIC). The study emphasises the importance of refining methods, materials, and test setups to improve the validation and applicability of surrogate models. Future research will focus on optimising test conditions and expanding surrogate variations to better capture a broad range of human biomechanical responses, contributing to enhanced accuracy and reliability in ballistic PPE assessments.