Development of additively manufactured novel 3D cellular structures for protective clothing

Abstract

Protective clothing shields body parts from impact, absorbing energy to minimise or prevent damage. Recent research has shown significant emphasis on the use of hard or a combination of hard and soft materials. The aim of this research was to design and manufacture novel 3D cellular structures that could provide low-velocity impact resistance and flexibility to wearers. Six different types of 3D cellular structures were developed using stereolithography (SLA) additive manufacturing technique with two different types of flexible resin materials. Theoretical and experimental studies were conducted to evaluate the low-velocity impact resistance of these flexible 3D cellular structures. Experimental studies were carried out using a customised inhouse free fall “impact drop test” setup, where impact forces transmitted through the impacted structures were captured via a capacitive force sensor underneath the structure, in the form of a real-time impact force versus time plot. The results indicated that the re-entrant honeycomb (AU) cellular structure made from Liqcreate and Prusa flexible materials experienced the lowest peak impact force, respectively. Additionally, a static uniaxial compression test was performed to examine the deformation behaviour of all 3D-printed cellular structures. The results revealed that the AU cellular structure had excellent energy absorption in a wide displacement range. To predict and validate the impact resistance response of two novel, AU and 3D honeycomb (HC) cellular structures, finite element (FE) models were developed using commercial FE software ABAQUS. Moreover, the predicted responses of FE models were highly correlated to the experimental results. Overall, the research for this study indicates that such a novel 3D AU cellular structure, made from a single flexible material, has the potential for application as personal protective equipment (PPE) to prevent impact injuries to knees, hips, elbows, and shoulders. This structure would ensure wear comfort, enable body motions while offering an impact-resistant solution.