Editor’s Highlights for Composites Science and Technology

Colin D. Cwalina, Charles M. McCutcheon, Richard D. Dombrowski, Norman J. Wagner

Colin D. Cwalina, Charles M. McCutcheon, Richard D. Dombrowski, Norman J. Wagner

Engineering Enhanced Cut and Puncture Resistance into the Thermal Micrometeoroid Garment (TMG) using Shear Thickening Fluid (STF) – Armor™ Absorber Layers

The low-earth orbit environment contains small micrometeoroid and orbital debris (MMOD) particles traveling at characteristic velocities of several kilometers per second. In addition to being a direct threat to astronauts and spacecraft, upon impact with the exterior surface of a space vehicle, these highly energetic MMOD particles can create cut and puncture hazards for astronauts performing extra-vehicular activities (EVA). In this work, we demonstrate that replacing the standard neoprene-coated nylon absorber layers with woven aramid textiles intercalated with colloidal shear thickening fluids, i.e., STF-Armor™, can provide a meaningful enhancement to the cut and puncture resistance of the thermal micrometeoroid garment (TMG). Quasi-static puncture testing is performed using hypodermic needles of varying gauge to simulate the cutting and puncture hazards at deformation rates characteristic of human motion. At equal areal densities, we find that a TMG lay-up containing STF-Armor™ greatly improves puncture protection with a reduction in weight and comparable flexibility.

The primary concern for spacecraft shielding engineers is mitigating the risks posed by natural micrometeoroids originating from comets and asteroids throughout the solar system [1] and [2]. Over the decades, the increasing number of vehicles and satellites launched into low-earth orbit (LEO) has broadened the focus of design engineers to manmade orbital debris threats [3] and [4]. These orbital debris particles, largely aluminum-based compounds broken off from LEO vehicles, typically travel at velocities of 1–15 km/s in LEO [2]. While generally on the order of a millimeter or less in size, these micrometeoroid and orbital debris particles (MMOD), are sufficiently energetic to be destructive upon impact. Of particular concern to manned missions is the threat posed by MMOD to astronauts as they perform extra-vehicular activities (EVA). To combat this threat, the current EVA suit consists of an assemblage of textile layers, known as the thermal micrometeoroid garment (TMG), which protects the exterior of the pressurized air bladder as shown in Fig. 1. The design of the TMG primarily seeks to prevent MMOD particles from reaching and puncturing the air bladder upon a direct impact [5]. Read More…

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