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.