Search

This research delves into nature-inspired designs for creating materials with exceptional impact resistance, leveraging cutting-edge 3D printing techniques. Our composite design features a nacre-like outer layer combined with a tubulane-resembling core, aiming to enhance energy dissipation significantly. By emulating the dense aragonite structure found in natural nacre and the unique porosity of tubulane, we were able to enhance ballistic impact resistance. To validate its effectiveness, we conducted ballistics tests using a 40-grain lead-tipped .22 LR bullet at an initial velocity of 330.7 m/s, with a specialized chronograph setup to measure both initial and post-penetration bullet velocities, quantifying energy absorption precisely. This study opens new frontiers in aviation safety, structural engineering, and personal protective equipment, showcasing the transformative potential of biomimicry and additive manufacturing in advancing public safety and material science. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced polymer (CFRP) composites hybridized with hydrogen-doped NiTi wires can be used to design structures requiring high stiffness and high damping in the low frequency range, such as helicopter blades. The current work investigates aging and hydrogen-doping for high damping without hydrogen embrittlement. We establish a hydrogenation treatment that (i) results in a response that is repeatable in the martensitic phase and after exposure to composite processing temperatures and (ii) increases the loss factor in NiTi wires by nearly 470%. By embedding H-doped wires exhibiting the highest damping into the interlayers of a [0/±45]s carbon/epoxy laminate at a volume fraction of 0.1, the hybrid NiTi-CFRP composite loss factor increases by 170%. The measured dynamic properties were found to be close to micromechanical predictions based on the properties of the NiTi and CFRP. [ABSTRACT FROM AUTHOR]

Design, fabrication, and performance of a 0.39-m diam., 6.8-kg flywheel rotor with only one bearing is discussed. To achieve low-loss energy storage, the rotor's segmented-ring permanent magnet (PM) is optimized for levitation and circumferential homogeneity. A PM figure of merit is proposed that appears to correlate with loss data. Pre compression of the PM with fiber-composite banding is necessary for practical rotor speeds.