Architected lattice materials are some of the stiffest and strongest materials at ultra‐light density (<10 mg cm−3), but scalable manufacturing with high‐performance constituent materials remains a challenge that limits their widespread adoption in load‐bearing applications. We show mesoscale, ultra‐light (5.8 mg cm−3) fiber‐reinforced polymer composite lattice structures that are reversibly assembled from building blocks manufactured with a best‐practice high‐precision, high‐repeatability, and high‐throughput process: injection molding. Chopped glass fiber‐reinforced polymer (polyetherimide) lattice materials produced with this method display absolute stiffness (8.41 MPa) and strength (19 kPa) typically associated with metallic hollow strut microlattices at similar mass density. Additional benefits such as strain recovery, discrete damage repair with recovery of original stiffness and strength, and ease of modeling are demonstrated.
Ultralight materials present an opportunity to dramatically increase the efficiency of load-bearing aerostructures. To date, however, these ultralight materials have generally been confined to the laboratory bench-top, due to dimensional constraints of the manufacturing processes. We show a programmable material system applied as a large-scale, ultralight, and conformable aeroelastic structure. The use of a modular, lattice-based, ultralight material results in stiffness typical of an elastomer (2.6 MPa) at a mass density typical of an aerogel 5.6 mg cm 3 (). This, combined with a building block based manufacturing and configuration strategy, enables the rapid realization of new adaptive structures and mechanisms. The heterogeneous design with programmable anisotropy allows for enhanced elastic and global shape deformation in response to external loading, making it useful for tuned fluid-structure interaction. We demonstrate an example application experiment using two building block types for the primary structure of a 4.27 m wingspan aircraft, where we spatially program elastic shape morphing to increase aerodynamic efficiency and improve roll control authority, demonstrated with full-scale wind tunnel testing.
Abstract. Real world systems that are candidates for vibrational energy harvesting rarely vibrate at a single frequency, nor are these frequencies constant over time. This necessitates that vibration harvesters operate over a wide bandwidth or tune their resonance. Most tunable devices require additional energy or active control to achieve resonance over various frequencies. This work presents a passively self-tuning energy harvester that autonomously adapts its resonant frequency to the input without requiring additional energy. The system consists of a clampedclamped beam, a movable proof mass, and a piezoelectric patch bonded to the underside of the beam. It demonstrated an open-circuit voltage output of 668 mVrms at 160Hz, 0.65g input excitation. Discrepancies between displacement and voltage magnification factors upon tuning at higher frequencies are discussed, as well as instabilities of the system and sensitivity to proof mass characteristics.
We present a modular, reconfigurable system for building large structures. This system uses discrete lattice elements, called digital materials, to reversibly assemble ultralight structures that are 99.7% air and yet maintain sufficient specific stiffness for a variety of structural applications and loading scenarios. Design, manufacturing, and characterization of modular building blocks are described, including struts, nodes, joints, and build strategies. Simple case studies are shown using the same building blocks in three different scenarios: a bridge, a boat, and a shelter. Field implementation and demonstration is supplemented by experimental data and numerical simulation. A simplified approach for analyzing these structures is presented which shows good agreement with experimental results.
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