There are few things man can create that nature has not already optimized for mass and energy efficiency while maintaining harmony with the environment. Lightweight foam structures with superior energy absorbing and dissipating characteristics are paramount for various engineering applications, ranging from packing and shipping materials, cushioning for air dropped supplies in relief zones, void fillers for furniture and doors and core materials for high strength sandwich composites. Strong literature precedent has shown that bio-inspired structures exhibit significant advancements over conventional engineered structures in energy absorption capacity. Physical Sciences Inc. (PSI) has developed a biomimetic approach for the design of a novel, lightweight, hierarchically structured biopolymer foam with excellent energy dissipation characteristics by taking inspiration from heavy tropical fruits. Fruits such as pomelos and durians have evolved high energy dissipating characteristics due to their need to survive the impact of falling from tall trees. The key innovation of the developed Fruit Inspired Energy Dissipating Foams (FRIED Foams) is the synergistic combination of low-cost, 100% bioderived biopolymer foam and novel biomimetic geometry. The biopolymer foam is made from pulverized cellulosic waste materials, including scrap wood and cardboard waste, combined with a cellulose-derived biopolymer binder. A design of experiments was performed for the FRIED Foam synthesis to develop a structure-function relationship between the controlled variables of foam production and the mechanical properties of the resulting foams. The synthesized foams were screened using quasi-static compression tests. Foams were evaluated for density, compressive strength, modulus, and energy absorption capacity. Using the screening results, George Mason University (GMU) developed a Finite Element (FE) model to explore various foam geometries for optimal energy dissipation characteristics. The down-selected final foam material was further evaluated in a dynamic impact test rig built in-house by PSI. This drop tower is capable of creating impacts of up to 32 ft/s, mimicking the impact of dropping 1,500 ft from a plane. This presentation details the FRIED Foam synthesis and characterization process, and results from the quasi-static compression and dynamic impact testing.
