Bioinspired airwings: Design and additive manufacturing of a geometrically graded microscale maple seed

Abstract

Additive manufacturing is a key enabler for the fabrication and industrial application of open-celled cellular lattice structures bearing significant potential for lightweight design with advantageous stiffness–weight ratio and reduced build time. For components with strut thicknesses in the micrometer region, however, the influence of the process dominates the quality and properties of the lattice component. This includes geometrical accuracy, surface roughness, internal porosity, nodal constrictions, and elongated grains in the microstructure. The utilization of process-property correlation in the additive design process is rarely shown in the available literature.In this contribution, we develop an ultralight thin-walled maple seed that exhibits a geometrically graded strut design to maintain center of gravity and load per area. This is done by a preliminary closed-form analytical consideration to determine the design space. Second, topology optimization is carried out to obtain a re-designable structure. Using non-dimensional scaling laws enables an accurate prediction of the desired strut thickness. The maple seed has been manufactured with each strut being assigned different process parameters according to the scaling law, coated with clear varnish, and subjected to a flight test as a proof of concept.