Abstract
Automatic design of mechanical metamaterials is key to achieving efficiencies in terms of a desired functionality that can far exceed the rationally designed man-made solutions. Here, we introduce a discrete element model capable of describing the mechanical response of three-dimensional trussed structures under a predetermined external perturbation and coupling it to an optimization algorithm in order to produce chiral mechanical metamaterials, twisting under compression and thus converting linear motion into rotation. By comparing the machine-designed structures with pre-existing human-designed solutions, we show that the former can achieve a much higher efficiency in terms of rotating angle per unit compressive strain. We confirm our results by finite element calculations and by experiments on 3D printed structures. The presented method paves the way to the discovery of novel functional mechanisms that can act over a broad size range, from micro- to macroscales, giving rise to a countless number of possible solutions for functional mechanical metamaterials.
Highlights
The design of materials with tailored mechanical properties and functionalities represents a major scientific and technological challenge with enormous potential for engineering and societal applications
We have presented an algorithm to generate automatically three-dimensional mechanical metamaterial actuators with predefined functions
The algorithm is based on a combination of discrete element model (DEM) and Monte Carlo (MC) optimization following the steps of a previously introduced two-dimensional algorithm
Summary
The design of materials with tailored mechanical properties and functionalities represents a major scientific and technological challenge with enormous potential for engineering and societal applications. Recent advances in additive manufacturing (3D printing) have made mass production and industrialization of the manufacture of complex and innovative design objects made in computer models technologically and economically feasible. This type of structures can have very interesting applications in all areas where a movement mode conversion is necessary, especially at very small scales where traditional actuators are not usable. We propose a generalization of the algorithm to three-dimensional (3D) structures This allows us to treat more complex input–output scenarios and design a wider variety of functional metamaterials. We apply our discrete element based algorithm to automatically design efficient chiral metamaterial architectures, starting from a three-dimensional elastic lattice.
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