Bio-Inspired Pressure-Dependent Programmable Mechanical Metamaterial with Self-Sealing Ability.

Self-sealing is one of the fascinating functions in nature that enables living material systems to respond immediately to damage. A prime plant model is Delosperma cooperi, which can rapidly self-seal damaged succulent leaves by systematically deforming until the wound closes. Inspired by this self-sealing principle, we have developed a novel programmable mechanical metamaterial that mimics the underlying damage management concept. This material is able to react autonomously to changes in its physical condition caused by an induced damage. To design this ability into the programmable metamaterial, we have developed a permeable unit cell design that can change size depending on the internal pressure. The parameter space and associated mechanical functionality of the unit cell design was simulated and analyzed under periodic boundary conditions and various pressures. We have investigated principles of self-sealing behavior in designed metamaterials, identified crack closure efficiency for different crack lengths, discuss the limitations of the proposed approach, and experimentally demonstrated successful crack closure in the fabricated metamaterial. Although this study facilitates the first step on the way of integrating new bio-inspired principles in the metamaterials, the results show how programmable mechanical metamaterials might extend materials design space from pure properties to life-like abilities. This article is protected by copyright. All rights reserved.