Analyzing the bi-directional dynamic morphing of a bi-stable water-bomb base origami

Abstract

Morphing structures have been a subject of much research recently because of their promising potentials in aerospace, wind turbine, and many other applications. There exists many different approaches to achieve shape morphing, among which the origami-inspired folding is particularly interesting in that folding is fundamentally three-dimensional, scalable, and customizable. However, activating and attaining large amplitude folding autonomously are challenging. Active materials, such as shape memory alloys, have been used to activate folding, but they are limited due to the power supply requirement to maintain the folded configurations. One possible solution is to embed bi-stability into the origami structure. Bi-stability can play two significant roles: First, it can significantly reduce the actuation requirement to induce shape morning; and second, it can maintain the shape change without demanding sustained energy supply. In this study, we demonstrate the feasibility of using dynamic excitation to induce shape morphing (or folding) between the two stable states of water-bomb base. For the first time, we derive the dynamic equation of motion for a water-bomb base origami and use it extensively to analyze its time responses under harmonic excitation. Via numerical simulations, we show that by harnessing the intra-well resonance of the water-bomb structure, we can achieve rapid bi-directional morphing using relatively low actuation magnitudes in comparison with quasi-static loading.