Pressure-actuated cellular structures

Abstract

Shape changing structures will play an important role in future engineering designs since rigid structures are usually only optimal for a small range of service conditions. Hence, a concept for reliable and energy-efficient morphing structures that possess a large strength to self-weight ratio would be widely applicable. We propose a novel concept for morphing structures that is inspired by the nastic movement of plants. The idea is to connect prismatic cells with tailored pentagonal and/or hexagonal cross sections such that the resulting cellular structure morphs into given target shapes for certain cell pressures. An efficient algorithm for computing equilibrium shapes as well as cross-sectional geometries is presented. The potential of this novel concept is demonstrated by several examples that range from a flagellum like propulsion device to a morphing aircraft wing.

Fast nastic motion of plants and bioinspired structures

“…There are additional examples of morphing structures inspired by the hydraulic redistribution driven plant movement. Inspired by the hydraulic movements of D. muscipula and M. pudica, Pagitz et al developed a model for morphing structures driven by pressure-actuated cellular structures [99]. The researchers further refined this model by introducing a shell-like structure that can, through its characteristic "snap-through" morphology, change the sign of its Gaussian curvature [100].…”

A modular approach to adaptive structures

“…Table 3: Trailing edge coordinates of first target shape. 9 Only one set of points is given for the trailing edge since available data is based on a rigid Fowler flap.…”

“…An advantage of such a fusion is that cell walls are prestressed by cell pressures which increases, decreases the overall structural stiffness, weight. Inspired by the nastic movement of plants, Pagitz et al 2012 Bioinspir. Biomim.…”

“…This leads to a synergistic effect since cell pressures introduce a prestress into the structure which increases, decreases the overall stiffness, weight. Compliant pressure actuated cellular structures with fixed properties can be made from single materials that range from elastomers to metals [12]. This allows the use of advanced manufacturing techniques such as injection molding or rapid prototyping.…”

Multi-functional extremely anisotropic structural element

“…The capability of structural elements to attain large deformation in one or more directions, while otherwise retaining high stiffness, constitutes an extraordinary property enabling a wide range of applications that span from morphing wings (Barbarino et al, 2011;Thill et al, 2008) to artificial muscles (Baughman, 1996;Pagitz et al, 2012), bio-inspired composites (Studart and Erb, 2014), and reactive textiles (Smela et al, 1995). Changes in shape can be based on the deformability of the material as in simple elastomers and flexible matrix composites (Shan, 2006).…”