Pneumatic elastostatics of multi-functional inflatable lattices: realization of extreme specific stiffness with active modulation and deployability

Abstract

As a consequence of intense investigation on possible topologies of periodic lattices, the limit of specific elastic moduli that can be achieved solely through unit cell-level geometries in artificially engineered lattice-based materials has reached a point of saturation. There exists a robust rationale to involve more elementary-level mechanics for pushing such boundaries further to develop extreme lightweight multi-functional materials with adequate stiffness. We propose a novel class of inflatable lattice materials where the global-level stiffness can be derived based on a fundamentally different mechanics compared with conventional lattices having beam-like solid members, leading to extreme specific stiffness due to the presence of air in most of the lattice volume. Furthermore, such inflatable lattices would add multi-functionality in terms of on-demand performances such as compact storing, portability and deployment along with active stiffness modulation as a function of air pressure. We have developed an efficient unit cell-based analytical approach therein to characterize the effective elastic properties including the effect of non-rigid joints. The proposed inflatable lattices would open new frontiers in engineered materials and structures that will find critical applications in a range of technologically demanding industries such as aircraft structures, defence, soft robotics, space technologies, biomedical and various other mechanical systems.

Current developments in elastic and acoustic metamaterials science

“…Programmability of thermal expansion and load-bearing capacity can be attained simultaneously in multi-phase metamaterials containing framework structures [37]. Recently, the concept of pneumatic elastostatics and deployability in elastic metamaterials was proposed based on inflatable lattices that may exhibit extreme specific stiffness along with on-demand tunability [38]. In the theme issue, Kundu et al [39] propose piezoelectric beam lattices where the effect of random multiple disorders and damages of complex shapes, sizes and distributions can be shielded through active cloaks controlled by voltage-dependent modulation of the stress fields within the cloaking region.…”

Active mechanical cloaking for unsupervised damage resilience in programmable elastic metamaterials

“…The recent developments in this direction include bi-level topology architected optimum metamaterials [5], hierarchical metamaterials [24], disordered metamaterials [25], anti-curvature metamaterials with programmed curvature [26][27][28][29], multi-material and space-filled lattices [30,31], origami-and kirigami-inspired metamaterials [19,32], to mention a few. Recently, the concept of pneumatic elastostatics and deployability in mechanical metamaterials has been proposed based on inflatable lattices that can exhibit extreme specific stiffness along with on-demand tunability [33].…”