Nonlinear functionally graded metamaterials for hydrogen storage and enhanced sustainability under extreme environments
Pratik Tiwari, Susmita Naskar, T. Mukhopadhyay
Abstract
Functionally graded materials can exhibit remarkable tolerance towards extreme hot or cold environments and chemical surface degradation. This article exploits such properties of functionally graded materials to propose a new class of transversely curved metamaterial architectures with high specific stiffness for operations under extreme surrounding conditions. We envisage the next-generation concept design of hydrogen storage tanks with functionally graded metamaterial core for aerospace and automotive applications. Based on such innovative lattice metamaterial based design of hydrogen storage tanks it is possible to enhance the storage capability in terms of internal pressure and resistance to external loads and impacts. Most importantly the proposed concept would lead to a breakthrough in developing load-bearing energy storage devices. For the metamaterial core, hexagonal bending-dominated unit cell architecture with transversely curved connecting beam-like geometries would ensure the dual functionality of high specific stiffness and energy absorption capability which are mutually exclusive in traditional lattice metamaterials. The functionally graded beams, a periodic network of which constitutes the lattice, are modelled here using 3D degenerated shell elements in a finite element framework. Geometric nonlinearity using Green–Lagrange strain tensor is considered for an accurate analysis. The beam-level nonlinear deformation physics is integrated with the unit cell mechanics following a semi-analytical framework to obtain the effective in-plane and out-of-plane elastic moduli of the metamaterials. The numerical results show that the curved beam lattice metamaterials have significantly enhanced in-plane elastic properties than straight lattices along with a reduced disparity among the in-plane and out-of-plane elastic moduli. • Functionally graded metamaterials for extreme surrounding environments. • Next-generation concept design of hydrogen storage tanks with functionally graded metamaterial core. • Enhanced storage capability in terms of internal pressure and resistance to external loads and impacts. • Load-bearing energy storage devices with high specific stiffness and energy absorption capability. • 3D degenerated shell element-based unit cell mechanics for nonlinear in-plane and out-of-plane elastic moduli.