Tailoring of Effective Moduli in Planar Lattices Composed of Rhombic Pneumatic Components

Active mechanical metamaterials with a broad tailoring range of effective moduli have received much attention for their increasing applications in engineering. The design and corresponding theoretical models have been proposed for triangular and square lattices composed of rhombic pneumatic components between each two neighboring joints. A rhombic pneumatic component is made of one nonlinear truss and four straight beams that form an air cavity inside which the pneumatic pressure can be mediated, resulting in programmable effective moduli. The deformation of the rhombic pneumatic components related to pneumatic pressure is computed using Green’s function stiffness method (GFSM). Micropolar theory is employed to model the constitutive behavior of these lattices, capturing both rotational and translational degrees of freedom. Effective elastic moduli of the lattice are calibrated through strain energy equivalence, ensuring that the strain energy of the structural model matches its continuum counterpart. Theoretical predictions are validated through finite element simulations. Parametric analyses are conducted to examine the effects of structural geometry and the mechanical properties of composed materials on the tailoring of effective moduli in planar lattices composed of pneumatic components. The research findings contribute to the optimization of materials and structures to achieve the required mechanical properties for applications, demonstrating engineering potentials.