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Owing to the architected void-filled low-density configurations, metamaterials are prone to defects during the complex manufacturing process, or damages under operational conditions. Recently mechanical cloaking has been proposed to shield the effect of such disorders in terms of homogenized mechanical responses. The major drawback in these studies are that the damage location should be known a priori, and the cloak is designed around that damaged zone before manufacturing. Such postulation does not allow unsupervised damage resilience during the manufacturing and service life of metamaterials by active reconfiguration of the stress field depending on the random and unpredictable evolution of damage. Here, we propose a radically different approach by introducing piezoelectric lattices where the effect of random appearance of any single or multiple disorders and damages with complex shapes, sizes and distributions can be shielded through active multi-physically controlled cloaks by voltage-dependent modulation of the stress fields within the cloaking region. Notably, this can be achieved without breaking periodicity and any additional material in the cloaking region unlike earlier studies concerning mechanical cloaks. The proposed active class of elastic metamaterials will bring a step-change in the on-demand mechanical performance of critically important structural components and unsupervised damage resilience for enhanced durability and sustainability. This article is part of the theme issue 'Current developments in elastic and acoustic metamaterials science (Part 1)'. [ABSTRACT FROM AUTHOR]

The electromechanical responses of single and multi-layered piezoelectric functionally graded graphene-reinforced composite (FG-GRC) plates are studied based on an accurate higher-order shear deformation theory (HSDT) involving quasi-3D sinusoidal plate theory and linear piezoelectricity. These FG-GRC plates are composed of randomly oriented graphene nanoplatelets (GPLs) reinforcing fillers and the piezoelectric PVDF matrix considering two different distribution patterns such as linear- and uniform- distribution (LD and UD) of GPLs across the thickness. The modified Halpin-Tsai (HT) and Rule of mixture (ROM) models are utilized to determine the effective material properties of FG-GRCs. The analytical model of FG-GRCs is extended further to analyze the time-dependent linear viscoelastic electromechanical behavior of the system based on Biot model of viscoelasticity in the framework of inverse Fourier algorithm. The viscoelastic electromechanical responses include the static deformation and electric responses of simply supported FG-GRC plates which are investigated by considering transverse mechanical and external electrical loading, as well as other critical parameters like aspect ratio and weight fraction of GPLs. The numerical results reveal that the electromechanical response of FG-GRC plates can be enriched due to the addition of a small weight fraction of GPLs. The coupled multiphysics-based computational framework proposed here for predicting the viscoelastic electromechanical behavior of laminated composites can be exploited for stimulating and developing a wide range of micro-electro-mechanical systems (MEMS) and devices incorporating time-dependent programming features. [ABSTRACT FROM AUTHOR]

The objective of this paper is to conduct a comprehensive investigation into the buckling and post-buckling behavior of hyperelastic beams through both computational and experimental means. Natural rubber is used in the construction of a beam with a square cross-section. To determine the mechanical properties of natural rubber, a uniaxial tensile test is performed in accordance with ASTM D412. In finite element modeling (FEM), the nonlinear behavior of rubber is modeled using hyperelastic theory and the Yeoh strain energy function. The Static-Riks method is also implemented using Abaqus for the analysis of nonlinear buckling. To validate the present investigation results with FEM, an experimental test of digital image correlation (DIC) is conducted. The critical buckling force obtained via numerical methods exhibits an error of nearly 5% when compared to the corresponding results obtained from experimental testing. In order to ascertain the impact of various design parameters on the buckling behavior of the system, a comprehensive parametric analysis has been conducted. The parameters studied include the cross-sectional thickness, length of the structure, eccentric loads, as well as the mechanical properties of the materials used in the system. Consistent with the FEM outcomes, the critical buckling force exhibited by the hyperelastic beam demonstrates a positive correlation with increasing levels of hardness, cross-sectional thickness, and eccentric loads. The buckling behavior of the system is adversely affected by increasing its length. To ultimately validate the precision and reliability of the model, a supervised neural network (NN) learning method is employed. [ABSTRACT FROM AUTHOR]