Postbuckling analysis of piezoelectric multiscale sandwich composite doubly curved porous shallow shells via Homotopy Perturbation Method

In this study postbuckling behaviors of multiscale composite sandwich doubly curved piezoelectric shell with a flexible core and MR layers by employing Homotopy Perturbation Method in hygrothermal environment has been investigated. By using Reddy third shear deformable theory the face sheets and third-order polynomial theory of the flexible core the strains and stresses are obtained. A mathematical model for the multiscale composite layered shell with a flexible core and magnetorheological layer (MR) that incorporates the nonlinearity of the in-plane and the vertical displacements of the core is assumed. Three-phase composite shells with polymer/Carbon nanotube/fiber and polymer/Graphene platelet/fiber either uniformly or non-uniformly based on different patterns according to Halpin–Tsai model have been considered. The governing equations of multiscale shell have been derived by implementing Hamilton’s principle. Meanwhile, simply supported boundary conditions are employed to the shell. For investigating correctness and accuracy, this paper is validated by other previous researches. Finally, different parameters such as temperature rise, various distribution patterns, magnetic fields and curvature ratio are considered in this article. It is found these parameters have significant effect on the frequency–amplitude curves.

     

Hygrothermal coupling analysis of magneto-electroelastic beams using finite element methods

In this article, the finite element (FE) method has been used to assess the coupled static behavior of hygro-thermo-magneto-electroelastic (HTMEE) beam. Influence of externally applied hygrothermal loads on the direct (displacements, electric and magnetic potentials) and derived quantities (stresses, electric displacement and magnetic flux densities) of HTMEE beam have been studied in detail. The principle of total potential energy and the coupled constitutive equations of HTMEE material are used for the FE formulation. A generalized condensation technique is adopted to solve the global FE equations of motion. Numerical examples are discussed to examine the effect of hygrothermal loads and distinct effect of moisture concentration on the behavior of the beam. Particular emphasis has been placed to analyze the influence of temperature and moisture dependent elastic stiffness coe?cients associated with empirical constants. Considering the independent effect of temperature and moisture on the coupled static responses, the most significant combination of the empirical constants corresponding to temperature dependency and moisture dependency are explored. Extensive computational examples are considered to examine the significant effect of boundary conditions, temperature gradient, moisture concentration gradient and empirical constants on the static behavior of HTMEE beam. It is observed that the static behavior of HTMEE beam is significantly influenced by the hygrothermal loads and empirical constants. The results presented in this article would serve as a benchmark results in design and analysis of HTMEE structures for sensors and actuators applications.     

Large deflection analysis of functionally graded magneto-electro-elastic porous flat panels

In this article, an attempt has been made on evaluating the large/nonlinear deflection of functionally graded magneto-electro-elastic porous (FG-MEEP) flat panels taking geometric skewness into consideration. Further, the flat panel is subjected to combined loads which include mechanical, electrical and magnetic loads. The mathematical formulation is derived through higher order shear deformation theory and von-Karman's geometric nonlinearity under the framework of finite element method (FEM). The effective material properties of FG-MEEP material are determined using modified power law. Two forms of material gradation such as ‘B’ rich bottom and ‘F’ rich bottom are modelled and implemented in the analysis. The numerical assessment is carried out to investigate the effect of prominent parameters such as skew angle, porosity distribution, gradient index, porosity volume, functionally graded pattern, electromagnetic loads on the nonlinear deflection of FG-MEEP flat panels. In addition, this study also makes an attempt to evaluate the degree of coupling associated with these parameters.

     

Chaotic dynamics and forced harmonic vibration analysis of magneto-electro-viscoelastic multiscale composite nanobeam

In this article, the damping forced harmonic vibration characteristics of magneto-electro-viscoelastic (MEV) nanobeam embedded in viscoelastic foundation is evaluated based on nonlocal strain gradient elasticity theory. The viscoelastic foundation consists of Winkler–Pasternak layer. The governing equations of nonlocal strain gradient viscoelastic nanobeam in the framework of refined shear deformable beam theory are obtained using Hamilton’s principle and solved implementing an analytical solution. In addition, a parametric study is presented to examine the effect of the nonlocal strain gradient parameter, magneto-electro-mechanical loadings, and aspect ratio on the vibration characteristics of nanobeam. From the numerical evaluation, it is revealed that the effect of electric and magnetic loading on the natural frequency has a predominant influence.

     

Vibration analysis of porous magneto-electro-elastically actuated carbon nanotube-reinforced composite sandwich plate based on a refined plate theory

In this article, the free vibration response of sandwich plates with porous electro-magneto-elastic functionally graded (MEE-FG) materials as face sheets and functionally graded carbon nanotube-reinforced composites (FG-CNTRC) as core is investigated. To this end, four-variable shear deformation refined plate theory is exploited. The properties of functionally graded material plate are assumed to vary along the thickness direction of face sheets according to modified power-law expression. Furthermore, properties of FG-CNTRC layer are proposed via a mixture rule. Hamilton’s principle with a four-variable tangential–exponential refined theory is used to obtain the governing equations and boundary conditions of plate. An analytical solution approach is utilized to get the natural frequencies of embedded porous FG plate with FG-CNTRC core subjected to magneto-electrical field. A parametric study is led to fulfill the effects of porosity parameter, external magnetic potential, external electric voltage, types of FG-CNTRC, and different boundary conditions on dimensionless frequencies of porous MEE-FG sandwich plate. It is noteworthy that the numerical consequences can serve as benchmarks for future investigations for this type of structures with porous mediums.