Thermomechanical Buckling Analysis of the E&P-FGM Beams Integrated by Nanocomposite Supports Immersed in a Hygrothermal Environment.

Mohammad Khorasani,Francesco Tornabene,Rossana Dimitri,Luca Lampani

doi:10.3390/molecules26216594

Abstract

Due to the widespread use of sandwich structures in many industries and the importance of understanding their mechanical behavior, this paper studies the thermomechanical buckling behavior of sandwich beams with a functionally graded material (FGM) middle layer and two composite external layers. Both composite skins are made of Poly(methyl methacrylate) (PMMA) reinforced by carbon-nano-tubes (CNTs). The properties of the FGM core are predicted through an exponential-law and power-law theory (E&P), whereas an Eshelby–Mori–Tanaka (EMT) formulation is applied to capture the mechanical properties of the external layers. Moreover, different high-order displacement fields are combined with a virtual displacement approach to derive the governing equations of the problem, here solved analytically based on a Navier-type approximation. A parametric study is performed to check for the impact of different core materials and CNT concentrations inside the PMMA on the overall response of beams resting on a Pasternak substrate and subjected to a hygrothermal loading. This means that the sensitivity analysis accounts for different displacement fields, hygrothermal environments, and FGM theories, as a novel aspect of the present work. Our results could be replicated in a computational sense, and could be useful for design purposes in aerospace industries to increase the tolerance of target productions, such as aircraft bodies.

Highlights

functionally graded material (FGM)-based structures serve as bi-phase beams, plates and shells whose properties vary across their thickness or length continuously
Motivated by the aforementioned studies, this paper aims to further contribute to the thermomechanical response of sandwich beams including an exponential-law/powerlaw-based functionally graded core (E&P-FGC) integrated by two CNTRC layers
Assumptions, we propose and compare a thermomechanical model based onthis foursandwich different kinematic namely, the third-order shear deformation based on four different kinematic assumptions, namely, the third-order shear deformation theory (TSDT), the hyperbolic shear deformation theory (HSDT), the sinusoidal shear theory (TSDT), the hyperbolic deformation theory (HSDT), theory the sinusoidal shear deformation theory (SSDT) andshear the exponential shear deformation (ESDT)

Summary

Introduction

FGM-based structures serve as bi-phase beams, plates and shells whose properties vary across their thickness or length continuously. FGMs have increasingly attracted the interest of the scientific community for their use in different high-tech industries due to their outstanding mechanical properties compared to singlephase materials and structures. Shen and Bever [1] considered graded material composites, despite their limited knowledge and a general lack of sophisticated fabrication equipment. Japanese scientists in 1984 [2] applied this technique to an aerospace project, due to their necessity to have a 10 mm thickness thermal barrier with an internal and external temperature of 1000 K and 2000 K, respectively. Fu et al [3]

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