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This study utilizes higher‐order shear deformation and non‐local strain gradient elasticity theories to analyze the thermo‐mechanical vibrations and buckling of smart sandwich plates featuring functionally graded ceramic (Si3N4) and metal (Ni) surface layers, along with a Ni tetrachiral auxetic core. The governing equations are established through Hamilton's principle, with the Navier approach incorporating thermal and viscoelastic effects. Critical parameters encompass the length‐to‐thickness ratio, temperature, non‐local effects, metal‐to‐ceramic ratio, and layer thickness. Results indicate that increased nickel content and material size parameter and decreased plate thickness augment stiffness, whereas elevated material gradation, temperature, thickness ratio, non‐local parameter, and core thickness diminish natural frequency. This study significantly contributes by offering a novel framework for optimizing tetrachiral core sandwich nanoplates, thereby advancing high‐performance nanoscale engineering. The study presented investigates the thermo‐mechanical behavior of a sandwich structure with a tetrachiral‐shaped auxetic core. The geometric configuration, unit cell architecture, and the influence of the material length scale on the effective stiffness under temperature variation are illustrated. Results indicate a clear dependency of λ11 on both temperature difference (ΔT) and microstructural parameters.

Although carbon nanotube (CNT) is a promising material due to its excellent mechanical and functional properties, CNT has not been effectively used for high performance composites due to the degradation of its mechanical properties as a result of insufficient dispersibility of CNT in its matrix. In this study, CNT/aluminum (Al) matrix functionally graded materials (FGMs) were fabricated by centrifugal slurry methods. The dispersion of CNT was carried out with the solvent of dimethylacetamide (DMAs), and the dispersant of potassium carbonate (K2CO3) under ultrasonic sonication conditions. Tribological characteristics on the FGMs were investigated using a ball-on-disk tribometer. It was demonstrated that the presence of CNT contributed to an increase of the coefficients of friction and an enhancement of wear resistances.

Functionally graded aluminium (Al) matrix composite materials reinforced with carbon nanotubes (CNT) and silicon carbide nanoparticles (nSiC) or nanodiamond (nD) were fabricated using a powder-metallurgical route. The nSiC and nD were not only used as a reinforcement but also as an active solid mixing agent for dispersing the CNT in the Al powder. Dual-nanoparticle-reinforced functionally graded multiple-layered composites were found to exhibit different mechanical characteristics. In particular, the hardnesses of the CNT-and nSiC-reinforced composites were dramatically increased, being up to eight times greater (330 HV) than that of bulk pure Al. In the case of the combination of the CNT and nD nanoparticles, the reinforced Al matrix composites exhibited the highest flexural strength (about 760 MPa). This functionally graded dual-nanoparticle approach could also be applied to other nanoreinforced systems, such as ceramics or complex hybrid-matrix materials. Keywords: Carbon nanotubes (CNT), nanosilicon carbide (nSiC), nanodiamond (nD), functionally graded materials (FGM), Powder metallurgy

In this work, we aim to investigate the photo-thermal-elastic waves interaction in a nano-composite semiconductor, elastic and functionally graded material (FGM). The governing equations are taken in one dimension during the influence of initial magnetic field when the elastic medium is isotropic and the material properties are non-homogeneity. In the domain of Laplace transform the basic equations in non- dimensional forms are formulated in a vector matrix differential equation and are solved by the eigenvalue and eigenvector approach. The physical quantities are obtained by applying the numerical inversion method of the transforms. The numerical results of the physical quantities (carrier density, displacement, temperature, stresses and strains) are discussed and illustrated graphically.

This paper studies the influence of main parameters on the mechanical properties and wear behaviour of functionally graded materials pure Aluminum reinforced by various weight fractions of aluminium oxide (Al2O3). A Functionally graded (FG) pure aluminium/Al2O3 tube was processed by horizontal centrifugal casting method. The hollow tube dimensions are 230 mm outer diameter x 12 mm thickness x 180 mm length. The properties of these FG tubes were compared with unreinforced alloy. Hardness and tensile results in the radial direction showed that the hardness and tensile in accordance with the gradient microstructure was improved from inner zone to outer zone. Wear tests were carried out for different test duration at a constant sliding speed of 8 m/s and loads applied are 14, 24 and 40 N. In all test conditions the wear rate in the outer layer was minimum compared to other layers. In the surface analysis, scanning electron microscope indicated the presence of delamination, wear debris and cracks. FG tubes reinforced by Al2O3 particles have increased mechanical properties and wear resistance compared to its unreinforced alloy (matrix alloy) and is suitable for use in automobile and transport applications.Graphic Abstract

Functionally graded materials (FGMs) are a new generation of engineered materials whose composition and structure are spatially varied through non-uniform distribution. This article presents a comprehensive overview of FGMs, including their conventional fabrication techniques in brief and a detailed analysis of their fabrication through additive manufacturing (AM). In contrast, the AM enables the fabrication of complex and intricate geometry. The combination of materials composition, manufacturing techniques, and modelling of FGMs is conferred with appropriate insistence on illuminating the fundamental structure–property-material relationships. Further, the challenges in the fabrication, modelling, and strategy to process of FGMs are discussed.

Functionally graded materials (FGMs) attract considerable interest in materials science and industry, since their composition or morphology gradually changes along their length, width, or height, which provides new approach for the development of multifunctional materials. In this paper, we studied the fabrication of a gradient microstructure in alumina (Al 2 O 3 ) by spark plasma sintering (SPS). During the SPS process, the applied asymmetric graphite tool configuration causes a large temperature gradient, which results in a gradually changing morphology in Al 2 O 3 ceramics. The local temperatures were quantitatively measured through extra thermocouples during SPS processes with various asymmetric configurations. In the most asymmetric configuration, a maximum vertical temperature difference of 225 °C was detected within the sample treated at a sintering temperature of 1300 °C and a pressure of 25 MPa applied 200 °C·min −1 heating rate. The microstructure investigations demonstrated the morphology gradient in the ceramic: one part of the Al 2 O 3 exhibited fine, nanostructured morphology with large open and permeable pores, whereas the other part was solid without pores. Our investigations show that a gradient Al 2 O 3 ceramic can be produced with a single-step SPS process, which offers new directions in FGMs research. With an asymmetric sintering configuration and the sintering conditions, the structure of the ceramic, such as porosity, can be designed according to the requirements of the application area.

In our study, we investigated the additive manufacturing (AM) of ceramic-based functionally graded materials (FGM) by the direct AM technology thermoplastic 3D printing (T3DP). Zirconia components with varying microstructures were additively manufactured by using thermoplastic suspensions with different contents of pore-forming agents (PFA), which were co-sintered defect-free. Different materials were investigated concerning their suitability as PFA for the T3DP process. Diverse zirconia-based suspensions were prepared and used for the AM of single- and multi-material test components. All of the samples were sintered defect-free, and in the end, we could realize a brick wall-like component consisting of dense (<1% porosity) and porous (approx. 5% porosity) zirconia areas to combine different properties in one component. T3DP opens the door to the AM of further ceramic-based 4D components, such as multi-color, multi-material, or especially, multi-functional components.

With the development of functionally graded materials (FGMs), the multi-field coupling of FGMs has received extensive attention. The analytical solutions of the thermal distribution, displacement, strain, and stress of a rotating functionally graded (FG) cylinder or circular disk are studied under a uniform constant magnetic field. In this paper, the FG cylinder or circular disk are subjected to axisymmetric mechanical and thermal loads. It is assumed that the material properties of the cylinder or circular disk change as the power functions along with the radius direction. On the basis of the dynamic equation of the rotating cylinder with the Lorentz force, the second-order ordinary differential equation is derived, and the analytical solutions of the multi-field coupling are obtained. The three simplified problems are solved as the special cases of the present analytical expressions. In addition, the effects of FG parameter, thermal load, magnetic field, internal pressure, and rotating velocity on the magneto-thermal–mechanical response of FG cylinder or circular disk are studied.

Background The gradation of thermal expansion coefficient was analyzed in the earlier study. The analytical formulation derived here, which is quite different, should be validated to understand the thermal stress distribution in a laminated composite and functionally graded material. Besides this solution, a validated numerical model can also be used to optimize the material gradation of plates in terms of sustainability. Objective To validate the analytical formulation derived here, an experimental model is presented to understand the thermal stress concentration for functionally graded and laminated composite plates. A numerical model is also validated to extend to understand the effects of the number of layers, the thickness of a layer, the gradation function, the ratio of elastic moduli, and the coating. Methods The experimental problems in the production of the experimental models with layers of different elastic moduli are discussed here. In the experimental analysis, a three-dimensional photoelastic stress analysis of two- and four-layer composite plate was used to mechanically model the thermal expansion. The analytical solution for the thermal stress in a free plate was derived by the strain suppression method based on the principle of superposition. The numerical models were analyzed using finite element software. The step variation in the experiment was used as a reference point for a continuous or multi-layer (> 2) step variation of material coefficients in the models. Results The variation of stress concentration is shown for various cases of laminated and continuous gradations of elastic modulus. The four-layer experimental model provides the difference in thermal stress distribution as a result of a layered coating. The validated analytical and numerical models provide reasonable results. An empirical formula to optimize the material gradation in terms of elastic modulus is derived. Conclusions The experimental model can be used to analyze thermal stress in functionally graded materials. The gradations of the material in the plate or the coating of the plates can be optimized by the validated analytical and numerical models. The empirical formula can be used to determine the elastic modulus of the coating to minimize the stress concentration.