In the present study, the mechanical properties of self-compacting concrete were investigated after the addition of different amounts of ZnO nanoparticles. The zinc oxide nanoparticles, with an average particle size of about 30 nm, were synthesized and their properties studied with the help of a scanning electron microscope (SEM) and X-ray diffraction. The prepared nanoparticles were partially added to self-compacting concrete at different concentrations (0.05, 0.1, 0.2, 0.5 and 1.0%), and the mechanical (flexural and split tensile) strength of the specimens measured after 7, 14, 21 and 28 days, respectively. The present results have shown that the ZnO nanoparticles were able to improve the flexural strength of self-compacting concrete. The increased ZnO content of more than 0.2% could increase the flexural strength, and the maximum flexural and split tensile strength was observed after the addition of 0.5% nanoparticles. Finally, ZnO nanoparticles could improve the pore structure of the self-compacted concrete and shift the distributed pores to harmless and less-harmful pores, while increasing mechanical strength.

In this paper, the thermopiezoelectric behavior of a thick walled cylinder with functionally graded materials is studied. The cylinder is loaded under the temperature gradient and inner and outer pressures. All the mechanical, thermal and piezoelectric properties except the Poisson ratio can be expressed as a power function in the radial direction. In the first step, with the solution of the heat transfer equation, a symmetric distribution of temperature is obtained. The stresses and electric displacement relations can be derived in terms of the temperature, electric field and strain. Substituting the resultant relations into the mechanical and electrical equilibrium equations yields the system of nonhomogeneous differential equations with two unknown variables (the mechanical displacement and the electrical potential). Solving the system of nonhomogeneous differential equations yields other mechanical and thermal terms such as the stress, displacement, electric field and electric displacement. The main result of the present study is that, by applying a proper distribution of mechanical and thermal properties in the functionally graded piezoelectric material (FGPM) solid structures, the distributions of stresses, electric potential and electric field in the FGPM can be controlled. Hence, the FGPM can be used in sensors or actuators.

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A simplified three-unknown shear and normal deformations nonlocal beam theory for thermo-electro-magneto mechanical bending analysis of a nanobeam with a functionally graded material core and two functionally piezomagnetic layers is studied in this paper. The assumed structure is subjected to mechanical, thermal, electrical, and magnetic loads. An initial applied voltage and magnetic load is considered on the functionally graded piezomagnetic material layers. Eringen’s nonlocal constitutive equations are considered in the analysis. Governing equations are derived according to the present refined theory using the principle of virtual displacements. The numerical results including the deflection, electric, and magnetic potential distribution are calculated in terms of important parameters of the problem such as applied electric and magnetic potentials, two parameters of temperature distribution, and nonlocal parameter. The numerical results indicate that increase in applied electric potential increases the deflection unlike the applied magnetic potential that decreases the deflection. Furthermore, it can be concluded that increasing the nonlocal parameter leads to increase in the deflection.

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