Dynamic analysis of piezoelectric perforated cantilever bimorph energy harvester via finite element analysis

Yousef A. Alessi,Ibrahim Ali,Mashhour A. Alazwari,Khalid Almitani,Alaa A Abdelrahman,Mohamed A. Eltaher Techno-Press 2023 Advances in aircraft and spacecraft science Vol.10 No.2

This article presents a numerical analysis to investigate the natural frequencies and harmonic response of a perforated cantilever beam attached to two layers of piezoelectric materials by using the finite element method for the first time. The bimorph piezoelectric is composed of 3 layers; two of them at the outer are piezoelectric, and the inner isotropic material. A higher order 3-D 20-node solid element that exhibits quadratic displacement behavior is exploited to discretize the isotropic layer, and coupled piezoelectric 3D element with twenty nodes is used to mesh the top and bottom layers. CIRCU94 element is added to act as a resistor part of the model. The proposed model is validated with previous works. The numerical parametric studies are presented to illustrate the effects of perforation geometry, the number of rows, the resistance on the natural frequencies, frequency response, and power. It is found that the thickness has a positive relationship with the natural frequency. Perforations help in producing higher voltage, and the best shape is rectangular perforations, and to produce higher voltage, two rows of rectangular perforations should be applied.

Novel quasi 3D theory for mechanical responses of FG-CNTs reinforced composite nanoplates

Alazwari, Mashhour A.,Daikh, Ahmed Amine,Eltaher, Mohamed A. Techno-Press 2022 Advances in nano research Vol.12 No.2

Effect of thickness stretching on free vibration, bending and buckling behavior of carbon nanotubes reinforced composite (CNTRC) laminated nanoplates rested on new variable elastic foundation is investigated in this paper using a developed four-unknown quasi-3D higher-order shear deformation theory (HSDT). The key feature of this theoretical formulation is that, in addition to considering the thickness stretching effect, the number of unknowns of the displacement field is reduced to four, and which is more than five in the other models. Two new forms of CNTs reinforcement distribution are proposed and analyzed based on cosine functions. By considering the higher-order nonlocal strain gradient theory, microstructure and length scale influences are included. Variational method is developed to derive the governing equation and Galerkin method is employed to derive an analytical solution of governing equilibrium equations. Two-dimensional variable Winkler elastic foundation is suggested in this study for the first time. A parametric study is executed to determine the impact of the reinforcement patterns, nonlocal parameter, length scale parameter, side-t-thickness ratio and aspect ratio, elastic foundation and various boundary conditions on bending, buckling and free vibration responses of the CNTRC plate.

Dynamic analysis of functionally graded (FG) nonlocal strain gradient nanobeams under thermo-magnetic fields and moving load

Alazwari, Mashhour A.,Esen, Ismail,Abdelrahman, Alaa A.,Abdraboh, Azza M.,Eltaher, Mohamed A. Techno-Press 2022 Advances in nano research Vol.12 No.3

Dynamic behavior of temperature-dependent Reddy functionally graded (RFG) nanobeam subjected to thermomagnetic effects under the action of moving point load is carried out in the present work. Both symmetric and sigmoid functionally graded material distributions throughout the beam thickness are considered. To consider the significance of strain-stress gradient field, a material length scale parameter (LSP) is introduced while the significance of nonlocal elastic stress field is considered by introducing a nonlocal parameter (NP). In the framework of the nonlocal strain gradient theory (NSGT), the dynamic equations of motion are derived through Hamilton's principle. Navier approach is employed to solve the resulting equations of motion of the functionally graded (FG) nanoscale beam. The developed model is verified and compared with the available previous results and good agreement is observed. Effects of through-thickness variation of FG material distribution, beam aspect ratio, temperature variation, and magnetic field as well as the size-dependent parameters on the dynamic behavior are investigated. Introduction of the magnetic effect creates a hardening effect; therefore, higher values of natural frequencies are obtained while smaller values of the transverse deflections are produced. The obtained results can be useful as reference solutions for future dynamic and control analysis of FG nanobeams reinforced nanocomposites under thermomagnetic effects.

On bending of cutout nanobeams based on nonlocal strain gradient elasticity theory

Mashhour A. Alazwari,Mohamed A Eltaher,Alaa A. Abdelrahman 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.43 No.6

This article aims to investigate the size dependent bending behavior of perforated nanobeams incorporating the nonlocal and the microstructure effects based on the nonlocal strain gradient elasticity theory (NSGET). Shear deformation effect due to cutout process is studied by using Timoshenko beams theory. Closed formulas for the equivalent geometrical characteristics of regularly squared cutout shape are derived. The governing equations of motion considering the nonlocal and microstructure effects are derived in comprehensive procedure and nonclassical boundary conditions are presented. Analytical solution for the governing equations of motion is derived. The derived non-classical analytical solutions are verified by comparing the obtained results with the available results in the literature and good agreement is observed. Numerical results are obtained and discussed. Parametric studies are conducted to explore effects of perforation characteristics, the nonclassical material parameters, beam slenderness ratio as well as the boundary and loading conditions on the non-classical transverse bending behavior of cutout nanobeams. Results obtained are supportive for the design, analysis and manufacturing of such nanosized structural system.

On static buckling of multilayered carbon nanotubes reinforced composite nanobeams supported on non-linear elastic foundations

Mashhour A. Alazwari,Ahmed Amine Daikh,Mohammed Sid Ahmed Houari,Abdelouahed Tounsi,Mohamed A Eltaher 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.40 No.3

This paper introduces a comprehensive buckling response of cross-ply orientation of carbon nanotube reinforced composite (CNTRC) multilayered nanobeams with different boundary conditions. The nonlocal strain gradient (NLSG) stress-strain governing relations are utilized to include the size-dependence and microstructure effects. Novel hyperbolic higher shear deformation beam theory including thickness stretching effect is used to fulfill both parabolic shear distribution through the thickness and the zero-shear at free boundaries. Parametric studies are performed to inspect the influences of arrangement of reinforcement material distributions functions, different functionally graded (FG) functions, and uniform distribution (UD). The balance equilibrium equations are derived, and Fourier functions are utilized to obtain the critical buckling loads of nanobeam under mechanical loadings. Mechanical properties are assumed to be temperature-dependent by using Touloukian principal. An exact solution is performed satisfying the edge boundary conditions. A detailed numerical analysis is illustrated to examine the impact of CNTs patterns, lamination, side-to-thickness, aspect ratios, microstructure and size scale parameters on critical buckling loads of CNTRC laminated nanobeams.

Static analysis of cutout microstructures incorporating the microstructure and surface effects

Mashhour A. Alazwari,Alaa A. Abdelrahman,Ahmed Wagih,Mohamed A Eltaher,Hanaa E. Abd-El-Mottaleb 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.38 No.5

This article develops a nonclassical model to analyze bending response of squared perforated microbeams considering the coupled effect of microstructure and surface stress under different loading and boundary conditions, those are not be studied before. The corresponding material and geometrical characteristics of regularly squared perforated beams relative to fully filled beam are obtained analytically. The modified couple stress and the modified Gurtin-Murdoch surface elasticity models are adopted to incorporate the microstructure as well as the surface energy effects. The differential equations of equilibrium including the Poisson’s effect are derived based on minimum potential energy. Exact closed form solution is obtained for bending behavior of the proposed model considering the classical and nonclassical boundary conditions for both uniformly distributed and concentrated loads. The proposed model is verified with results available in the literature. Influences of the microstructure length scale parameter, surface energy, beam thickness, boundary and loading conditions on the bending behavior of perforated microbeams are investigated. It is observed that microstructure and surface parameters are vital in investigation of the bending behavior of perforated microbeams. The obtained results are supportive for the design, analysis and manufacturing of perforated nanobeams that commonly used in nanoactuators, nanoswitches, MEMS and NEMS systems.

Dynamic vibration response of functionally graded porous nanoplates in thermal and magnetic fields under moving load

Ismail Esen,Mashhour A. Alazwari,Khalid H. Almitani,Mohamed A Eltaher,A. Abdelrahman Techno-Press 2023 Advances in nano research Vol.14 No.5

In the context of nonclassical nonlocal strain gradient elasticity, this article studies the free and forced responses of functionally graded material (FGM) porous nanoplates exposed to thermal and magnetic fields under a moving load. The developed mathematical model includes shear deformation, size-scale, miscorstructure influences in the framework of higher order shear deformation theory (HSDT) and nonlocal strain gradient theory (NSGT), respectively. To explore the porosity effect, the study considers four different porosity models across the thickness: uniform, symmetrical, asymmetric bottom, and asymmetric top distributions. The system of quations of motion of the FGM porous nanoplate, including the effects of thermal load, Lorentz force, due to the magnetic field and moving load, are derived using the Hamilton's principle, and then solved analytically by employing the Navier method. For the free and forced responses of the nanoplate, the effects of nonlocal elasticity, strain gradient elasticity, temperature rise, magnetic field intensity, porosity volume fraction, and porosity distribution are analyzed. It is found that the forced vibrations of FGM porous nanoplates under thermal and live loads can be damped by applying a directed magnetic field.

Dynamic response of FG porous nanobeams subjected thermal and magnetic fields under moving load

Ismail Esen,Mashhour A. Alazwari,Mohamed A Eltaher,Alaa A. Abdelrahman 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.42 No.6

The free and live load-forced vibration behaviour of porous functionally graded (PFG) higher order nanobeams in the thermal and magnetic fields is investigated comprehensively through this work in the framework of nonlocal strain gradient theory (NLSGT). The porosity effects on the dynamic behaviour of FG nanobeams is investigated using four different porosity distribution models. These models are exploited; uniform, symmetrical, condensed upward, and condensed downward distributions. The material characteristics gradation in the thickness direction is estimated using the power-law. The magnetic field effect is incorporated using Maxwell's equations. The third order shear deformation beam theory is adopted to incorporate the shear deformation effect. The Hamilton principle is adopted to derive the coupled thermomagnetic dynamic equations of motion of the whole system and the associated boundary conditions. Navier method is used to derive the analytical solution of the governing equations. The developed methodology is verified and compared with the available results in the literature and good agreement is observed. Parametric studies are conducted to show effects of porosity parameter; porosity distribution, temperature rise, magnetic field intensity, material gradation index, non-classical parameters, and the applied moving load velocity on the vibration behavior of nanobeams. It has been showed that all the analyzed conditions have significant effects on the dynamic behavior of the nanobeams. Additionally, it has been observed that the negative effects of moving load, porosity and thermal load on the nanobeam dynamics can be reduced by the effect of the force induced from the directed magnetic field or can be kept within certain desired design limits by controlling the intensity of the magnetic field.