Article
Mathematics
Francesco Paolo Pinnola, Raffaele Barretta, Francesco Marotti de Sciarra, Antonina Pirrotta
Summary: This paper proposes a consistent nonlocal viscoelastic beam model and investigates a Timoshenko bending problem considering size- and time-dependent effects. A stress-driven nonlocal formulation is used to inspect scale phenomena, and fractional linear viscoelasticity is considered to simulate time-dependent effects. Analytical solutions and application samples are presented, and parametric analyses are provided to show influences of viscoelastic and size effects on mechanical response.
Article
Construction & Building Technology
Mashhour A. Alazwari, Mohamed A. Eltaher, Alaa A. Abdelrahman
Summary: This article investigates the size-dependent bending behavior of perforated nanobeams considering the nonlocal and microstructure effects. The study incorporates the shear deformation effect due to the cutout process using the Timoshenko beams theory. Closed-form formulas for the equivalent geometrical characteristics of regularly squared cutout shape are derived. Governing equations of motion, comprehensive procedure, and nonclassical boundary conditions are presented and an analytical solution is derived. The analytical solutions are verified by comparing with the available results and good agreement is observed. Numerical results and parametric studies are conducted to explore the effects of perforation characteristics, material parameters, beam slenderness ratio, and boundary/loading conditions on the bending behavior of cutout nanobeams. The obtained results are supportive for the design, analysis, and manufacturing of nanosized structural systems.
STEEL AND COMPOSITE STRUCTURES
(2022)
Article
Mechanics
Francesco P. Pinnola, Marzia S. Vaccaro, Raffaele Barretta, Francesco Marotti de Sciarra
Summary: This study investigates the stochastic flexural vibrations of small-scale Bernoulli-Euler beams with external damping using stress-driven nonlocal mechanics. Damping effects are simulated by considering viscous interactions between the beam and its surrounding environment. Loadings are modeled by accounting for their random nature, providing a comprehensive description of the beam's dynamic behavior.
Article
Computer Science, Interdisciplinary Applications
Mahsa Najafi, Isa Ahmadi
Summary: In this paper, an efficient method based on nonlocal elasticity theory and Layerwise theory is proposed for the analysis of bending, buckling, and vibration of functionally graded nanobeam. The method takes into account the transverse shear and normal strains of nanobeam and the small-scale effect. The proposed theory is validated by comparing with other theories and shows accurate results in predicting vibration, buckling, and bending of nanobeams.
ENGINEERING WITH COMPUTERS
(2023)
Article
Engineering, Mechanical
Lior Medina, Ashwin A. Seshia
Summary: The study focuses on the limit point behavior of a metastructure composed of two double-clamped beams under distributed electrostatic load. Results indicate the potential for bistable and tristable properties in the structure, depending on certain geometric parameters. The analysis utilizes a reduced order model and local stability analysis to study the complex equilibrium paths and behavior.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2021)
Article
Engineering, Multidisciplinary
Andrea Caporale, Hossein Darban, Raimondo Luciano
Summary: In this study, a unified approach is used to determine the strain-driven and stress-driven differential equations of Timoshenko nano-beams with loading discontinuities. The proposed models can simulate small scale effects with different types of constitutive laws and consider points of discontinuities for generalized internal forces. Novel constitutive continuity conditions are imposed at the beam interior points of loading discontinuities, providing an alternative to Dirac delta function. Closed-form solutions to practical cases are obtained using the proposed models.
INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE
(2022)
Article
Chemistry, Multidisciplinary
Marzia Sara Vaccaro, Francesco Paolo Pinnola, Francesco Marotti de Sciarra, Raffaele Barretta
Summary: The dynamic behavior of micro- and nano-beams is investigated using nonlocal continuum mechanics, with size effects modeled by expressing elastic curvatures in terms of stress-driven local and nonlocal phases. Relevant nonlocal equations of motion for slender beams are formulated and integrated using an analytical approach. The presented strategy is applied to simple case problems of nanotechnological interest, and the validation of the proposed nonlocal methodology is provided by comparing natural frequencies with those obtained by the classical strain gradient model of elasticity. Overall, the outcomes obtained can be useful for the design and optimization of micro- and nano-electro-mechanical systems (M/NEMS).
Article
Engineering, Multidisciplinary
Rosa Penna
Summary: This paper investigates the bending response of Bernoulli-Euler nanobeams made of a functionally graded material with different cross-sectional shapes. A stress-driven model incorporating surface energy effects is used. The nanobeam consists of a bulk volume and a surface layer perfectly adhered to the bulk continuum. The nonlocal governing equations of the elastostatic bending problem are derived and the main results of a parametric investigation are presented.
INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE
(2023)
Article
Mechanics
Lior Medina, Ashwin A. Seshia
Summary: The stability of electrostatically actuated micro-meta-structure is studied using a reduced order model and Lyapunov stability analysis, revealing that instability in one beam can nullify tristable properties in another. A new equilibrium branch is disclosed through the analysis, and it is concluded that the stability of a metastructure depends on the stability of its sub-structures. The newly developed dynamic RO model shows promise in stability analysis and quasi-static loadings.
EUROPEAN JOURNAL OF MECHANICS A-SOLIDS
(2022)
Article
Mechanics
S. Adhikari, D. Karlicic, X. Liu
Summary: The research investigates the free and forced bending vibration of damped nonlocal nano-beams on an elastic foundation, considering two types of nonlocal damping models. A frequency-dependent dynamic finite element method is developed to analyze the forced vibration response. The study reveals that the dynamic stiffness matrix can be defined by six unique coefficients and reduces to well-known special cases under different conditions, with a numerical algorithm suggested for extracting eigenvalues in the undamped case.
EUROPEAN JOURNAL OF MECHANICS A-SOLIDS
(2021)
Article
Engineering, Mechanical
Francesco Paolo Pinnola, Marzia Sara Vaccaro
Summary: The paper investigates the random flexural vibrations of small-scale Bernoulli-Euler beams with internal and external damping. The study is relevant in the design and optimization of structural components for smart miniaturized electromechanical systems. The proposed formulation incorporates Boltzmann superposition integral, fractional-order viscoelasticity, and an integral nonlocal formulation to account for non-conventional phenomena and size effects. The methodology is suitable for modeling and capturing the effective behavior of miniaturized devices.
PROBABILISTIC ENGINEERING MECHANICS
(2023)
Article
Mechanics
Lior Medina
Summary: In this study, a rigorous limit point and bifurcation analyses are carried out to investigate the reaction of a curved beam driven by a bell-shaped electrode. The study presents criteria for bistability and symmetry breaking as a function of beam and electrode geometries. The results show the importance of actuation voltages and electrode curvature in determining symmetric and asymmetric responses of the beam, which can be useful for designing curved beam-electrode systems in MEMS-based applications.
EUROPEAN JOURNAL OF MECHANICS A-SOLIDS
(2023)
Article
Mechanics
Mohamed-Ouejdi Belarbi, Mohammed-Sid-Ahmed Houari, Ahmed Amine Daikh, Aman Garg, Tarek Merzouki, H. D. Chalak, Hicham Hirane
Summary: An efficient nonlocal finite element model was developed to study the bending and buckling behavior of functionally graded nanobeams. The new theory provides accurate transverse shear stress distribution without the need for correction factors, showing high accuracy and convergence rate. Detailed numerical studies validated the performance and reliability of the proposed model.
COMPOSITE STRUCTURES
(2021)
Article
Mechanics
E. Salari, S. A. Sadough Vanini
Summary: The research aims to study the nonlinear thermo-mechanical bending and thermal postbuckling of nanobeams, as well as to address the snap-through phenomenon in thermally preloaded graded porous nanobeams. Different parameters' effects on the nonlinear thermo-mechanical bending and instability of FG nanobeams are considered, and two strategies are proposed to extract the nonlinear bending and postbuckling curves of the nanobeams. The cylindrical arch-length technique is adopted to capture the snapping behavior beyond the limit loads of the thermally preloaded nanobeam.
EUROPEAN JOURNAL OF MECHANICS A-SOLIDS
(2021)
Article
Mathematics, Applied
Amin Anjomshoa, Behrooz Hassani
Summary: This paper focuses on increasing the bending analysis accuracy of nanobeams using nonlocal integral models. It explores the influence of kernel normalization on the deflections of nanobeams, finding that one normalization procedure can cause unexpected behaviors in the nonlocal model. The study proposes a consistent normalization scheme for bending analysis of nanobeams and thoroughly investigates the effects of kernel function distribution and edge support condition on the deflection of the model.
ZAMM-ZEITSCHRIFT FUR ANGEWANDTE MATHEMATIK UND MECHANIK
(2021)
Article
Mechanics
M. A. Eltaher, R. A. Shanab, N. A. Mohamed
Summary: This article presents an enhanced mathematical model and closed-form solutions to explore the dynamic vibration response of perforated viscoelastic nanostructure thin/thick nanobeams with a size-dependent continuum model and different boundary conditions. The influences of viscoelastic parameter, nonlocal softening coefficient, supporting conditions, and filling/spacing ratio on the vibration response are analyzed.
ARCHIVE OF APPLIED MECHANICS
(2023)
Article
Mechanics
Ahmed-Amine Daikh, Mohamed-Ouejdi Belarbi, Drai Ahmed, Mohamed Sid Ahmed Houari, Mehmet Avcar, Abdelouahed Tounsi, Mohamed A. Eltaher
Summary: In this study, a quasi-3D analytical plate theory is developed to explore the bending behavior of a new model of functionally graded plate structures (FGPSs). Different types of functionally graded nanoplates are examined, and the material gradation is described using cosine functions. The modified continuum nonlocal strain gradient theory is utilized, and the Galerkin method is used to solve the equilibrium equations under various boundary conditions. The results are compared to existing literature to confirm the accuracy and consistency of the analytical model. A comprehensive parametric study is also performed to determine the sensitivity of the bending response to various factors.
Article
Energy & Fuels
Radi A. Alsulami, Saad A. El-Sayed, Mohamed A. Eltaher, Akram Mohammad, Khalid H. Almitani, Mohamed E. Mostafa
Summary: This study used TGA to evaluate the thermal degradation characteristics of date palm leaves, seeds, leaf stems, and their blends at different heating rates. The kinetic parameters were determined using the KAS and OFW methods, and it was found that the heating rate significantly affected the thermal degradation. Higher heating rates resulted in better pyrolysis performance.
Article
Materials Science, Multidisciplinary
Huchhanagouda H. Patil, Jeyeraj Pitchaimani, M. A. Eltaher
Summary: This work investigates the buckling and vibration characteristics of axially functionally graded graphene platelet (GPL) composite beams exposed to axially varying loads (AVLs). Five types of axial grading GPLs subjected to six types of AVLs are studied using the Timoshenko beam theory. The effective elastic properties are obtained using the Halpin-Tsai model, and the equations of motion are solved using the Ritz method for buckling and vibration analysis. Parametric studies reveal the influences of grading pattern, load, GPL content, and structural boundary conditions on the beam's behavior. The study provides insights into the nature of graded distribution of GPLs for specific AVLs and aids in designing structural members.
MECHANICS OF ADVANCED MATERIALS AND STRUCTURES
(2023)
Article
Mathematics
Alaa A. Abdelrahman, Hussein A. Saleem, Gamal S. Abdelhaffez, Mohamed A. Eltaher
Summary: The electromechanical-size-dependent bending of piezoelectric composite structural components with flexoelectricity has been studied using nonlocal strain gradient elasticity theory. The accuracy of the proposed methodology is verified by comparing the results with existing literature. Parametric studies are conducted to explore the effects on the bending behavior and it is found that controlling the parameters can improve the electromechanical and mechanical behaviors.
Article
Mathematics
Emad E. Ghandourah, Ahmed Amine Daikh, Samir Khatir, Abdulsalam M. Alhawsawi, Essam M. Banoqitah, Mohamed A. Eltaher
Summary: This study proposes a new model for functionally graded shell structures called Tri-coated FGM, which investigates the free vibration response by incorporating porosities and microstructure-dependent effects. Two types of tri-coated FG shells are investigated, and five distribution patterns are proposed. A novel modified field of displacement is proposed by considering the shear deformation effect. Extensive parametric analysis is conducted to investigate the influence of various factors on the fundamental frequencies.
Article
Mechanics
Ahmed Amine Daikh, Mohamed-Ouejdi Belarbi, Sattar Jedari Salami, Miloud Ladmek, Abdelkader Belkacem, Mohamed Sid Ahmed Houari, Hani Magdy Ahmed, Mohamed A. Eltaher
Summary: This paper presents a mathematical model to analyze the static bending response of laminated composite beams reinforced by functionally graded fibers and randomly oriented single-walled carbon nanotubes. Various schemes of material distributions and types of elastic foundations are considered, and the equilibrium equations are derived using the virtual work principle and solved numerically using Fourier series. A detailed parametric analysis is performed to investigate the impact of different distribution patterns, volume fractions, and elastic foundation parameters on the deflection of the composite beam.
Article
Engineering, Aerospace
Hao-Xuan Ding, M. A. Eltaher, Gui-Lin She
Summary: A nonlinear analysis is conducted to study the low-velocity impact behavior of a graphene platelets-reinforced metal foam cylindrical shell with spinning motion in a thermal environment. The effects of geometric imperfections, spinning velocity, boundary conditions, graphene platelets distribution patterns, foam distribution types, foam coefficient, graphene platelets weight fraction, temperature changes, impactor's radius and initial velocity, prestressing force, and damping coefficient on the impact problems are discussed in detail using the Runge-Kutta method.
AEROSPACE SCIENCE AND TECHNOLOGY
(2023)
Article
Engineering, Civil
Ahmed Amine Daikh, Mohamed-Ouejdi Belarbi, Abdelhak Khechai, Li Li, Samir Khatir, Alaa A. Abdelrahman, Mohamed A. Eltaher
Summary: The main objective of this research is to analytically analyze the static problem of a new model of functionally graded materials, known as the bi-coated FGM plate, and propose a Quasi-3D higher-order shear deformation plate theory. The model is validated and numerical results demonstrate the impact of hardcore and softcore distributions, gradation indices, and boundary conditions on static bending deflection and stresses of the bi-coated FGM plate.
ENGINEERING STRUCTURES
(2023)
Article
Mechanics
Mohammed Y. Tharwan, Ahmed Amine Daikh, Amr E. Assie, Ali Alnujaie, Mohamed A. Eltaher
Summary: A novel theory is developed to analyze the buckling behavior of multi-directional FG curved beams, considering different material distributions and boundary conditions. The study aims to provide a comprehensive understanding of the factors influencing critical buckling loads.
MECHANICS BASED DESIGN OF STRUCTURES AND MACHINES
(2023)
Article
Engineering, Civil
Salwa A. Mohamed, Amr E. Assie, Mohamed A. Eltaher
Summary: The manuscript introduces a nonlinear mathematical model for investigating the nonlinear bending response of Bi-directional functionally graded plates resting on elastic foundations. A unified higher order shear plate theory is employed to account for the shear influence with parabolic distribution. The gradation of materials is described by a power law function. The developed model is solved using a novel incremental-iterative method and the differential/integral quadrature method to numerically discretize the governing equations with variable-coefficients.
THIN-WALLED STRUCTURES
(2023)
Article
Construction & Building Technology
Amr E. Assie, Salwa A. Mohamed, Alaa A. Abdelrahman, Mohamed A. Elather
Summary: This paper investigates the deviation between the middle surface (MS) and neutral surface (NS) formulations on the static response of bi-directionally functionally graded (BDFG) porous plate. The displacement field of BDFG plate is defined using the higher order shear deformation plate theory with a four variable. New boundary conditions are derived based on the displacement field variables on both NS and MS. The mathematical formulation is proven with previous published work, and additional numerical and parametric results are developed to analyze the influences on the static response of BDFG porous plate.
STEEL AND COMPOSITE STRUCTURES
(2023)
Article
Engineering, Aerospace
Ola A. Siam, Rabab A. Shanab, Mohamed A. Eltaner, Norhan A. Mohamed
Summary: This manuscript aims to derive the closed form solutions for the free vibration of a viscoelastic nanobeam embedded in an elastic medium using nonlocal differential Eringen elasticity theory. The kinematic displacements based on Euler-Bernoulli and Timoshenko theories are developed to consider the nanobeam's thin and moderate thickness structures. Kelvin/Voigt constitutive relation is proposed to consider the internal damping viscoelastic effect. The derived equations of motion and boundary conditions are evaluated to obtain closed form solutions for damped and natural frequencies.
ADVANCES IN AIRCRAFT AND SPACECRAFT SCIENCE
(2023)
Article
Engineering, Aerospace
Yousef A. Alessi, Ibrahim Ali, Mashhour A. Alazwari, Khalid Almitani, Alaa Abdelrahman, Mohamed A. Eltaher
Summary: This article presents a numerical analysis of the natural frequencies and harmonic response of a perforated cantilever beam connected to two layers of piezoelectric materials using the finite element method. The effects of perforation geometry, the number of rows, and resistance on natural frequencies, frequency response, and power are investigated. The study finds that thickness is positively correlated with natural frequency, and rectangular perforations produce higher voltage.
ADVANCES IN AIRCRAFT AND SPACECRAFT SCIENCE
(2023)
Article
Nanoscience & Nanotechnology
Ismail Esen, Mashhour A. Alazwari, Khalid H. Almitani, Mohamed A. Eltaher, A. Abdelrahman
Summary: This article investigates the free and forced responses of functionally graded material (FGM) porous nanoplates under thermal and magnetic fields using nonclassical nonlocal strain gradient elasticity. The mathematical model considers shear deformation, size-scale effects, and miscorstructure influences. Four different porosity models and their distribution across the thickness are studied. The derived equations of motion are solved analytically using the Navier method, and the effects of various factors such as nonlocal elasticity, strain gradient elasticity, temperature rise, magnetic field intensity, porosity volume fraction, and porosity distribution are analyzed. The study shows that a directed magnetic field can dampen the forced vibrations of FGM porous nanoplates under thermal and live loads.
ADVANCES IN NANO RESEARCH
(2023)
