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CONTENTS
Volume 10, Number 4, August 2021
 


Abstract
The present article deals with a dynamic response analysis of a foam-based nanoscale plate based on finite strip method (FSM). The nanoscale plate formulation has been adopted based upon a higher order plate theory and then, a higher order finite strip has been used to solve the problem. The considered finite strip is capable of considering the bending displacement and also shear deformation effects. The foam-based material has been treated as a porous material with some particular pore distribution. The non-uniformity of strain field as well as the nonlocality of stress field have been incorporated with the usage of nonlocal strain gradient elasticity. It is clearly showen that the proposed solution based on finite strip method can accurately simulate the dynamic response of considered plate under external forces. The scale factors due to small size of the plate and foam-based material will show a remarkable impact on the dynamic response.

Key Words
dynamic response; finite strip; foams; higher-order plate; nanoscale

Address
Zahra Sadeghi: Engineering Department, Respina Lubricant Supply Company, Tehran, Iran

Abstract
This paper presents a careful theoretical investigation into interfacial stresses in damaged RC cantilever beam with bonded prestressed FRP composites, taking into account loading model, shear lag effect and the prestressed composites impact. These composites are used, in particular, for rehabilitation of structures by stopping the propagation of the cracks. They improve rigidity and resistance, and prolong their lifespan. In this paper, an original model is presented to predict and to determine the stresses concentration at the FRP end, with the new theory analysis approach. This research gives more precision related to the others studies which neglect the effect of prestressed composites coupled with the applied loads. A parametric study has been conducted to investigate the sensitivity of interface behavior to parameters such as laminate and adhesive stiffness, the thickness of the laminate and the fiber orientations where all were found to have a marked effect on the magnitude of maximum shear and normal stress in the composite member. The numerical resolution was finalized by taking into account the physical and geometric properties of materials that may play an important role in reducing the stress values. This research is helpful for the understanding on mechanical behaviour of the interface and design of the FRP-damaged RC hybrid structures.

Key Words
interfacial stresses; prestressed composite; RC cantilever beam; shear lag effect; strengthening

Address
Rabahi Abderezak, Tahar Hassaine Daouadji and Benferhat Rabia: Civil Engineering Department, Laboratory of Geomatics and sustainable development, University of Tiaret, Algeria

Abstract
A delamination analysis of a multilayered inhomogeneous beam structure under linear creep is developed. A viscoelastic model that consists of an arbitrary number of linear springs and linear dashpots is used. The cross-section of the beam is a circle. The beam is made of concentric longitudinal layers. Each layer is continuously inhomogeneous in thickness and length directions. Therefore, the shear moduli and the coefficients of viscosity of the viscoelastic model are distributed continuously along the thickness and length of each layer. Two concentric delamination cracks are located arbitrary between layers. The beam is loaded in torsion. Time-dependent solutions to the strain energy release rate for the two delaminations are derived by using the time-dependent strain energy in the beam. The strain energy release rates are derived also by the compliance method for verification. The variation of the strain energy release rate with time due to creep is evaluated. The effects of material inhomogeneity, external loading and delamination length on the strain energy release rate are investigated.

Key Words
creep; delamination; inhomogeneous material; multilayered beam; torsion

Address
Victor I. Rizov: Department of Technical Mechanics, University of Architecture, Civil Engineering and Geodesy, 1 Chr. Smirnensky blvd., 1046-Sofia, Bulgaria

Abstract
The surface effect for a forced vibration of a double-nanobeam-system (DNS) coupled by a viscoelastic layer under a moving constant load is studied in this paper. The viscoelastic layer that couples the nanobeams to each other, is modelled as spring-damper system. The Euler- Bernoulli theory and a simply supported boundary condition are considered for both nanobeams. By using the analytical solution, the dynamic displacement is obtained by considering the surface elasticity and residual tension effect on each nanobeams. Furthermore, the several significant parameters such as the velocity of the moving load, spring constant, damping coefficient and also the surface effect have been studied using some plots and examples. Finally, by observing the diagrams it was concluded that as the length of the beams reduces, the surface effect has a considerable effect on each of nanobeams especially at Nano scale, where it was not achieved by classic theories.

Key Words
double-nanobeam-system; forced vibration; surface effect; viscoelastic layer

Address
S.A.H. Hosseini: Buin Zahra Higher Education Center of Engineering and Technology, Imam Khomeini International University, Qazvin, Iran
O. Rahmani: Smart Structures and New Advanced Materials Laboratory, Department of Mechanical Engineering, University of Zanjan, Zanjan, Iran
H. Hayati: Faculty of Engineering and Information Technology, University of Technology Sydney, PO Box 123, Broadway, Ultimo, NSW 2007, Australia
A. Jahanshir: Buin Zahra Higher Education Center of Engineering and Technology, Imam Khomeini International University, Qazvin, Iran

Abstract
The paper is devoted to the study of thermomechanical interactions in a homogeneous nonlocal magneto-thermoelastic rotatingmediumunder the effect of hall current and two temperaturewithmemory dependent derivatives.Atwo-dimensionalmodel has been assumed. Laplace and Fourier transforms have been used to find the solution to the problemin transformed domain. The analytical expressions of components of displacement, stress and current density and conductive temperature are obtained in the transformed domain. Numerical inversion technique has been applied to obtain the results in the physical domain and the results are depicted graphically to show the effect of nonlocal parameter on the components of displacements, stresses, current density and conductive temperature. The effect of nonlocal parameter and hall current parameter has been represented graphically by taking different values.

Key Words
hall current; memory dependent derivatives; nonlocality; rotation; stress components; thermoelasticity

Address
Parveen Lata: Department of Basic and Applied Sciences, Punjabi University Patiala, India
Sukhveer Singh: Punjabi University APS Neighbourhood Campus, Dehla Seehan, India


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