A refined nonlocal hyperbolic shear deformation beam model for bending and dynamic analysis of nanoscale beams

Bensaid, Ismail Techno-Press 2017 Advances in nano research Vol.5 No.2

This paper proposes a new nonlocal higher-order hyperbolic shear deformation beam theory (HSBT) for the static bending and vibration of nanoscale-beams. Eringen's nonlocal elasticity theory is incorporated, in order to capture small size effects. In the present model, the transverse shear stresses account for a hyperbolic distribution and satisfy the free-traction boundary conditions on the upper and bottom surfaces of the nanobeams without using shear correction factor. Employing Hamilton's principle, the nonlocal equations of motion are derived. The governing equations are solved analytically for the edges of the beam are simply supported, and the obtained results are compared, as possible, with the available solutions found in the literature. Furthermore, the influences of nonlocal coefficient, slenderness ratio on the static bending and dynamic responses of the nanobeam are examined.

Thermal stability analysis of temperature dependent inhomogeneous size-dependent nano-scale beams

Bensaid, Ismail,Bekhadda, Ahmed Techno-Press 2018 Advances in materials research Vol.7 No.1

Thermal bifurcation buckling behavior of fully clamped Euler-Bernoulli nanobeam built of a through thickness functionally graded material is explored for the first time in the present paper. The variation of material properties of the FG nanobeam are graded along the thickness by a power-law form. Temperature dependency of the material constituents is also taken into consideration. Eringen's nonlocal elasticity model is employed to define the small-scale effects and long-range connections between the particles. The stability equations of the thermally induced FG nanobeam are derived via the principal of the minimum total potential energy and solved analytically for clamped boundary conditions, which lead for more accurate results. Moreover, the obtained buckling loads of FG nanobeam are validated with those existing works. Parametric studies are performed to examine the influences of various parameters such as power-law exponent, small scale effects and beam thickness on the critical thermal buckling load of the temperature-dependent FG nanobeams.

Bending and stability analysis of size-dependent compositionally graded Timoshenko nanobeams with porosities

Bensaid, Ismail,Guenanou, Ahmed Techno-Press 2017 Advances in materials research Vol.6 No.1

In this article, static deflection and buckling of functionally graded (FG) nanoscale beams made of porous material are carried out based on the nonlocal Timoshenko beam model which captures the small scale influences. The exact position of neutral axis is fixed, to eliminate the stretching and bending coupling due to the unsymmetrical material change along the FG nanobeams thickness. The material properties of FG beam are graded through the thickness on the basis of the power-law form, which is modified to approximate the material properties with two models of porosity phases. By employing Hamilton's principle, the nonlocal governing equations of FG nanobeams are obtained and solved analytically for simply-supported boundary conditions via the Navier-type procedure. Numerical results for deflection and buckling of FG nanoscale beams are presented and validated with those existing in the literature. The influences of small scale parameter, power law index, porosity distribution and slenderness ratio on the static and stability responses of the FG nanobeams are all explored.

Improvement of thermal buckling response of FG-CNT reinforced composite beams with temperature-dependent material properties resting on elastic foundations

Bensaid, Ismail,Kerboua, Bachir Techno-Press 2019 Advances in aircraft and spacecraft science Vol.6 No.3

Current investigation deals with the thermal stability characteristics of carbon nanotube reinforced composite beams (CNTRC) on elastic foundation and subjected to external uniform temperature rise loading. The single-walled carbon nanotubes (SWCNTs) are supposed to have a distribution as being uniform or functionally graded form. The material properties of the matrix as well as reinforcements are presumed to be temperature dependent and evaluated through the extended rule of mixture which incorporates efficiency parameters to capture the size dependency of the nanocomposite properties. The governing differential equations are achieved based on the minimum total potential energy principle and Euler-Bernoulli beam model. The obtained results are checked with the available data in the literature. Numerical results are supplied to examine the effects of numerous parameters including length to thickness ratio, elastic foundations, temperature change, and nanotube volume fraction on the thermal stability behaviors of FG-CNT beams.

Static deflection and dynamic behavior of higher-order hyperbolic shear deformable compositionally graded beams

Bensaid, Ismail,Cheikh, Abdelmadjid,Mangouchi, Ahmed,Kerboua, Bachir Techno-Press 2017 Advances in materials research Vol.6 No.1

In this work we introduce a higher-order hyperbolic shear deformation model for bending and frees vibration analysis of functionally graded beams. In this theory and by making a further supposition, the axial displacement accounts for a refined hyperbolic distribution, and the transverse shear stress satisfies the traction-free boundary conditions on the beam boundary surfaces, so no need of any shear correction factors (SCFs). The material properties are continuously varied through the beam thickness by the power-law distribution of the volume fraction of the constituents. Based on the present refined hyperbolic shear deformation beam model, the governing equations of motion are obtained from the Hamilton's principle. Analytical solutions for simply-supported beams are developed to solve the problem. To verify the precision and validity of the present theory some numerical results are compared with the existing ones in the literature and a good agreement is showed.

Dynamic analysis of higher order shear-deformable nanobeams resting on elastic foundation based on nonlocal strain gradient theory

Bensaid, Ismail,Bekhadda, Ahmed,Kerboua, Bachir Techno-Press 2018 Advances in nano research Vol.6 No.3

Present investigation deals with the free vibration characteristics of nanoscale-beams resting on elastic Pasternak's foundation based on nonlocal strain-gradient theory and a higher order hyperbolic beam model which captures shear deformation effect without using any shear correction factor. The nanobeam is lying on two-parameters elastic foundation consist of lower spring layers as well as a shear layer. Nonlocal strain gradient theory takes into account two scale parameters for modeling the small size effects of nanostructures more accurately. Hamilton's principal is utilized to derive the governing equations of embedded strain gradient nanobeam and, after that, analytical solutions are provided for simply supported conditions to solve the governing equations. The obtained results are compared with those predicted by the previous articles available in literature. Finally, the impacts of nonlocal parameter, length scale parameter, slenderness ratio, elastic medium, on vibration frequencies of nanosize beams are all evaluated.

Phytochemical analysis and antioxidant properties of organic extracts obtained from Cynoglossum cheirifolium L.

Ilhem Bensaid,Fawzia Atik Bekkara,Imad Abdelhamid El Haci,Karima Belarbi,Fawzia Beddou,Chahrazed Bekhechi 경희대학교 융합한의과학연구소 2017 Oriental Pharmacy and Experimental Medicine Vol.17 No.4

The valorization of the local flora is the goal of the laboratory of Natural Products from the University of Tlemcen (Algeria). In this work, we report the scientific study of a medicinal plant Cynoglossum cheirifolium L. The crude methanol and tannin extracts of C. cheirifolium were preliminary analyzed for their phenolic contents (total phenolics, total flavonoids and total tannins). These extracts were evaluated for their antioxidant properties using different methods. The results showed that crude methanolic extract of the leaves part revealed high phenolic (134.93 ± 9.76 mg Gallic Acid Equivalent/g Dry Weigth), flavonoid (99.99 ± 0.72 mg Catechin Equivalent/g Dry Weigth) and condensed tannin contents (1.65 ± 0.05 mg Catechin Equivalent/g Dry Weigth). Furthermore, the results obtained from the study of the antioxidant activity showed that tannin extract of stems displayed the highest DPPH• scavenging ability with the inhibition concentration of 50% (IC50) value of 70 ± 1 μg/mL, it was comparable to the Vitamin E with an IC50 value of 60 ± 1 μg/mL. The vitamin E concentration required to reduce the ferric iron was lower (242 ± 6 μg/mL) than tannins extracted from leaves (214 ± 4 μg/mL). Hence, using an RP-HPLC-PDA (Reverse Phase-High Pressure Liquid Chromatography-PhotoDiode Array Detector) analysis, it was possible to identify phenolic acids and flavonoid like rutin; naringenin; rosmarinic acid; sinapic acid; p-coumaric acid; ferulic acid; caffeic acid and syringic acid.

Investigating nonlinear thermal stability response of functionally graded plates using a new and simple HSDT

Ismail Bensaid,Ahmed Bekhadda,Bachir Kerboua,Cheikh Abdelmadjid 한국풍공학회 2018 Wind and Structures, An International Journal (WAS Vol.27 No.6

In this research work, nonlinear thermal buckling behavior of functionally graded (FG) plates is explored based a new higher-order shear deformation theory (HSDT). The present model has just four unknowns, by using a new supposition of the displacement field which enforces undetermined integral variables. A shear correction factor is, thus, not necessary. A power law distribution is employed to express the disparity of volume fraction of material distributions. Three kinds of thermal loading, namely, uniform, linear, and nonlinear and temperature rises over z-axis direction are examined. The non-linear governing equations are resolved for plates subjected to simply supported boundary conditions at the edges. The results are approved with those existing in the literature. Impacts of various parameters such as aspect and thickness ratios, gradient index, type of thermal load rising, on the non-dimensional thermal buckling load are all examined.

On static bending of multilayered carbon nanotube-reinforced composite plates

Ahmed Amine Daikh,Ismail Bensaid,Attia Bachiri,Mohamed Sid Ahmed Houari,Abdelouahed Tounsi,Tarek Merzouki 사단법인 한국계산역학회 2020 Computers and Concrete, An International Journal Vol.26 No.2

In this paper, the bending behavior of single-walled carbon nanotube-reinforced composite (CNTRC) laminated plates is studied using various shear deformation plate theories. Several types of reinforcement material distributions, a uniform distribution (UD) and three functionally graded distributions (FG), are inspected. A generalized higher-order deformation plate theory is utilized to derive the field equations of the CNTRC laminated plates where an analytical technique based on Navier’s series is utilized to solve the static problem for simply-supported boundary conditions. A detailed numerical analysis is carried out to examine the influence of carbon nanotube volume fraction, laminated composite structure, side-to-thickness, and aspect ratios on stresses and deflection of the CNTRC laminated plates.

A novel first order refined shear-deformation beam theory for vibration and buckling analysis of continuously graded beams

Bekhadda, Ahmed,Cheikh, Abdelmadjid,Bensaid, Ismail,Hadjoui, Abdelhamid,Daikh, Ahmed A. Techno-Press 2019 Advances in aircraft and spacecraft science Vol.6 No.3

In this work, a novel first-order shear deformation beam theory is applied to explore the vibration and buckling characteristics of thick functionally graded beams. The material properties are assumed to vary across the thickness direction in a graded form and are estimated by a power-law model. A Fourier series-based solution procedure is implemented to solve the governing equation derived from Hamilton's principle. The obtained results of natural frequencies and buckling loads of functionally graded beam are checked with those supplied in the literature and demonstrate good achievement. Influences of several parameters such as power law index, beam geometrical parameters, modulus ratio and axial load on dynamic and buckling behaviors of FGP beams are all discussed.