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Mofareh Hassan Ghazwani,Ali Alnujaie,Pham Van Vinh,Abdelouahed Tounsi Techno-Press 2024 Advances in nano research Vol.16 No.3
The main aims of this study are to develop a new nonlocal quasi-3D theory for the free vibration behaviors of the functionally graded sandwich nanobeams. The sandwich beams consist of a ceramic core and two functionally graded material layers resting on elastic foundations. The two layers, linear spring stiffness and shear layer, are used to model the effects of the elastic foundations. The size-effect is considered using nonlocal elasticity theory. The governing equations of the motion of the functionally graded sandwich nanobeams are obtained via Hamilton's principle in combination with nonlocal elasticity theory. Then the Navier's solution technique is used to solve the governing equations of the motion to achieve the nonlocal free vibration behaviors of the nanobeams. A deep parametric study is also provided to demonstrate the effects of some parameters, such as length-to-height ratio, power-law index, nonlocal parameter, and two parameters of the elastic foundation, on the free vibration behaviors of the functionally graded sandwich nanobeams.
Hakim Bentrar,Sidi Mohammed Chorfi,Sid Ahmed Belalia,Abdelouahed Tounsi,Mofareh Hassan Ghazwani,Ali Alnujaie 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.88 No.6
In this work, the free vibration analysis of functionally graded material (FGM) sandwich plates with porosity is conducted using the p-version of the finite element method (FEM), which is based on the first-order shear deformation theory (FSDT). The sandwich plate consists of two face-sheet layers of FGM and a homogeneous core layer. The obtained results are validated using convergence and comparison studies with previously published results. Five porosities distribution models of FGM sandwich plates are assumed and analyzed. The effect of the thickness ratio, boundary conditions, volume fraction exponents, and porosity coefficients of the top and bottom layers of FGM sandwich plates on the natural frequency are addressed.
Study and analysis of a tapered shaft in composite materials with variable speed of rotation
Rachid Zahi,Abderahmane Sahli,Djafar Ait Kaci,Fouad Bourada,Abdelouahed Tounsi,Mofareh Hassan Ghazwani 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.87 No.2
This paper presents a mechanical model of a “tapered composite shaft” rotating at a constant speed around its axis. The spatial equations of motion are solved using the Lagrange technique, and a finite element approach is employed to construct the model. Theoretical analysis is used to compute the kinetic and strain energies. A comparison is made between conventional finite element methods and hierarchical finite element methods, indicating that the former uses fewer elements and provides higher accuracy in determining natural frequencies. Numerical calculations are performed to determine the eigen frequencies and critical speeds of the rotating composite shaft. The critical speeds of composite shaft systems are compared with existing literature to validate the proposed model.
Abdelkader Tamrabet,Belgacem Mamen,Abderrahmane Menasria,Abdelhakim Bouhadra,Abdelouahed Tounsi,Mofareh Hassan Ghazwani,Ali Alnujaie,S.R. Mahmoud 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.85 No.3
The main objective of this paper is to study the effect of porosity on the buckling behavior of thick functionally graded sandwich plate resting on various boundary conditions under different in-plane loads. The formulation is made for a newly developed sandwich plate using a functional gradient material based on a modified power law function of symmetric and asymmetric configuration. Four different porosity distribution are considered and varied in accordance with material propriety variation in the thickness direction of the face sheets of sandwich plate, metal foam also is considered in this study on the second model of sandwich which containing metal foam core and FGM face sheets. New quasi-3D high shear deformation theory is used here for this investigate; the present kinematic model introduces only six variables with stretching effect by adopting a new indeterminate integral variable in the displacement field. The stability equations are obtained by Hamilton’s principle then solved by generalized solution. The effect of Pasternak and Winkler elastic foundations also including here. the present model validated with those found in the open literature, then the impact of different parameters: porosities index, foam cells distribution, boundary conditions, elastic foundation, power law index, ratio aspect, side-to-thickness ratio and different in-plane axial loads on the variation of the buckling behavior are demonstrated.
Bending and buckling of porous multidirectional functionality graded sandwich plate
Lazreg Hadji,Fabrice Bernard,Royal Madan,Ali Alnujaie,Mofareh Hassan Ghazwani 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.85 No.2
Bending and buckling analysis of multi-directional porous functionally graded sandwich plate has been performed for two cases namely: FG skin with homogeneous core and FG core with homogeneous skin. The principle of virtual displacements was employed and the solution was obtained using Navier’s technique. This theory imposes traction-free boundary conditions on the surfaces and does not require shear correction factors. The validation of the present study has been performed with those available in the literature. The composition of metal-ceramic-based FGM changes in longitudinal and transverse directions according to the power law. Different porosity laws, such as uniform distribution, unevenly and logarithmically uneven distributions were used to mimic the imperfections in the functionally graded material that were introduced during the fabrication process. Several sandwich plates schemes were studied based on the plate's symmetry and the thickness of each layer. The effects of grading parameters and porosity laws on the bending and buckling of sandwich plates were examined.
A mechanical behavior of composite plates using a simple three variable refined plate theory
Ahmed Bakoura,Ibrahim Klouche Djedid,Fouad Bourada,Abdelmoumen Anis Bousahla,S.R. Mahmoud,Abdelouahed Tounsi,Mofareh Hassan Ghazwani,Ali Alnujaie 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.83 No.5
A novel three variable refined plate theory (TVRPT) is developed in this article for laminated composite plates for the first time. The theory takes into account the nonlinear variation of transverse shear deformations, and satisfies the boundary conditions of zero traction on the plate surfaces without considering the “shear correction factor”. The important characteristic of this new kinematic is that the unknowns numbers is only 3 as is employed in “classical plate theory” (CPT). The numerical results of the current theory are compared with 3D-elasticity solutions and the calculations of “first order theories” and other higher order models found in the literature.
Nasrine Belbachir,Fouad Bourada,Abdelmoumen Anis Bousahla,Abdelouahed Tounsi,Mohamed A. Al-Osta,Mofareh Hassan Ghazwani,Ali Alnujaie,Abdeldjebbar Tounsi 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.85 No.4
The current paper discusses the dynamic and stability responses of cross-ply composite laminated plates by employing a refined quasi-3D trigonometric shear deformation theory. The proposed theory takes into consideration shear deformation and thickness stretching by a trigonometric variation of in-plane and transverse displacements through the plate thickness and assures the vanished shear stresses conditions on the upper and lower surfaces of the plate. The strong point of the new formulation is that the displacements field contains only 4 unknowns, which is less than the other shear deformation theories. In addition, the present model considers the thickness extension effects (εz≠0). The presence of the Winkler-Pasternak elastic base is included in the mathematical formulation. The Hamilton’s principle is utilized in order to derive the four differentials’ equations of motion, which are solved via Navier’s technique of simply supported structures. The accuracy of the present 3-D theory is demonstrated by comparing fundamental frequencies and critical buckling loads numerical results with those provided using other models available in the open literature.
Investigation of the mechanical behavior of functionally graded sandwich thick beams
Fethi Mouaici,Abed Bouadi,Mohamed Bendaida,Kada Draiche,Abdelmoumen Anis Bousahla,Fouad Bourada,Abdelouahed Tounsi,Mofareh Hassan Ghazwani,Ali Alnujaie 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.44 No.5
In this paper, an accurate kinematic model has been developed to study the mechanical response of functionally graded (FG) sandwich beams, mainly covering the bending, buckling and free vibration problems. The studied structure with homogeneous hardcore and softcore is considered to be simply supported in the edges. The present model uses a new refined shear deformation beam theory (RSDBT) in which the displacement field is improved over the other existing high-order shear deformation beam theories (HSDBTs). The present model provides good accuracy and considers a nonlinear transverse shear deformation shape function, since it is constructed with only two unknown variables as the Euler-Bernoulli beam theory but complies with the shear stress-free boundary conditions on the upper and lower surfaces of the beam without employing shear correction factors. The sandwich beams are composed of two FG skins and a homogeneous core wherein the material properties of the skins are assumed to vary gradually and continuously in the thickness direction according to the power-law distribution of volume fraction of the constituents. The governing equations are drawn by implementing Hamilton’s principle and solved by means of the Navier’s technique. Numerical computations in the non-dimensional terms of transverse displacement, stresses, critical buckling load and natural frequencies obtained by using the proposed model are compared with those predicted by other beam theories to confirm the performance of the proposed theory and to verify the accuracy of the kinematic model.
On the effect of porosity on the shear correction factors of functionally graded porous beams
Ben Abdallah Medjdoubi,Mohammed Sid Ahmed Houari,Mohamed Sadoun,Aicha Bessaim,Ahmed Amine Daikh,Mohamed-Ouejdi Belarbi,Abdelhak Khechai,Aman Garg,Mofareh Hassan Ghazwani Techno-Press 2023 Coupled systems mechanics Vol.12 No.3
This article presents a new analytical model to study the effect of porosity on the shear correction factors (SCFs) of functionally graded porous beams (FGPB). For this analysis, uneven and logarithmic-uneven porosity functions are adopted to be distributed through the thickness of the FGP beams. Critical to the application of this theory is a determination of the correction factor, which appears as a coefficient in the expression for the transverse shear stress resultant; to compensate for the assumption that the shear strain is uniform through the depth of the cross-section. Using the energy equivalence principle, a general expression is derived from the static SCFs in FGPB. The resulting expression is consistent with the variationally derived results of Reissner's analysis when the latter are reduced from the two-dimensional case (plate) to the one-dimensional one (beam). A convenient algebraic form of the solution is presented and new study cases are given to illustrate the applicability of the present formulation. Numerical results are presented to illustrate the effect of the porosity distribution on the (SCFs) for various FGPBs. Further, the law of changing the mechanical properties of FG beams without porosity and the SCFare numerically validated by comparison with some available results.