For the first time, by applying a modified high order sandwich plates theory, vibration behaviour of two types of porous FG circular sandwich plates are investigated. In the first type, the face sheets and in the second one, the core is made of FGM which is modelled by power law rule that is modified by considering two types of porosity distributions. All materials are temperature dependent and uniform temperature distribution is used to model the effect of the temperature changing in the sandwiches. Governing equations are obtained by the Hamilton's energy principle and solved by Galerkin method for a clamped boundary condition. To verify the results, they are compared with FEM results obtained by Abaqus software and for special cases with the results in literatures. تفاصيل المقالة

In this paper, crushing length, deformations and energy absorption of thin walled square and rectangular composite tubes which are reinforced with Aluminium and SMA wires and without wire have been investigated under a quasi-static lateral load, both experimentally and numerically. To experimental study, square and rectangular composite tubes have been fabricated with SMA wire, Aluminium wire and without wire. To validate the results, a finite element model is constructed and analysed under the same conditions by using FEM27 and LS-DYNA software packages for composite tubes with Aluminium wire and without wire. The numerical results are in a good agreement with the experimental data. The results show that section geometry and the types of reinforcement wires have a considerable effect on the energy absorption. Rectangular cross-section samples with SMA wires have the most energy absorption capacity. تفاصيل المقالة

In this paper, the vibration behavior of the sandwich beams with functionally graded face-sheets is investigated based on the high order sandwich beam theory.The properties of the FGM are varied gradually across the thickness of the structures in accordant with the power-law rule. First-order shear deformation theory and polynomial patterns are used to model the displacements of the face-sheets and the core, respectively. The governing equations of the motion are obtained based on Hamilton’s energy principle and solved by a Galerkin method. An algebraic method is used to reduce the number of equations. Boundary conditions are considered as simply supported and clamped.The effect of the power-law index and geometrical variations are surveyed on the fundamental frequency parameter for different sandwich beams in some numerical examples. In order to verify the results of the present study, they are compared with special cases of the literature. تفاصيل المقالة

In recent years, there has been a demand for the production of materials with high thermal resistance and manufacturing structures with high mechanical strength in modern industries. In this paper, the frequency responses analysis of the sandwich beams with functionally graded core and homogeneous face sheets are presented based on the high-order sandwich beam theory. All materials are temperature dependent and the properties of FGM are varied gradually by a power-law rule which is modified by considering even and uneven porosity distributions across the thickness. Nonlinear Lagrange strain and thermal stresses of the face sheets and in-plane strain and transverse flexibility of the core are considered. Governing equations of the motion are obtained based on Hamilton’s principle and solved by a Galerkin method for the clamped-free boundary condition. To verify the results of this study, they compared with special cases of the literature. Based on the numerical results, it is concluded that by increasing the temperature, power-law index, length, thickness, porosity volume fraction the fundamental frequency parameter decreases, and increasing the wave number causes the frequency increases. تفاصيل المقالة

In this paper, the nonlinear buckling behavior of two types of functionally graded sandwich beams was studied using a high-order sandwich beam theory. Type I consists of functionally graded layers coating a homogeneous core, while type II features an FG core covered by homogeneous face sheets. All materials are considered temperature dependent, with FGM properties modified through even and uneven porosity distributions modeled by a power law rule. The sandwich beam theory was adjusted to account for nonlinear Lagrange strains, thermal stresses of the face sheets, in-plane strain, and the transverse flexibility of the core. The governing equations were derived from the minimum potential energy principle, and a Galerkin method was employed to solve them for simply supported and clamped boundary conditions. Comparisons with existing literature demonstrate good agreement. The resultes showed that critical load parameter decreases with increasing temperature, power law index, length-to-thickness ratio, thickness, and porosity volume fraction in both distributions, but increases with the wave number. Additionally, the stability of type II sandwich beams surpasses that of type I in high-temperature conditions. تفاصيل المقالة

Free vibration of sandwich plates with temperature dependent functionally graded (FG) face sheets in various thermal environments is investigated. The material properties of FG face sheets are assumed to be temperature-dependent and vary continuously through the thickness according to a power-law distribution in terms of the volume fractions of the constituents. Also, the material properties of the core are assumed to be temperature dependent. The governing equations of motion in polar system and in free natural vibration are derived using Hamilton’s principle and Galerkin method is used to solve the equations and obtain the natural frequency. In-plane stresses of the core that usually are ignored in the vibration characteristics of the sandwich structures are considered in this formulation. The results obtained by Galerkin method for symmetric circular sandwich plate with fixed support is compared with finite element method that obtained by ABAQUS and good agreement is found. The results show that varying the power-law index and temperature have important effects on natural frequency. تفاصيل المقالة

In this paper, the frequency responses analysis of the sandwich beams with functionally graded face sheets and homogeneous core is investigated based on the high order sandwich beam theory. All materials are temperature dependent and the functionally graded materials properties are varied gradually by a power law rule which is modified by considering the even and uneven porosity distributions. The nonlinear Lagrange strain and the thermal stresses of the face sheets and in-plane strain and transverse flexibility of the core are considered. Hamilton’s principle and Galerkin method are used to obtain and solve the equations for the clamped-free boundary condition. To verify the results of this study, they compared with special cases of the literatures. Based on the numerical results, it is concluded that by increasing the temperature, power law index, length, thickness, porosity volume fraction the fundamental frequency parameter decreases and increasing the wave number causes the frequency increases. تفاصيل المقالة

Analysing the buckling behaviour of the two kinds of sandwich beams, the first one with functionally graded material faces and homogeneous core and the second one with functionally graded material core and homogeneous faces are presented in this paper based on a high order sandwich beam theory. Properties of the constituent materials are assumed temperature dependent and functionally graded materials are modelled by a power law rule. Even and uneven porosity distributions are considered to improve the accuracy of the model. Minimum potential energy principle is used to obtain the govern equations and Galerkin method is applied used to solve the equations in a clamped free boundary conditions. Lateral displacement, and thermal stresses of the core and Lagrange strains are considered. To verify the procedure, the results of the present study are compared with the literature. Thickness, length, porosity, wave number and temperature effect on the critical load are investigated too. تفاصيل المقالة