سعید امیر

Orthotropic plates used in composite structures are subject to local buckling, including compressive buckling. In the process of designing and building most large structures or instruments with complex geometry, joints in the structure are unavoidable. Today, adhesive joints are widely used in connecting composite structures due to some advantages over mechanical joints. In this article, the buckling phenomenon of orthotropic rectangular multilayer plates connected with glue has been investigated, and the force effects of the glue layer under buckling loading conditions have been studied. In order to obtain the critical buckling loads under different boundary conditions, the generalized differential quadrature method (GDQM) has been used. Buckling analysis is presented based on first-order shear deformation theory (FSDT) for carbon/epoxy, glass/epoxy and Kevlar/epoxy composite materials with different porcelain layers. The effect of thickness and type of the adhesive as a bonding layer has been investigated. In plates made of a type of porcelain layer, two-way carbon epoxy plates show higher buckling strength, and in general, the higher the ratio of length to width of the plates is, the higher the buckling strength will be. In the connections, the obtained results have been compared with the results from the finite element analysis in ABAQUS commercial software.

In this research, aerodynamic and vibrational behaviors of sector plates made from metal foams reinforced by graphene nanoplatelets are considered. Metal foams are a new and advanced branch of porous materials and their main advantage is their high stiffness to density ratio. Although due to their lightweight, metal foams are welcomed nowadays, this causes a decrease in their strength and is one of their main weaknesses that by adding nanoparticles, this weakness is eliminated. Today, graphene nanoplatelets are known as one of the best reinforcements. Under Gaussian random field for closed-cell cellular solids, the effective properties of the matrix are obtained and by employing two Halpin-Tsai and rule of mixture micromechanical models, elasticity modulus and other mechanical properties of the plate are determined. Pores distribution and also graphene nanoplatelets dispersion through the thickness direction, each is based on three different patterns and their effect on the vibrational behavior of the under consideration model is observed. With the aid of the variational approach and Hamilton’s principle, the governing equation and associated boundary conditions are derived and solved numerically, and the effect of different parameters such as pores distribution, nanoparticles dispersion and other important parameters on the results is discussed.