In this article, free vibration analysis of variable stiffness composite laminate (VSCL) plates with flat and folded shapes is studied. In order to consider the concept of variable stiffness, in each layer of these composite laminated plates, the curvilinear fibers are used instead of straight fibers. The analysis is based on a semi-analytical finite strip method which follows classical laminat...

It has been documented that AE signals propagate in thin plates as extensional and flexural plate modes. This was demonstrated using simulated AE sources (pencil lead breaks) by Gorman [1] on thin aluminum and gr/ep composite plates and by Gorman and Prosser [2] on thin aluminum plates. A typical signal from a pencil lead break source which identifies these two modes is shown in Figure 1. AE si...

multiple sclerosis (ms) is one of the autoimmune diseases with an unknown cause. the aim of this study was to explore the link between air quality and ms relapses in patients who suffer from ms.this time-series study was conducted on patients registered at the iranian multiple sclerosis society in 2011-2012. they were randomly selected from patients lived in tehran in the last five years, and h...

Steel plate shear walls (SPSWs) in buildings are known to be an effective means for resisting lateral forces. By using un-stiffened walls and allowing them to buckle, their energy absorption capacity will increase significantly due to the postbuckling capacity. The post-buckling tension field action of SPSWs can provide substantial strength, stiffness and ductility. This paper presents the Fini...

Conventional compression strength formulas for corrugated fiberboard boxes are limited to geometry and material that produce an elastic postbuckling failure. Inelastic postbuckling can occur in squatty boxes and trays, but a mechanistic rationale for unifying observed strength data is lacking. This study employs a finite element model, instead of actual experiments, to generate experimentally d...

‎    The Narumi-Katayama index is the first topological index defined by the product of some graph theoretical quantities. Let G be a simple graph. Narumi-Katayama index of G is defined as the product of the degrees of the vertices of G. In this paper, we define the Narumi-Katayama polynomial of G. Next, we investigate some properties of this polynomial for graphs and then, we obtain ...

Recently, graphene sheets have shown significant potential for environmental engineering applications such as wastewater treatment. In the present work, the posbuckling response of orthotropic single-layered graphene sheet (SLGS) is investigated in a closedform analytical manner using the nonlocal theory of Eringen. Two opposite edges of the plate are subjected to normal stresses. The nonlocali...

Thermal buckling loads of laminated composite plates are maximized for a given total thickness. Fiber directions and relative thickness of layers are considered as design variables. Analysis of buckling temperature is carried out by using the finite element method, while the imperialist competitive algorithm (ICA) is employed to optimize as many as seven variables for the different layered plat...