Experimental and Numerical Investigation of Effects of Stiffener in Buckling Resistance of square laminated composites with Circular Hole

Using a stiffener is one of the ways to increase the buckling load capacity of the plate. However, to reduce the weight, the optimum design of the stiffener is necessary. In this study, buckling and post buckling behavior of composite plate with circular cut-out at its center with three types of stiffeners is investigated to achieve a plate with highest resistant to axial loading as buckling load. The Planer stiffener is made in the form of a thin, square layer and is attached around the opening. Two other stiffeners are named as Longitudinal and Ring types. These two stiffeners are thin layers which are attached perpendicular to the compression loading direction and at hoop direction around the openness, respectively. Plate and stiffeners are made as an orthogonal and symmetric layered composite. To model the above items in the Ansys software, tensile and shear tests on composite specimens were performed in accordance with international standards to achieve the required mechanical properties. Buckling behavior of plate with stiffener is analyzed by finite element method and the results are consistent with experimental results. The results of this research show that among the offered stiffeners, the plate with a longitudinal stiffener has maximum buckling load in comparison to the weight and minimum ratio of the buckling load to the weight is related to the ring stiffener.