INFLUENCE OF STRINGER GEOMETRY ON THE STRUCTURAL INTEGRITY OF CRACKED STIFFENED PLATES

Aluminum stiffened panels are extensively used in aeronautical, automotive, marine industry, and in many other fields. They are light sheets reinforced by stringers in order to increase their strength and stiffness and are designed to cope with a variety of loading conditions. Usual stiffener cross-sections used in industry are rectangular, T-shaped, Lshaped, I-shaped, U-shaped, etc. They can be continuously attached to the plate or discretely attached by welding, bolting, riveting, bonding, etc. Stiffeners improve the strength and stability of the structure and are also used to decrease or even stop the growth of cracks that can appear during the manufacturing process or in service. In order to avoid catastrophic failures, the knowledge of the crack size, stress field, material properties and the parameters used to assess the integrity of structures containing cracks should be known or calculated. Such parameters are the stress intensity factor (SIF), the J-integral or the crack tip opening displacement (CTOD). They can be obtained using analytical, numerical, or experimental methods. In this paper, a part of a research involving the influence of different type of stringers on the structural integrity of thin aluminum plates is presented. Continuously attached stiffeners with rectangular, L and T-shaped cross-section are considered. Further, the results obtained using the finite element method (FEM) for a cracked plate with a rectangular stiffener are presented in two variants: with the stiffener broken and unbroken. The proposed numerical model is also validated by comparing the obtained results with those calculated using the compounding method.