Structural Integrity Evaluation of Cracked Plates with Different Types of Stiffeners: A Numerical Study

Many structures use stiffeners to improve their strength and stability and especially to stop the growth of cracks that can appear during the manufacturing process or in service. The most used stiffeners have rectangular cross-sections, other shapes being less used to strengthen mechanical structures. A numerical study of cracked aluminum plates reinforced with different types of stiffeners is presented in this paper to study the influence of different types of stringers on the structural integrity of the plates. Continuously attached stiffeners with rectangular, L- and T-shaped cross-sections are considered in two variants: with the stiffener broken and unbroken. A numerical model is developed and validated by comparing the obtained results with those calculated using the compounding method. It is shown that an important variation in the stress intensity factor occurs though the thickness of the plate and that stiffeners with the same area yield approximately the same average values of the stress intensity factor. However, the shape of the stiffeners influences the maximum stress intensity factors, which are responsible for the crack growth. Conclusions are drawn about the shape that provides a longer lifetime and higher critical stresses at which catastrophic failure may occur.