Experimental and numerical investigation of fatigue crack growth behavior and optimizing fatigue life of riveted joints in Al-alloy 2024 plates

The purpose of this paper is to investigate the crack growth and fatigue life estimation of the optimized rivet joints in aluminum 2024 sheets numerically and experimentally. For this point, the optimal model is obtained using the Taguchi and finite element method (FEM), with respect to the cost functions and the defined levels for the parameters. The relevant geometrical parameters such as rivets length, holes diameter, and dimensional tolerances as well as pattern of where the rivets are and the material of the rivet joints are optimally determined and subsequently the fatigue life of the aluminum joint is obtained by experimental tests. The Taguchi method with its own algorithm reduced the number of experiments to 32 design points. These experiments are simulated by the FEM with a three-dimensional (3D) elastoplastic model. After the determination of optimal joint, a 3D boundary element model (BEM) of fatigue crack growth is performed on the optimal model and its fatigue life is evaluated. Then, to validate the numerical results of the fatigue life of this optimized joint, the samples are fabricated and subjected to constant-range alternative loading by a servo-hydraulic machine. The results showed that the mode of failure in the samples is the fracture at the front plate, where the punch was applied to the rivets shank and occurred in the first row. Also, the results of experimental tests for fatigue crack growth are compared with the numerical method that results in acceptable achievements.