Fatigue crack propagation has been one of the foremost reasons for failure of dynamically loaded components. Replacement cost of components with a propagating crack is many times costlier than the methods to repair them. Wherever possible, efforts are made to delay crack initiation, and arrest the crack propagation by reducing the stress intensity factor (SIF). Interference fits, provision of additional holes around the crack, stop drilled holes are some of the methods to reduce the SIF. Most of the literature focused on single method of reducing the SIF. First part of the current work attempts to study the synergistic effect of combination of two of the methods- i.e., interference fit at pin to hole interface and provision of additional hole near a pin loaded cracked central hole in a rectangular plate. 2-D plane stress Finite Element analysis using ANSYS® was carried out for evaluating the SIFs. Initial studies were performed on the pin-loaded plate with various crack sizes at the center of the plate, with different interference levels, typical of industrial components. Later, parametric studies were conducted by inserting an additional hole of different diameters placed at a distance from the central cracked hole that acts as stress relievers. The synergistic effect of interference and additional hole in reducing the SIF has been analyzed and the most beneficial interference level, diameter of additional hole and its position has been identified.

The second part of the work focuses on the study of SIFs in rivet joints arranged in 3-2-1 Lozenge pattern. In literature, several studies have been carried out to understand the response of lap joints and butt joints with single and double row of rivets emphasizing on total fatigue life and residual stress evaluation. Studies that deal with initial crack and stress intensity factors (SIF) during its progress are very less. In addition, there is very less data on joints formed in Lozenge pattern. So, work was carried out to bridge this gap, with studies on the Lozenge pattern of rivets with focus on the SIF in strap plates, as the initial cracks appear on them when the strap thickness is less than or equal to the plate thickness. Cracks were induced at different joint locations and variation of the stress intensity factor with progress in crack size was evaluated at various interference levels. The most critical location of the crack and the most beneficial levels of interference were identified. Limits of interference, beyond which SIF increases significantly, were identified. Combined influence of interference and neighboring geometrical aspects such as holes and boundaries was studied. Studies were also conducted to evaluate if there is a need for uniform interference at all joint locations. Also, to simulate the real world scenario, several combinations of random interference were induced at the joints and the SIF results were compared with that of uniform interference values. The effect back pitch of the joints on the SIF was also studied. Load sharing pattern and the phenomenon of crack shadowing at the joints were studied in the presence of several combinations of cracks. The resulting consequences on the stresses and the stress intensity factors were evaluated at different interference levels.