Flexural static and fatigue response of patch repaired laminated composites for different patch-parent configurations

This work involves an experimental investigation of the static and fatigue behavior of patch repaired laminates under flexural loading. At first, a static flexural study is conducted for two types of parent laminates comprising 4-plies ([0°]₄ & [45°]₄) and 8-plies ([0°]₈ & [45°]₈) of woven carbon fiber. The repair is conducted by two types of patches with stacking sequence [0°]₂ and [45°]₂. Three different repair configurations involving patch bonded on the compressive side, tensile side, and both the sides of the parent specimens, have been tested. Digital image correlation has been employed to capture the deflection of the specimens. In order to understand the vulnerability of patch repaired laminates to cyclic loading, the load controlled constant amplitude fatigue tests have been conducted on 8-ply repaired laminates. Different failure modes, distinctive to each type of repair configurations have been observed. The results of this work provide more insight to the influence of various parameters viz. number of plies, fiber orientation, patch placement, and so forth, on the flexural behavior of repaired laminates.