Laminated FRP composite patch design for arresting joint fractures (Adhesion/cohesion) in resin-infilled centrally inclined V-notched Al-6061-T6 plate

Abstract

Present analysis investigates overall failure mechanisms, critical fracture modes, and fracture sequences for designing optimum ply-layups against arresting all sorts of joint fractures (adhesion/cohesion) for FRP-based repairing on a resin-infilled centrally inclined both end sharp V-notched plate. Onset of individual joint fractures corresponding to the locations near the periphery of the infilled V-notch/patch leading-edge is studied using Three-Dimensional FEM. Implemented VCCT approach extracts the SERR modes for characterizing individual joint fractures. The numerical model developed for stress/fracture analysis has been validated in several aspects through: (a) comparing the experimental load ∼ displacement plot to corresponding numerical results (b) numerically obtaining debonding prone region through implementing Parabolic Yield Criteria (PYC) at the V-notch surface resin interface/Patch leading-edge and comparing to the experimentally obtained region (c) comparing the cohesive fracture growth direction at the V-notch tip (extracted through SERR-based G-max criteria) to the experimentally obtained direction for both unfilled/infilled cases. Onset analysis reveals resin infilling at V-notched surfaces causes a drastic reduction of normal stresses. Out-of-plane shear (τyz, τzx) and normal (σz) stresses are responsible for failure corresponding to V-notch edges and near the patch's leading edge. Fracture analysis yields the sequence of joint fractures with dominated fracture modes as follows: V-Notch-Edges Adhesion Fracture (VNE-AF, Mode-III), Patch Leading-Edge Adhesion Fracture (PLE-AF, Mode-II & Mode-III),V-Notch-Surface Adhesion Fracture (VNS-AF, Mode-II), V-Notch Tip Cohesive Fracture (VNT-CF, Mode-I). Angle-ply [45/-45]4S has been observed to arrest all joint fractures except VNT-CF, where Quasi-isotropic [90/±45/0]2S arrests better.