Numerical optimizing and experimental evaluation of stepwise rapid high-pressure microwave curing carbon fiber/epoxy composite repair patch

Abstract Numerical models of multi-layer composite laminates with various fiber orientations and fiber layers were investigated under adhesively bonded repair condition by ABAQUS. Stress intensity factors (SIF) of bonded structure systems were calculated by J integral method. Results indicated that composite laminate with [90/90/90] fiber orientation and three fiber layers exhibited the lowest numerical SIF value. The laminates reinforced by carbon fiber with corresponding orientation were experimentally prepared in a two-step high-pressure microwave curing and traditional thermal curing methods on the basis of simulated results, respectively. Mechanical and curing properties of laminates prepared by two curing methods were characterized and compared by means of tensile tests and differential scanning calorimetry (DSC). In comparison to the thermal curing method, the laminate can be prepared more effectively by means of microwave curing method, and the laminate with [90/90/90] fiber orientation and three fiber layers showed the optimal static mechanical performance and the highest curing degree due to the synergistic effect of dipolar induced effect and heating effect generated by microwave, which was in well agreement with the results of numerical simulation.