Effects of Working Temperature on Mechanical Performance and Failure Characteristics of Carbon Fiber Reinforced Plastic and Adhesive–Repaired Titanium Structures with Central Inclined Cracks

Carbon fiber reinforced plastic (CFRP) composites exhibit great potential in repairing damaged metallic structures. This work aims to investigate the influences of working temperature on the mechanical performance of adhesively bonded CFRP repair of Ti6Al4V substrate with various central inclined cracks including strength recovery rate, failure displacement, energy absorption and failure modes. Differential scanning calorimeter (DSC) measurement was first performed under nitrogen environment to identify the glass transformation temperature (Tg) of adhesive and CFRP. Digital image correlation (DIC) technique was carried out to study the full-field strain distribution and damage evolution of repaired structures. Results showed that the repaired structures possessed the best repair effectiveness at the temperature of 80 °C, regardless of the types of original central inclined cracks. The failure mode was identified, and corresponding mechanisms were investigated. It was found that the working temperature presented limited influence on failure mode, and the dominant one was interfacial failure. The failure strength of repaired structures was mainly affected by the properties of adhesive rather than CFRP laminates.