Whole‐field strain distribution and fracture characteristics of CFRP‐repaired titanium plates with central inclined cracks

Abstract CFRP composites with the advantages of enhanced mechanical properties and lightweight are recognized as an ideal material in repairing cracked structures. This paper aims to comprehensively investigate whole‐field strain distribution and fracture characteristics of central inclined titanium plates repaired with CFRP laminates, with consideration of various overlap length and repair type. Results indicated that the initial central cracks significantly deteriorated mechanical performance, while inclined direction of it exhibited limited influence on repair behavior. Repairs with increased overlap length possessed superior mechanical performance and repair effectiveness. When increasing the overlap length to 80 mm, strength recovery rate for four types of repairs reached above 80.0%. Digital image correlation (DIC) results indicated that central hole was the highly strained zone for all repairs, and hole repairs presented relatively higher strain values compared with cracked repairs. Progressive failure analysis showed that repairs with initial cracks presented premature fracture of titanium plates, while hole repairs were capable to sustain load until adhesive layer fractured. Adhesive failure, cohesive failure and substrate fracture predominated on fractured surfaces irrespective of repair type and overlap length. With the increase of overlap length, cohesive failure was enhanced and light‐fiber‐tear/fiber‐tear could be found, which corresponded to relatively higher repair effectiveness.