Evaluation of insert design on the performance of repaired composite-Ti alloy joints

• Published in: Composite structures 2019-12, Vol.230, p.111506, Article 111506
• Main Authors: Zhu, Yun-tao, Akkerman, Remko, Xiong, Jun-jiang, Luo, Chu-yang, Du, Yi-sen
• Format: Article
• Language: English
• Subjects: CFRP-titanium alloy screwed joints; Joint stiffness; Metal inserts; Repair effect
• ISSN: 0263-8223; 1879-1085
• DOI: 10.1016/j.compstruct.2019.111506

Two kinds of titanium alloy inserts, namely bushing and embedded conical nut, were designed to repair the bearing damaged zone of screwed single-lap carbon fiber/polyimide composite-TC4 alloy joints, respectively. Quasi-static tensile tests were conducted to determine the effects of such repairs in terms of joint strength and joint stiffness concepts. Based on a simplified bearing model, the deformation mechanisms of titanium inserts influencing the joint performance are further discussed. It is concluded that: 1) the load-displacement curves of screwed joints consist of five characteristic stages; 2) the screw tilt significantly increases the failure load of the screw; 3) the use of an embedded conical nut aggravates the screw tilt, while the use of a bushing reduces the effect of screw tilt by distributing the bearing deformation evenly through the thickness. This difference leads to a different repair effect in terms of joint stiffness.