Failure of CFRP and Titanium Tubular Adhesive Lap Joints at Extreme Temperatures

In this work, carbon fiber reinforced polymer and titanium adhesive tubular lap- joints (TLJs) at cold-temperature, room-temperature, and elevated-temperature are studied. Finite element analysis is employed to investigate the competing damage mechanisms within the TLJs. The relationship between the joint strength and adhesive bondline length is also determined. X-ray micro-computed tomography (μCT) technique is utilized to analyze composite damage characteristics; whilst statistical design of experiment (DoE) approach is used to understand the interaction between bondline length and temperature on the mechanical performance of TLJs. Results show a mixed-mode failure region at elevated-temperatures, causing the TLJ to fail by either interlaminar shear or titanium net-section fracture. Results further reveal that deformation within the titanium creates shear stresses on the composite tube, leading to the initiation, propagation, and coalescence of delamination. Employing numerical, experimental, and statistical techniques, this works provides insights into the parameters and mechanisms affecting the behavior and failure of adhesive TLJs at extreme temperature conditions.