Interfacial Fracture Toughness Assessment of a New Titanium–CFRP Adhesive Joint: An Experimental Comparative Study

• Published in: Metals (Basel ) Vol. 10; no. 5; p. 699
• Main Authors: Tsokanas, Panayiotis, Loutas, Theodoros, Nijhuis, Peter
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.05.2020
• Subjects: Adhesion tests; Adhesive bonding; Adhesive joints; Aluminum; Bonded joints; Calibration; Cantilever beams; Carbon fiber reinforced plastics; Carbon fibers; co-bonding; Comparative studies; Compliance; Composite materials; Data reduction; Dissimilar metals; double cantilever beam; Energy consumption; Experiments; Flexing; Fracture toughness; Geometry; Laminates; Manufacturing; metal–composite adhesive joint; Methods; Passenger aircraft; Physical properties; Pollutants; Resin transfer molding; secondary bonding; Studies; Thermal stress; Thermosetting resins; Titanium; vacuum-assisted resin transfer molding; Weight reduction; Wings (aircraft)
• ISSN: 2075-4701; 2075-4701
• DOI: 10.3390/met10050699

Adhesive joints between dissimilar layers of metals and composites are increasingly used by different industries, as they promise significant weight savings and, consequently, a reduction in energy consumption and pollutant emissions. In the present work, the interfacial fracture behavior of a new titanium–carbon fiber reinforced plastic (CFRP) adhesive joint is experimentally investigated using the double cantilever beam (DCB) and end-notched flexure (ENF) test configurations. A potential application of this joint is in future large passenger aircraft wings. Four characteristic industry relevant manufacturing approaches are proposed: co-bonding with/without adhesive and secondary bonding using thermoset/thermoplastic CFRP. For all of them, the vacuum-assisted resin transfer molding (VARTM) technique is utilized. To prevent titanium yielding during testing, two aluminum backing beams are adhesively bonded onto the primary joint. A data reduction scheme recently proposed by the authors, which considers effects such as bending–extension coupling and manufacturing-induced residual thermal stresses, is utilized for determination of the fracture toughness of the joint. The load–displacement responses, fracture behaviors during testing, and fracture toughness performances of the four manufacturing options (MOs) under consideration are presented and compared.