Environmental degradation of adhesively-bonded composite joints

Adhesive bonding of aircraft primary composite structures of large transport aircraft is seen as one of enabling technologies being investigated for next generation aircraft design and fabrication. Adhesive bonding offers many advantages as compared to riveted construction by eliminating mechanical fasteners, and better and more uniform load transfer that translates to improved fuel efficiency and more efficient aircraft design. Although certification of adhesively-bonded joints for primary structures still poses a significant challenge, there has been extensive effort to advance technologies that would ultimately contribute to advanced joint design, including emphasis on proper process control during manufacture, advancement in surface preparation, ongoing development of Non-Destructive Inspection (NDI) to monitor bond strength, advancement of environmentallyresistant adhesives and primers, and design for damage arrest amongst many other things. This massive amount of work, along with years of positive experience with adhesive bonding on aircraft, has inspired much confidence in the more widespread application of structural adhesive bonding.