Adhesive thickness effects of a ductile adhesive by optical measurement techniques. (March 2015)

• Record Type: Journal Article
• Authors: Campilho, R.D.S.G.; Moura, D.C.; Banea, M.D.; da Silva, L.F.M.
• Is Part Of: International journal of adhesion & adhesives. Volume 57(2015:Mar.)
• Page Start: 125
• Page End: 132
• Publication Date: 2015-03
• Subjects: Polyurethane -- Aluminium and alloys -- Fracture toughness -- Fracture -- Joint design; Adhesion -- Periodicals; Adhesives -- Periodicals; Adhésion (Physique) -- Périodiques; Adhésifs -- Périodiques; Adhesie; Kleefstoffen; Adhesion; Adhesives; Periodicals; 668.3
• DOI: 10.1016/j.ijadhadh.2014.12.004
• Languages: English
• ISSNs: 0143-7496

Abstract

Abstract: Adhesive bonding is an excellent alternative to traditional joining techniques such as welding, mechanical fastening or riveting. However, there are many factors that have to be accounted for during joint design to accurately predict the joint strength. One of these is the adhesive layer thickness ( t A ). Most of the results are for epoxy structural adhesives, tailored to perform best with small values of t A, and these show that the lap joint strength decreases with increase of t A (the optimum joint strength is usually obtained with t A values between 0.1 and 0.2 mm). Recently, polyurethane adhesives were made available in the market, designed to perform with larger t A values, and whose fracture behaviour is still not studied. In this work, the effect of t A on the tensile fracture toughness ( G n c ) of a bonded joint is studied, considering a novel high strength and ductile polyurethane adhesive for the automotive industry. This work consists on the fracture characterization of the bond by a conventional and the J -integral techniques, which accurately account for root rotation effects. An optical measurement method is used for the evaluation of crack tip opening ( δ n ) and adherends rotation at the crack tip ( θ o ) during the test, supported by a Matlab ® sub-routine for the automated extraction of these parameters. As output of this work, fracture data is provided in traction for the selected adhesive, enabling the subsequent strength prediction of bonded joints.