On the effect of pulsed laser ablation on shear strength and mode I fracture toughness of Al/epoxy adhesive joints
2015; Taylor & Francis; Volume: 29; Issue: 17 Linguagem: Inglês
10.1080/01694243.2015.1049325
ISSN1568-5616
AutoresGiovanni Chiodo, Marco Alfano, Stefano Pini, A. Pirondi, Franco Furgiuele, R. Groppetti,
Tópico(s)Laser Material Processing Techniques
ResumoThe present work describes an experimental study about the shear strength and the mode I fracture toughness of adhesive joints with substrates pre-treated by pulsed laser ablation. An ytterbium-doped pulsed fiber laser was employed to perform laser irradiation on AA6082-T4 alloy. Morphological and chemical modifications were evaluated by means of surface profilometry, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Thick adherend shear tests were carried out in order to assess the shear strength while the mode I fracture toughness was determined using the double cantilever beam. For comparison, control samples were prepared using classical surface degreasing. The results indicated that laser ablation has a favorable effect on the mechanical behavior of epoxy bonded joints; however, while a + 20% increase was recorded for shear strength, a remarkable threefold enhancement of fracture toughness was observed with respect to control samples. XPS analyses of treated substrates and SEM observations of the fracture surfaces indicated that laser pre-treatment promoted chemical and morphological modifications able to sustain energy dissipation through mechanical interlocking. As a result cohesive failure within the adhesive bond-line was enabled under predominant peel loading.
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