Influence of the texturing quality consecutive to Abrasive Water Jet machining on the adhesive properties in mode I of 3D woven composite assemblies

Abstract

The aim of this study is to analyse the suitability of Abrasive Water Jet Machining (AWJM) as a surface preparation technique for adhesive bonding of 3D woven CFRP substrates and to investigate the influence of the texture-induced quality of the adherends on the adhesive properties of the bonded joints. For this, three specimens with varying levels of texturing qualities were produced by AWJM and quantified using classical criteria such as average roughness “Ra and Sa” as well as a new criterion named “crater volume” (Cv). After adhesive bonding, the assemblies with different levels of texturing quality were subjected to Double Cantilever Beam tests to obtain their critical energy release rate in mode I (GIc), which was compared to values of bonded assemblies prepared by sanding as performed in the industrial context. For the analysis of the damage mechanisms, DCB tests were multi-instrumented with different techniques such as X-ray tomography and digital image correlation. The obtained results showed that, the evolution of GIc as a function of the textured surface quality presented a good correlation with Cv compared to the classical parameter Ra or Sa. In addition, assemblies prepared by AWJM present higher values of GIc compared to sanded ones (up to +60%), with a downward parabolic relationship between GIc and Cv. Post-mortem X-Ray tomography analysis has revealed a change in the crack propagation scenario as Cv increases.