Abstract: The relationship between surface topography and surface free energy is very important to reveal the fundamental mechanisms that govern adhesion for bonding repair of glass fibre reinforced resin matrix composites. The surfaces were created by sanding that used different items of sandpaper. The topography of the surfaces was measured using laser confocal and the contours were generated. The surface free energy was computed by measured contact angles. Feature-preserving contour filtering was carried out based on chord and angle-deviation criterion. The contour feature consisted of contour feature points, chord height distribution curve and angle-deviation distribution curve was acquired simultaneously. The relationship between contour features and surface free energy was analyzed. The results show that the contour has larger numbers of feature points, greater differences between the chord and angle-deviation distribution curve, and the corresponding surface energy will be larger which effectively supports the adhesion theory based on mechanical interlocking.

Key words: surface free energy, contour features, surface topography, adhesion, composite materials