A method for automated digital image-based tracking of delamination fronts in translucent glass fibre-laminated composite materials

A new automated digital image-based method for tracking both the position and shape of the crack front of delaminations in translucent glass fibre-laminated test specimens is proposed. The method is applicable to both fracture toughness tests and fatigue tests. The digital image-based algorithm identifies the newly formed crack area by the change in reflected light and then extracts both the crack front shape and the position. The method is used in a standard double cantilevered beam specimen test setup with the addition of light sources and a camera. The method does not rely on subjective test operator interpretations or calibrations. A reference pattern on the specimen is used to correctly map between the camera coordinate system and the specimen coordinate system, which makes the method insensitive to the camera position and camera or specimen movement during the test. Experimental test examples are provided, which shows that the whole crack front can be tracked with significantly higher accuracy than possible with existing methods.