Using ultrasound to map ply layup sequence, and to quantify fibre and ply orientations in carbon-fibre reinforced polymer laminates


Mechanical properties of components manufactured from carbon-fibre reinforced polymer laminates are strongly influenced by the ply and fibre orientations locked into the component on curing.  This drives the need to non-destructively measure features such as ply stacking sequence, ply wrinkling and fibre waviness in manufactured components. This paper presents methods capable of producing 3D maps of such features, allowing them to be visualised and quantified. Ultrasonic pulse-echo non-destructive data is acquired from laminates and pre-processed to provide instantaneous amplitude and phase datasets. These are further processed using the structure-tensor and Radon-transform image-processing methods to quantify ply orientations and fibre orientations (stacking sequence and in-plane fibre waviness). As well as obtaining a visual 3D map and a quantified evaluation of these features, it is possible to use this geometrical microstructure data to construct finite-element models to predict the mechanical performance of components. Such a process provides an acceptance-into-service route based on the modelled mechanical characteristics of each manufactured component.