EFFECT OF IN-PLANE FIBRE WAVINESS IN CONTINUOUS TOW SHEARING ON LAMINATE PROPERTIES

Continuous Tow Shearing (CTS) is a novel automated fibre placement process that enables fibre-steering using wide unidirectional prepreg tapes without tape buckling. However, when the CTS process steers the fibres utilising the in-plane shear deformation of the tape, the inherently misaligned fibres within the tape buckle generating fibre waviness. This behaviour may pose a new challenge in assessing the fibre waviness in a large area and predicting its impact on mechanical properties. In this work, a large-area optical scaning method in conjunction with a Structure Tensor based image Analysis (STA), which is often used in cellular biology to analyse fibrillar structures, was applied, and its feasibility to quantitatively assess the fibre waviness in a non-destructive way was investigated. First, the STA process parameters were calibrated by comparing microscopic STA with a conventional method. Then, STA was used to investigate the relationship between the shear angle and the fibre waviness level within CTS fibre-steered lay-ups. This process was followed by finding correlations between the fibre waviness and the mechanical properties of the cured laminates obtained experimentally. The results showed that STA is a fast and cost-effective way to analyse the quality of CTS produced fibre-steered laminates with potential for in-line quality inspection.