• Ivanov, Dmitry S.
• Wang, Yi
• Belnoue, Jonathan P.-H.
• Hallett, Stephen R.

Abstract

Tack, which is an expression used to characterise prepreg’s stickiness, is one of the key material parameters controlling product quality in automated composites manufacturing. More specifically in the automated fibre placement (AFP) process, the tack level of prepreg directly affects the generation of defects, i.e. a higher tack value can provide a larger resistant force to out-of-plane deformation and tape buckling. Hence, the number of defects, such as wrinkles, could be mitigated if prepreg’s tack performance could be adjusted. Therefore, a better understanding of tack is fundamental to the digitalisation of the AFP process which would lead to the production of parts of better quality and higher production rates.<br/>However, despite its significance, there are no standard characterisation methods and the modelling frameworks for tack are few and far between. There is even a disagreement within the community on what physical quantity needs to be measured. This is, in part, due to the complexity of the phenomenon as highlighted in the literature (i.e., prepreg tack depends on a number of variables such as temperature, pressure, deformation rate and the measured quantities, namely peak traction and separation energy, are associated with large variability levels).<br/>In the present contribution, a comprehensive prepreg tack modelling framework (inspired by Gutowski and Forghani) is proposed (as shown in Figure 1). A modified probe tack test is developed to perform the experimental characterisation of prepreg tack at different test conditions consistent with the AFP process. The obtained database forms the basis of the proposed modelling framework. The results demonstrate the model’s ability to capture the non-monotonic evolution of tack with process conditions. This provides one of the building blocks for the development of an AFP simulation platform.

Topics

• impedance spectroscopy
• simulation
• composite
• defect