Mechanical evaluation and failure analysis of composite laminates manufactured using automated dry fibre tape placement followed by liquid resin infusion

Automated tape placement is seen as a promising technique for the manufacture of net-shape dry fibre preforms using carbon fibre tapes. However, most of the dry fibre tapes (DFT) available on the market are proprietary and aimed mainly at the aerospace sector. In the current study, two different binders (polyurethane and phenoxy water based binder) were used to coat and hence stabilise the carbon fibre tows. A net shaped preform was manufactured using Laser-Assisted Dry Fibre Tape Placement (LDFTP) and subsequently infused by vacuum assisted liquid resin infusion. The mechanical properties of the resulting laminates were compared to the laminates where the preform was manually laid up by hand with and without a coating (baseline). Failure mechanism analysis was carried out using scanning electron microscopy (SEM). The LDFTP process improved cured ply thickness (17-20% reduction) and fibre volume fraction (+9%). Interlaminar shear strength (ILSS) showed a significant improvement of 35-48%. However, only laminates manufactured using phenoxy coated LDFTP manufactured preforms showed comparable flexural strength to the uncoated baseline. Flexural modulus reduced in all cases. Further optimisation of binder content and process parameters (layup rate, consolidation temperature) is required for high speed deposition, better consolidation and improvements in mechanical properties.

Automated summary

Automated tape placement is a promising technique for manufacturing net-shape dry fibre preforms using carbon fibre tapes. Different binders were used to coat and stabilize carbon fibre tows, resulting in improvements in mechanical properties. However, further optimization is required for better results.