INFLUENCE OF PRE-CURING STAGE IN ADDITIVE MANUFACTURING OF ADVANCED THERMOSETTING COMPOSITES

The arising of cure-related defects during manufacturing of thermosetting composites and their hardly predictable effect on mechanical performance is often cause for part rejection, which is detrimental for both cost and sustainability. Additive Manufacturing (AM) of continuous fibre-reinforced thermosets is envisaged to bring significant benefits in terms of reducing temperature overshoot, and consequently residual stresses. The work investigates the influence of the introduction of a pre-curing phase upon the exothermic overshoot and the defects induced during deposition of pre-cured tows (i.e. microbuckling). A Finite Element Analysis (FEA) addressing the cure simulation has been developed, and pre-cured specimens have been tested. The findings point out that a pre-cure level between 20% and 30% reduces the temperature overshoot within the laminate by 90%, generating in-plane waviness with a severity that should not compromise its performance.