Abstract

Fracture toughness is a critical property of composites, especially in the case of materials manufactured by liquid composite moulding processes because of the brittleness of the thermoset polymeric matrix. The use of thermoplastic interleaving veils can improve the fracture behaviour affecting only slightly other mechanical properties. Also, the veils can affect the manufacturability of the composites. This work presents a study of the influence of commercial and homemade veils on the manufacturability process and mechanical properties of carbon fibre reinforced composites. Results obtained show a significant improvement of fracture toughness without affecting manufactubarility.

Abstract

The inclusion of reliable void formation and transport models in process models for LCM is paramount to guarantee the reliability of the manufactured parts, since it allows the estimation of part in-situ void content after mould filling, as well as the estimation of the ideal bleeding time.

The incorporation of void dynamics into mould filling simulations has traditionally been under the form of unsaturated flow, where a continuous saturation field is advected. However, these models lack the prediction of the morphological properties of voids, which are known to influence their mobility through the reinforcement, as well as the final part mechanical properties. Also, direct numerical simulation methodologies, which are fundamentally based on the Volume of Fluid (VoF) method, can provide void morphological data but are too computationally expensive to apply directly into an entire mould filling domain.

Particle tracking methodologies have extensively been used in computational fluid dynamics (CFD), to solve problems in which the fluid flow carries solid particles, such as in sediment deposition. This methodology could prove to be a computationally efficient way to deal with the different void morphologies registered, both during void generation, as well as transport, since each void is taken as a discrete particle, thus possessing its own set of properties.

As of today, mould filling simulation software do not encompass such a methodology to allow mould design optimization. This work discusses the implementation of such a methodology, envisioning a streamlined application into process design.