Chopped Tape Thermoplastic Composites (CTTCs) offer high formability and performance for complex-shaped components in the aerospace and automotive industries. However, the mesoscopic discontinuity leads to spatial variabilities and correspondingly high scatter in the elastic properties of CTTCs due to the random orientations of chopped tapes and chopped tape-cavity edge interactions. Here we propose a new approach to investigate the effect of mould cavity edges on chopped tape orientation and hence the mechanical properties of CTTCs. Based on this approach, a Set Voronoi tessellation was implemented to represent the variability of local Young's Modulus and chopped tape-cavity edge interactions occurring during the manufacturing process. It was confirmed that the chopped tapes align along the edges, and progressively transition to a random orientation towards the middle of the specimen. The results were validated on moulded specimens and demonstrated the ability to deconvolute the edge interaction.

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In this study, composites with discontinuous 'brick-and-mortar' architecture, consisting of conceptually stiff load-carrying bricks connected by a mortar material, were treated. The bricks were composed of unidirectional pre-impregnated tapes with a thermoplastic matrix, and a very thin interface of thermoplastic material represented the mortar. The problem was simplified to a unit cell containing a single overlap between two bricks, where the stresses between the bricks are transferred purely by shear in the mortar material. The stress-strain response of the unit cell in tension was determined by experiments and compared to predictions by a numerical model available from literature, which is based on shear-lag stress transfer. The results showed that it is possible to create a highly non-linear stress-strain response with this ordered discontinuous architecture. The effect of the interface shear strength and fracture toughness and the influence of the brick geometry on the achievable tensile strength were discussed.@en