Influence of the lay-up and curing steps in the manufacturing process of thick laminate composites on their compressive strength

The influence of the lay-up and curing steps in the manufacturing process of CFRP is investigated in terms of compressive strength. Automated Fibre Placement (AFP) and manual lay-up (HLU), from the same pre-preg material, are compared as well as the use of a porous or non-porous consumable during curing. It is shown that the latter factor may result in heterogeneous mesostructures with gradients in fibre volume content from the top of the laminate to its centre. This made it necessary to propose a specific data analysis of the four-point bending test, used to evaluate the compressive strength of the most loaded unidirectional ply. Experimental results suggest a better performance of AFP vis-à-vis HLU plates, especially in terms of reproducibility. The increase in performance for plates using non porous consumables is discussed with respect to the relevance of using such a strategy on thin laminates for designing thick parts.