Fiber Volume Fraction and Distribution in Thermoplastic Composites for in-situ AFP

Abstract

Thermoplastic in-situ Automated Fiber Placement promises advantages in cost and manufacturing time for large composite structures. With this technology, the consolidation quality depends on both process parameters and prepreg tape composition. In this paper, an automated digitized analysis tool based on micrographs is presented and applied to a selection of commercial prepreg materials and laminates manufactured with in-situ AFP and additional consolidation. The tapes are analyzed with respect to fiber volume fraction and distribution, thickness, porosity and surface roughness, allowing predictions for the in-situ suitability. Significant variations are found between manufacturers. The fiber fraction histograms reveal major deviations from the ideal fiber distribution. Microstructural characteristics are identified that may be used to assess the suitability for in-situ consolidation. This includes a thickness-wise fiber volume fraction distribution with matrix rich surfaces, as well as overall low porosity and surface roughness.