Tracking consolidation of out-of-autoclave prepreg corners using pressure sensors. (December 2022)

• Record Type: Journal Article
• Authors: Maes, Vincent K.; Radhakrishnan, Arjun; Hartley, Jamie; Sykes, Stuart; Kratz, James
• Is Part Of: Composites. Volume 163(2022)
• Publication Date: 2022-12
• Subjects: D. Process monitoring -- E. Consolidation -- E. Prepreg processing -- Pressure sensors; Composite materials -- Periodicals; Manufacturing processes -- Periodicals; Composite materials; Manufacturing processes; Periodicals; 620.11805
• DOI: 10.1016/j.compositesa.2022.107172
• Languages: English
• ISSNs: 1359-835X

Abstract

Abstract: A total of eight corner pieces with the four different thickness-to-radius ratio, one set using external and one set using internal tooling, were made to identify how unidirectional carbon-epoxy prepreg layers consolidate during lay-up and oven vacuum bag moulding. Flexible thin-film pressure sensors were introduced to both internal and external corner mould surfaces and pressure measurements were taken during hand lay-up. A second sensor was added to monitor how the pressure gradient changes during oven vacuum bag moulding. Time-lapsed pressure measurements found that the geometry-induced excess pressure on the external corners decreases during moulding, leading to some corner thinning but this effect is small. Meanwhile, internal corner parts saw significant ply-bridging in high thickness-to-radius conditions that could not be resolved during consolidation, resulting in corner thickening and voids. The flexible sensors are a viable option for in-situ pressure monitoring for potential meso -structural defects during composite product development or manufacture.