In this paper, we set to examine the inter-laminar shear strength of a fiber-reinforced composite part manufactured via a stepped-concurrent ultraviolet curing and layering process. This process was specifically proposed for making epoxy-based thick parts, whereby a layer-by-layer, model-based, optimal layering time and ultraviolet control scheme is set up with the objective of minimizing the degree of cure deviation across the final thick part. We focus on a cationic curing process wherein additional energy savings are possible by switching off the ultraviolet source after initiating the curing reaction with the ultraviolet source at each layer addition. Since the inter-laminar sheer strength of parts made via a layering process is often a concern, we consider the application of in-situ consolidation pressure in the layering process. We then characterize the inter-laminar shear strength by manufacturing samples with application of different in-situ consolidation pressures and measuring the inter-laminar shear strength of each sample by the short-beam shear test. The results showed that the inter-laminar shear strength of composite parts fabricated with the proposed stepped-concurrent curing, and layering process increases with the applied consolidation pressure up to a point. Scanning electron microscopy of samples cured at different in-situ consolidation pressure showed that the sample with optimum consolidation pressure has relatively uniform fiber to resin distribution and hence improved inter-laminar shear strength.
A low-cost, low-waste manufacturing method for advanced thermoset composite parts could improve market penetration of composites compared to other engineering materials such as aluminum or steel. Such a method could combine some of the new trends in composites manufacturing such as resin infusion (eliminates need for prepreg), out-of-autoclave consolidation, and snap curing. The feasibility of a hybrid process with these characteristics has been demonstrated by uniting liquid composite molding, resin curing by electron beam irradiation, and high pressure consolidation with specialized elastomeric tooling. To demonstrate feasibility, a mold set was designed to make flat, square four-ply woven carbon fiber parts by (1) vacuum-infusing dry preforms with an electron beam–curable epoxy resin in minutes, (2) applying 690 kPa of uniform pressure and consolidating in seconds using an elastomer-faced specialized elastomeric tooling tool and simple hydraulic press, and (3) curing in seconds using a 3 MeV electron beam source. To better understand how various process parameters affect part performance, parameters are varied in a simple design of experiments, and flexural strength and stiffness, thickness distribution, fiber and void volume fractions, surface roughness, and cross-sectional characteristics (via microscopy) are measured and compared.
more » « less- PAR ID:
- 10546981
- Publisher / Repository:
- SAGE Publications
- Date Published:
- Journal Name:
- Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture
- Volume:
- 233
- Issue:
- 4
- ISSN:
- 0954-4054
- Format(s):
- Medium: X Size: p. 1168-1181
- Size(s):
- p. 1168-1181
- Sponsoring Org:
- National Science Foundation
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Highlights Hydroxyapatite is used for natural fiber composite interfacial modification.
Nanoindentation shows the interfacial region exhibits 31.4% higher stiffness.
Modified composites possess superior mechanical performance.
Jute fibers are thermally functionalized for composite additive manufacturing.
A direct writing method is developed for continuous functionalized jute fiber.
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