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Characterization and simulation of process-induced wrinkling in manufacture of aerospace textile composites

University of British Columbia

Textile fibre-reinforced composites are among the top materials of choice in prominent sectors such as aerospace and automotive. The rapid rise in demand for this class of materials has also led to the development of their automated manufacturing processes and improved production rates. However, this rapid development is still compromised by forming defects such as wrinkling, particularly in producing 3D complex parts at large scales. The process-induced wrinkles arising from the soft and compliant nature of the fibres at dry state and the curing resin below the gelation point are known to have a significant impact on the final structural properties of the composite, thereby underlining the importance of fundamental understanding of the forming and consolidation phases taken place during composites manufacturing. This research aims to expand the existing knowledge on autoclave processing of woven composite prepregs, especially in the uncured state, through a combined experimental and numerical approach including enhanced modelling of the mechanics involved during the forming and consolidation stages. An emphasis is placed on the efficiency of proposed numerical models to provide faster solutions as demanded by the industry. In the first phase of the work, a modified bias extension test has been proposed to better understand and characterize the influence of boundary conditions and interaction of the prepreg with the tooling during forming. Thereby, a novel shear stress formulation is introduced, allowing for a more accurate approximation of shear patterns during forming, by considering the effect of frictional interactions between the fabric and tooling at different shear angles. In the second phase, an extensive manufacturing characterization routine has been developed to better understand the lubrication modes during the autoclave processing, as well as the compaction stage of fabric prepregs when formed in multi-layers. A generic mixed lubrication model was then developed, capable of capturing the inter-ply frictional response under a wide range of processing conditions given the fabric geometry, surface roughness, and resin properties. Finally, a number of industrially relevant case studies were investigated to demonstrate the formation of process-induced wrinkling defects and validate all the developed models, including the integration of forming and consolidation stages.

Text

2021-04-21

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/77861

Mechanical Engineering

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/4.0/