10:50
Session 5: Thermoplastic Composites
10:50
20 mins
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Therplastic composite cylindrical shell made by 4D printing
Suong Van Hoa, Mahmoud Fereidouni
Abstract: 4D Printing of Composites (4DPC) is a technique of composites manufacturing where structures of complex shape can be made without the use of molds of complex shapes. Only a flat mold is used. The technique has been used to make structures such as cylindrical shell, conical shell, S shaped structure, leaf spring, omega stiffener, letters of the alphabet, corrugated core for flexible wing, and vertical wind turbine blades [1]. These have been made using thermoset composites such as carbon/epoxy, which are composite prepregs that have been used to make aircraft structures. The principle of the method depends on the anisotropy of the laminate where layers of different fiber orientations interact with each other when the composite laminate is cooled from cure temperature to room temperature. For thermoset composites such as carbon/epoxy, after the resin is cured (usually at about 177 oC) the laminate is rigid during the whole period of cooling from cure temperature down to room temperature (20 oC). As such, the interaction between the layers of different fiber orientations is effective throughout this temperature range.
While thermoset composites can be used in many aircraft applications, for space applications, the problem of outgassing can be an issue. This and consideration for recycling lead to consideration to use thermoplastic composites. However, during the cooling from melt down to room temperature, thermoplastic composites exhibit stress relaxation. This gives rise to the variation of properties such as moduli not only due to the temperature change, but also due to the viscoelastic nature of the material. In addition, the use of automated fiber placement (AFP) machine to make the structure gives rise to additional issues such as variation in temperature gradients which in turn creates distortion.
The work presented by this abstract investigates different aspects of manufacturing unsymmetric laminates of thermoplastic composites using an AFP machine. The possibility of using laminate theory to predict the final shape of cylindrical shells is examined. The results are compared with results obtained from an elaborate experimental set up to measure the radii of curvature of the laminate at different temperatures.
References: 1. Suong Van Hoa, 4D Printing of composites, De Gruyter, 2025.
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11:10
20 mins
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Achieving autoclave-level consolidation during in-situ Automated Fiber Placement of thermoplastics
Allyson Fontes, Farjad Shadmehri
Abstract: In-situ Automated Fiber Placement (AFP) of thermoplastic composites is an emerging technology that addresses the growing need for rapid throughput and automation, which are essential for Industry 4.0. However, despite extensive research and development, its widespread adoption has been limited due to issues with incomplete consolidation, which requires post-consolidation in an oven or autoclave. This work proposes and validates an approach to solve incomplete consolidation during in-situ AFP by introducing a novel in-situ treatment process. This in-situ treatment follows the initial ply deposition and reapplies heat and pressure to the laminate, effectively reducing void content and increasing contact time for healing. The quality achieved with this intervention is compared to a baseline established using the thermoplastic AFP head available at the Concordia Centre for Composites, along with autoclave-post-consolidated samples. Bond quality is assessed via a single lap shear (SLS) test of carbon fiber/polyetheretherketone coupons. A design of experiments was conducted to determine the operating window for the process parameters. The results demonstrate that this in-situ treatment can greatly enhance SLS strength without the need for post-consolidation in an autoclave.
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11:30
20 mins
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Non-conventional strategies for manufacturing tank structures using Automated Fiber Placement
Sovit Agarwal, Dominik Delisle, Julius Biermann, Stefan Junker
Abstract: As we move closer to the 2050 climate goal of achieving net-zero carbon emissions, the aviation industry faces a challenge to rapidly develop new aircraft propulsion technologies that would align with the emission targets. Hydrogen is emerging as one of the most promising fuel alternatives which would enable aircrafts to fly with zero emissions. However, several challenges still remain before hydrogen can be used as a clean aviation fuel and one of the major ones is the development of reliable, safe and light-weight hydrogen storage technologies and its integration into the aircraft.
Research interest towards developing Type V liner-less composite tanks has significantly increased, especially for commercial aviation because of its huge advantage in weight reduction when compared to tanks with metal / plastic liners. Therefore, the main objective of this research is to advance the manufacturing technology and methodology required to produce Type V CFRP tank structure using Automated Fiber Placement (AFP) technique. The research focuses on challenges faced when conventional AFP manufacturing methodologies and strategies, that are mostly used for flat or slightly curved surfaces, are applied to rotational bodies like a tank structure and attempts to provide new solutions to overcome these challenges.
AFP-related parameter settings such as layup strategy, staggering of consecutive plies and starting & cutting sequences were studied as these parameters directly influence the degree of coverage, gap overlaps and layup quality respectively. CAM simulations and experimental trials were performed to compare the conventional tape placement strategies with the newly proposed strategies and it was found that the new strategies improved the overall degree of coverage, gap distribution and layup quality significantly, especially in the spherical region of the tank structure where steering of the material by the AFP head causes majority of the problems. A detailed quantitative and qualitative discussion on the major drawbacks associated with conventional tape placement strategies and the advantages of the newly proposed strategies will be presented in the full paper.
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