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Session: Session 7: Thermoplastic Composites
Session starts: Wednesday 15 April, 16:10
Presentation starts: 16:50
Room: Main

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Suong Hoa (Concordia University)
Mahmoud Fereidouni (Concordia University)

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.