Thermoformage de composites thermoplastiques pour la fabrication de composantes de vélos

Abstract

The master’s project presented in this document concerns the design and manufacturing of a bicycle fork made of thermoplastic matrix composite materials using the thermoforming process. The three main topics addressed are those enabling the fabrication of a hollow part through thermoforming : the manufacture of blanks, the thermoforming of two half-shells, and the assembly of these shells into a finished hollow product. To achieve this, in the first specific objective, flat plates are manufactured using the vacuum consolidation process. This manufacturing method allows the production of blanks that incorporate ply drops to optimize thicknesses in the thermoformed half-shell. The quality of the blanks is assessed by checking their flatness and the thickness variation compared to the theoretical laminate thickness. An average flatness of 2.186 mm was measured, which is below the established 3 mm threshold. Regarding thicknesses, the laminate was measured at 2.476 mm and 3.484 mm for the nominal 2.5 mm and 3.5 mm regions, respectively. The standard deviation of these measurements is under 0.02 mm in both cases. The second specific objective uses the fabricated blanks, this time for thermoforming half-shells. To implement the thermoforming process, two experimental setups were designed to support the blank during heating and forming. Additionally, two molds were designed to mold the front and rear half-shells of the fork, with several configurations and a self-heating mold system. These molds were validated using process simulation with Aniform software. Then, for shell manufacturing, different molding configurations were qualitatively evaluated based on the presence of defects on the parts. The fixed metal punch configuration was chosen, as it showed better consolidation quality. The press closure control by displacement did not allow for uniform consolidation of the parts. For the third specific objective, the two half-shells are assembled to form the fork. To do this, a bladder molding process is used, requiring the design of a female mold to manufacture the bladder, and then a second tool enabling pressure consolidation of the two half-shells. In this part of the project, two joint configurations are considered : a butt joint and an internal overlap joint. Overall, the overlap joint shows no disadvantages compared to the other type and is therefore preferred for its better mechanical properties. The fork was scanned, and a significant deviation of 5.592 mm was observed at the fork legs. This could pose problems during mechanical testing, but the fork was successfully installed on an Argon 18 Krypton frame during functional analysis. Finally, with the two half-shells assembled, bonded metallic dropouts were designed to enable the fork’s installation in the industrial partner’s test rig. The fork will be tested according to ISO 4210 :2023 standards at the industrial partner’s facilities following this project. The mass of the production fork from the Argon 18 Krypton (294 g) was compared with the mass of the fork manufactured with two joint configurations, and it was found to be lighter in both cases (234 g and 256 g). The cost of consumables was calculated, and the labor time was estimated for the fork manufactured in this project.

Date	28 Aug 2025
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Martine Dubé (Supervisor) & Louis Laberge Lebel (Co-supervisor)