Optimisation des paramètres de détourage des composites à fibres de lin et comparaison avec le détourage des composites à fibres de verre

Abstract

With growing environmental concerns, plastic matrix composite materials reinforced with natural fibers such as flax fibers are increasingly attracting for both the industrial and research communities. They are particularly interesting considering their biodegradability. Moreover, their intrinsic properties are comparable to those of glass fiber reinforced polymers (GFRP), especially their intrinsic modulus and strength. For these reasons, flax fibers have been identified by several researchers as a real substitute for glass fibers, as reinforcement in composite materials. However, it is known that the machining processes of synthetic and some natural fibers composites generate several defects such as delamination and a poor surface quality. The main objective of this study is to qualify the machinability of the flax fiber composites in order to identify the optimal cutting conditions for given cutting tools (cutting speed and feed rate). The trends of the cutting forces and the surface integrity (roughness and delamination) are studied regarding the cutting parameters, the fibers orientation and the cutting tool geometry. The second objective of this study is to evaluate the potential of flax fibers, in terms of machinability, as a substitute reinforcement material to the glass fibers for some applications. Dry trimming experiments were both conducted on unidirectional flax/epoxy laminates and glass/epoxy laminates. Two cutting tools with different materials and geometries were selected for this study. The surface finish and material integrity as well as the cutting forces are the two requirements to optimize in this research. The experimentation proposed is based on a split-split-plot randomized complete block design with input factors being the cutting speed, feed rate, fiber orientation and cutting tool. The responses are the cutting forces, the delamination and the surface roughness. The results show that the flax fiber composite is easily machined and not abrasive. The detouring process lead to approximatively no tool wear and very low cutting forces. It is also shown that the measured responses are correlated with the preselected factors. The feed rate is proved to be the most influent factor on the responses, followed by fiber orientation. The 0° oriented fibers have the best trimming quality and thus regardless the reinforcement nature (flax or glass). Optimum cutting conditions when trimming the flax fiber composite are a low feed rate and a high cutting speed. In the case of the glass fiber composite, an intermediate feed and a low cutting speed are the optimum conditions. The potential of flax fibers to replace glass fibers as reinforcement in composites has been confirmed within a range of intermediate to high feed rates.

Date	18 Dec 2017
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Jean-François Chatelain (Supervisor), Yves Beauchamp (Co-supervisor) & Gilbert Lebrun (Co-supervisor)