Nowadays, composite materials are widespread in different applications for their many properties. One of their advantages is the shaping of the material near the final shape of the required part. Furthermore, for applications requiring precision in the final dimensions of the components, it is necessary to resort to finishing operations such as trimming, drilling and sometimes even milling. Since composites are very abrasive materials, these operations are subject to heat generation at the knife/material interface. This is the source of many defects, such as the tearing of fibers, the appearance of uncut fibers, the delamination and sometimes even the alteration of the polymer matrix when the cutting temperature exceeds that of the glass transition of the matrix. Such thermal damage to the surface can severely degrade the mechanical properties of the material.
The goal of this research is to modify the epoxy matrix of a glass fiber composite, Glass Fiber Reinforced Polymer (GFRP), during its shaping, by adding additives in the form of micro particles to study the effect on the cutting temperature for the trimming operation. The study also focuses on analyzing the effect of different additives on the finish of the surfaces produced, the cutting forces, as well as on certain mechanical properties of the material. The additives considered are clay, wax and a wetting agent. A total of seven mixtures were compared with a reference composite produced with a resin without additive.
The three additives and their combination, have a very beneficial effect allowing to reduce the cutting temperature to a proportion of nearly 25% for a cutting length of 100 mm. The surface condition evaluated by roughness measurements (Ra) was improved by 73.1 % in the case of the mixture including a combination of the three additives. For this same combination, it was also observed a significant reduction in the cutting advance force of a value of nearly 82 %. However, the axial tensile performance for all the laminates containing the wetting agent (AM) additive was deteriorated. The opposite effect was observed when the wetting agent is absent from the mixtures. In this case, tensile properties were increased by 25% for the laminate including clay combined with wax. However, tests in bending and shear without AM, have instead led to a stress reduction of about 20%. With respect to the cutting surface energy, the laminate containing the wetting agent revealed a higher cutting surface energy than that without AM. In fact, the cutting surface energy containing the wetting agent reaches a maximum value of 45.2 mJ/m² evaluated with the Owens/Wendt method.
Kuate Togue, H. (Author),
Chatelain (Supervisor) &
Ouellet-Plamondon (Co-supervisor),
4 Jun 2019Student thesis: Master's thesis › Master in Engineering: Automated Manufacturing Engineering