Issue 48

S. E. Oliveira et alii, Frattura ed Integrità Strutturale, 48 (2019Y) 249-256; DOI: 10.3221/IGF-ESIS.48.26 255 Failure surface of some samples was observed in the Scanning Electron Microscope. Fig. 10 shows a SEM micrograph feature for 6mm length fiber composites fiber composites, which reveals a fair adhesion between resin matrix and fibers. It can also be observed some lack of polymers between the fiber and the fiber pullout, as reported in literature for high dosage composites [8, 10]. On the other hand, as shown in Fig. 5, the composites with 0.5mm fiber length shows much better fiber dispersion and lower resin lacks. Figure 9 : Stiffness modulus against drilling speed. Figure 10 : SEM observations of fracture surfaces for 6mm fibers composites. C ONCLUSIONS his work studied the effect of rotation-cutting speed on the cutting temperature, roughness and tensile properties of two epoxy based composites reinforced with 17.5% and 40% in volume fraction short carbon fiber. The main conclusions drawn can be summarized as follows: - The increasing of rotation-cutting speed significantly increases the temperature generated in the tool reaching the glass transition temperature, Tg of the polymer matrices. - The surface roughness (Rz) only slightly increases with the drilling speed. T