Experimental investigation on the cutting mechanism and surface generation in orthogonal cutting of UD-CFRP laminates

As carbon fiber reinforced polymer (CFRP) have been widely used as the main material of aeronautic load-carrying parts, there are more and more demands of relevant machining work. Due to the significant anisotropy of CFRPs, defects may easily occur in the machining process. This paper investigated the stress state of carbon fiber and resin microelements and the formation mechanism of machined surface defects at the micro level, and analyzed the fracture mechanism of carbon fibers and its effects on machined surface morphology at various fiber orientation angles θ in the process of CFRP cutting. The results revealed that the cutting mechanism under parallel fiber cutting conditions is the interface layering separation dominated by in-plane shear stress and the machined surface is relatively flat and smooth; the cutting mechanism under perpendicular fiber cutting conditions is shear-fracture separation dominated by shear stress and the machined surface is mainly characterized by regular fiber cross fractures; the cutting mechanism includes the interface layering separation and shear-fracture separation, and the machined surface is characterized by a regular fluctuating surface composed of fiber cross fractures with fiber orientation angle 0°