Investigation of cutting mechanisms and strain fields during orthogonal cutting in CFRPs

Abstract

Cutting mechanisms in fiber reinforced plastics (FRPs) have been studied in the present work. Full field strains are measured using the digital image correlation (DIC) technique, and force signals are measured using a dynamometer. With the aim of understanding the influence of the pronounced heterogeneity and anisotropy observed in FRPs due to the presence of fiber and matrix phases, an idealized CFRP (I CFRP) plate has been prepared using epoxy resin with embedded, equispaced tows of carbon fibers at 5 mm center to center spacing. Orthogonal cutting of these I CFRPs has been carried out, and the chip formation characteristics, cutting force signals, and strain distributions obtained during machining have been analyzed. In addition, strain distributions during machining have been analyzed for unidirectional carbon fiber–reinforced plastics (UD CFRPs). The effects of depth of cut and fiber orientation have been studied extensively. Experimental results are encouraging and indicate that in situ, full field strain measurements from DIC, coupled with force measurements, provide an adequate measure of anisotropy and heterogeneity during orthogonal cutting. Finite element (FE) modeling of orthogonal cutting of I GFRP specimens has also been carried out. 3D FE modeling of I GFRP cutting has been conducted in ABAQUS/Explicit. Failure mechanisms during orthogonal cutting have been incorporated in the FE model through a cohesive zone model (CZM) of the fiber–matrix interface, and a ductile damage criterion with damage evolution has been employed for the epoxy matrix. The model shows that matrix damage is significant, with marginal fiber–matrix debonding. Strains in the model have been compared with results from DIC and show a close match.