Three-dimensional finite element simulations of milling carbon/epoxy composites

Mechanical milling is an extensively used finishing process for fiber-reinforced polymer (FRP) composites. To better understand the characteristics in machining FRPs for higher quality and efficiency, various studies have been conducted based on the finite element (FE) method as it can give insight on the mechanisms of material removal during cutting. Yet there is still a lack of three-dimensional FE models suitable for studying the mechanisms involved in the milling of FRPs. This paper developed a 3D meso-scale FE model for simulating CFRP milling by considering the damage behavior of the composites in 3D stress state. A progressive damage model was proposed and implemented using the VUSDFLD subroutine to predict the continuous damage evolution and stiffness degradation of the laminae. The simulated cutting forces and sub-surface damage agreed with the experimental observations. Numerical studies also showed that the failure criterion affected the simulated cutting forces and sub-surface damage. Upon increasing the tool edge radius, the simulated sub-surface damage affected a larger zone beneath the machined surface; however, the simulated cutting force and the sub-surface post-failure-initiation damage area experienced no obvious changes for the studied edge radius range.