Numerical Investigation Into the Cutting Forces, Chip Formation Mechanism, and Burr Formation During Slot Milling of Laminated CFRP Composites

Abstract

Abstract Carbon Fiber Reinforced Polymer (CFRP) composites have been attracting wide attention to industrial applications, such as in aerospace and automotive industries, because of their superior specific strength/ stiffness, excellent damage tolerance and fatigue life, and outstanding corrosion resistance along with their distinguished thermal and acoustic insulation capacity. The availability of laminated CFRP sheets has made it easy to manufacture many complex shapes accompanied by these wonderful properties Machining (post-processing) the laminated CFRP workpiece is of great importance, as it helps to achieve the desired shapes along with the desired dimensional accuracy. In this research, ABAQUS, a powerful commercial finite element method (FEM) software package, is utilized to model and simulate the milling of laminated CFRP composites. The effect of machining parameters (spindle speed, feed rate, and depth of cut) has been assessed in terms of stress distribution, temperature distribution, cutting forces, burr formation, and material removal mechanisms. In this research, coupled temperature-displacement elements are used in order to capture the effect of machining on both deformation and temperature distribution. A combination of shear damage, ductile damage and Johnson-Cook constitutive and damage models have been used to account for the damages in the fiber and matrix. A total of 12 laminates are stacked together using traction separation laws with quadratic damage cohesive model. Layers with four different fiber orientations (0-135-90-45 degrees) have been stacked. A rigid plate is modeled and attached to the bottom face of the bottom laminate and the reference point of this rigid plate is used to capture the history of cutting forces in three directions. It is found that the maximum cutting forces generated has almost linear relationship with respect to feed rate per revolution as well as with spindle speed. The chip formation mechanism is influenced by the rigidity of the tool, cutting tool geometry, fiber reinforcement directions, and laminate workpiece properties. During machining CFRP composites, failure mechanisms of fibers and matrix are different than those during traditional metal machining. Finally, the simulation results reveal that the ABAQUS FEM model can predict the cutting, stress and temperature distributions, chip formation, and burr formation during machining of CFRP laminate composites.