Finite element model of the drilling process of carbon fiber reinforced plastic (CFRP)

Abstract

Carbon fiber reinforced plastic (CFRP) is a composite, composed of reinforcing carbon fiber and matrix resin. CFRP is widely used in various fields, such as aerospace, automotive, robotics, and civil infrastructures, due to its excellent corrosion resistance and superior physical characteristics like strength-to-weight ratio, compared with traditional metals. Therefore, it has been constantly utilized and developed as the state-of-the-art material in numerous applications. Machining is indispensable when applying CFRP in these various industries, among which drilling process is indispensable for assembling different parts into products. However, unlike metals, CFRP holds heterogeneous properties. During the drilling process, delamination and uncut fibers are generated by the thrust force generated in the feed direction. While delamination at the outer surface can be detected by visual inspection, internal defect cannot be observed by the naked eye. These defects need to be predicted because of not only reducing the durability of the product but also causing deterioration in quality. This thesis presents the simplified FE model and method to predict the mechanical phenomena during the drilling process. To investigate these phenomena, a simulation model was developed with commercial FEM software, ABAQUS. Through the developed FE model, it was possible to predict the delamination through the stress distribution of each layer generated after the drilling process. In addition, it was possible to identify uncut fibers for each layer through this, and furthermore, the possibility of suggesting optimum processing conditions can be confirmed. Also, based on the analysis data obtained from the FE model, the change in the thrust force according to the drill entry position at the time of drilling was confirmed, and the accuracy of the developed analytical model was confirmed by comparing the experimental data with the analytical data. Therefore, FE model was developed to investigate defect prediction, and the results from FE analysis was compared this with experimental data to minimize errors in CFRP drilling process.