Experimental investigation and modeling of surface machining of high performance CFRP for the aerospace industry

Abstract

Carbon fiber reinforced plastics (CFRP) have been widely used in many aircraft structures due to their light weight, high specific strength, good resistance to fatigue/corrosion and flexibility in design. Although CFRP components are produced to near-net shape, machining is often needed to remove excess materials and bring the parts to the final size and shape. However, their machining still is a big challenge due to their inherent anisotropy and inhomogeneity, which are the source of several types of damage, such as delamination, fibers pullout, and fiber-fragmentation. In order to improve machining quality and decrease the damages, a better understanding of their machining is required. Surface milling is one of the most practical processes for finishing operations but very few studies have been dedicated to its use for composite components. Thus, the purpose of this study is to use numerical and experimental methods to minimize the machining problems of CFRP materials and to gain a better understanding of CFRP surface milling process. First, the effects of different cutting conditions such as cutting speed, feed rate, and lead angle on cutting forces and surface quality were studied and the optimum cutting condition was determined. The experimental results showed that the best surface quality was achieved by using lower cutting feed rate, moderate cutting speeds, and zero degree tool lead angle. In the second part, the effects of cutting conditions and fiber orientation on cutting temperature were investigated. It was found that the cutting temperature increases linearly with the cutting speed. The maximum and minimum cutting forces and temperatures were achieved for fiber orientations of 90 and 0 degrees, respectively. Then, a finite element model was developed to predict cutting forces, chip formation mechanism and machining damages obtained during milling of unidirectional CFRP. The modeling results were validated by experimental data, including cutting forces and SEM images. A comparison of modeling and experimental results indicated that the proposed model is able to successfully predict the cutting forces and machining damages. The developed model showed that the machining damages, the chip formation, and the cutting force profile strongly depend on fiber orientation in CFRP milling process.

Date	21 Dec 2015
Original language	American English
Awarding Institution	École de technologie supérieure
Supervisor	Jean-François Chatelain (Supervisor) & Gilbert Lebrun (Co-supervisor)