Drilling in carbon/epoxy composites: Experimental investigations and finite element implementation
Introduction
Composite materials offer excellent strength-to-weight ratio, damage tolerance, fatigue and corrosion resistance, which make them good candidates for replacement of conventional materials for structural applications. As a result, advanced composite materials make about 50% of the structural weight of Boeing 787 and Airbus A350XWB [1]. Generally, parts made of composites are produced to a near-net shape, but additional machining operations are often required to facilitate component assembly. For example, joining of composite components to a structure often requires manufacturing holes in them in order to place bolts or rivets. To manufacture these holes, drilling is a commonly used machining process. In it a rigid tool, typically a twist drill, cuts out the required area of the composite workpiece. During this process the tool encounters alternatively matrix and reinforcement materials, of which response to machining can be completely different. The process implies destruction of fibre continuity with generation of large stress concentration in the material and delamination at the hole entry and exit [2], [3], [4], [5], [6], [7]. The damage caused can significantly reduce the fatigue strength of the component, thus degrading the long-term performance of composite laminates [8], [9]. Previous studies have shown that machining fibre-reinforced polymer (FRP) composites materials differs significantly in many aspects from machining conventional metals and alloys primarily due to the underlying heterogeneity and anisotropy of FRP materials [2], [3], [4], [5], [6], [7], [8], [9].
In the literature, experimental, analytical and numerical modelling techniques have been used to study cutting mechanisms in FRP machining; excellent reviews on composite machining can be found in [5], [6], [10], [11], [12], [13], [14]. Experimental findings, though useful, provide limited information on underlying mechanics of composite deformation and damage propagation. Recently, numerical modelling has been used as a tool for a better understanding of machining of these composites. These studies typically focus on 2D models of cutting [15], [16], [17], which cannot account realistically for actual complex three-dimensional shape of cutting tool and the kinematics of the drilling process. However, advances in computational power led to the development of modelling tools and numerical strategies, which cover a wide range of temporal and geometrical length scales, as well as higher dimensionality.
This paper deals with drilling of CFRP composites and is arranged as follows: In Section 2, a comprehensive overview of drilling experiments and an X-ray micro computed tomography (μCT) scanning procedure is provided followed by discussion of experimental results. In Section 3, a detailed strategy used to develop a 3D finite-element model of drilling in a CFRP laminate is discussed. In Section 4, we present the results of finite-element simulations along with an optimisation study focussed on determination of an appropriate combination of machining parameters in order to mitigate drilling-induced damage.
Section snippets
Machine setup
The drilling experiments were conducted on a Harrison M-300 lathe machine with 2.24 kW spindle power and a maximum speed of 2500 rpm. A Jobber carbide TiN-coated twist drill bit with diameter 3 mm was mounted in its three-jaw universal chuck. The experimental setup and the drill bit are shown in Fig. 1.
A dynamometer was placed on the cross-slide of the lathe using an angle plate. The two-channel Kistler™ (Model number 9271 A) dynamometer was used to acquire thrust force and torque data. The
Finite element model of drilling in carbon/epoxy composites
In case of composite laminates, to increase drilling efficiency along with damage mitigation, it is imperative to understand the effect of machining parameters on CFRP. Various experimental studies were carried out in the past [4], [7], [14], [20], [21], [22], [23], [24] to optimise the machining parameters in order to obtain better performance in drilling of CFRP composites. Several analytical models [25], [26], [27], [28] were also developed to determine the critical thrust force and torque
Conclusions
In this paper the effect of discrete machining parameters on thrust force and torque in drilling of a cross-ply T300/LTM45-EL composite laminate was investigated both experimentally and numerically. Drilling-induced delamination, being one of the critical modes of damage in CFRP, was quantified experimentally from micro-tomography images after appropriate image processing. A 3D FE model of drilling in CFRP was developed. The underlying user-defined material model accounts for an orthotropic
References (38)
- et al.
Machining of fibre reinforced plastics
CIRP Annals – Manuf Technol
(1985) - et al.
Drilling carbon fibre reinforced plastics manufactured by autoclave—experimental and statistical study
Mater Design
(2003) - et al.
Experiment–calculation comparison of the cutting conditions representative of the long fiber composite drilling phase
Compos Sci Technol
(2005) - et al.
Experimental study of drilling glass fiber reinforced plastics (GFRPs) manufactured by hand lay-up
Compos Sci Technol
(2004) - et al.
Effects of hole machining defects on strength and fatigue life of composite laminates
Compos Part A: Appl Sci Manuf
(1997) - et al.
Machining of composite materials
Part I: Tradit Method Compos Manuf
(1992) Machining of composite materials
CIRP Annal – Manuf Technol
(2002)- et al.
Modeling of machining of composite materials: a review
Int J Mach Tool Manuf
(2012) - et al.
The path towards delamination-free drilling of composite materials
J Mater Process Technol
(2005) - et al.
Out-of-plane failure mechanisms in LFRP composite cutting
Compos Struct
(2011)
Influence of tool geometry and numerical parameters when modelling orthogonal cutting of LFRP composites
Compos Part A: Appl Sci Manuf
A micro–macro combined approach using FEM for modelling of machining of FRP composites: cutting forces analysis
Compos Sci Technol
Design, manufacture and evaluation of bending behaviour of composite beams embedded with SMA wires
Compos Sci Technol
Effects of high speed in the drilling of glass fibre reinforced plastic evaluation of the delamination factor
Int J Mach Tool Manuf
Evaluation of thrust force and surface roughness in drilling composite material using Taguchi analysis and neural network
J Mater Process Technol
Some experimental investigations in the drilling of carbon fiber-reinforced plastic (CFRP) composite laminates
Int J Mach Tool Manuf
A novel approach based on digital image analysis to evaluate the delamination factor after drilling composite laminates
Compos Sci Technol
Machinability analysis in drilling woven GFR/epoxy composites: Part I – effect of machining parameters
Compos Part A: Appl Sci Manuf
Multi-objective optimization of cutting parameters for drilling laminate composite materials by using genetic algorithms
Compos Sci Technol
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