Study On Cutting Performance Of Carbon Fiber Composites By Abrasive Water Jet

Composite material,especially carbon fiber reinforced plastic(CFRP)are increasingly and widely used in aerospace field.With advantages of high specific strength,high temperature,fatigue,corrosion,wear resistance,CFRP can be used to produce complex load-bearing composites with both a reduced fabrication time and lower costs,compared with conventional manufacture of metals.However,Traditional machining technology cannot efficiently and high-quality process this material,which is not conducive to the wider application of this material.As for CFRP,which is quite anisotropic,depends obvious on the process parameters such as temperature,pressure,velocity and so on.The process of traditional manufacturing CFRP involved breakup of fiber,matrix cracking,separation of fiber and matrix.Compared with the traditional and other non-traditional machining methods,abrasive water jet(AWJ)cutting technology presents great benefits in terms of efficiency,productivity,versatility and surface quality managing to cut difficult shapes quickly and precisely with no thermal damage to the workpiece and minimal burrs.A wide range of experiments have been conducted to study the principles of cutting metal,glass,ceramic and metal matrix composites,and cutting model for corresponding materials has been established.The principles and models of machining these materials can't be applied to CFRP for the difference in structure and matrix materials.In this paper,the energy dissipation rate,power spectra,and surface roughness belong to the surface profile are studied,according to the experiment of machining CFRP.Meanwhile,the cutting model for machining CFRP is proposed.The results and conclusions are described briefly as follows:(1)This thesis introduces the principles and classification of abrasive waterjet,and machining model for ductility material cut by AWJ In the direction of feeding and drilling.The forces acting on the particles in AWJ are analyzed,including Stocks force,pressure gradient force,additive mass force,Saffman lift,Magnus lift and Bassett force.Meanwhile,Structural properties of CFRP is introduced.(2)This paper introduces the performance AWJ machining system,and others equipments required in the experiment,such as surface measuring instrument,and CFRP.Designs the experiment of cutting CFRP,surface measurement scheme,and program to process the data.(3)The B-spline interpolation method was used to describe the cut surface of CFRP.Energy dissipation rate of surface profile was obtained by integration,and the influence of various parameters on the energy dissipation rate in the cutting process was analyzed.(4)Fourier analysis is adopted to investigate amplitude spectrum of cutting front,distribution of the amplitude spectrum along drilling direction,influences of traverse speed,abrasive mass flow,pressure,standoff distance,and sample thickness on amplitude spectral distribution are explored.According to the corresponding critical value,the principles of peak of amplitude spectrum and length of the main component interval and the sub-major component interval of cutting front along with process parameters.(5)The filtering effect of sharp cut-off low-pass filter,box filter and Gaussian filter is compared,and the effects of direct filtering and B-spline pre-filtering is contrasted,and the effects of different order B-spline pre-Gaussian filtering is analyzed.The results show that B-spline pre-Gaussian filtering has the best effect,and the order of B-spline has no significant effect on the effect of B-spline pre-Gaussian filtering.(6)Combind with priciples of roughness of cutting front,and cutting front model for ductile material cut by AWJ,a "three-stage" cutting front model for CFRP is proposed,which has three zone in the direction of drilling.And the relationship between process parameters and length of smooth cutting zone is analyzed.