Study On Process Optimization And Surface Integrity Of CFRP Material Following Abrasive Waterjet Cutting Process

With the large-scale application of lightweight material technology in the aerospace and automotive industries,carbon fiber reinforced composites(CFRP)have attracted the attention of many researchers due to its comprehensive performance of light weight and high strength.when CFRP components is assembled with other stuctures,it needs to be processed with various kinds of post machining methods,such as milling and drilling to achieve the dimensional tolerance.However,CFRP laminate,which served as a typical difficult-to-machine material,has the characteristics of high hardness,anisotropy and heterogeneity.In conventional machining of CFRP,processing defects such as burrs,delamination,and rapid tool wear are generally occurred,which seriously restricted the production efficiency and service performance of CFRP components.High-pressure abrasive waterjet machining is an emerging cold cutting technology.Compared with traditional methods,it has many advantages such as low cutting force,no thermal stress and higher machining quality during processing of CFRP materials.However,there are still some problems such as low processing accuracy and poor efficiency which need to be solved immediately in order to be widely used in industries.In this paper,thin-walled CFRP composites were adopted as the main research objects.A series of research work has been carried out on the surface integrity and process optimization of CFRP following abrasive waterjet machining.The main research results of this paper are as follows:(1)The removal mechanism of CFRP material during AWJ machining was studied by integrating erosion theory of brittle material with the experimental results.The influence of process parameters on machining quality and mechanical properties of finished products were also studied in detail.The results show that the abrasive particles within waterjet stream played an important role in the removal of materials and the improvement of the kerf surface quality during AWJ machining of CFRP.Most of the material failure was induced by the the intrusion of waterjet fluid into the micro cracks beneathed the kerf surface.(2)The influence of processing parameters(SOD,hydraulic pressure,traverse speed)on the kerf width,kerf taper and the surface roughness were studied by single-factor experiment.Response surface method was employed to study the the modeling and optimizing of machining parameters.In addition,the mechanical milling operation was proposed to be applied in postprocessing of CFRP cutting surface made by abrasive waterjet machining.Results show that the kerf taper of CFRP is effectively suppressed,and the surface roughness is significantly improved without apparent machining defects.(3)In order to evaluate the feasibility of applying AWJ for cutting stacks as a substitute of conventional machining,the kerf characteristics including kerf width,taper angle and kerf profile,hole characteristics including cutting diameter and roundness error as well as machined surface integrity were studied when using abrasive waterjet to machining Ti6Al4V/CFRP stack with various processing conditions.The machining performance of CFRP/titanium alloy multilayer structure by abrasive waterjet was also studied.In summary,this paper deeply explains the processing mechanism of CFRP and the formation mechanism of machining defects.The fitting model of process parameters is established and post-processing technology of mechanical milling was proposed.Experimental research on the machining perfoemance of abrasive waterjet cutting of CFRP/Ti6Al4 V stacks has been conducted.All these studies have lay the foundation for expanding the application range of abrasive waterjet machining and improving the engineering application value of CFRP abrasive waterjet machining technology in practical scenes.