Study On Drilling Damages And Evaluation Method Of Carbon/Epoxy Composite

Carbon/Epoxy composite as an advanced composite material has been widely used in aeronautical and aerospace industry, automotive industry and sports goods because of its particular mechanical and physical properties such as high specific modulus, high specific stiffness, corrosion resistance, light weight. However, because of their anisotropy characteristic, inhomogeneous, poor delamination resistance and hardness of carbon fibers, C/E composite belongs to one of the typically difficult-to-machine materials. Various damages appear such as burrs, spalling and delamination when drilling C/E composite. These damages not only influence assembly quality, but also reduce the strength and rigidity of the whole component. As a result, an accurate method to evaluate the drilling quality is extremely important. So far, there has not a comprehensive evaluation method to characterize the damage level. Seeking for a suitable method to assess the drilling damage of C/E composite is an urgent problem.In this paper, aiming at the drilling problems of C/E composite, an evaluation method applying to assess the damage level of C/E composite was proposed. The main work and results are listed as following:(1)A lot of observations on the damages of produced holes were done through the analysis of damage features. Damage type was redefined by comparing the positions of different damages and also analyzing factors influenced the quality of produced holes.(2)Summarize the evaluation methods that often used at present, utilizing relative indicators of statistical analysis to propose a damage factor formula which contains burrs, spalling, delamination on the exit edge.(3)In order to reflect the effect extent of each damage, adding weighting coefficients in the formula to express this information. With the wear experiment of diamond coated tool confirmed the coefficients in the formula.(4)In view of the effectiveness and credibility of evaluation method, compared damage factors with different evaluation methods, using the detection result of ultrasonic A scanning as a judgement rule. As a result, the evaluation method proposed in this paper, as comprehensively considered the damage, with this evaluation method to assess the quality of produced holes having a reasonable and effective result.