平纹编织CFRP制孔分层形成机制的热-力学理论建模及试验分析

碳纤维增强复合材料(Carbon fiber reinforced plastics, CFRP)在航空航天领域获得了广泛应用，但由于各向异性和层间连接较差等特点，钻削过程中极易出现分层缺陷，严重影响构件的使用性能。为分析钻削温度对平纹编织CFRP制孔缺陷的影响机制，基于弹性地基梁理论、黏聚力学模型和热力学理论，建立了新钻型钻削平纹编织CFRP制孔分层形成的理论模型。结果表明：当新钻型多刃尖(Ⅲ)钻削孔边缘的最表层材料时，钻削温度达到最大值，对最终分层的形成最为关键；钻削温度和制孔分层随着主轴转速的增大而逐渐降低，随着进给速度的增大而逐渐升高。当纤维角度(θ)在0°/90°/180°/270°附近时，层间分层的临界轴向力达到最大值，分层相对较大，当纤维角度(θ)在45°/135°/225°/315°附近时，临界轴向力最小，分层并非极大。因此，临界力的大小只能反映产生分层缺陷的难易程度，不能决定分层的最终形状和大小。考虑温度影响时的制孔分层形态预测与试验观测基本吻合，而不考虑温度影响下所获得的预测值总体上偏小。此外，平纹编织CFRP分层形状基本呈近似圆形。

Thermo-mechanical Modeling and Experimental Analysis of the Plain-woven CFRP Drill-exit Delamination

Carbon fiber reinforced plastics (CFRP) is widely used in the aerospace industry. However, due to the characteristics of anisotropy and poor interlayer connection, the delamination is very easy to occur in the drilling process, which seriously affects the performance of the components. In order to analyze the influence mechanism of drilling temperature on the hole-making delamination of plain-woven CFRP, a thermo-mechanical theoretical model of the delamination formation for the drilling of plain-woven CFRP by using the novel drill is established, based on the elastic foundation beam theory, cohesion mechanics model and thermo-mechanical theory. The results show that when the novel drill candle stick edges (Ⅲ) drill the exit top layer materials, the drilling temperature reaches the maximum value, and this period is the most critical for the formation of the final delamination. The drilling temperature and the delamination gradually decrease with the increase of the spindle speed, and gradually increase with the increase of the feed speed. When the fiber angle (θ) is near 0°/90°/180°/270°, the critical axial force of the interlayer delamination reaches its maximum value, and the delamination is relatively large. When the fiber angle (θ) is around 45°/135°/225°/315°, the critical axial force is the smallest and the delamination is not extremely large. Therefore, the critical force can only reflect the difficulty of generating delamination, but can't determine the final shape and size of the delamination. The prediction of delamination morphology obtained by the thermo-mechanical theoretical model is consistent with the experimental observations. However, the predicted value obtained without considering the temperature is generally small. In addition, the delamination shape of plain-woven CFRP is almost circular.