陶瓷基复合材料钻孔出口损伤影响规律研究

Research on Influence Law of the Ceramic Matrix Composite Drilling Holes Outlet Damage

陶瓷基复合材料具有高硬度、高强度、耐高温、耐腐蚀等诸多优点,在航空航天、核工业、刹车系统中表现出巨大的应用潜力。然而,由于其各向异性、不均质性、硬脆性的特点,使加工变得十分困难。为了减少钻削加工陶瓷基复合材料产生的孔口损伤,根据断裂力学的止裂原理,提出了名义断裂韧性的概念,建立了孔出口损伤的半经验模型,研究了名义断裂韧性对孔出口损伤带来的影响。实验结果表明,所建立的预测模型能很好的预测试验结果,验证孔出口损伤半经验模型的准确性,揭示名义断裂韧性和孔口损伤的关系;随着名义断裂韧性的提高,孔出口的损伤得到改善,且改善效果呈先快后慢的趋势。因此,通过提高工件材料名义断裂韧性的方式,可以有效抑制孔出口的损伤。

The ceramic-based composites have many advantages of high hardness,high strength,high temperature resistance and corrosion resistance,and have great application potential in aerospace,nuclear industry and brake system;however,processing is very difficult due to its heterisotropy,heterogeneity and hard fragility. In order to reduce the orifice damage caused by drilling and processing ceramic-based composite,the concept of nominal fracture toughness is proposed according to the cracking principle of fracture mechanics in this paper,and a semi-empirical model of pore outlet damage is established,the impact of nominal fracture toughness on pore outlet damage is also studied. The experimental results show that the predicted value and the experimental value are very consistent,which verifies the accuracy of the semi-empirical model,reveals the relationship between the nominal fracture toughness and the hole outlet damage;with the increase of nominal fracture toughness,the hole outlet damage is improved,and the improvement effect is fast before slow. Therefore,by improving the nominal fracture toughness of the work piece material,it can effectively inhibit the damage of the hole outlet.