基于树脂/纤维界面温变特性的CFRP力-热耦合钻削机理及疲劳特性研究

Carbon fiber reinforced polymer (CFRP) materials has been widely applied in aviation and aerospace fields. But defects occurring in connecting holes drilling of CFRP, including delamination, tear, burr, etc., deteriorated drilling quality and service reliability, which was regarded as a key technical issue to be solved urgently. Currently, researches of CFRP drilling quality mainly focused on the effects of the shape and material of bit tools, processing parameters and machining temperature. The interphase between fiber and resin, although regarded as the most important factor for composite properties, was rarely noted in drilling process research so far. Temperature-dependent character of resin machinability and interface strength were found in our previous research, which influenced the quality and fatigue character of drilled hole, especially when the temperature of drilling area was near the glass transition temperature (Tg) of CFRP. Based on the research results above, theoretical analysis, experimental research and numerical simulation methods will be used in this project to study the evolvement regulation of interface strength and its effect on defects formation during the hole drilling process. Moreover, the relationship among cutting force, cutting heat, interface strength, drilling quality and fatigue properties base on thermo-mechanical coupling mechanism will also be explored, and a low-temperature drilling process for CFRP and temperature controlling principal will be put forward based on the Tg and the plastic brittle temperature of resin. Consequently, this project will provide a theoretical basis for CFRP drilling process with high quality and reliability, and the research is very important to the solution of drilling defects technological problems during drilling process.

随着碳纤维复合材料（CFRP）在航空航天等领域中的广泛应用，其制孔过程中存在的分层、撕裂、毛刺等缺陷严重影响制孔质量及服役可靠性，已成为亟待解决的技术难题。目前对CFRP制孔工艺研究主要集中在刀具、工艺，和温度等对制孔质量的影响上，很少关注力热耦合对树脂/纤维界面影响这一核心因素。课题组研究发现：树脂基体加工工艺性及树脂/纤维的界面性能具有显著的温变特性，其在玻璃化转变温度附近强度与刚度发生突变的特性对制孔质量及疲劳特性有十分重要的影响。因此本项目通过理论分析、试验研究和计算仿真，重点研究钻削制孔中树脂/纤维界面性能的演变规律及对缺陷形成的影响机制，探索力-热耦合作用导致的切削力-热-界面强度-制孔质量-疲劳特性之间相互作用机制与规律，建立基于基体玻璃化转变温度和脆化温度的低温钻削工艺，为高质量CFRP钻孔工艺提供理论基础，项目的研究工作对于解决钻削缺陷共性技术难题具有十分重要的科学意义。

通过理论分析、试验研究和计算仿真等方法，重点研究了钻削制孔中碳纤维复合材料（CFRP）力学性能的温变特性对材料切削过程及缺陷形成机制的影响，探索钻削力-钻削温度-材料温变特性-制孔质量之间的相互作用机制与规律，提出了基于复合材料力学性能温变特性的低温钻削工艺方法，为高质量CFRP钻削制孔工艺提供理论基础。.明确了切削温度对树脂基体、界面强度及层间断裂韧性的影响规律，在此基础上采用有限元仿真方法建立了基于复合材料细观各相本构的三维切削有限元模型，对不同温度下的CFRP细观切削过程进行了仿真模拟，分析了CFRP力学性能的温变特性对材料去除过程的影响，揭示了切削温度对多相非均质复合材料切削过程影响的本质原因。.提出了由于CFRP力学性能温变特性的影响，临界轴向力随钻削温度的变化而变化的理论观点，通过三维钻削有限元仿真定性的分析了钻削分层的失效模式，并基于CFRP力学性能的温变特性建立了力热耦合作用下的CFRP钻削分层临界轴向力预测模型，提高了临界轴向力预测精度，为高质量钻削工艺参数制定提供了理论依据。.通过CFRP钻削正交实验，揭示了力热耦合作用下钻削温度对制孔质量和制孔精度的影响机制与规律，并对影响钻削缺陷产生的主要原因进行了分析和归类。依据树脂基体、界面强度及层间断裂韧性随温度变化的力学特性，提出了基于CFRP力学性能温变特性的低温钻削工艺方法，丰富和补充了非均质复合材料钻削加工理论。.通过开孔法测残余应力的方法，明确了低温制孔工艺方法对孔边残余应力的影响规律。分析了残余应力和损伤程度对材料静态和疲劳力学性能的影响，发现损伤程度仍是影响材料力学性能的主要因素，阐明了低温钻削CFRP制孔工艺对开孔件疲劳力学性能的影响规律，为提高复合材料连接构件疲劳寿命提供有益参考。