多层膜结构的金刚石复合涂层刀具在冲击载荷作用下损伤与失效行为研究

Previous experimental results have shown that, comparing with the monolayer diamond films, multilayer composite diamond coated insert can greatly prolong its working lifetime. But the coated insert generally suffer from the catastrophic delamination induced by impact load derived from cutting material and machine tool during cutting processing. This significantly decreases the cutting precision and tool lifetime. In this project, the fundamental works are performed to investigate the structural evaluation of multilayer composite diamond coated insert under impact load. The combination of experimental measurement, theoretical analysis and numerical computation is conducted to study the damage and failure behavior of multilayer composite diamond coated insert after loading impact wave. The experiments using different impact loads will be performed on the impact equipment to observe the inner relationship between impact load and coating structure and the relative law between coating transfer and damage/failure behavior of film. Then the impact dynamics theory is used for obtaining the elastic-plastic wave equation to model the mechanical process of multilayer composite diamond coated insert under impact load. The dynamic finite element method is applied to generate the corresponding data by numerical calculation that can provide the observable evaluation of damage and failure process of multilayer composite diamond coated insert under impact load. Similarly, the mechanism also can be understood clear. Finally, this project will present the correlation between impact load and damage/failure behavior of multilayer composite diamond coated insert in detail. Such results can provide the powerful technical support for cutting theory of coated insert, and also facilitate forming the theoretical and technical base that guide and expand the widespread applications of diamond coated insert in industrial fields.

试验表明，相对于单层膜结构，多层膜结构的金刚石复合涂层刀具可大幅延长刀具的使用寿命，然而，切削过程中涂层刀具常受到加工材料和设备等冲击载荷作用，严重影响了切削精度和刀具寿命。本项目旨在对多层膜结构的金刚石复合涂层刀具在冲击载荷作用下的结构完整性进行基础研究。拟采用实验研究、理论分析和数值仿真相结合，对涂层刀具在冲击载荷作用下的损伤和失效进行分析。利用冲击实验平台对多层膜结构的金刚石复合涂层刀具进行冲击实验，获取冲击载荷与涂层结构、涂层性能转变和损伤失效的作用规律；引入冲击动力学理论，建立多层膜结构的金刚石复合涂层的弹塑性波动方程；利用动力有限元方法解析涂层损伤和失效演化过程，掌握损伤和失效机理，结合实验结果，揭示多层膜结构的金刚石复合涂层冲击与损伤和失效的内在关联。本项目的研究成果可为涂层刀具的切削理论提供技术支撑，也将为金刚石涂层刀具的广泛应用奠定理论和技术基础。

切削过程中涂层刀具常受到加工材料和设备等冲击载荷作用，严重影响了切削精度和刀具寿命，相对于超硬金刚石涂层，耐冲击性能对其在刀具和工具应用具有重要意义，同时，实验表明，相对于单层膜结构，多层膜结构的金刚石复合涂层刀具可大幅延长刀具的使用寿命。本项目针对金刚石涂层在冲击载荷作用下的损伤和失效进行深入研究，研究了多层膜结构金刚石涂层的冲击失效实验；多层膜结构金刚石涂层的冲击动力学理论与仿真和多层膜结构金刚石涂层结构和质量优化。采用冲击实验和疲劳冲击实验的方法，获取了单层、双层和三层金刚石涂层的冲击损伤和失效规律，引入能量计量分析方法，揭示了多层膜结构金刚石涂层冲击性能强化的作用机理，其中纳米金刚石涂层和层数对缓解涂层冲击破坏具有重要作用。提出了多层膜结构金刚石涂层结构和质量优化方法，设计出三种新型涂层结构，提高了涂层耐冲击、耐磨性和摩擦性能，为涂层耐冲击性能提供了有效的思路和工艺技术支撑。提出了弹簧-质量系统动力学和板壳结构静力学分析模型，揭示了外载荷大小和频率对金刚石涂层应力和应变的影响规律；利用量子力学和范德华力学耦合，研究了界面间脱落和摩擦过程的微观机理，发现了界面剥离和摩擦过程中界面能量非连续变化的规律，主要在于量子力场与范德华力场的差异引起，两种力场边界处将出现非稳态区域，对涂层的脱落起到重要作用；进行了多层膜结构金刚石涂层在冲击载荷作用下的有限元仿真计算，获得了多层膜结构金刚石涂层应力波传播规律，层间和层厚等参数与涂层能量的关系，揭示涂层在受到冲击力作用下的能量分布特点。本项目揭示了多层膜结构的金刚石复合涂层冲击与损伤和失效的内在关联，研究成果可为涂层刀具的切削理论提供技术支撑，也将为金刚石涂层刀具的广泛应用奠定理论和技术基础。