PBX炸药疲劳损伤演化与控制修复的原位研究

Polymer bonded explosive are subjected to fatigue load in their service. The damage accumulation accompanied by this process is a main factor to their failure at low stress condition. Currently, macroscopic fatigue law of PBX has been constructed. While, for lack of mesoscopic cognition of damage evolution process, modification of PBX and structure optimization of weapon system are partly influenced. In this program, HMX-based PBX will be selected as a research object and its in-situ fatigue test method will be established. In virtue of tensing fatigue experiments in different stress conditions, stress-number (S-N) curves of the material will be obtained. Then, crack initiation and propagation law will be explored by in-situ observation and analysis of fatigue response behavior, and variation relations between fatigue degradation degree and cyclic loading will be clarified by quantitative characterization of damage evolution process. On the basis of above studies, damage control and repairment method of PBX will be explored by resorting to shape memory alloy (SMA) composite patches, and the impacts of the patches on fatigue characteristics and degradation degree of PBX will be revealed. This program will enrich our cognition on fagitue failure mechanisms of PBX, and at the same time, provide research foundation to its structural reliability evaluation, strength optimization and integrative performance improvement.

PBX炸药在服役期间会经受疲劳载荷的作用，这一过程引发的损伤积累是导致材料在低应力水平下失效的重要因素之一。目前，PBX炸药宏观的疲劳特性规律虽已初步建立，但由于缺乏对其损伤演化过程的细观认识，而在一定程度上影响了PBX材料改性和武器结构优化等。本项目拟以HMX基压装PBX炸药为研究对象，建立其疲劳行为的原位实验方法，借助不同应力水平下的拉-拉疲劳实验，获得疲劳寿命（S-N）曲线；根据对疲劳响应行为的原位监测与分析，探索裂纹的萌生、扩展规律，基于对损伤演化的定量表征，揭示疲劳劣化程度随循环载荷的变化关系；在此基础之上，借助形状记忆合金（SMA）复合材料补片，探索PBX炸药的损伤控制与修复方法，揭示补片对材料疲劳特性及劣化程度的影响。本项目将丰富对PBX炸药疲劳失效机制的认识，并为其结构可靠性评估、强度优化与综合性能提升等提供研究基础。

PBX炸药在服役期间会经受疲劳载荷的作用，这一过程引发的损伤积累是导致材料在低应力水平下失效的重要因素之一。研究PBX炸药的疲劳寿命、认识其疲劳响应行为，在此基础之上进一步探索其损伤控制修复方法，对于武器的可靠性评估、强度优化与综合性能提升等具有重要意义。本项目以HMX基压装PBX炸药为研究对象，围绕其疲劳问题，开展了试验方法、响应行为和损伤控制修复方法研究：①针对HMX基PBX炸药的低强度脆性特征，建立了基于小尺寸力学加载台、高速相机和数字图像相关技术的原位疲劳试验方法，实现了对PBX炸药疲劳裂纹萌生、扩展和变形断裂全过程的原位监测与记录；②开展了不同应力水平下的疲劳实验，获得了其疲劳寿命曲线，证实PBX炸药最大应力S（σmax）与疲劳破坏周数N符合对数形式S-N规律；同时，开展了对裂纹扩展过程的原位观察，发现疲劳加载条件下HMX基PBX炸药并未经历稳态的裂纹扩展过程，依然呈现典型的脆断特征，但相比准静态加载条件，其裂纹扩展速率显著降低；③建立了基于补片增强的PBX炸药疲劳损伤控制方法，发现高强补片在提升PBX炸药疲劳寿命的同时，可以有效抑制疲劳裂纹扩展；此外，探索了基于胶体弥合的PBX炸药疲劳损伤修复方法，实现了含裂纹PBX炸药疲劳寿命的大程度恢复。本项目的研究丰富了对PBX炸药疲劳失效机制的认识，同时为其结构可靠性评估、强度优化与综合性能提升等提供了一定的基础。