摘要
基于霍普金森压杆技术,采用新设计的微型纯Ⅰ型断裂试样和配套夹具,提出了一种针对陶瓷材料的新型动态断裂测试方法,试样的起裂时间由应变片法测得;对氧化铝陶瓷开展了不同加载速率下的动态断裂实验,采用实验-数值方法得到了材料的Ⅰ型动态应力强度因子曲线及动态断裂韧性。结果显示:随着加载速率从0.45 TPa·m^(1/2)·s^(-1)提高到1.83 TPa·m^(1/2)·s^(-1),氧化铝陶瓷的Ⅰ型动态断裂韧性值由8.39 MPa·m^(1/2)增加至15.76 MPa·m^(1/2),而起裂时间则随着加载速率的增加而不断提前。由断口分析可知,随着加载速率的增加,氧化铝陶瓷由沿晶断裂占主导的失效模式逐步转变为以穿晶-沿晶相混合的断裂模式。这期间,更多的微缺陷被激活并扩展形成微裂纹,从而导致混合型断裂模式的发生。材料失效模式的转变将引起更多的能量耗散,这是断裂韧性升高的根本原因。
To address the longstanding challenge of accurately evaluating the dynamic fracture toughness of ceramic materials,a new mode I dynamic fracture testing method was developed based on the conventional split-Hopkinson pressure bar(SHPB)technique.This approach introduced a miniature fracture specimen specifically designed to ensure pure mode I loading,along with a custom fixture system that enabled stable and repeatable dynamic fracture experiments on alumina ceramics with varying loading rates.The combined experimental-numerical method was used to obtain the variation of the mode I dynamic stress intensity factor at the crack tip under different loading rates.Fracture initiation time was obtained with high precision using the strain gauge method,allowing for the determination of mode I dynamic fracture toughness.To further validate the accuracy of the measured fracture initiation time,high-speed photography was employed to capture the entire failure process in real time and corroborate the onset of fracture of the tested specimens.The results show that as the applied loading rate increases from 0.45 TPa·m^(1/2)·s^(-1) to 1.83 TPa·m^(1/2)·s^(-1),the dynamic fracture toughness of alumina ceramics rises significantly from 8.39 MPa·m^(1/2) to 15.76 MPa·m^(1/2),indicating a pronounced strengthening effect induced by higher loading rates.Meanwhile,the crack initiation time decreases notably with increasing loading rate.Fractographic analysis using scanning electron microscopy reveals a clear fracture mode transition behavior.Under lower loading rates,the fracture of alumina ceramics predominantly exhibits intergranular fracture features.Under higher loading rates,the fracture shows a mixed-mode fracture involving both intergranular and transgranular features.This transition is attributed to the activation and propagation of more micro-defects under higher rates,resulting in increased microcracking.The emergence of this mixed fracture mode is associated with greater energy dissipation,which fundamentally contributes to the increase in mode I dynamic fracture toughness.The proposed method offers a robust framework for accurately assessing the mode I dynamic fracture properties of ceramic materials.
作者
蔡治城
许泽建
范昌增
武刚
黄风雷
CAI Zhicheng;XU Zejian;FAN Changzeng;WU Gang;HUANG Fenglei(State Key Laboratory of Explosion Science and Safety Protection,Beijing Institute of Technology University,Beijing 100081,China;No.42 Team,No.91550 Unit of PLA,Dalian 116021,Liaoning,China)
出处
《爆炸与冲击》
北大核心
2026年第2期97-106,共10页
Explosion and Shock Waves
基金
爆炸科学与安全防护全国重点实验室基金项目(QNKT21-5)。
