冲击载荷下2-2型水泥基压电复合材料力电响应特性

研究2-2型水泥基压电复合材料在冲击载荷下的力电响应特征,利用分离式Hopkinson压杆装置进行冲击加载,借助超高速摄影技术观察试样在冲击载荷下的破坏形貌。结果表明:冲击载荷下,压电复合材料具有明显的应变率效应,是应变率敏感材料;压电复合材料的力电响应存在一个临界值,当应力小于该临界值时,试样的电信号与施加载荷之间具有良好的线性关系;动态增强因子可以有效描述压电复合材料压缩强度的率效应规律,在线性范围内,随着应变率的增大,试样的动态增强因子也增大,且具有稳定的增长率;由Maxwell模型得到的压电复合材料应力松弛时间随应变率增大单调递减;冲击载荷下,2-2型水泥基压电复合材料与压电陶瓷的电学失效发生在力学失效之前,且均呈现“爆炸式”破碎,压电陶瓷还伴随着明显的电弧放电现象。

Mechanical-Electrical Response Characteristics of 2-2 Type Cement-Based Piezoelectric Composites under Impact Loading

The mechanical-electrical response characteristics of 2-2 type cement-based piezoelectric composites under impact loading by using the split Hopkinson pressure bar were studied. With the help of ultra-high-speed photography technology, the sample morphological failure was observed. The results indicate that piezoelectric composites have obvious strain rate effect under impact loading and they are strain rate sensitive materials. There is a threshold value of mechanical-electrical response of composites. When the stress is less than the threshold value, there is a good linear relationship between the electrical signal of sample and the applied loading. The dynamic increase factor effectively describes the rate-effect law of compressive strength of composites. In the linear range, with the increase of strain rate, the dynamic increase factor increases and grows with stable growth rate. Based on the Maxwell model, the stress relaxation time of piezoelectric composites decreases monotonously with the increase of strain rate. Under impact loading, the electrical failure of 2-2 type cement-based piezoelectric composites and piezoelectric ceramics occurs before their mechanical failure. All of their morphologies are "explosive" fragmentation and there is obvious arc discharge phenomenon for the piezoelectric ceramics.