水泥基材料损伤自诊断机理声发射研究

Self-diagnosis Mechanism of Carbon Fiber Reinforced Cementitious Materials Studied by Acoustic Emission Technique

采用声发射与电阻技术对碳纤维混水泥基材料土在单轴受压和三点弯曲负荷下内部损伤进行了监测 .研究表明 ,在三点弯曲负荷下 ,碳纤维混凝土的荷载 -挠度曲线与试件的电阻和声发射事件数存在良好的对应关系 .对于碳纤维水泥基复合材料 ,其导电率主要依赖分散于水泥基体中相互搭接的碳纤维的渗流网络 .材料内部的损伤引起相互搭接的渗流网络破坏 ,而致使材料电阻增大 .因此 ,在整个加载过程中 ,体系的电阻反映了材料内部的损伤 .另一方面 ,通过声发射信号的分析 ,可以鉴定材料内部损伤的机理 .

Real time damage detection of concrete structure is becoming more and more critical.In this paper,damage in carbon fiber-reinforced concrete (CFRC) under uniaxial compression and three-point bending conditions was monitored by both electrical resistance measurement and acoustic emission (AE) analysis.The research showes a good correlation exists among curve of load-deflection,changes in electrical resistance and AE hits.For CFRC,the electrical conductivity depends on the percolation network formed by the contacting carbon fiber.The damage occurring inside materials causes breakdown of percolation network and brings an increase in electrical resistance.Therefore,the change in electrical resistance reflects the damage during the entire loading process.On the other hand,by analysis of AE parameters,AE technique can detect and possibly identify damage mechanisms in fiber reinforced composites.These two techniques are complementary for monitoring damage in CFRC.