基于声发射技术的Q345B疲劳裂纹扩展研究

Fatigue Crack Growth of Q345B Using Acoustic Emission Technique

在实验室环境下利用声发射(AE)技术对铁塔常用钢材Q345B的疲劳裂纹扩展过程进行监测。研究表明:声发射累计计数的3个阶段与断裂力学描述的3个阶段有很好的对应关系,可以很好地表征整个疲劳过程,并通过试验数据分析,证明声发射信号具有疲劳预警的属性。首次提出用一段时间内的平均振铃计数ΔC/ΔN来表征疲劳损伤进程,可以有效地克服振铃计数率数据分散性大,对材料失效不易判断的缺点,更便于预警疲劳断裂,为实现声发射监测预警模式识别提供依据;同时在累积计数值表征疲劳损伤的第二阶段内,一段时间内的平均振铃计数ΔC/ΔN与强度因子幅值ΔK的对数值存在明显地线性关系,可以为Q345B疲劳裂纹扩展的监测和预警提供依据。

In the laboratory environment,using acoustic emission( AE) technique to monitor the fatigue crack growth process of steel tower commonly used in steel Q345 B. Test results show that,there is a good corresponding relationship between the three stages of the cumulative count of acoustic emission and the three stages of the description of the fracture mechanics,the whole process can be well characterized,through the analysis of test data,it is proved that AE signal has the property of fatigue warning; For the first time to put forward the fatigue damage process characterized by the average counts within a period of time ΔC / ΔN,can effectively overcome the large dispersion of data,the material failure is not easy to judge the faults of counting rate,it is more convenient to early warning fatigue fracture,in order to provide the basis for acoustic emission monitoring and early warning pattern recognition. At the same time in the second stage of cumulative fatigue damage,the logarithm value of the average counts within a period of time ΔC / ΔN and intensity factor amplitude ΔK exist the apparent ground relation,can provide the basis for the monitoring and early warning of fatigue crack growth of Q345 B.