摘要
针对实际工程中裂纹失稳扩展临界特征提取的难题,从一个新的角度引入金属磁记忆技术,通过Q345钢标准三点弯曲试验,获取裂纹稳态扩展到失稳扩展整个演化过程的磁记忆信号变化规律,提取裂纹临界失稳扩展时的磁记忆特征。结果表明,当裂纹处于失稳扩展的临界状态时,磁记忆信号梯度值发生显著跳跃上扬,最大值是稳态扩展的2倍以上,失稳特征显著,磁记忆正交矢量合成梯度G_(vs)的临界特征,真实反映了裂纹临界失稳扩展时应力强度因子K的临界特征。首次建立了磁记忆特征参数G_(vs)与裂纹尖端应力强度因子K之间的数学模型,验证试验结果表明误差为7.9%,为实际工程中利用磁记忆参数特征判定裂纹失稳扩展临界状态提供一种新的思路。
In order to extract the critical characteristics of crack instability extension,metal magnetic memory testing（ MMM） is adopted. The experimental material is steel Q345. And the standard three point bending experiments is operated to find the MMM law of crack extension from steady to instability extension. The MMM characteristics of crack critical instability extension is given. It has been found that the MMM gradients increase dramatically in the period of the critical instability extension,and its maximum value is twice than that of the steady extension. The MMM vector synthesis gradient G_（vs）truly reflects the critical characteristics of stress intensity factor K of the critical instability extension. The relationship between G_（vs）and K is first present,the error of which is 7. 9%. This provides a new method which judges the critical state of crack instability extension in order avoid accidents in practical engineering.
出处
《压力容器》
2016年第2期74-80,共7页
Pressure Vessel Technology
基金
国家自然科学基金项目(11272084
11472076)
中国石油科技创新基金项目(2015D-5006-0602)
黑龙江省博士后科研启动基金项目(LBH-Q13035)
关键词
断裂力学
磁记忆检测
三点弯曲
梯度值
fracture mechanics
magnetic memory testing
three point bending
gradient
