疲劳载荷下金属材料的磁记忆信号特征

Magnetic memory signal characteristic of metal under fatigue loading

设计拉伸疲劳试验,研究了疲劳载荷下磁信号暂时到达的稳定状态的特点以及疲劳过程中磁信号的分布、变化情况,并结合改进的J-A理论进行分析和讨论.结果显示:磁信号暂时到达的稳定状态在一个循环周期内沿环线变化,并且环线随循环载荷类型不同而变化,说明用改进的J-A理论描述磁记忆现象合理;疲劳过程中磁信号分三个阶段变化,这个特征由改进的J-A模型中描述磁畴壁运动所受阻碍的参数(ξ″)随疲劳损伤发展的变化规律解释;磁信号在缺陷附近呈"⌒"形的分布,这个特征由缺陷附近ξ″的分布规律解释.

Tensile fatigue experiments were performed to study the characteristic of temporary stable magnetiza- tion states under fatigue loading, as well as the distribution and variation of magnetic memory signal in the process of fatigue. Experimental results were analyzed and discussed using the modified J-A model. It is found that the temporary stable magnetization state of magnetic signal varies along a loop in a stress cycle and the loop changes when the fatigue load type changes, which indicates that it is reasonable using the modified J-A model to describe the magnetic memory phenomenon of metal. The change of magnetic signal is divided into three stages in the process of fatigue, which is explained according to the change law of parameter ξ″ （the parameter expresses the obstruction to magnetic domain wall motion） using the modified J-A model. The magnetic signal distributing in a ‘⌒’ shape around a defect is explained according to the distribution law of ξ″around the defect.