Under the effect of applied fatigue loads, high stress concentration appears at the coating/substrate interface where cracks tend to initiate. In order to monitor the interfacial crack initiation, a two-dimensional cohesive zone model is introduced to actuate the magnetomechanical model to describe the interfacial damage evolution process by measuring the residual magnetic field. The variation of residual magnetic field strength at the interfacial pre-crack tip with loading cycles under the tensile fatigue tests is analyzed. Then, the residual magnetic field strength threshold of interfacial crack initiation is determined. The physical mechanism underlying generation and variation of interfacial magnetization is also revealed from the perspective of magnetic domain movement. Furthermore, the low- and high-cycle fatigue three-point bending tests are conducted to verify the applicability of residual magnetic field measurement for interfacial crack initiation monitoring. It indicates that this measurement method can provide the guidance of crack initiation monitoring for magnetic nondestructive testing of coating/substrate interface.

在施加的疲劳载荷的影响下，涂层/基材界面处出现高应力集中，裂纹往往在此处开始。为了监测界面裂纹的萌生，引入二维凝聚区模型来驱动磁力学模型，通过测量剩余磁场来描述界面损伤演化过程。分析了拉伸疲劳试验下界面预裂纹尖端剩余磁场强度随加载循环的变化。然后，确定界面裂纹萌生的剩余磁场强度阈值。还从磁畴运动的角度揭示了界面磁化强度产生和变化的物理机制。此外，进行了低周疲劳三点弯曲试验和高周疲劳三点弯曲试验，验证了剩磁测量在界面裂纹萌生监测中的适用性。表明该测量方法可为涂层/基体界面磁性无损检测提供裂纹萌生监测指导。