磁弹噪讯技术无损检测铁磁材料疲劳损伤

铁磁材料加工制造的机械构件，在服役的过程中，受外力作用、在其内部会产生应力集中与松驰，引起构件局部或全部的扭曲、变形，造成构件的疲劳，使设备运行不安全或破损，对铁磁构件内部应力和疲劳寿命检测一直是人们重视的检测难题。从工程应用的角度，迫切需要一种既能检测构件应力大小，分布以及构件的疲劳，而不需要通过测量应变而测应力，并能瞬间、定点、在线的检测方法，铁磁构件在交变磁场的作用下，磁畴壁的不连续运动在其表面释放一种磁弹波--巴克毫森噪讯。该巴氏噪讯对材料所受外加载荷及材料的微观结构的变化十分敏感。采用该技术可开展在线无损检测铁磁构件服役应力及疲劳损伤。本文介绍该技术的原理及对平板构件疲劳损伤无损检测的实验结果。

Nondestructive testing of ferromagnetic material by magneto-elasticity noise technique for fatigue damage

Under the influence of external forces, stresses may develop inside the mechanical components of ferromagnetic material in service, and cause distortion and deformation of mechanical components and result in fatigue failure. The detection of stresses and fatigue in ferromagnetic mechanical components has been a difficult problem for a very long time. Therefore a method for testing the magnitude and distribution of residual and fatigue lives of mechanical components inside ferromagnetic components without testing their strains is urgently needed. And this method must be able to be used in the field conditions. When a ferromagnetic material is magnetized by an alternating magnetic field, the abrupt irreversible motion of magnetic domain walls inside the material will induce Magnetic Barkhausen Noise (MBN). Due to its sensitivity to the microstructure and stress state of the material, MBN can be used to test fatigue and residual stresses inside ferromagnetic materials. In this paper, the principle of this technique and the measurement of fatigue failure in a plate component are introduced.