Innovative Magnetic NDE System for Micromagnetic Imaging

This project is investigating the application of magnetic recording and micromachine technologies to the development of a novel magnetic nondestructive evaluation (NDE) system. Magnetic NDE methods based on Barkhausen signal detection and analysis can provide valuable information about the state of stress of steel materials. However, Barkhausen signals do not appear to be correlated with the extent of mechanical damage or stress in the case of complex stress states or combined microstructural effects. It is well known that the domain structure of magnetic material is dependent on the state of stress. This is the basis of magnetic NDE techniques. Much more information about the state of stress may be obtained from imaging the domain walls or wall motion. We propose to investigate the domain imaging capabilities of a two-dimensional array of micron scale magnetic field sensors (recording heads). In Phase I SFA will develop a simulation model for the imaging capabilities of an array of micron scale heads. This will be accomplished by using finite element modeling of the head field and the reciprocity theorem. The imaging properties of the array will be investigated by developing a phenomenological simulation of domain wall motion. Techniques to fabricate the array based on macromachining processes will also be investigated.