Quantitative study of metal magnetic memory signal versus local stress concentration

The technique of metal magnetic memory (MMM) has attracted great attentions in the field of non-destructive tests due to its unique advantages of easy-operation, low cost, and high efficiency. However, a thorough understanding of the physical mechanism of MMM phenomenon has not been clearly addressed. Generally, MMM tests can only find the possible locations of defects without quantitative descriptions about the defect characteristics. To promote study in this area, a linear magnetic-charge model is employed to analyze the self-magnetic flux leakage (SMFL) distribution in the local stress-concentration zone. Theoretical results based on this model can capture some basic characteristics of SMFL signals of ferromagnets observed in experiments. Specially, the model provides some quantitative results about the effects of defect depth and location (surface- or inner-defects) on SMFL signals. (C) 2010 Elsevier Ltd. All rights reserved.