A novel approach for surface corrosion detection based on Barkhausen effect开题报告

1. 研究目的与意义（文献综述包含参考文献）

As the most widely used material, metal has been applied to social and industrial infrastructures. But corrosion induced fatigue and failures cause fatal disaster which costs billions of dollars per year in the U.S. alone, and 40% mechanical failure due to corrosion. Corrosion characterization is meaningful for safety of society and industry. Therefore, many nondestructive testing and evaluation (NDTs movement.During domain wall movement, domain wall energy is spent to overcome the pinning sites. The abrupt jumps due to energy spending lead to sudden changes in the magnetization of the material. Even though the applied magnetic field changes smoothly, these so-called Barkhausen jumps are the reasons of the discontinuity that is directly observable in the hysteresis loop.The changes in the magnetization, induce electrical pulses which generate a noise-like signal called Barkhausen noise. Barkhausen noise, the irreversible jumps of domain wall over pinning sites, is called noise because of the sound heard from the speaker used in the original experiment.

2. 研究的基本内容、问题解决措施及方案

1. Research task of this project there are two types of Barkhausen noise experiments that are usually per-formed. If the detection coil is placed on the surface of the specimen, the emissions are termed surface Barkhausen noise, whereas a coil wrapped around the specimen detects encircling MBN.According to skin depth considerations [12], the estimated depth for minimum penetration of the magnetizing eld is roughly 1 mm, whereas the depth from which the MBN signal originates is ～30μm. A typical MBN experimental setup [13] is sketched in Fig.2.3. The MBN signal is detected by a search coil with a large number of turns of insulated copper wire wound around a ferrite cylinder. The output of the search coil is amplied and ltered.