Research Of Signal Processing Method Of Electromagnetic Detection About Surface Crack Of Steel Bars

Steel bars are widely used in many areas, such as sucker rod in oil field, steel structure in construction industry, and mechanical equipment such as machine light pestle and transmission shaft. Because of working environment influence, there are often crack, corrosion, porosity, potholes defects on these material surfaces, and the proportion of crack defects is great. These defects greatly influenced bar stock service life and not only affect the sustainability of the work, but also the safety of workers.In industrial production, considering of automation and precision detection, workers generally use electromagnetic nondestructive test method to detect crack defects. In the certain premise of test system, the choice of electromagnetic signal processing method plays an important role, it decides the overall performance of testing equipment. But among the current treatment methods, there is no professional treatment methods to electromagnetic signal, causing blind choose on signal processing method, it results treated detection signal not only can’t really reflect crack defects information, but also reduced the treatment efficiency.This article bases on improving eddy current testing and magnetic flux leakage testing precision, Firstly, discusses the common signal processing methods of theory and algorithm. Secondly, according to the characteristics on experimental results signal, choose the classical filter method, wavelet decomposition and reconstruction, wavelet threshold de-noising method, wavelet packet threshold de-noising method. Based on the advantages and disadvantages on these methods, extracts a new method:threshold de-noising and wavelet decomposition and reconstruction comprehensive treatment method, this method not only can remove high-frequency noise, but also eliminate low frequency interference, can greatly improve the signal processing effect. Finally, in order to reach the industrial application, founded the reasonable and friendly user interface with Visual Basic programming language and MATLAB, it achieves the electromagnetic detection professional processing method on crack, increasing the crack detection accuracy and efficiency.