Research On Key Technologies And Development Of Magnetostrictive Guided Wave Testing Software

The guided wave testing technology based on the magnetostrictive effect has been one ofresearch hotspots in the nondestructive testing field in recent years due to its advantage ofefficient inspection. As key technologies of the magnetostrictive guided wave testing software,the calculation method of dispersion curves and the unidirectional testing method areresearched and the testing software is developed in the thesis.Firstly, the large frequency-thickness product problem in calculating dispersion curves ofthick walled pipes is researched. Find out that the causes of the large frequency-thicknessproduct problem are the floating point overflow in calculation. Then, the arithmetic of thebinary floating point number is analyzed accordingly. The solution based on exponents isresearched in consequence. In order to speed up the calculation of dispersion curves, the quickscanning method and the multithread parallel computing method are researched, which canrealize fast calculation of dispersion curves of thick walled pipes.Secondly, it’s difficult to analyze complicated signals and locate the defect inbidirectional testing. The acknowledged unidirectional testing has high demands on thehardware. Therefore, the principle of extracting unidirectional excited magnetostrictiveguided wave signals is derived by analyzing the time relationship of the corresponding echoesof two sets of bidirectional guided wave signals. The extracting method is carried out basedon cross-correlation algorithm. The delayed time of the corresponding wave packet iscalculated by self-adapting wave packet extraction and the cross-correlation algorithm. Then,the unidirectional stimulated signal is obtained by time-shifting and differencing using thedelayed time. The experimental results show that the method has low demands on thehardware and contributes to simplify echo analysis and improve the defect positioning ability.Finally, the testing software is developed based on the testing hardware. The softwareconsists of dispersion module, simulation module, parameter setting module, data acquisitionmodule, signal analysis module and testing reports module, which provide functions ofselecting detection frequency, optimizing sensors arrangement, collecting data, displaying signals, storing data, analyzing signals, generating testing reports, and so on.