發(fā)布時間：2018-03-30 00:11

  本文選題：電磁渦流　切入點：無損檢測　出處：《天津工業(yè)大學(xué)》2017年碩士論文

【摘要】：電磁渦流無損檢測技術(shù)利用施加于電磁線圈上的交變電流產(chǎn)生磁場,繼而在被測導(dǎo)體上產(chǎn)生交變的電渦流,交變的電渦流又產(chǎn)生了渦流場,通過檢測渦流場即可間接獲取被測導(dǎo)體的特征參數(shù)。提離噪聲和集膚效應(yīng)是電磁渦流無損檢測技術(shù)存在的主要問題。文本基于電磁渦流無損檢測系統(tǒng)的等效變壓器模型,通過理論分析證明了等效變壓器模型中勵磁電流相位與耦合系數(shù)無關(guān)。在電磁渦流無損檢測系統(tǒng)的等效變壓器模型中,勵磁電流代表著被測材料表面的磁通密度,而提離高度則是影響耦合系數(shù)的重要因素。因此,這一結(jié)論表明磁通密度的相位信息不受提離高度的影響。在理論分析的基礎(chǔ)上進行了仿真研究,仿真結(jié)果證明,在被測金屬材料表面特定位置上檢測出的法向磁通密度BZ與提離高度呈現(xiàn)出良好的線性特征,且該點也是法向磁通密度的極值點,證明在該點處的磁通密度數(shù)據(jù)與理論分析的等效變壓器模型具有最優(yōu)的近似性。繪制不同提離高度下BZ在極值點pmax處的相軌跡,其斜率代表了 BZ的相位信息。分別對無缺陷、表面缺陷、亞表面缺陷和內(nèi)部缺陷材料進行仿真研究發(fā)現(xiàn),該方法可有效識別存在于被測金屬材料不同位置的缺陷信息。進一步將該方法擴展至多頻激勵的情況,數(shù)據(jù)分析結(jié)果表明,相軌跡的頻率響應(yīng)特性可有效區(qū)分被測材料缺陷的深度信息。最后,設(shè)計了適合本文所述相軌跡方法的實驗系統(tǒng),通過實驗驗證了理論分析的正確性。
[Abstract]:Electromagnetic eddy current is applied to the electromagnetic coil to produce magnetic field, and then alternating eddy current is generated on the tested conductor, and the alternating eddy current produces the eddy current field. The characteristic parameters of the tested conductor can be obtained indirectly by detecting the eddy current field. The lifting noise and skin effect are the main problems in the electromagnetic eddy current nondestructive testing technology. The text is based on the equivalent transformer model of the eddy current nondestructive testing system. It is proved by theoretical analysis that the phase of excitation current in the equivalent transformer model is independent of the coupling coefficient. In the equivalent transformer model of electromagnetic eddy current nondestructive testing system, the excitation current represents the flux density on the surface of the measured material. Therefore, this conclusion shows that the phase information of magnetic flux density is not affected by the lift height. Based on the theoretical analysis, the simulation results show that the phase information of the magnetic flux density is not affected by the lift height. The simulation results show that the phase information of the magnetic flux density is not affected by the lift height. The normal flux density BZ and the lift height detected on the surface of the metal material tested show a good linear characteristic, and this point is also the extreme point of the normal flux density. It is proved that the magnetic flux density data at this point have the optimal approximation with the equivalent transformer model analyzed in theory. The phase trajectories of BZ at the extreme point pmax at different lift heights are plotted, and its slope represents the phase information of BZ. The simulation of surface defect, subsurface defect and internal defect material shows that the method can effectively identify the defect information existing in different positions of the metal material under test, and further extend the method to the case of multi-frequency excitation. The data analysis results show that the frequency response characteristics of the phase trajectory can effectively distinguish the depth information of the material defect. Finally, an experimental system suitable for the phase trajectory method described in this paper is designed, and the correctness of the theoretical analysis is verified by experiments.
【學(xué)位授予單位】：天津工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG115.28

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