振动筛横梁疲劳裂纹的脉冲涡流检测技术研究

发布时间：2018-08-07 13:37

【摘要】：基于法拉第电磁感应原理的脉冲涡流检测技术具有渗透深度大、信息丰富等优点,是保证在役状态下含包覆层振动筛横梁疲劳裂纹检测的首选技术之一。本文围绕振动筛横梁疲劳裂纹的脉冲涡流检测技术展开研究,主要研究成果与创新点如下:首先,利用Comsol仿真软件建立了振动筛横梁疲劳裂纹的仿真模型,仿真研究了激励频率与上升时间对检测信号的影响从而优化了激励参数;在此基础上,仿真研究了缺陷深度以及提离对检测信号的影响,为后文的实验研究提供理论基础。其次,设计开发了一套脉冲涡流检测实验系统,主要包括探头、信号发生、信号处理、信号采集以及上位机软件5个部分。最后,利用开发的实验系统,针对不同深度的表面与亚表面缺陷进行了实验研究。本文采用多次测量取平均值、小波去噪对差分信号进行了预处理以去除噪音。随后分别提取差分信号的时域、频域和统计信号特征并对其进行分析比较。结果表明,与频域和统计信号特征相比,时域信号特征在表面与亚表面缺陷的位置识别、分类及深度量化方面性能最优,且具有提取简单、物理意义明确等优点。最后验证有包覆层时该结论仍然成立本文研究结果为振动筛横梁疲劳裂纹检测提供了理论依据,具有重要的理论与应用价值。
[Abstract]:The pulsed eddy current testing technology based on Faraday electromagnetic induction principle has the advantages of large penetration depth and abundant information. It is one of the first choice techniques to ensure fatigue crack detection of vibrating sieve beams with cladding layers in service. The main achievements and innovations of this paper are as follows: firstly, the simulation model of fatigue crack of vibrating sieve crossbeam is established by using Comsol software. The effects of excitation frequency and rising time on the detection signal are simulated and the excitation parameters are optimized. On this basis, the effects of defect depth and lift on the detection signal are simulated and studied, which provides a theoretical basis for the later experimental study. Secondly, a pulse eddy current testing system is designed and developed, which includes five parts: probe, signal generation, signal processing, signal acquisition and upper computer software. Finally, the surface and subsurface defects of different depths are studied by using the developed experimental system. In this paper, wavelet denoising is used to pre-process the differential signal to remove the noise. Then the time domain, frequency domain and statistical signal characteristics of the differential signal are extracted and compared. The results show that, compared with frequency domain and statistical signal features, time domain signal features have the best performance in location recognition, classification and depth quantization of surface and subsurface defects, and have the advantages of simple extraction and clear physical meaning. Finally, when the cladding layer is verified, the result of this paper provides a theoretical basis for the fatigue crack detection of the vibrating sieve beam, and has important theoretical and practical value.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TH237.6;TG115.28

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