Abstract: The automatically thickness measurement method for pipeline corrosion detection of ultrasound, which has the significant features as large amount of data and much interference, is required high adaptability.However, many algorithms for pipeline corrosion detection of ultrasound have many defects, such as high misdiagnosis rate, low accuracy or more time-consumed.For solving this problem, the two-step method which is based on FFT is proposed in this paper.Firstly, twice FFT algorithm is researched for solving high misdiagnosis rate problem.Secondly, the improved twice FFT method is presented to solve the low precision of traditional twice FFT method.The theoretical analysis and experiments shows that the presented method has high precision and low misdiagnosis rate which is the same as FFT and twice FFT respectively.The automatically thickness measurement for pipeline corrosion detection of ultrasound can be realized by this method.

Key words: ultrasonic inspection, autonomous system, pipeline corrosion, twice FFT

摘要： 管道腐蚀超声波内检测具有数据量大、干扰多的特点,其自动测厚算法要求适应性强,但各类超声波检测数据处理算法用于管道内检测自动测厚时存在误判率高、精度较低、耗时长等缺点。针对此问题,本文首先提出了基于两步法的一次FFT自动测厚算法;对其存在的误判率高的问题,提出了二次FFT自动测厚算法;对二次FFT算法精度降低的问题,提出了改进的二次FFT自动测厚算法。理论分析和各类实验证明,该算法具有一次FFT自动测厚算法精度高和二次FFT自动测厚算法误判率低的特点,较好地实现了管道腐蚀壁厚自动测量。

关键词: 超声检测, 自动检测系统, 管道腐蚀, 二次FFT