基于小波包能量谱的管道缺陷磁记忆检测信号特征研究

现有磁记忆检测技术判定准则,只能指示应力集中位置,无法进一步获取应力集中信息。为获取应力集中信息,提出一种基于小波包能量谱的磁记忆信号分析方法,进行试件拉伸试验。拉伸应力为200 MPa时,信号小波包能量谱分布较为均匀,各频带能量占总能量之比均小于15%,不存在集中分布的频带范围。拉伸应力为410 MPa时,信号小波包能量谱最大值分布在1,3,4频带,1~4频带能量之和占总能量的73.8%,小波包能量主要集中在低频段。试件屈服后,信号小波包能量谱最大值分布在1,2频带,能量谱分布极为分散,能量主要集中在低频段的1,2频带,1~3频带能量之和占总能量的87.3%。管道试件应力集中程度与磁记忆信号的小波包能量谱分布特征有关,应力集中程度越低,小波包能量谱分布越均匀;应力集中程度越高,小波包能量谱分布越集中,能量主要向低频段集中。

Study on Magnetic Memory Testing Signal Feature of Pipeline Defect Based on Wavelet Packet Energy Spectrum

At present,the judging principle of magnetic memory testing technology(MMT) can only indicate the stress concentration zone,but can not get information of the stress concentration further.In the research,to get information of the stress concentration zone,an MMT signal analysis method based on wavelet packet energy spectrum is proposed.The specimen tension load experiment shows that when the tension load is P=200 MPa,the signal wavelet packet energy spectrum distributes uniformly,the percentage of separate energy is lower than 15%,and it has no concentration zone.When the tension load is P=410 MPa,the maximum wavelet packet energy locates in spectrum 1,3 and 4,the percentage of spectrum 1–4 energy to total energy is 73.8%,the distribution of wavelet packet energy spectrum is separate,and the main wavelet packet energy locates in low frequency area.After the specimen yields,the maximum wavelet packet energy locates in spectrum 1 and 2,and the percentage of spectrum 1–3 energy to total energy is 87.3 %.The distribution of wavelet packet energy spectrum is more separate,and the main wavelet packet energy locates in spectrum 1 and 2.The stress concentration degree is related to the MMT signal’s wavelet packet energy spectrum distribution characteristic.If the stress concentration degree is low,then the wavelet packet energy spectrum distribution is equal;if the stress concentration degree is high,then the wavelet packet energy spectrum distribution is concentrated,and the main energy is concentrated in low frequency area.