基于非轴对称激励的管道裂纹时反导波检测研究

为解决目前管道导波时间反转检测方法需采用较多通道同步激励、接收的问题,在分析管中弯曲纵向模态簇导波激发特性的基础上,提出一种基于单一斜探头局部加载激励L(M,2)簇的时反检测方法。通过超声斜探头阵列和自行研制的时反激励/接收板卡验证该方法的可行性,并试验研究初始激励信号的类型、频率及时反窗宽等因素对管道裂纹时反检测效果的影响。结果表明,在不同检测频率,采用窄带和宽带信号进行初始激励,时反后相对时反前缺陷回波幅值均有较大提高,且回波信噪比也有较大改善,能明显区分出缺陷波包。

Time Reversal Guided Waves for Inspecting Crack in Pipeline by Non-axisymmetric Excitation

Currently guided wave time-reversal method for pipe inspection requires using multi-channels to excite and receive signal at the same time.After studying the flexural modal cluster exciting properties,a new time-reversal method based on single oblique transducer with partial loading exciting L(M,2) modal cluster is presented.The feasibility of time reversal focusing method with L(M,2) modal cluster is verified using oblique transducer array and self-developed excitation/receiving board.The focusing effect is experimentally studied in pipeline with crack by using different initial excitation signal types,center frequencies and time reversal window width.The results show that in different inspection frequencies with narrow or wide bandwidth initial excitation signal,amplitude of the defect echo and S/N ratio have significant improvement after using time reversal focusing method,thus defect echo signal can be obviously distinguished by time reversal focusing inspection.