斜入射SH波厚壁管道内壁裂纹检测方法研究

厚壁管道常被用于军事装备及其他流程工业中，长期使用后内壁会产生较多微裂纹，成为影响构件安全运行的重大隐患。为此，本文针对厚壁管道内壁裂纹难以检测的问题，提出基于斜入射SH(Shear Horizontal)波的厚壁管道检测方法，对厚壁管道内壁不同深度的裂纹进行检测。本文首先对斜入射SH波的激励原理进行分析，建立声场模型优选激励频率，研究斜入射SH波与厚壁管道内壁裂纹径向深度的作用规律，并通过实验对仿真结果进行验证。研究结果表明，斜入射SH波对该型管道最佳检测频率为1MHz；随着裂纹径向深度增加，缺陷回波幅值呈现曲折型上升；斜入射SH波可有效对厚壁管道内壁轴向长8mm，径向深1mm和周向宽1mm的微裂纹进行检测，验证了斜入射SH波厚壁管道内壁裂纹检测方法的科学性和可行性。

Study on the detection method of cracks on the inner wall of thick wall pipes with inclined beams of SH waves

Thick-walled pipes are often used in military equipment and other process industries. After long-term use, the inner wall will produce more cracks, which will become a major hidden danger affecting the safe operation of components. For this reason, this paper proposes a thick-walled pipeline detection method based on inclined beams of SH waves for the problem that the cracks on the inner wall of thick-walled pipelines are difficult to detect, and detects cracks at different depths on the inner wall of thick-walled pipelines. In this paper, the excitation principle of inclined beams of SH waves is analyzed firstly, the excitation frequency of sound field model is established, and the action law of inclined beams of SH waves and radial depth of thick wall inner wall crack is studied. The simulation results are verified by experiments. The results show that the optimal detection frequency of the inclined beams of SH waves is 1MHz. With the increase of the radial depth of the crack, the amplitude of the defect waves increases in a zigzag pattern. The inclined beams of SH waves can effectively detect micro-cracks with an axial length of 8mm, a radial depth of 1mm and a circumferential width of 1mm in thick-walled pipelines.