Focusing behaviors of ultrasonic phased arrays in anisotropic and inhomogeneous weldments

It meets some difficulties in the case of ultrasonic phased arrays testing for the nickel-based alloy welded joint, since the ultrasound will propagate with curvilinear paths in this kind anisotropic joint. Thus, it is hard to calculate the phased array time delays properly according to the traditional focusing approach, which is based on the assumption that the sound beam will propagate in straight lines. In order to focus the phased arrays beam in this kind anisotropic joint, we provide a modified focusing approach by combining the ray tracing method and the bisectional searching optimization. With the help of this focusing approach, the curved ray path connecting each element position in phased arrays to the expected focus point in weldments can be determined, so that it can be used to calculate the proper time delay and control the beam focusing in the anisotropic weldment. Furthermore, some experimental examinations are carried out to compare the focusing behaviors between the traditional and the modified focusing approach. It shows that the provided focusing approach is more accurate than the traditional method in the case of inspection on the nickel-based alloy weldments. © 20120Editorial Board of CHINA WELDING.