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对材料进行超声波检查时,必须首先确定波型,在习惯上采用超声横波检查管子内外壁纵向缺陷,而在管内实现横波折射的方法则是利用不同介质分界面上的波型转换。具体地说:如对管子进行检查时是利用水和管子交界面上的纵波波型和横波波型间的转换,由于管子的形状,至使当平面声波射至管壁时在管内将会发生多种型式的波型。因此,为在管内得到横波折射(注:忽略管波导),必须使到管材表面的所有声束都落在一定的入射角范围内,这对平面声波来说是不可能的。我们提出横波检查时管材入射角窗口这一概念,并对过去单一为集中能量而用的聚焦声束,如何使它全部落入入射角窗口中的条件进行了讨论,发现:对满足一定管子探头配置的聚焦声束能完全落入入射角
Ultrasonic examination of the material, we must first determine the wave shape, the use of ultrasonic shear wave in the pipe wall longitudinal defects, and in the pipe to achieve the principle of shear wave is the use of different media interface wave mode conversion. Specifically, the inspection of a pipe takes advantage of the transition between the longitudinal and transverse wave modes at the interface of the water and the pipe, due to the shape of the pipe so that it will occur in the pipe when the plane acoustic wave is incident on the pipe wall Various types of wave patterns. Therefore, in order to obtain transverse wave refraction in the tube (note that tube waveguides are ignored), it is imperative that all beams to the surface of the tube fall within a certain angle of incidence, which is not possible with planar acoustic waves. We put forward the concept of shear angle of the tube in the transverse wave inspection, and discussed the conditions of how the focused beam used in the past to concentrate the energy completely into the angle of incidence window. It is found that for a certain tube probe The focused focused beam can fall completely into the incident angle