以双曲正割型杆为基础的新型扭振变幅杆

New types of complex torsional angle transformers based on hyperbolic secant taper

推导出不存在外缘剪应力极大点的扭振超声变幅杆─－１／４波长双曲正割型杆，以此为基础组成半波长复合杆，另外１／４波长杆可以是圆柱型、指数型、类圆锥型、类悬链线型或类余弦型。对一些复合杆的谐振频率和放大系数进行了实验验证，实验结果与理论值基本一致。复合杆具有放大系数大，输人阻抗随工作频率偏移变化小，不存在外缘剪应力极大点，可输出的扭振能量大大高于同种材料的其它类型杆等一系列优点，因而对于大功率超声领域是非常有用的。

The new type of torsional angle transformer-quarter-wave length hyperbolic secant taper in which the maximum point of surface shear stress is inexistent was derived. The half-wave length complex horns can be composed on the basis of the new taper and the other quarter-wave taper may be cylinder, exponential, similar-conical, similar-catenary or similar-cosine. The resonant frequency and angle amplification ratio of some complex transformers were measured. Experimental results basically agree with theoretical values. The complex horns have a series of good characteristics, such as: the amplification ratio is very large,the change of input impedance with the deviation of the frequency is little, the maximum output ultrasonic power is much higher than that of other types of the same material. Therefore, they are very useful horns in high-intensity ultrasonic field.