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

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.