A new calibration method for dynamically loaded transducers and its application to cavitation impact measurement

The erosion produced by cavitation is a serious problem in hydraulic machin ery. During investigations of the dynamic loading generated by collapsing c avitation on a surface, a dynamic pressure transducer was developed The pie zoelectric polymer PVDF (Polyvinylidene fluoride) was used as the pressure sensitive material. A novel method of dynamic calibration has also been dev eloped. The transducer is loaded at the center by weights. As the static lo ad is increased, the pencil lean breaks and the through pencil lend by a be am supported at its other end on a knife edge and loaded load is released s uddenly. The unloading time is faster than for any other conventional calib ration method and is of the same order as cavitation loaning, Descriptions of the developments of both the calibration method and the transducer are g iven. The principal advantages of the new method are the short pulse durati on and the simplicity of the test procedure. The paper is an extension of the previously reported work by Momma and Lich tarowicz (1994), giving further information on the operating characteristic s of the transducer in comparison with the traditional ball-dropping method .