| 摘要 |
Ultrasonic non-destructive testing of a solid object 20 by applying a force 30 to hold a transducer 10 directly to the surface of the object, driving the transducer 10 with a coded input ultrasound signal and detecting the reflected or transmitted output signal after it passes through the object. The transducer may be driven non-resonantly and may produce shear waves. The input signal may be coded in a variety of ways such as a pulse sequence, a random or pseudo-random sequence or a chirp, but a Golay code is preferred. The cross-correlation of the input and output signals may be calculated. The force 30 holding the transducer 10 to the object 20 (such as a pipe) may be from an integral magnet or clamp, and either the object itself or the clamp may provide the transducer with an electrical ground connection. Encoding the input signal achieves a high performance with low coupling forces, low contact pressures, low voltages, low power and low detection times. |
