| 摘要 |
A device for generating an acoustic stress wave in metal structures in real-time. A cylindrical housing suitable for mounting on the metal structure includes a chamber and a piezostack actuator mounted inside the housing chamber, and may include a suppport ring for relieving strain between the chamber and the actuator. The actuator has a high tensile strength block extending therefrom for contacting the surface. A pulse wave generator with a power amplifier are connected to the actuator to drive the actuator in accordance with a predetermined frequency to cause microindentation in the surface and thereby generate an acoustic stress wave in the surface at a desired frequency. The thus generated acoustic stress wave is transmitted to a signal transformer for producing a signal from the stress wave for use in systems for interpreting the significance of the signal. In a preferred embodiment, the high tensile block has a ceramic tip for engagement with the surface. The end is preferably adapted to move a distance of from about 3 to about 7 mu m over application of a voltage of up to 1000 volts. The preferred piezostack actuator includes a poled element having a poling axis, and the actuator generates a tensile force along the axis when the output voltage of the actuator is the opposite polarity as the poled element and compressive force when the output voltage of the actuator is the same polarity as the poled element.
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