| Autor: |
Marcia Patton-Mallory, Kent D. Anderson |
| Rok vydání: |
1988 |
| Předmět: |
|
| Zdroj: |
Acousto-Ultrasonics ISBN: 9781475719673 |
| DOI: |
10.1007/978-1-4757-1965-9_23 |
| Popis: |
The application of an acousto-ultrasonics technique to detect decay in wood members is discussed. The method uses a 75 kHz pulsing transducer to introduce a stress wave into the material being tested. The stress wave is received by a 60 kHz resonant transducer. The method uses a through transmission arrangement with transducers on opposite faces of the member being tested. Measurements have been taken on members up to 9–1/2 inches measured across the grain. Measurements on the received waveform are the traditional acoustic emission waveform parameters (Fig. 1a) and additional acousto-ultrasonic parameters (Fig. 1b). Measurements in addition to the traditional acoustic emission parameters were centroid time, start time, RMS voltage, and negative and positive peak voltage times. The acousto-ultrasonic system is detailed in Fig. 2. It is best described in terms of signal flow. The pulse generator output a short pulse to the pulsing transducer, and at the same time was connected to the oscilloscope to start the oscilloscope trace. The stress wave generated by the pulsing transducer was transmitted into the wood through a couplant and was detected by a similar transducer at the other end of the wood. The receiving transducer converted the stress wave to an electrical signal which was amplified and filtered before being captured by the oscilloscope. Once captured by the oscilloscope, the signal was transmitted to a microcomputer for further processing and storage. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
|
