Observation of Acoustic Emission Behavior During Embedding Tests Using Drift Pins
Hideki AOI and Takanori ARIMA
Abstract:The acoustic emission (AE) behavior on dowel-bearing tests with a drift pin was investigated. The comparison of AE behavior in elastic region and that in plastic region was carried out. The drift pin diameter and the end distance from center of drift pin were changed to compare their effect on AE behavior. From AE behavior side, the safety of embedding stress from ASTM-D5764 and EN383 was examined. The results were as follows. 1) AE was observed in plastic region, while few AE was found in elastic region. It is estimated that minute fracture in embedding wood causes the AE generation. 2) On the specimen with short end distance, AE was observed actively. On the contrary, on the specimen with long end distance, AE was observed slowly. 3) As regards AE amplitude, large number of ratio over 70dB was seen in plastic region. The ratio was increased approximately with increasing AE count rate. Very small number of the ratio was observed in the region showing less than 100 (event/sec) AE count rate. 4) Both 5% offset stress value from ASTM-D5764 and embedding strength from EN383 did not show significant difference. However through the examination of the AE behavior, it was indicated that both values might be accompanied with the minute fracture. Key Words:Acoustic emission, Timber joints, Embedding test, AE count rate, AE amplitude