| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1989: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1988: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Research Abstract |
I simulated AE generation, propagation and its relation to received signal by means of stress wave visualization techniques. In order to simulate the AE wave generation, I introduced a slit into a glass model specimen as a simulation of a crack and put a piezoelectric transducer in the slit tip to deform like crack tip fracture by applying an electric pulse.
Two types of PZT transducers, having rectangular shape, were used to simulate the actual crack tip fracture; one was deformed to thickness direction as mode I fracture and the other made shear deformation as mode II fracture. Applying the stress wave visualization technique, I used glass model specimens which have similar sound velocities to that of steel. Square shape and bar type specimens were used to study the effects of specimen shape to the AE wave generation.
The system for stress wave visualization used in this study was originally developed for ultrasonic wave visualization in a solid.
Two types of wide band AE sensors and re
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sonant type one were used to receive the AE wave for characterizing these AE sensors. In this simulation method, the same AE wave can be generated repeatedly so that exact comparison is enable to evaluate receiving characteristics of the AE sensors by receiving the same AE wave.
Results obtained in this study are as follows. 1. In spite of the different types of PZT put in the slit tip, both longitudinal and shear wave were emitted as an AE wave from the slit tip. However, a main wave generated by the thickness deformation mode PZT was a longitudinal wave and the wave generated by the shear deformation mode PZT was a shear wave, and each wave has different directivity. 2. There are differences in the AE wave generation and propagation between the specimen shapes. In the bar type specimen, part of longitudinal waves propagating along the specimen surface were inode-coriverted to shear waves. 3. Received AE signals by the AE sensors were similar to actual burst type AE signal. When receiving the same AE wave generated by the PZT put at the slit tip, different signal were observed from each AE sensor. Less
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