Two cylindrical vessels under internal pressure are used for this work in order to study the influence of the position and size of defects on their elastic and elastoplastic behavior. One contains two external longitu...Two cylindrical vessels under internal pressure are used for this work in order to study the influence of the position and size of defects on their elastic and elastoplastic behavior. One contains two external longitudinal semi-elliptic defects of different dimensions realized diametrically opposed. The other contains the same defects but is circumferential. These defects are carried out by elect-erosion. Strain gauges are placed in the neighborhood of the defects of which the purpose is to obtain the strain distribution. This work also allows the comparison between two defects of different dimensions, which are of the same shape or different shapes. These defects are longitudinal and circumferential semi-elliptical. The position of these defects relative to the inner radius of a cylindrical pressure vessel is considered. The deformations results are discussed.展开更多
The multi-modes and disperse characteristics of torsional modes in pipes are investigated theoretically and experimentally. At all frequencies, both phase velocity and group velocity of the lowest torsional mode T（0,...The multi-modes and disperse characteristics of torsional modes in pipes are investigated theoretically and experimentally. At all frequencies, both phase velocity and group velocity of the lowest torsional mode T（0,1） are constant and equal to shear wave velocity. T（0,1） mode at all frequencies is the fastest torsional mode. In the experiments, T（0,1） mode is excited and received in pipes using 9 thickness shear vibration mode piezoelectric ceramic elements. Furthermore, an artificial longitudinal defect of a 4 m long pipe is detected using T（0,1） mode at 50 kHz. Experimental results show that it is feasible for longitudinal defect detection in pipes using T（0,1） mode of ultrasonic guided waves.展开更多
文摘Two cylindrical vessels under internal pressure are used for this work in order to study the influence of the position and size of defects on their elastic and elastoplastic behavior. One contains two external longitudinal semi-elliptic defects of different dimensions realized diametrically opposed. The other contains the same defects but is circumferential. These defects are carried out by elect-erosion. Strain gauges are placed in the neighborhood of the defects of which the purpose is to obtain the strain distribution. This work also allows the comparison between two defects of different dimensions, which are of the same shape or different shapes. These defects are longitudinal and circumferential semi-elliptical. The position of these defects relative to the inner radius of a cylindrical pressure vessel is considered. The deformations results are discussed.
基金This project is supported by National Natural Science Foundation of China(No. 10272007, No.60404017, No.10372009)Municipal Natural Science Foundation of Beijing, Clina(No.4052008).
文摘The multi-modes and disperse characteristics of torsional modes in pipes are investigated theoretically and experimentally. At all frequencies, both phase velocity and group velocity of the lowest torsional mode T（0,1） are constant and equal to shear wave velocity. T（0,1） mode at all frequencies is the fastest torsional mode. In the experiments, T（0,1） mode is excited and received in pipes using 9 thickness shear vibration mode piezoelectric ceramic elements. Furthermore, an artificial longitudinal defect of a 4 m long pipe is detected using T（0,1） mode at 50 kHz. Experimental results show that it is feasible for longitudinal defect detection in pipes using T（0,1） mode of ultrasonic guided waves.
