论文信息 - Calculated signal amplitudes for ultrasonic Time-of-Flight diffraction signals for tilted or skewed cracks

Calculated signal amplitudes for ultrasonic Time-of-Flight diffraction signals for tilted or skewed cracks

Abstract Calculations of the signal amplitudes expected with Time-of-Flight Diffraction are presented for tilted or skewed cracks. The model calculations are based on the geometrical theory of diffraction and are valid for cracks larger than about three ultrasonic wavelengths with the cracks in the far field of the probes. The signal amplitudes are given relative to signals from a 9·5 mm diameter side-drilled hole at the same depth as the defects. Results are presented for elliptical and strip-like defects of through-wall extent between 15 and 25 mm and at depths from the inspection surface of between 100 and 225 mm. These results show that the signal amplitudes expected correspond to about 1% DAC (distance amplitude correction) on conventional equipment, that the signal levels increase with increasing tilt (unlike pulse-echo or Tandem inspections) and that the signal levels remain constant for defects skewed by up to about 60°.

J.A.G. Temple

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