Characterization of material flaws using ultrasonic ramp responses
This report validates a new nondestructive evaluation (NDE) technique that characterizes inclusions within solids using ultrasound. The main feature of this technique is to interrogate the scatterer with stress waves preprocessed to have ramp wave shapes. Thus a ramp in time and the ramp designation is defined to mean only one abrupt change of the first derivative of the shape of the pulse. The signal obtained from the backscattered wave supposedly contains information as to the size, shape, orientation and material properties of the inclusion. A new theory was developed because the physical optics approximation depends on the scatterer being a rigid smooth body of a generally convex shape, a condition which is not met in elastic solids. This new theoryis an extension of the formal aspects of the theory of the scattering of ultrasound in elastic solids. The new theory states that when a ramp waveform strikes an inclusion the backscattered wave (ramp response) is a product of two parts. One part contains material property changes between the host and scatterer. The other is predicted to be a mapping of the inclusions area profile as a function of line-of-sight distance. To validate this new theory we use exact calculations for a known case. These calculations relte incoming, scattered, and bounded wave fields for inclusions or voids located in elastic solids. Separate calculations are presented for incoming shear and longitudinal waves. The shear wave ramp response is compared to the longitudinal wave ramp response which yields information concerning the material properties of the scatterer.
- Research Organization:
- Lawrence Livermore National Lab., CA (USA)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 6534583
- Report Number(s):
- UCID-19656; ON: DE83006132
- Country of Publication:
- United States
- Language:
- English
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