NONDESTRUCTIVE METHODS DEVELOPMENT FOR THE EVALUATION OF THIN AND ULTRATHIN SHEET MATERIALS.
Abstract
The FM Lamb wave system was modified to permit two modes of operation, a swept frequency mode and a single frequency mode. This modification proved to be extremely useful for laboratory testing because in the single frequency mode, amplitude and frequency measurements can be made digitally with a resultant accuracy of better than 1%, while in the swept frequency mode several modes can be observed simultaneously. All the electronics of the FM Lamb wave system were packaged into a mobile console to facilitate field testing. This included rebuilding of the receiver section with a resulting increase in sensitivity and adding an additional mode of data display. In addition, a precision miniwheel scanner was designed and fabricated for inspecting large samples and for on-line field testing. The results of laboratory testing showed the system to be very sensitive to laminar defects, thickness, and anisotropic properties. An IBM 1130 computer was programmed to solve the equations describing Lamb wave propagation and with the use of an on-line plotter, the curves of incident transducer angle versus frequency-thickness product were generated for many materials. Many points on these curves were then verified experimentally. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1967
- Accession Number
- AD0832035
Entities
People
- E. J. Kubiak
- L. M. Frank