DEVELOPMENT OF NONDESTRUCTIVE TESTING METHODS FOR THE EVALUATION OF THIN AND ULTRATHIN SHEET MATERIALS.
Final rept. 16 Jul 65-15 Jun 66,
GENERAL AMERICAN TRANSPORTATION CORP NILES ILL GENERAL AMERICAN RESEARCH DIV
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This report describes activity on the subject program for the third year. Electronic modifications were made to the FM Lamb wave system during the period which resulted in a signal-to-noise ratio improvement of better than one order of magnitude. In addition, the use of a sound absorbing medium in the area of the transducers was found to significantly reduce crosstalk and stray reflections. Laboratory testing with the FM Lamb wave system has proved the technique to be capable of detecting small flaws or defects, but relatively insensitive to material property variations. A brief analytical investigation of a forked-coil eddy current system has shown that the technique can be effectively used to measure material properties of only certain alloys provided sheet thickness is simultaneously monitored. A theoretical and experimental investigation of beta backscatter has shown the method to be related to thin sheet hardness and surface finish by a second order effect. Theoretical and experimental work on a counterfeit waveguide microwave technique for measuring material properties has been encouraging and further work is recommended to reduce the technique to practice. A survey of thin sheet manufacturers and users has established the fact that most of the present thin sheet problems requiring continuous on-line inspection are indigenous to the manufacture and fabrication of refractory materials. Author
- Fabrication Metallurgy
- Test Facilities, Equipment and Methods