Measurement of the Energy Content in Acousto-Ultrasonic Signals
Important features of the techniques currently employed for the measurement of acousto-ultrasonic (AU) parameter commonly referred to as stress wave factor are briefly described. An alternate procedure for characterizing this AU parameter, in which the energy content of the received signal is used to rank the material’s interaction with the propagating stress wave is proposed. This procedure employs simultaneous counting of acousto-ultrasonic signals at a number of threshold levels, suitably distributed across the amplitude range of the signals encountered in a particular test. The resulting counts at different threshold levels are given weightings according to their amplitudes and are summed up to provide a measure of energy. The accuracy of this scheme is verified by measuring the acoustical signals produced by the impact of steel spheres of different masses on a borosilicate glass block. In a related study, the same procedure was applied to measure acoustic emission signals from composite materials and was found to provide an estimate of the damage level with fair degree of success.
KeywordsAcoustic Emission Stress Wave Acoustic Emission Signal Steel Sphere Total Energy Content
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- 1.A. Vary and R. F. Clark, “Correlation of Fiber Composite Tensile Strength with the Ultrasonic Stress Wave Factor, TM 78846,” NASA, Cleveland (1978).Google Scholar
- 2.J. C. Duke, E. G. Henneke, and W. W. Stinchcomb, “Ultrasonic Stress Wave Factor Technique for the Characterization of Composite Materials, CR-3876,” NASA, Cleveland (1986).Google Scholar
- 3.E. G. Henneke, J. C. Duke, W. W. Stinchcomb, A. Govada and A. Lemascon, “A Study of the Stress Wave Factor Technique for the Characterization of Composite Materials, CR-3670,” NASA, Cleveland (1983).Google Scholar
- 6.J. H. Williams, Jr. and N. R. Lampert, Ultrasonic Evaluation of Impact Damaged Graphite Fiber Composite, Matls Eval. 38:68 (1980).Google Scholar
- 7.A. K. Govada, J. C. Duke, E. G. Henneke, and W. W. Stinchcomb, “A Study of the Stress Wave Factor Technique for the Characterization of Composite Materials, CR-174870,” NASA, Cleveland (1984).Google Scholar
- 8.M. J. Sundaresan, E. G. Henneke, K. L. Reifsnider and D. Post, “Nondestructive Evaluation of Filament Wound Pressure Vessels, CCMS-87–02,” Center for the Composite Materials and Structures, Virginia Tech, (1987).Google Scholar
- 9.M. J. Sundaresan, “Acoustic Emission Energy Measurement Through an Improved Count Technique, TM-ST-407/243–81,” National Aeronautical Laboratory, Bangalore, India.Google Scholar
- 10.M. J. Sundaresan, L. C. Manoharan, H. N. Sudheendra and Viveka Naik, Evaluation of Damage Growth in Composite Materials Using Acoustic Emission Energy Measurement Technique, in: “Proceedings of the 6th Intl. Symposium on Acoustic Emission,” Susuno, Japan (1982).Google Scholar