Experimental Mechanics

, Volume 4, Issue 5, pp 129–134 | Cite as

Stress-wave propagation in axiallysymmetric test specimens

A piezoelectric transducer is buried in the throat of a tensile-test specimen to produce an internal impulsive stress-wave source. The resulting stress-wave propagation is determined
  • R. J. Kroll
  • C. A. Tatro
Article

Abstract

When a body is stressed, dislocations tend to pile up against an obstacle. If they suddenly break through the obstacle, then a small stress wave, known as an acoustic emission, is generated. Acoustic-emission research is attempting to correlate this phenomenon to the onset of yielding of a tensile-test specimen. The reliable detection of the acoustic emissions depend on the proper design of the system consisting of the test specimen, the instrumentation and the experimental techniques. In turn, the design must be based on a fundamental knowledge of the stress-wave propagation through the specimen.

In this paper, a theoretical and experimental investigation of the stress-wave propagation through a test specimen due to a stress-wave source, similar to an acoustic emission, is presented. This stress-wave propagation is shown to be typical for more general types of excitation of any similar type of axiallysymmetric body.

The method of producing the stress-wave source is described. The instrumentation system for detection of the stress wave must contain a variable electronic filter to clean up the signal and eliminate noise. Several different size and differently proportioned test specimens are used to determine scale effects and to optimize the specimen design.

Stress waves are also mechanically introduced into separate components of the test specimen to confirm the theoretical predictions for the modes of stress-wave propagation through these components.

The theoretical predictions of the stress-wave propagation through the entire test specimen are verified by the experimental investigations.

An optimum design of the entire system is presented.

Keywords

Fluid Dynamics Experimental Investigation Acoustic Emission Theoretical Prediction Test Specimen 

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Bibliography

  1. 1.
    Tatro, C. A., andLiptai, R. G., “Acoustic Emission From Crystalline Substances,”Proceedings of the Symposium on Physics and Non-Destructive Testing, Warren J. McGonnogle, Editor, Southwest Research Institute, San Antonio, Tex., 145–173, 1962.Google Scholar
  2. 2.
    Johnston, W. G., andGilman, J. J., “Dislocation Velocities, Dislocation Densities, and Plastic Flow in Lithium Fluoride Crystals,”Jnl. Appl. Phys., 30 (2),129–144 (1959).Google Scholar
  3. 3.
    Bell, J. F., “The Initial Development of an Elastic Strain Pulse Propagating in a Semi-Infinite Bar,” Johns Hopkins University, 1–31, November 1960.Google Scholar
  4. 4.
    Kroll, R. J., “Stress Waves in Test Specimens due to Simulated Acoustic Emissions,” Ph.D. Dissertation, Michigan State University, 91–97, 1962.Google Scholar
  5. 5.
    Huth, J. H. andCole, J. D., “Impulsive Loading on an Elastic Hall-Space,”Jnl. Appl. Mech., 21 (3),294–295 (September, 1954).Google Scholar
  6. 6.
    Aseltine, J. A., “Transform Methods in Linear Systems Analysis,”McGraw-Hill, N. Y., 24–25, 1958.Google Scholar
  7. 7.
    Ripperger, E. A., andAbramson, H. N., “Reflection and Transmission of Elastic Pulses in a Bar at a Discontinuity in Cross Section,”Proceedings of the Third Midwestern Conference on Solid Mechanics, Ann Arbor, Michigan Press, pp. 135–145, April 1957.Google Scholar
  8. 8.
    Davies, R. M., “A Critical Study of the Hopkinson Pressure Bar,”Phil. Trans. Roy. Soc. London, Ser. A, 24, 375–457 (1948).Google Scholar

Copyright information

© Society for Experimental Mechanics, Inc. 1964

Authors and Affiliations

  • R. J. Kroll
    • 1
  • C. A. Tatro
    • 2
  1. 1.University of CincinnatiCincinnati
  2. 2.Tulane UniversityNew Orleans

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