Longitudinal Impact Tests of Long Bars with a Slingshot Machine

    Published: Jan 1956

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    The history of the longitudinal impact test from Thomas Young (1807) to the present is reviewed briefly to show its importance for a study of the dynamic strength of materials and to bring out some of the difficulties in the interpretation of the results of impact tests. These difficulties call for further tests under controlled conditions. A slingshot machine for making impact tests at the National Bureau of Standards is described, and results obtained from these tests on bars of steel and of copper are given. These show that the strain pulses were attenuated in the steel with much less change in shape than that represented by the simple von Kármán theory of plastic strain waves. The high-strength steel exhibited a time delay between the sudden application of a high stress and the initiation of yielding, which decreased with increasing stress in accord with the dislocation locking theory of Cottrell as developed by Yokobori. The need for further work in this field is emphasized.

    Author Information:

    Ramberg, W.
    Chief, National Bureau of Standards, Washington, D. C.

    Irwin, L. K.
    Chief, National Bureau of Standards, Washington, D. C.

    Committee/Subcommittee: E01.01

    DOI: 10.1520/STP47582S

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