Engineering Mechanics

International Conference

Proceedings Vol. 27/28 (2022)


May 9 – 12, 2022, Milovy, Czech Republic
Editors: Cyril Fischer and Jiří Náprstek

Copyright © 2022 Institute of Theoretical and Applied Mechanics of the Czech Academy of Sciences, Prague

ISBN 978-80-86246-48-2 (printed)
ISBN 978-80-86246-51-2 (electronic)
ISSN 1805-8248 (printed)
ISSN 1805-8256 (electronic)

list of papers scientific commitee

Analytical and experimental analysis of stress uniformity in specimen during direct impact Hopkinson bar test
Fíla T.
pages 109 - 112, full text

Stress uniformity in a specimen represents a crucial parameter for validity of impact experiment conducted in a split Hopkinson bar. Principle of the experimental method is to measure elastic stress waves that propagate in the bars of an experimental setup and to calculate stress to strain relations at the interfaces with the specimen. However, standard procedure to evaluate the experiment can only be valid when stress is distributed approximately uniformly along the specimen. As the stress wave has to propagate through the specimen during the experiment, a time period of significantly non-uniform stress distribution is present and a certain number of wave transits is required to achieve approximately uniform stress distribution. In this paper, a simple analytical model assuming one-dimensional wave propagation theory, non-equal mechanical impedance of the bars and linear elastic material model of the specimen is introduced to determine a number of transits required to achieve uniform stress distribution in the specimen. Potential of the calculated results is discussed in an experiment using a direct impact Hopkinson bar and a material with significant plateau in its stress-strain response.

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Ownership of copyright in original research articles remains with the Authors, and provided that, when reproducing parts of the contribution, the Authors acknowledge and/or reference the Proceedings, the Authors do not need to seek permission for re-use of their material.

All papers were reviewed by members of the scientific committee.

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