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Observations on Differences Between the Energy Determined Using an Instrumented Striker and Dial/Encoder Energy

Published

Author(s)

M P. Manahan, R B. Stonesifer, Thomas A. Siewert, Christopher N. McCowan, D P. Vigliotti

Abstract

Instrumented stricker systems and optical encoders are widely used for measurement of absorbed energy in both conventional and miniature Charpy tests. It has been observed that the total absorbed energy measured using these two technologies, while generally in good agreement, sometimes differs by up to 20% (3 to 4.5 J) at low absorbed energies. This paper presents experimental evidence from high-speed photography of Charpy tests that the differences between dial/encoder energies and instrumented striker energies (measured with U-hammers) can largely be explained by post-fracture collisions with the striker. However, experimental and numerical studies show that vibrational energy of the pendulum and striker as well as load cell errors due to contact load distribution and inertial effects also significantly contribute to the energy differences. Experimental evidence from the literature that was originally expected to show the significance of residual vibrational energy in the test machine may show that low energy Charpy specimen behavior can be significantly affected by the design of the test machine. A simple dynamic model of a specimen and test machine system shows that a 20% increase in the stiffness of the striker and hammer assembly can lead to a 9% decrease in the energy required to fracture a low energy Charpy specimen.
Proceedings Title
Charpy Cententary Conference | | | Elsevier
Volume
No. 30
Conference Dates
October 1, 2001
Conference Location
Poitiers, 1, FR
Conference Title
ESIS Publication

Keywords

adsorbed energy, charpy, encoder, instrumented impact test, vibration

Citation

Manahan, M. , Stonesifer, R. , Siewert, T. , McCowan, C. and Vigliotti, D. (2002), Observations on Differences Between the Energy Determined Using an Instrumented Striker and Dial/Encoder Energy, Charpy Cententary Conference | | | Elsevier, Poitiers, 1, FR, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=851234 (Accessed April 21, 2024)
Created May 31, 2002, Updated October 12, 2021