Characterization of the Damping Behavior of a Nanoindentation Instrument for Carrying Out Dynamic Experiments |
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Authors: | S P Singh J F Smith R P Singh |
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Institution: | (1) Department of Mechanical Engineering, Stony Brook University, Stony Brook, NY 11794, USA;(2) Micro Materials Ltd., Unit 3 The Byre, Wrexham Technology Park, Wrexham, LL13 7YP, UK;(3) School of Mechanical and Aerospace Engineering, Oklahoma State University, Stillwater, OK 74078, USA |
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Abstract: | A new displacement modulation based dynamic indentation method is demonstrated and shown to be effective for viscoelastic
characterization of a glassy polymer. The analysis of dynamic experiments requires a complete understanding of the measuring
system’s dynamic characteristics especially the damping. Accordingly, an improved method, based on the use of a wire spring,
is developed for determining the damping characteristics. In general, damping in an indentation instrument is contributed
by two elements: the eddy current damping from the electromagnetic loading coil and the squeeze film damping from the capacitive
displacement transducer. Therefore, a method to determine the relative contribution from the different damping elements present
in the system is demonstrated and the results are compared with the calibration obtained from the wire spring method. Finally,
dynamic indentation tests are carried out on a glassy polymer to obtain the complex modulus; the values of which are compared
with those obtained from bulk dynamic mechanical analysis (DMA) tests. Storage modulus values are found to be in good agreement
with bulk data but some divergence in the case of loss modulus is observed. The calibration procedure of the measuring instrument
is critically examined in view of these observations. Overall, displacement modulation based dynamic indentation is shown
to be a promising method for viscoelastic characterization at the micron length scales.
An erratum to this article can be found at |
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Keywords: | Dynamic indentation Eddy current damping Squeeze film damping |
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