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Proceedings Paper

A novel methodology to determine needle position for DC potential difference method to evaluate hardening depth from surface
Author(s): Akira Sasamoto; Takayuki Suzuki; Masahiro Iwata; Natsuko Ike; Tatsuya Kaneda
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Paper Abstract

DC potential difference method are simple and fast non destructive testing method. It measures voltage between two points on surface touched by each needle. In some kind of engineering structural member, neighborhood of iron surface is required to have higher hardness than normal iron ’s one. To meet this demand, quench hardening process is a popular process to make iron hard from surface and hardening depth is important parameter to be ensured in target member after process. Because quench iron increases its resistance by 20 %, D.C.potential method is able to be used for evaluating hardening depth. However output voltage was insensitive for change of deep hardening depth over 5.0mm, measurement would fail over 2.0 mm with improper needle array probe in reality. We developed a novel methodology to determine needle position to improve its applicability over 5.0 mm depth which is demanded in some member. In this methodology, needle position are optimized for cost function that is voltage gradient to hardening depth. Throughout this optimization, (1) an analytical expression of surface voltage which are obtained solve Laplace equation in three dimensional space. (2) CAS system (Maple / MAXIMA) . are invoked. Experimental data shows good coincidence to those numerical computation, and monotone increasing property of voltage to depth are kept up to 10 mm hardening depth. Proposed needle positions have made DC potential difference method possible to evaluate hardening depth over 5.0 mm. The algorithm is most likely to work well with only one response function for this type probe.

Paper Details

Date Published: 16 April 2013
PDF: 7 pages
Proc. SPIE 8694, Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2013, 869420 (16 April 2013); doi: 10.1117/12.2013654
Show Author Affiliations
Akira Sasamoto, National Institute of Advanced Industrial Science and Technology (Japan)
Takayuki Suzuki, National Institute of Advanced Industrial Science and Technology (Japan)
Masahiro Iwata, EMIC (Japan)
Natsuko Ike, EMIC (Japan)
Tatsuya Kaneda, EMIC (Japan)


Published in SPIE Proceedings Vol. 8694:
Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2013
Tzu Yang Yu, Editor(s)

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