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Proceedings Paper

Comparisons of thermal radiation characteristics between rocks and PMMA subjected to free-fall impacts
Author(s): Lixin Wu; Yuhua Wu; Wenzhong Shi; Sheng Zhong; Daqing Ge
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Paper Abstract

Utilizing the Thermal Infrared (TIR) imaging technology, the transient process of solids (Three kinds of rocks and one kind of PMMA) impacted by free-falling steel balls are monitored with an infrared camera. It is discovered that: (1) as for rock materials, the increments of IR temperature (both the maximum and average, i.e., ΔTmax and ΔTavr) are all linear related to the impacting height, the difference are the statistical correlation coefficients (R): relatively homogeneous rock (marble, R=0.93~0.95); non-homogeneous rocks (granite: R=0.88~0.92; gabbro: R=0.80~0.84); while for PMMA, there exists a critical height (h≈5m), within this height, ΔTmax is quadratic related and ΔTavr is linear related to the impacting height, and when above this critical height, both ΔTmax and ΔTavr are linear related, comparison to rocks, the statistical correlation coefficients are somewhat higher (R=0.94~0.96); (2) the amplitude of IR temperature increments are different, it is somewhat less of IR temperature variations for relatively hard rocks (granite) than others (gabbro, marble and PMMA), for example, when impacted at a height of 2 meter with a standard ball (1 inch in diameter), the higher ΔTmax≈2~4K, while others are within 1K, and (3) it is verified that the parameters about the impaction could be well inversed qualitatively to quantitatively, not only the type of rocks can be identified exactly, but also the impacting height can be accurately estimated especially for the relatively homogenous materials, as for marble rock and PMMA, the relative mean errors of inversion are less than 11.3% and 6.2%, respectively.

Paper Details

Date Published: 28 March 2005
PDF: 8 pages
Proc. SPIE 5782, Thermosense XXVII, (28 March 2005); doi: 10.1117/12.602149
Show Author Affiliations
Lixin Wu, China Univ. of Mining and Technology (China)
Institute of Rock and Soil Mechanics, CAS (China)
Yuhua Wu, China Univ. of Mining and Technology (China)
Wenzhong Shi, Hong Kong Polytechnic Univ. (Hong Kong China)
Sheng Zhong, China Univ. of Mining and Technology (China)
Daqing Ge, China Univ. of Mining and Technology (China)

Published in SPIE Proceedings Vol. 5782:
Thermosense XXVII
G. Raymond Peacock; Douglas D. Burleigh; Jonathan J. Miles, Editor(s)

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