## 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., Δ T_{max} and Δ T_{avr}) 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, ΔT_{max} is quadratic related and T_{avr} is linear related to the impacting height, and when above this critical height, both Δ T_{max} and ΔT_{avr} 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(1inch in diameter), the higher ΔT_{max}≈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.

Original language | English |
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Article number | 34 |

Pages (from-to) | 264-271 |

Number of pages | 8 |

Journal | Proceedings of SPIE - The International Society for Optical Engineering |

Volume | 5782 |

DOIs | |

Publication status | Published - 2005 |

Event | Thermosense XXVII - Orlando, FL, United States Duration: 29 Mar 2005 → 31 Mar 2005 |

## Keywords

- Back analysis
- Free-fall impact
- PMMA
- Rock
- Thermal radiation

## ASJC Scopus subject areas

- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Computer Science Applications
- Applied Mathematics
- Electrical and Electronic Engineering