28 May 2014 Deformation kinetics of layered personal protective material under impact via terahertz reflectometry
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Abstract
Terahertz dynamic scanning reflectometry (TDSR) was used for measuring layered materials’ deformation kinetics spectra. Multi-layered materials are used for protective devices such as helmet and body armor. An in-situ measurement of deformation profile and other dynamic characteristics is important when such material is subjected to ballistic impacts. Current instrumentation is limited in their abilities to provide sub-surface information in a non-destructive fashion. A high sensitivity TDSR has been used to measure dynamic surface deformation characteristics in real-time (in-situ) and also at post deformation (ex-situ). Real-time ballistic deformation kinetics was captured with a high speed measurement system. The kinetics spectra was used to compute a number of crucial parameters such as deformation length and its propagation profile, the relaxation position, and the macroscopic vibration profile. In addition, the loss of mass due to impact was quantified for accurate determination of the trauma causing energy. For non-metallic substrates, a transmitted beam was used to calibrate mass loss, a priori, of the laminate layers due to impact. Deformation kinetics information may then be used to formulate trauma diagnosis conditions from blunt hit via the Sturdivan criterion [1]. The basic difference in the proposed approach is that here diagnostic criteria are inferred by measuring the helmet itself; no need to draw blood or any biopsy from the patient.
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Anis Rahman, Anis Rahman, Aunik Rahman, Aunik Rahman, Mark A. Mentzer, Mark A. Mentzer, } "Deformation kinetics of layered personal protective material under impact via terahertz reflectometry", Proc. SPIE 9110, Dimensional Optical Metrology and Inspection for Practical Applications III, 91100K (28 May 2014); doi: 10.1117/12.2049792; https://doi.org/10.1117/12.2049792
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