Examinando por Autor "Li G"

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    Effects of polar solvents on the mechanical behavior of fish scales
    (Elsevier Ltd, 2016-04-01) Murcia S; Li G; Yahyazadehfar M; Sasser M; Ossa A; Arola D; Murcia S; Li G; Yahyazadehfar M; Sasser M; Ossa A; Arola D; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de Ingeniería
    Fish scales are unique structural materials that serve as a form of natural armor. In this investigation the mechanical behavior of scales from the Cyprinus carpio was evaluated after exposure to a polar solvent. Uniaxial tensile and tear tests were conducted on specimens prepared from the scales of multiple fish extracted from near the head, middle and tail regions, and after exposure to ethanol for periods from 0 to 24 h. Submersion in ethanol caused instantaneous changes in the tensile properties regardless of anatomical site, with increases in the elastic modulus, strength and modulus of toughness exceeding 100%. The largest increase in properties overall occurred in the elastic modulus of scales from the tail region and exceeded 200%. Although ethanol treatment had significant effect on the tensile properties, it had limited influence on the tear resistance. The contribution of ethanol to the mechanical behavior appears to be derived from an increase in the degree of interpeptide hydrogen-bonding of the collagen molecules. Spatial variations in the effects of ethanol exposure on the mechanical behavior arise from the differences in degree of mineralization and lower mineral content in scales of the tail region. (C) 2015 Elsevier B.V. All rights reserved.
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    Temperature effects on the fracture resistance of scales from Cyprinus carpio
    (ELSEVIER SCI LTD, 2015-03-01) Murcia S; McConville M; Li G; Ossa A; Arola D; Murcia S; McConville M; Li G; Ossa A; Arola D; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de Ingeniería
    In this investigation the fracture resistance of scales from Cyprinus carpio was evaluated as a function of environmental temperature. Tear specimens were prepared from scales obtained from three characteristic regions (i.e. head, mid-length and tail) of multiple fish. The fracture resistance was characterized in Mode III loading and over temperatures ranging from 150 degrees C to 21 degrees C. Results showed that there was a significant reduction in tear resistance with decreasing temperature and the lowest resistance to fracture was obtained at 150 degrees C. There was a significant difference in the relative tear toughness between scales from the three locations at ambient conditions (21 degrees C), but not below freezing. Scales obtained near the head exhibited the largest resistance to fracture (energy 150 25 kJ m(-2)) overall. The fracture resistance was found to be primarily dependent on the thickness of the external mineralized layer and the number of external elasmodine plies, indicating that both the anatomical position and the corresponding microstructure are important to the mechanical behavior of elasmoid fish scales. These variables may be exploited in the design of bioinspired armors and should be considered in future studies concerning the mechanical behavior of these interesting natural materials. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.