Examinando por Materia "Toughness"
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Ítem Designed for resistance to puncture: The dynamic response of fish scales(ELSEVIER SCIENCE BV, 2019-01-01) Ghods S.; Murcia S.; Ossa E.A.; Arola D.; Ghods S.; Murcia S.; Ossa E.A.; Arola D.; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de IngenieríaNatural dermal armors are serving as a source of inspiration in the pursuit of “next-generation” structural materials. Although the dynamic strain response of these materials is arguably the most relevant to their performance as armors, limited work has been performed in this area. Here, uniaxial tension and transverse puncture tests were performed on specimens obtained from the scales of Asian carp over strain rates spanning seven decades, from 10-4 to 103 s-1. The importance of anatomical variations was explored by comparing the performance of scales from the head, middle and tail regions. In both loading orientations, the scales exhibited a significant increase in the resistance to failure with loading rate. The rate sensitivity was substantially higher for transverse loading than for in-plane tension, with average strain rate sensitivity exponents for measures of the toughness of 0.35 and 0.08, respectively. Spatial variations in the properties were largest in the puncture responses, and scales from the head region exhibited the greatest resistance to puncture overall. The results suggest that the layered microstructure of fish scales is most effective at resisting puncture, rather than in-plane tension, and its effectiveness increases with rate of loading. X-ray microCT showed that delamination of plies in the internal elasmodine and stretching of the fibrils were key mechanisms of energy dissipation in response to puncture loading. Understanding contributions from the microstructure to this behavior could guide the development of flexible engineered laminates for penetration resistance and other related applications. © 2018 Elsevier LtdÍtem Effect of different types of fibers and fiber mixes on fresh and hardened properties of UHPC(Universidad EAFIT, 2022) Patiño Baquero, José Carlos; Núñez López, Andrés MauricioÍtem Escamas de pescado: una referencia para construir mejores materiales(2021-04-05) Martinez Guerrero, Christian Alexander; Christian Alexander Martinez-Guerrero; Jiang, H.; Ghods, S.; Weller, E; Ossa, E.A.; Yang, F; Arola, D.; Vicerrectoría de Descubrimiento y CreaciónÍtem Indentation damage and crack repair in human enamel.(ELSEVIER SCIENCE BV, 2013-05-01) Rivera C; Arola D; Ossa A; Rivera C; Arola D; Ossa A; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de IngenieríaTooth enamel is the hardest and most highly mineralized tissue in the human body. While there have been a number of studies aimed at understanding the hardness and crack growth resistance behavior of this tissue, no study has evaluated if cracks in this tissue undergo repair. In this investigation the crack repair characteristics of young human enamel were evaluated as a function of patient gender and as a function of the distance from the Dentin Enamel Junction (DEJ). Cracks were introduced via microindentation along the prism direction and evaluated as a function of time after the indentation. Microscopic observations indicated that the repair of cracks began immediately after crack initiation and reaches saturation after approximately 48 h. During this process he crack length decreased up to 10% of the initial length, and the largest degree of reduction occurred in the deep enamel, nearest the DEJ. In addition, it was found that the degree of repair was significantly greater in the enamel of female patients.Ítem Interfibril hydrogen bonding improves the strain-rate response of natural armour(Royal Society Publishing, 2019-01-01) Arola D.; Ghods S.; Son C.; Murcia S.; Ossa E.A.; Arola D.; Ghods S.; Son C.; Murcia S.; Ossa E.A.; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de IngenieríaFish scales are laminated composites that consist of plies of unidirectional collagen fibrils with twisted-plywood stacking arrangement. Owing to their composition, the toughness of scales is dependent on the intermolecular bonding within and between the collagen fibrils. Adjusting the extent of this bonding with an appropriate stimulus has implications for the design of next-generation bioinspired flexible armours. In this investigation, scales were exposed to environments of water or a polar solvent (i.e. ethanol) to influence the extent of intermolecular bonding, and their mechanical behaviour was evaluated in uniaxial tension and transverse puncture. Results showed that the resistance to failure of the scales increased with loading rate in both tension and puncture and that the polar solvent treatment increased both the strength and toughness through interpeptide bonding; the largest increase occurred in the puncture resistance of scales from the tail region (a factor of nearly 7). The increase in strength and damage tolerance with stronger intermolecular bonding is uncommon for structural materials and is a unique characteristic of the low mineral content. Scales from regions of the body with higher mineral content underwent less strengthening, which is most likely the result of interference posed by the mineral crystals to intermolecular bonding. Overall, the results showed that flexible bioinspired composite materials for puncture resistance should enrol constituents and complementary processing that capitalize on interfibril bonds. © 2019 The Author(s) Published by the Royal Society. All rights reserved.