Examinando por Autor "Arola D"

Mostrando 1 - 8 de 8
  • No hay miniatura disponible
    Ítem
    Differences in the microstructure and fatigue properties of dentine between residents of North and South America.
    (PERGAMON-ELSEVIER SCIENCE LTD, 2014-10-01) Ivancik J; Naranjo M; Correa S; Ossa A; Tay FR; Pashley DH; Arola D; Universidad EAFIT. Departamento de Ingeniería Mecánica; Bioingeniería GIB (CES – EAFIT)
    UNLABELLED: Spatial variations in the microstructure of dentine contribute to its mechanical behaviour. OBJECTIVE: The objective of this investigation was to compare the microstructure and fatigue behaviour of dentine from donors of two different countries. METHODS: Caries-free third molars were obtained from dental practices in Colombia, South America and the US to assemble two age-matched samples. The microstructure of the coronal dentine was evaluated at three characteristic depths (i.e. deep, middle and superficial dentine) using scanning electron microscopy and image processing techniques. The mechanical behaviour of dentine in these three regions was evaluated by the fatigue crack growth resistance. Cyclic crack growth was achieved in-plane with the dentine tubules and the fatigue crack growth behaviour was characterized in terms of the stress intensity threshold and the Paris Law parameters. RESULTS: There was no difference in the tubule density between the dentine of patients from the two countries. However, there were significant differences (p
  • No hay miniatura disponible
    Ítem
    Differences in the microstructure and fatigue properties of dentine between residents of North and South America.
    (PERGAMON-ELSEVIER SCIENCE LTD, 2014-10-01) Ivancik J; Naranjo M; Correa S; Ossa A; Tay FR; Pashley DH; Arola D; Universidad EAFIT. Departamento de Ingeniería de Diseño; Ingeniería de Diseño (GRID)
    UNLABELLED: Spatial variations in the microstructure of dentine contribute to its mechanical behaviour. OBJECTIVE: The objective of this investigation was to compare the microstructure and fatigue behaviour of dentine from donors of two different countries. METHODS: Caries-free third molars were obtained from dental practices in Colombia, South America and the US to assemble two age-matched samples. The microstructure of the coronal dentine was evaluated at three characteristic depths (i.e. deep, middle and superficial dentine) using scanning electron microscopy and image processing techniques. The mechanical behaviour of dentine in these three regions was evaluated by the fatigue crack growth resistance. Cyclic crack growth was achieved in-plane with the dentine tubules and the fatigue crack growth behaviour was characterized in terms of the stress intensity threshold and the Paris Law parameters. RESULTS: There was no difference in the tubule density between the dentine of patients from the two countries. However, there were significant differences (p
  • No hay miniatura disponible
    Ítem
    Differences in the microstructure and fatigue properties of dentine between residents of North and South America.
    (PERGAMON-ELSEVIER SCIENCE LTD, 2014-10-01) Ivancik J; Naranjo M; Correa S; Ossa A; Tay FR; Pashley DH; Arola D; Ivancik J; Naranjo M; Correa S; Ossa A; Tay FR; Pashley DH; Arola D; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de Ingeniería
    UNLABELLED: Spatial variations in the microstructure of dentine contribute to its mechanical behaviour. OBJECTIVE: The objective of this investigation was to compare the microstructure and fatigue behaviour of dentine from donors of two different countries. METHODS: Caries-free third molars were obtained from dental practices in Colombia, South America and the US to assemble two age-matched samples. The microstructure of the coronal dentine was evaluated at three characteristic depths (i.e. deep, middle and superficial dentine) using scanning electron microscopy and image processing techniques. The mechanical behaviour of dentine in these three regions was evaluated by the fatigue crack growth resistance. Cyclic crack growth was achieved in-plane with the dentine tubules and the fatigue crack growth behaviour was characterized in terms of the stress intensity threshold and the Paris Law parameters. RESULTS: There was no difference in the tubule density between the dentine of patients from the two countries. However, there were significant differences (p
  • No hay miniatura disponible
    Ítem
    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.
  • No hay miniatura disponible
    Ítem
    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 Ingeniería
    Tooth 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.
  • No hay miniatura disponible
    Ítem
    The natural armors of fish: A comparison of the lamination pattern and structure of scales
    (ELSEVIER SCIENCE BV, 2017-09-01) Murcia S; Lavoie E; Linley T; Devaraj A; Ossa EA; Arola D; Murcia S; Lavoie E; Linley T; Devaraj A; Ossa EA; Arola D; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de Ingeniería
    Fish scales exhibit a unique balance of flexibility, strength and toughness, which is essential to provide protection without encumbering locomotion. Although the mechanical behavior and structure of this natural armor are of recent interest, a comparison of these qualities from scales of different fish species has not been reported. In this investigation the armor of fish with different locomotion, size and protection needs were analyzed. Scales from the Arapaima gigas, the tarpon (Megalops atlanticus) and the carp (Cyprinus carpio) were compared in terms of the stacking sequence of individual plies and their microstructure. The scales were also compared with respect to anatomical position to distinguish site-specific functional differences. Results show that the lamination sequence of plies for the carp and tarpon exhibit a Bouligand structure with relative rotation of 75 degrees between consecutive plies. The arapaima scales exhibit a cross-ply structure, with 90 degrees rotation between adjacent plies. In addition, results indicate that the volume fraction of reinforcement, the number of plies and the variations in thickness with anatomical position are unique amongst the three fish. These characteristics should be considered in evaluations focused on the mechanical behavior.
  • No hay miniatura disponible
    Ítem
    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.
  • No hay miniatura disponible
    Ítem
    Time dependent deformation behavior of dentin
    (PERGAMON-ELSEVIER SCIENCE LTD, 2017-04-01) Montoya C; Arola D; Ossa EA; Montoya C; Arola D; Ossa EA; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de Ingeniería
    Objective The viscoelastic behavior of dentin and its ability to undergo time dependent deformation are considered to be important to oral functions and its capacity to resist fracture. There are spatial variations in the microstructure of dentin within the crown, which could be important to the viscous behavior. However, a spatially resolved description for the viscoelastic behavior of coronal dentin has not been reported. Methods In this investigation spherical indentations were made in three regions of coronal dentin including the outer, middle and inner regions. Power law relations were developed to quantitatively describe the stress-strain responses of the tissue. Results Results showed that the deformation behavior was strongly dependent on the composition (mineral to collagen ratio) and microstructure (tubule density), which contributed to an increase in the rate of viscous deformation with increasing proximity to the pulp. Conclusions A model accounting for spatial variations in composition and microstructure was developed to describe the steady-state time dependent deformation behavior of coronal dentin, and a good agreement was found with the experimental results. © 2017 Elsevier Ltd