Examinando por Materia "Armor"

Mostrando 1 - 6 de 6
  • No hay miniatura disponible
    Ítem
    Analysis of the procedure for suspension evaluation of civil armoured vehicles: Reliability and safety driving criteria
    (Inderscience Enterprises, 2013-01-01) Martinod, R.M.; Betancur, G.R.; Mesa, J.F.; Benavides, O.M.; Castañeda, L.F.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Estudios en Mantenimiento (GEMI)
    The present study exposes an analysis of the suspension system technical state evaluation for civil vehicles that have been subject to armouring processes. Such evaluation is performed through a mechanised revision established by state regulation and is based on the method defined by EuSAMA. The development of this analysis focuses on establishing the existing relation between the ballistic resistance integrated to a vehicle and the dynamic effect exercised for the modification of its mass, according to two reliability/safety driving measurement criteria: (i) tyre-road adhesion index and (ii) tyre excitation phase angle. The study proposes new elements to the current procedure established to evaluate the suspension of civil armoured cars considering the two measurement criteria, which can be acquired by a standard commercial suspension tester machine. Copyright © 2013 Inderscience Enterprises Ltd.
  • No hay miniatura disponible
    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 Ingeniería
    Natural 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 Ltd
  • No hay miniatura disponible
    Ítem
    Impact tolerant bioinspired materials
    (Universidad Eafit, 2020) Estrada Hernández, Susana María; Ossa Henao, Edgar Alexander
    In highly demanding applications, such as sports protective gear and personal body armor, there is a growing demand for lightweight materials able to absorb impact energy while being flexible to allow easy movement to the user. These requirements are generally challenging for typical engineered materials since increased mechanical strength is usually associated with reduced flexibility and increased weight. Fortunately, this dichotomy has been successfully surpassed by natural armor through millions of years of evolution. Through biomimetics, this dissertation sought to introduce the functional principles of segmented natural armor into synthetic devices obtaining a family of cost-efficient materials with enhanced protection and flexibility. Remarkably, these bioinspired materials exhibited a minimum increase of weight enabling its implementation in personal protection applications.
  • No hay miniatura disponible
    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 Ingeniería
    Fish 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.
  • 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
    Natural flexible armor as an inspirationfor body armor design
    (Soc. for the Advancement of Material and Process Engineering, 2015-05-21) Alexander Ossa, E.; Alexander Ossa, E.; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de Ingeniería
    Animals have developed different strategies to protect themselves from environmental and predatory threats. One of these strategies concerns with the development of natural flexible dermal armor, usually consisting of rigid and highly mineralized units (e. g. scales or osteoderms) attached by flexible collagen fibers. These kinds of arrangements have been proven to achieve high flexibility without significant reduction in strength in comparison to monolithic structures. These are in fact features extremely valued by body armor users. This work studies the mechanical characteristics of scales and osteoderms of different animals (including mammals, reptiles and fishes), in order to compare them with other characteristics of the animal itself (like length and mobility) and characteristics of their predators like geometry and composition of their teeth and strength of bite. This comparison extends our knowledge and open new ways of understanding on how to design body armor materials and structures looking into improvements on flexibility and mobility. Copyright 2015. Used by the Society of the Advancement of Material and Process Engineering with permission.