Browsing by Author "Brear, Kevin"

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    Notch sensitivity of mammalian mineralized tissues in impact
    (The Royal Society, 2004-03-07) Currey, John D.; Brear, Kevin; Zioupos, Peter
    The toughness of bone is an important feature in preventing it from fracturing. We consider the notch sensitivity in impact, and the associations between brittleness, notch sensitivity and post–yield energy absorption of mammalian mineralized tissues. Specimens of bone–like tissues covering a wide range of mineralization were broken, either notched or un–notched, in impact. The greater the mineral content, the greater was the notch sensitivity. Also, the more brittle tissues dissipated the least post–yield energy and were the most notch sensitive. It is suggested that since antler bone, the least mineralized of all known mammalian mineralized tissues, seems to be notch insensitive in impact, no adaptive purpose would be served by having mineralized tissues of a lower mineralization than antler. This may explain the lower cut–off in mineralization seen in mammals
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    Strain rate dependence of work of fracture tests on bone and similar tissues: reflections on testing methods and mineral content effects
    (Elsevier, 2019-08-22) Currey, John D.; Brear, Kevin; Zioupos, Peter
    This paper is concerned with the effect of different strain rate on the Work of Fracture (Wf) of various vertebrate mineralised tissues, controlling for the effect of mineral content and Young's modulus of elasticity. Using specimens of uniform shape and size values for the Work of Fracture of specimens tested at various deformation rates, and also the energy absorbed by notched specimens in impact, are reported. The results indicated that, of those tested, for most bone specimens the Work of Fracture measurements were constant like in the case for a ‘material property’. Variations due to loading conditions (deformation rate) were small, with the exemption of antler, which is relatively poorly mineralised and in which the Work of Fracture values increased by a factor of 4 across the range from quasistatic loading to impact. The Tattersall and Tappin (1966) test has shown itself to offer some great advantages: if the quest is for a fracture toughness test for an unknown tissue it offers reliability, it is perhaps more forgiving to handling errors, it also suffers less of the influence of strain rate effects and uses relatively simple instrumentation. It is also able to demonstrate the remarkable toughness of antler bone which other more commonly used fracture toughness methods cannot do.