EXPERIMENTAL AND THEORETICAL QUANTIFICATION OF THE DEVELOPMENT OF DAMAGE IN FATIGUE TESTS OF BONE AND ANTLER

This study concerns the development of damage (as measured by a reduct ion in elastic modulus) in two kinds of bones differing considerably i n their degrees of mineralisation: laminar bone from bovine femur and osteonal bone from red deer antler. Antler bone is much tougher than ' ordinary' bone and its failure properties have been investigated in: ( i) monotonic tensile tests and (ii) creep rupture experiments. Tensile fatigue is another way of examining how damage develops in bone. The development of damage in the present fatigue tests was non-linear with the cycle number, the degree of non-linearity was dependent on the le vel of stress and followed a clearly different course for bone and ant ler. Antler was a more damage-tolerant material, bring able to achieve a reduction in the final modulus of elasticity, just prior to failure , three times greater than 'ordinary' bone. The evolution of damage is quantified by an empirical and a graphical method and by the use of C ontinuum Damage Mechanics (CDM) expressions. The CDM method shows impo rtant conditions, found in antler, but not in bone, that seem necessar y for achieving stable fractures and consequently producing very tough materials. Copyright (C) 1996 Elsevier Science Ltd.