Fracture Mechanics in Biology and Medicine

Abstract

Many biological materials have load-bearing functions: examples include bone, cartilage, wood, insect cuticle and eggshell. These materials have evolved into structures such as skeletal parts, wings, plant stems and shells. This paper presents examples of research investigating failure at both the material level (where crack initiation and propagation is a common fracture mechanism) and the structural level, where competing failure mechanisms exist such as buckling, splitting and fatigue.The study of these fracture problems from nature is interesting and rewarding of itself, to increase our knowledge of the world around us. But it also has two important practical applications. Firstly, new materials and structures can be developed by mimicking Nature’s solutions. One example is the development of tough materials arising from the study of nacre, conch shells and other natural materials based on calcium carbonate. These materials have achieved increases in fracture toughness of more than an order of magnitude by the use of toughening micromechanisms. Secondly, improved medical treatments and diagnostic procedures arise from the study of bone and soft tissues in the body, contributing to the understanding and prevention of stress fractures, osteoarthritis and other debilitating conditions.There is an important role here for those of us who have expertise in fracture mechanics and structural integrity, to apply the lessons learnt from engineering materials, to biological materials, and vice versa.