Engineering Seminar Series 18_2010: Learning from Nature – How does Bone Fail?

Ms Rui Ping Hoo, School of Materials Science and Engineering, the University of New South Wales

Date: 2010-10-20
Time: 12:00 to 13:00
Venue: 9-3-05


Cortical bone, like many other natural materials, has a complex hierarchical structure. It uniquely combines brittle-like mineral crystals and soft-compliant organic matrix at different length-scales and orientations that gives a stiff and tough material.

The aim of this study is to investigate the failure mechanisms of bone at four different material levels: (1) the atomic level (mineral crystal phase); (2) the nano level (collagen fibrils), (3) the micro level (lamellar structure); and (4) the macroscopic level (cortical bone). This was achieved by a combination of techniques: high-energy X-rays, nanoindentation testing, and transmission electron microscopy imaging, digital image correlation method, and mechanical models.

Materials at all length scales deform elastically before yielding. The mineral phase and the nanostructure of bone are the key features in providing stiffness. Large macroscopic strain level causes partial failure in the nano-structure. A higher material level takes over the deformation process, while accumulation of microcrackings eventually leads to failure. The longitudinal and lateral orientations have stiffening and toughening role respectively.

The better understanding of the structure-property mechanical relationship of the hierarchical bone structure can be the basis to enhance the research in biomimetics, developing new advanced materials, and more importantly to find solutions for orthopaedics problems.

About the Speaker

Rui Ping Hoo is currently a PhD candidate in the School of Materials Science and Engineering, the University of New South Wales, under the supervision of Prof. Mark Hoffman. Her PhD project involves investigating failure mechanisms of the natural material – bone at different length scales, ranging from macroscopic to the atomic level. In the course of her PhD work, she has been travelling to the European Synchrotron Radiation Facility in France to perform some experiments, to the Max Planck Institute in Germany for research collaboration, and has attended workshops and conferences both locally in Australia, as well as in Europe and USA. She is finishing her PhD this coming December, and she has decided to share her research experience while having her holidays in Malaysia.