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International Journal of Biomaterials
Volume 2013, Article ID 639841, 6 pages
Research Article

Weibull Analysis of Fracture Test Data on Bovine Cortical Bone: Influence of Orientation

1Department of Engineering and Physics, University of Central Oklahoma, Edmond, OK 73034, USA
2Department of Mechanical Engineering, Texas Tech University, Lubbock, TX 79409, USA

Received 30 June 2013; Revised 3 October 2013; Accepted 3 October 2013

Academic Editor: Abdelwahab Omri

Copyright © 2013 Morshed Khandaker and Stephen Ekwaro-Osire. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The fracture toughness, , of a cortical bone has been experimentally determined by several researchers. The variation of values occurs from the variation of specimen orientation, shape, and size during the experiment. The fracture toughness of a cortical bone is governed by the severest flaw and, hence, may be analyzed using Weibull statistics. To the best of the authors’ knowledge, however, no studies of this aspect have been published. The motivation of the study is the evaluation of Weibull parameters at the circumferential-longitudinal (CL) and longitudinal-circumferential (LC) directions. We hypothesized that Weibull parameters vary depending on the bone microstructure. In the present work, a two-parameter Weibull statistical model was applied to calculate the plane-strain fracture toughness of bovine femoral cortical bone obtained using specimens extracted from CL and LC directions of the bone. It was found that the Weibull modulus of fracture toughness was larger for CL specimens compared to LC specimens, but the opposite trend was seen for the characteristic fracture toughness. The reason for these trends is the microstructural and extrinsic toughening mechanism differences between CL and LC directions bone. The Weibull parameters found in this study can be applied to develop a damage-mechanics model for bone.