3.032 Mechanical Behavior of MaterialsFall 2007Fatigue fracture/failure case study: Human boneLecture 36 (12.10.07)Image source: Naza, Krulick, Kinney and Ritchie. Biomaterials 26 (2005) 217-226.Images removed due to copyright restrictions. Please see:http://www.lbl.gov/Ritchie/Programs/Tissue/image002.gif______________________________________Image source: Nallaa, Kinney and Ritchie. Nature Materials 2 (2003).3.032 Mechanical Behavior of MaterialsFall 2007How to test bone fracture: Double-cantilevered beamLecture 36 (12.10.07)Courtesy of R. O. Ritchie. Used with permission.optical micrograph of crack tipK = fΔσ(πa)1/23D tomographyof osteonsand cracks Image source: Naza, Krulick, Kinney and Ritchie. Biomaterials 26 (2005) 217-226.Lecture 36 (12.10.07)Courtesy of Elsevier, Inc., http://www.sciencedirect.com. Used with permission.Cracks follow “cement line”, or mineralized surface surrounding osteons.3D tomographicreconstructionLecture 36 (12.10.07)Image source: Naza, Krulick, Kinney and Ritchie. Biomaterials 26 (2005) 217-226.Courtesy Elsevier, Inc., http://www.sciencedirect.com. Used with permission.Crack growth follows a Paris-law relation based in time:Conclusion:Image source: Naza, Krulick, Kinney and Ritchie. Biomaterials 26 (2005) 217-226.Lecture 36 (12.10.07)Courtesy of Elsevier, Inc., http://www.sciencedirect.com. Used with permission.Fig. 8 and Table 3 in Nalla, R. K., et al. "Mechanistic aspects of fracture and R-curve behavior in human cortical bone."Biomaterials 26 (2005): 217-231.Stress concentrations generate new cracks ahead of old cracks (bridging)Image source: Naza, Krulick, Kinney and Ritchie. Biomaterials 26 (2005) 217-226.Lecture 36 (12.10.07)Figure and table removed due to copyright restrictions. Please see:Fig. 7 and Table 2 in Nalla, R. K., et al. "Mechanistic Aspects of Fracture and R-curve Behavior in Human Cortical Bone." Biomaterials 26 (2005): 217-231.How bone breaks:Image source: Nallaa, Kinney and Ritchie. Nature Materials 2 (2003).Lecture 36 (12.10.07)Courtesy of R. O. Ritchie. Used with
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