Mechanistic aspects of fracture and R-curve behavior in human cortical bone
Mechanistic aspects of fracture and R-curve behavior in human cortical bone
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DOI：
10.1016/j.biomaterials.2004.02.017
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发表时间：
2005-01-01
期刊：
影响因子：
14
通讯作者：
Ritchie, RO
中科院分区：
文献类型：
--
作者：
Nalla, RK;Kruzic, JJ;Ritchie, RO
韧性的演变的理解是必不可少的机制解释的皮质骨骨折。在本研究中，在体外骨折实验进行了人类皮质骨，以确定和定量评估突出的增韧机制。发现断裂韧性随裂纹延伸线性上升（即，上升阻力-或R-曲线行为），平均裂纹起始韧性K-0与近端-远端方向裂纹扩展的2 MParootm相似。未开裂的韧带桥接，这是观察到的裂纹后，被确定为占主导地位的增韧机制，所观察到的R曲线行为负责。桥接区的范围和性质进行了定量研究，使用多切口顺应性实验，以评估桥接区的长度和估计的桥接应力分布。此外，在远低于过载断裂所需应力强度的应力强度下观察到随时间变化的开裂行为;具体地说，当应力强度比裂纹起始韧性低35%时，裂纹以2 × 10（-9）m/s的速率缓慢扩展。在尝试测量较慢的增长速率时，发现该行为切换到由时间依赖性裂纹钝化主导的状态，类似于牙质报告的情况;然而，这种钝化在骨中慢得多的时间尺度上是明显的，这使得亚临界裂纹增长在较高的应力强度下容易发生。(C)2004爱思唯尔有限公司保留所有权利。
An understanding of the evolution of toughness is essential for the mechanistic interpretation of the fracture of cortical bone. In the present study, in vitro fracture experiments were conducted on human cortical bone in order to identify and quantitatively assess the salient toughening mechanisms. The fracture toughness was found to rise linearly with crack extension (i.e., rising resistance- or R-curve behavior) with a mean crack-initiation toughness, K-0 of similar to2MParootm for crack growth in the proximal-distal direction. Uncracked ligament bridging, which was observed in the wake of the crack, was identified as the dominant toughening mechanism responsible for the observed R-curve behavior. The extent and nature of the bridging zone was examined quantitatively using multicutting compliance experiments in order to assess the bridging zone length and estimate the bridging stress distribution. Additionally, time-dependent cracking behavior was observed at stress intensities well below those required for overload fracture; specifically, slow crack growth occurred at growth rates of similar to2 x 10(-9) m/s at stress intensities similar to35% below the crack-initiation toughness. In an attempt to measure slower growth rates, it was found that the behavior switched to a regime dominated by time-dependent crack blunting, similar to that reported for dentin; however, such blunting was apparent over much slower time scales in bone, which permitted subcritical crack growth to readily take place at higher stress intensities. (C) 2004 Elsevier Ltd. All rights reserved.