Zioupos P, Currey J D, Casinos A
Department of Materials and Medical Sciences, Cranfield University, Shrivenham, SN6 8LA, UK.
J Theor Biol. 2001 Jun 7;210(3):389-99. doi: 10.1006/jtbi.2001.2316.
In life, bones are subjected to fatigue loading which has different frequency and amplitude components, as well as various kinds of loading modes like tension, compression, shear and combinations of them. Considerable variability is observed in fatigue results of bone, which may be caused by these experimental variables or by the bone itself. In past studies the effect of magnitude and mode of loading have been examined in standard fatigue strength (stress vs. cycles to failure) diagrams. The effect of frequency is not clear, but there is clear evidence (from Carter & co-workers) that, at least in human bone, tension "fatigue" failure was determined solely by time rather than by cycles. We sought to confirm these results in the same and a different species. We cycled human and bovine bone in tension at two frequencies: 0.5 and 5 Hz. There was no cycle number effect; the results from the tests at the two frequencies were different if plotted and analysed as a function of cycles to failure, but were not separable if plotted and analysed as a function of time to failure. In this respect bone differs from tendon, in which failure in tension is a function of both cycles and time.
在生活中，骨骼会受到具有不同频率和振幅成分的疲劳载荷，以及各种加载模式，如拉伸、压缩、剪切及其组合。在骨骼的疲劳结果中观察到相当大的变异性，这可能是由这些实验变量或骨骼本身引起的。在过去的研究中，已经在标准疲劳强度（应力与失效循环次数）图中研究了载荷大小和模式的影响。频率的影响尚不清楚，但有明确的证据（来自卡特及其同事）表明，至少在人类骨骼中，拉伸“疲劳”失效仅由时间而非循环次数决定。我们试图在同一物种和不同物种中证实这些结果。我们以0.5赫兹和5赫兹这两种频率对人类和牛的骨骼进行拉伸循环。没有循环次数效应；如果将两种频率下的测试结果作为失效循环次数的函数进行绘制和分析，结果是不同的，但如果作为失效时间的函数进行绘制和分析，则无法区分。在这方面，骨骼与肌腱不同，肌腱的拉伸失效是循环次数和时间的函数。
