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首页> 外文期刊>Journal of Biomechanics >Development of residual strains in human vertebral trabecular bone after prolonged static and cyclic loading at low load levels.
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Development of residual strains in human vertebral trabecular bone after prolonged static and cyclic loading at low load levels.

机译：在低负荷水平下长时间承受静态和循环负荷后，人椎骨小梁骨中残余应变的发展。

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Development of irreversible residual strains in trabecular bone may be a mechanism by which age-related non-traumatic vertebral fractures occur. To investigate this concept, static and cyclic loading tests were conducted at low loading levels for cylindrical cores of cadaveric vertebral trabecular bone. Stresses were applied equivalent to elastic strains of either 750 or 1,500 microstrain. Creep strains were measured during the tests, which lasted for 125,000 seconds (about 35 h), and for an additional 125,000 seconds after complete unloading. Emphasis was placed on the residual strains that developed, defined as the strain remaining at the end of the unloading phase. The results indicated that appreciable residual strains did develop, and were similar for static and cyclic loading. Irrespective of the applied load levels and loading modes, the residual strains that remained after the unloading phase were similar in magnitude to the originally applied elastic strain. Extrapolation of the observed residual strains to full recovery indicated that the time that would be required for full recovery was over 20 times longer than the duration of the applied loads. These results indicate that human vertebral trabecular bone does not creep in a linear viscoelastic fashion at low stress levels, and that creep mechanisms dominate the residual strains regardless of the loading mode. Taken together, these findings support the concept that non-traumatic vertebral fractures may be related to long-term creep effects because the trabecular bone does not have sufficient time to recover mechanically from creep deformations accumulated by prolonged static or cyclic loading.
机译：小梁骨中不可逆残余应变的发展可能是与年龄相关的非创伤性椎骨骨折发生的机制。为了研究这一概念，对尸体椎骨小梁骨的圆柱芯在低载荷水平下进行了静态和循环载荷测试。施加的应力等于750或1,500微应变的弹性应变。在测试过程中测量了蠕变应变，该应变持续了125,000秒（约35小时），并在完全卸载后又增加了125,000秒。重点放在产生的残余应变上，该残余应变定义为卸载阶段结束时剩余的应变。结果表明确实出现了明显的残余应变，并且在静态和循环载荷下相似。不管所施加的载荷水平和载荷模式如何，卸载阶段之后残留的残余应变的大小都与最初施加的弹性应变相似。将观察到的残余应变外推至完全恢复表明，完全恢复所需的时间比所施加载荷的持续时间长20倍以上。这些结果表明，人椎骨小梁骨在低应力水平下不会以线性粘弹性方式蠕变，并且蠕变机制在残余应变中起着主导作用，而与载荷模式无关。综上所述，这些发现支持了非创伤性椎骨骨折可能与长期蠕变效应相关的概念，因为小梁骨没有足够的时间从长期的静态或周期性载荷累积的蠕变变形中机械恢复。

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