We measured speed of sound in bovine articular cartilage as a function of compressive strain. Using techniques we developed, it was possible to apply strain starting from the unstrained, full height of a sample. Our measurements showed that speed of sound was not a monotonic function of strain as reported in earlier investigations. Speed increased with increasing strain over a range of lower strains. It reached a maximum, and then decreased as the strain increased further. These results were corroborated using a model of wave propagation in deformable porous materials. Using this model, we also established conditions under which a maximum in the speed would exist for samples in compression. Our measurements and analysis resolve the conflicting results reported in previous studies.

我们测量了牛关节软骨中作为压缩应变的函数的声速。使用我们开发的技术，可以从样品的无应变全高度开始施加应变。我们的测量表明，声速不是早期调查中报告的应变的单调函数。在较低应变范围内，速度随着应变的增加而增加。它达到最大值，然后随着应变的进一步增加而减小。使用可变形多孔材料中的波传播模型证实了这些结果。使用该模型，我们还建立了压缩样本存在最大速度的条件。我们的测量和分析解决了先前研究中报告的相互矛盾的结果。