Damage Mechanics of Porcine Flexor Tendon: Mechanical Evaluation and Modeling
Damage Mechanics of Porcine Flexor Tendon: Mechanical Evaluation and Modeling
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DOI：
10.1007/s10439-012-0538-z
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发表时间：
2012-08-01
影响因子：
3.8
通讯作者：
Vanderby, Ray, Jr.
中科院分区：
文献类型：
--
作者：
Duenwald-Kuehl, Sarah;Kondratko, Jaclyn;Vanderby, Ray, Jr.
猪屈肌腱在应变超过弹性极限（“过度拉伸”）之前和之后进行了循环和应力松弛测试，以检查哪些机械参数在亚失效损伤后发生变化。根据这些数据，我们开发了一个“有效应变”损伤模型（其中肌腱被建模为好像被拉至较低应变）。在三个应变水平上诱发损伤，以确定损伤后参数变化受过度拉伸应变水平影响的程度。我们发现过度拉伸引起的扩散损伤降低了测试过程中获得的弹性和粘弹性参数。因此，肌腱对应变的应力响应在损伤后发生改变。接下来，我们将应变相关参数行为与损伤相关行为进行比较，以确定每个参数的有效应变。随着过度拉伸过程中应变的增加，损伤的影响变得更加明显。过度拉伸至 6.5%、9% 或 13% 应变后，有效应变分别为 2.43 +/- A 0.33、1.98 +/- A 0.3 或 0.88 +/- A 0.43% 应变。通过确定有效应变并用其计算损伤后力学参数的预测值，可以利用 Schapery 非线性粘弹性模型来预测肌腱的应力松弛行为。使用这种方法，单个参数可以根据已知的应变相关行为预测弹性和粘弹性折衷。
Porcine flexor tendons underwent cyclic and stress relaxation testing before and after strain exceeding elastic limit ("overstretch") to examine which mechanical parameters undergo changes following subfailure damage. From these data, we developed an "effective strain" damage model (in which the tendon is modeled as if being pulled to a lower strain). Damage was induced at three strain levels to determine the extent to which post-damage parameter changes were affected by overstretch strain level. We found that diffuse damage induced by overstretch decreased elastic and viscoelastic parameters obtained during testing. The stress response of tendon to strain is therefore altered following damage. We next compared the strain-dependent parameter behavior to damage-dependent behavior to determine the effective strain for each parameter. Effects of damage became more pronounced as strain during overstretch increased; following overstretch to 6.5, 9, or 13% strain, effective strain was 2.43 +/- A 0.33, 1.98 +/- A 0.3, or 0.88 +/- A 0.43% strain, respectively. By determining the effective strain and using it to calculate predicted values of post-damage mechanical parameters, it was possible to predict the stress relaxation behavior of tendons with Schapery's nonlinear viscoelastic model. Using this approach, a single parameter predicts both elastic and viscoelastic compromise from known, strain-dependent behaviors.