Bursa Jiri, Zemanek Miroslav
Institute of Solid Mechanics, Mechatronics and Biomechanics, FME, BUT, Brno, Czech Republic.
Stud Health Technol Inform. 2008;133:45-55.
Soft tissues are pseudoelastic anisotropic materials; various formulas for their strain energy density have been proposed for modelling of their constitutive behaviour. However, the individual variance of elastic parameters is often more pronounced than their anisotropy, so that their constitutive relations can be modelled as either isotropic or orthotropic. Any hyperelastic model requires more mechanical tests to be input for an identification of its parameters than mere uniaxial tension tests; especially biaxial tension tests are very important also for isotropic hyperelastic materials. A design of a testing rig produced in cooperation of our institute with some local companies is presented. It enables us to carry out not only equibiaxial tension tests, but also some other biaxial tensile tests, because displacements in both mutually perpendicular directions can be controlled independently. The proposal of various types of biaxial tests is presented in the paper, with examples of their realization with porcine aortic wall tissue. The contribution focuses on ways of evaluation of the results and on identification of parameters of various constitutive models. The use of more mechanical tests in identification of constitutive parameters can improve the predictive capability of the models substantially.
软组织是伪弹性各向异性材料；已经提出了各种关于其应变能密度的公式来模拟其本构行为。然而，弹性参数的个体差异通常比其各向异性更为显著，因此其本构关系可以被建模为各向同性或正交各向异性。任何超弹性模型都需要比单纯的单轴拉伸试验更多的力学试验来输入以识别其参数；特别是双轴拉伸试验对于各向同性超弹性材料也非常重要。本文介绍了我们研究所与一些当地公司合作生产的一种试验装置的设计。它使我们不仅能够进行等双轴拉伸试验，还能进行其他一些双轴拉伸试验，因为在两个相互垂直方向上的位移可以独立控制。本文提出了各种类型的双轴试验，并给出了用猪主动脉壁组织实现这些试验的例子。本文的贡献集中在结果评估方法和各种本构模型参数的识别上。在本构参数识别中使用更多的力学试验可以显著提高模型的预测能力。
