MOX-Modeling and Scientific Computing, Dipartimento di Matematica F. Brioschi, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy.
Biomech Model Mechanobiol. 2010 Apr;9(2):177-86. doi: 10.1007/s10237-009-0168-z. Epub 2009 Aug 13.
A thermodynamically consistent framework for describing the response of materials undergoing deformation-induced degradation is developed and applied to a particular biodegradable polymer system. In the current case, energy is dissipated through the mechanism of hydrolytic degradation and its effects are incorporated in the constitutive model by appropriately stipulating the forms for the rate of dissipation and for the degradation-dependent Helmholtz potential which changes with the extent of the degradation of the material. When degradation does not occur, the response of the material follows the response of a power-law generalized neo-Hookean material that fits the response of the non-degraded poly(L: -lactic acid) under uniaxial extension. We study the inflation and extension of a degrading cylindrical annulus and the influence of the deformation on the mechanism of degradation and its consequent mechanical response. Depreciation of mechanical properties due to degradation confers time-dependent characteristics to the response of the biodegradable material: the material creeps when subjected to constant loads and stresses necessary to keep a fixed deformation relax.
开发了一种用于描述经历变形诱导降解的材料响应的热力学一致框架，并将其应用于特定的可生物降解聚合物系统。在当前情况下，能量通过水解降解的机制耗散，并且通过适当规定耗散率的形式和与材料降解程度相关的亥姆霍兹势来将其影响纳入本构模型，该亥姆霍兹势随材料降解的程度而变化。当不发生降解时，材料的响应遵循幂律广义 neo-Hookean 材料的响应，该响应适合非降解聚（L-丙交酯）在单轴拉伸下的响应。我们研究了降解圆柱环的膨胀和延伸，以及变形对降解机制及其随后的力学响应的影响。由于降解导致的机械性能下降赋予了可生物降解材料的响应时间依赖性特征：当施加恒载和保持固定变形所需的应力时，材料会蠕变，从而使应力松弛。
