Abstract

Computer modeling of internal damage evolution in elastomeric nanocomposites with high structural phase inhomogeneity (hard dispersed filler and soft elastomeric matrix) has been carried out. The concentration of filler particles was chosen to be sufficiently high, so that their mutual interaction affected significantly the strength properties of the material. Dispersed inclusions were assumed to be absolutely rigid and durable. Only a finitely deform able incompressible matrix (the mechanical properties of which were set using the neo-Hookean elastic potential) could be damaged. The model takes into account the following specific features of the composite structure: a high stress concentration in the gaps between closely located inclusions, the presence of elastomeric layers with increased stiffness on the surface of filler particles, different interphase contact conditions (full adhesion or slip at the matrix–inclusion interface), and the possibility of anisotropic hardening during uniaxial stretching (due to the reorientation of molecular chains in the elongation direction). The latter factor made it possible to study theoretically the mechanism of formation of high-strength microstrands in the gaps between adjacent particles. The occurrence of such formations in filled elastomers, which was observed in numerous experiments, is a proven fact. A new (anisotropic) fracture criterion has been developed to describe it, because this phenomenon cannot be simulated within the generally accepted strength criteria. The calculations based on this new approach showed that local matrix discontinuities occur not in the gaps between particles (sites of highest stress concentration) but at a certain distance, forming a hollow ring (microstrand) around it. The link between neighboring inclusions is not violated, and the material retains its load-carrying capacity at the macrolevel. Thus, the presence of microstrands is a possible reason for hardening an elastomer when a hard dispersed filler is introduced into it.

中文翻译：

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考虑界面相互作用的分散填充弹性纳米复合材料结构损伤演化的建模

摘要

进行了具有高结构相不均匀性的弹性体纳米复合材料（硬分散填料和软弹性体基质）内部损伤演变的计算机建模。选择填料颗粒的浓度要足够高，以使它们之间的相互作用显着影响材料的强度性能。假定分散的夹杂物是绝对刚性和耐用的。仅能有限变形的不可压缩基质（其机械性能是使用新霍克弹性势设定的）会受到破坏。该模型考虑了复合材料结构的以下特定特征：紧密结合的夹杂物之间的缝隙中存在较高的应力集中；在填充剂颗粒表面上存在具有增加刚度的弹性体层；不同的相间接触条件（在基体-包裹体界面处完全粘附或滑移），以及在单轴拉伸过程中各向异性硬化的可能性（由于分子链在伸长方向上的重新定向）。后一因素使得理论上研究相邻颗粒之间的间隙中高强度微链形成的机理成为可能。在许多实验中观察到，在填充的弹性体中会出现这种形成现象，这已被证明是事实。已经开发了一种新的（各向异性）断裂准则来描述它，因为这种现象无法在公认的强度准则内进行模拟。基于这种新方法的计算表明，局部基体不连续性不是出现在颗粒之间的间隙中（应力集中最高的位置），而是发生在一定距离处，从而在其周围形成了空心环（微链）。相邻夹杂物之间的联系没有受到破坏，并且该材料在宏观水平上仍保持了其承载能力。因此，当将硬分散的填料引入弹性体时，微链的存在是使弹性体硬化的可能原因。