The BioRobotics Institute, Scuola Superiore Sant'Anna, Piazza Martiri della Libertà 33, 56127 Pisa, Italy.
Department of Excellence in Robotics & AI, Scuola Superiore Sant'Anna, Piazza Martiri della Libertà 33, 56127 Pisa, Italy.
Int J Mol Sci. 2022 Jul 30;23(15):8467. doi: 10.3390/ijms23158467.
In this work, an innovative model is proposed as a design tool to predict both the inner and outer radii in rolled structures based on polydimethylsiloxane bilayers. The model represents an improvement of Timoshenko's formula taking into account the friction arising from contacts between layers arising from rolling by more than one turn, hence broadening its application field towards materials based on elastomeric bilayers capable of large deformations. The fabricated structures were also provided with surface topographical features that would make them potentially usable in different application scenarios, including cell/tissue engineering ones. The bilayer design parameters were varied, such as the initial strain (from 20 to 60%) and the bilayer thickness (from 373 to 93 µm). The model matched experimental data on the inner and outer radii nicely, especially when a high friction condition was implemented in the model, particularly reducing the error below 2% for the outer diameter while varying the strain. The model outperformed the current literature, where self-penetration is not excluded, and a single value of the radius of spontaneous rolling is used to describe multiple rolls. A complex 3D bioinspired hierarchical elastomeric microstructure made of seven spirals arranged like a hexagon inscribed in a circumference, similar to typical biological architectures (e.g., myofibrils within a sarcolemma), was also developed. In this case also, the model effectively predicted the spirals' features (error smaller than 18%), opening interesting application scenarios in the modeling and fabrication of bioinspired materials.
在这项工作中，提出了一种创新模型作为设计工具，用于预测基于聚二甲基硅氧烷双层的轧制结构的内外半径。该模型代表了对 Timoshenko 公式的改进，考虑了由于超过一转的滚动引起的层间接触产生的摩擦，从而拓宽了其应用领域，使其适用于基于能够发生大变形的弹性双层的材料。所制造的结构还具有表面形貌特征，使其在不同的应用场景中具有潜在的可用性，包括细胞/组织工程。改变了双层设计参数，例如初始应变（从 20%到 60%）和双层厚度（从 373μm 到 93μm）。该模型很好地匹配了内外半径的实验数据，尤其是在模型中实施高摩擦条件时，特别是在外径应变变化时，误差降低到 2%以下。该模型优于当前文献，其中不排除自穿透，并且使用单个自发滚动半径值来描述多个滚动。还开发了一种复杂的 3D 仿生分层弹性微结构，由七个类似于内接在圆周上的六边形排列的螺旋组成，类似于典型的生物结构（例如，肌原纤维在肌节内）。在这种情况下，该模型也有效地预测了螺旋的特征（误差小于 18%），为仿生材料的建模和制造开辟了有趣的应用场景。
