多层级手性结构生物丝束力学性能的理论模拟

Theoretical modeling of the mechanical properties of biological fibers and bundles with hierarchical chiral structures

高度有序的多层级手性结构赋予肌腱、韧带和植物卷须等生物丝束优异的力学性能.然而,多层级手性结构如何影响丝束的力学性能尚不清楚.本文建立了具有自相似多层级手性结构的生物丝束的理论模型.基于此模型,研究了丝束载荷传递机制、材料手性和手性组装形式及结构层级数对生物丝束的模量、刚度等力学性能的影响.结果表明,丝束的力学性能显著依赖于纤维的材料手性和多层级手性结构.材料手性可以使纤维更加柔软,多层级手性结构使丝束能够承受大的拉伸变形.此工作不仅加深了对生物丝束结构-性能关系的理解,还有助于人造肌肉和柔性致动器、传感器等的设计.

Due to the existence of highly ordered hierarchical chiral structures,biological fibers and bundles such as tendons,ligaments,and climbing tendrils usually have excellent mechanical properties.How the hierarchical chiral structures affect the mechanical properties of fibers and bundles,however,remains unclear.In this paper,a theoretical model of the biological fibers and bundles with self-similar hierarchical chiral structures is developed by virtue of a simple homogenization treatment.Using the built model,the load transfer behavior and effect of material chirality,the chiral assembly forms,and structure level number on the mechanical properties are investigated.The results show that the mechanical properties of fibers and bundles are significantly dependent on the material chirality of fibrils and hierarchical chiral structures.The material chirality of fibrils can make the fiber much softer.And the hierarchical chiral structure provides the fibers and bundles with superior capability to endure large elongation and storage energy.The work is not only helpful for understanding the structure-property of biological fibers and bundles,but also for the design of artificial muscles and soft devices such as strain sensors.