仿生异质结构的非线性力学与优化设计

Nonlinear mechanics and optimization design of bioinspired heterostructures

轻质高强韧结构设计一直是力学和材料等学科交叉的前沿问题,也是工程应用的不懈追求.生物材料经历数百万年进化,兼具轻质、高强度和高韧性力学性能,成为高性能工程材料设计的模板.然而,生物材料往往具有跨尺度、多层级的复相结构和界面特征,会产生非线性、多过程的变形和断裂行为,进而决定强度和韧性等力学性能.如何发展定量的力学模型、阐明生物材料的结构-界面-强韧力学性能间的关系,并为高性能仿生材料制备提供优化设计方案成了近期的研究前沿.本文以极具代表性的生物“砖泥交错结构”和“扭转纤维结构”为例,从力学模型和力学机制方面,首先梳理仿生异质结构代表性单元体(RVE)的非线性力学响应与其结构间的关联;然后讨论含主裂纹仿生异质结构的断裂行为及其与RVE结构间的关联;进一步,基于力学模型和机制,给出优化强度、韧性、抗冲击性和断裂韧性等性能的力学设计方案;最后,提出仿生异质结构非线性力学与优化设计中存在的挑战和未来的发展方向.

Designing lightweight structures with high strength and toughness is a fundamental scientific problem in mechanics and materials science and an everlasting theme in engineering applications.Through millions of years of evolution,biological materials have developed delicate structures with stronger,tougher and lighter mechanical properties,which have become templates for the design of high-performance engineering materials.However,biological materials are often composed of multiscale and hierarchical structures and interfaces that display nonlinear and multiprocess deformation and fracture behaviors,which in turn determine their mechanical properties,such as strength and toughness.The development of nonlinear mechanical models to elucidate the fundamental nonlinear structure-interface-property relationships in biological materials and to provide optimized designs for high-performance biomimetic materials is key nonlinear mechanical issues.This paper provides a featured review of the representative biological"brick and mortar staggered structure"and "twisted fibrous structure".This review first discusses the nonlinear mechanical models and structure-interface-property mechanisms for representative volume element(RVE)of bioinspired heterostructures.Then,the fracture behaviors and their correlation with the mechanics of RVE are demonstrated in bioinspired heterostructures with cracks.Furthermore,based on the above mechanical models and mechanisms,some design schemes are proposed to optimize mechanical properties,such as strength,toughness,kinetic energy dissipation,and fracture toughness.Finally,the remaining challenges and future perspectives for the nonlinear mechanics and optimization design of bioinspired heterostructures are proposed.