Zhao Yiqiu, Hu Haitao, Huang Yulu, Liu Hanqing, Yan Caishan, Xu Chang, Zhang Rui, Wang Yifan, Xu Qin
Department of Physics, The Hong Kong University of Science and Technology, Hong Kong SAR, China.
Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.
Nat Commun. 2024 Feb 24;15(1):1691. doi: 10.1038/s41467-024-45964-y.
Soft composite solids are made of inclusions dispersed within soft matrices. They are ubiquitous in nature and form the basis of many biological tissues. In the field of materials science, synthetic soft composites are promising candidates for building various engineering devices due to their highly programmable features. However, when the volume fraction of the inclusions increases, predicting the mechanical properties of these materials poses a significant challenge for the classical theories of composite mechanics. The difficulty arises from the inherently disordered, multi-scale interactions between the inclusions and the matrix. To address this challenge, we systematically investigated the mechanics of densely filled soft elastomers containing stiff microspheres. We experimentally demonstrate how the strain-stiffening response of the soft composites is governed by the critical scalings in the vicinity of a shear-jamming transition of the included particles. The proposed criticality framework quantitatively connects the overall mechanics of a soft composite with the elasticity of the matrix and the particles, and captures the diverse mechanical responses observed across a wide range of material parameters. The findings uncover a novel design paradigm of composite mechanics that relies on engineering the jamming properties of the embedded inclusions.
软质复合固体由分散在软质基体中的内含物组成。它们在自然界中无处不在，是许多生物组织的基础。在材料科学领域，合成软质复合材料因其高度可编程的特性，有望成为制造各种工程器件的材料。然而，当内含物的体积分数增加时，预测这些材料的力学性能对经典的复合材料力学理论构成了重大挑战。困难源于内含物与基体之间固有的无序多尺度相互作用。为应对这一挑战，我们系统地研究了含有刚性微球的密集填充软质弹性体的力学性能。我们通过实验证明了软质复合材料的应变硬化响应是如何由所含颗粒剪切堵塞转变附近的临界标度所控制的。所提出的临界性框架将软质复合材料的整体力学性能与基体和颗粒的弹性定量地联系起来，并捕捉了在广泛的材料参数范围内观察到的各种力学响应。这些发现揭示了一种依赖于设计嵌入式内含物堵塞特性的复合材料力学新设计范式。
