Meng Weipeng, Liu Mingchao, Gan Yixiang, Pauchard Ludovic, Chen C Q
Department of Engineering Mechanics, CNMM & AML, Tsinghua University, 100084, Beijing, China.
Mathematical Institute, University of Oxford, OX2 6GG, Oxford, UK.
Eur Phys J E Soft Matter. 2020 Oct 1;43(10):64. doi: 10.1140/epje/i2020-11985-4.
Drying-induced cracking is widely encountered in nature and is of fundamental interest in industrial applications. During desiccation, the evolution of water content is nonlinear. Considering the inhomogeneous procedure of desiccation, it is worth considering whether water content will affect the crack pattern formation. To address this concern, in this paper, we report an experimental investigation on the effect of water content on the failure mode in drying colloidal films. A distinct failure transition from random cracking to curling is found when the initial water content increases gradually. When the water content is below a critical value for given film thickness, random desiccation cracking driven by shrinkage is observed. Beyond this critical water content, the film curls with the advent of several main cracks. It is also found that the critical water content corresponding to the transition point depends on the film thickness. In order to qualitatively interpret the experimental observation, a theoretical model is established by adopting the fracture mechanics based on the energy method. The model is found to agree well with the experimental results, elucidating the effects of initial water content on the crack patterns and the transition of failure modes.
干燥诱导的开裂在自然界中广泛存在，并且在工业应用中具有重要的基础研究价值。在干燥过程中，含水量的变化是非线性的。考虑到干燥过程的不均匀性，值得考虑含水量是否会影响裂纹图案的形成。为了解决这一问题，在本文中，我们报告了一项关于含水量对干燥胶体薄膜失效模式影响的实验研究。当初始含水量逐渐增加时，发现了从随机开裂到卷曲的明显失效转变。当含水量低于给定薄膜厚度的临界值时，观察到由收缩驱动的随机干燥开裂。超过这个临界含水量，薄膜会随着几条主要裂纹的出现而卷曲。还发现对应于转变点的临界含水量取决于薄膜厚度。为了定性地解释实验观察结果，基于能量法采用断裂力学建立了一个理论模型。发现该模型与实验结果吻合良好，阐明了初始含水量对裂纹图案和失效模式转变的影响。
