Abstract.

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.

Graphical abstract

中文翻译：

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在干燥胶体薄膜中从裂纹到卷曲过渡

摘要。

干燥引起的开裂在自然界中很普遍，并且在工业应用中具有根本的意义。在干燥过程中，水分的释放是非线性的。考虑到干燥的不均匀过程，值得考虑水分含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，我们报告了对含水量对干燥胶体薄膜破坏模式的影响进行的实验研究。当初始含水量逐渐增加时，会发现从随机裂纹到卷曲的明显破坏过渡。当水含量低于给定膜厚度的临界值时，观察到由收缩引起的随机干燥裂纹。超出此临界水含量，薄膜会随着几个主要裂缝的出现而卷曲。还发现对应于转变点的临界水含量取决于膜厚度。为了定性解释实验结果，采用基于能量方法的断裂力学方法建立了理论模型。该模型与实验结果非常吻合，阐明了初始含水量对裂纹模式和破坏模式转变的影响。

图形概要