Stretchable devices composed of layered hyperelastic materials are under rapid development to interact with human body, and merge the gap between human and machines. These devices are required to sustain large deformation without mechanical failure over a long time, which remains a challenge. Compared to the fast movement in functions design, the failure mechanism of layered hyperelastic structures has been much less explored. Here we study the cracking modes in layered hyperelastic structures made of relatively brittle films bonded to tougher substrates. An initial surface crack in the film is considered. It is found that the surface crack always tends to penetrate through the thickness of the film at first. With the increase of stretch, two cracking modes – crack channeling and interface debonding – are observed one after the other. The sequence is determined by the ratio of interfacial debonding energy to fracture energy of the film, and a dimensionless cracking number which depends on the film-to-substrate modulus ratio, thickness ratio and dimensionless fracture energy of the film. We establish the critical conditions for different cracking modes and build the phase diagram. This work provides a pathway to design cracking-resistant stretchable devices.

由层状超弹性材料组成的可伸缩装置正在快速发展，以与人体相互作用，弥合人与机器之间的差距。这些设备需要长时间承受大变形而不会出现机械故障，这仍然是一个挑战。与功能设计的快速发展相比，层状超弹性结构的失效机制的探索要少得多。在这里，我们研究了层状超弹性结构的开裂模式，该结构由粘合到较坚硬基底上的相对脆性薄膜制成。考虑薄膜中的初始表面裂纹。发现表面裂纹总是倾向于先穿透薄膜的厚度。随着拉伸的增加，两种开裂模式——裂纹沟道和界面脱粘——相继出现。该序列由界面脱粘能与薄膜断裂能的比值以及无量纲开裂数决定，后者取决于薄膜与基板的模量比、厚度比和薄膜的无量纲断裂能。我们为不同的裂解模式建立了临界条件并构建了相图。这项工作为设计抗裂可拉伸设备提供了途径。