To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video Movie S3. In a composite of identical fiber and matrix composition (A:B = 10:1), the crack cut through the fibers sequentially at a small stretch at around 1.1. The behavior is similar to a crack running in a homogenous hard PDMS (Movie S1). Stretchable materials of high toughness and low hysteresis Zhengjin Wang, Chunping Xiang, Xi Yao, Paul Le Floch, Julien Mendez, and Zhigang Suo PNAS. 2019. 116:5967-5972 DOI: 10.1073/pnas.1821420116 Download Original Video Browse All Videos »