Time lapse In situ observation of crack growth in 3D mechanical metamaterials

We can make extremely fine architected metamaterials comprising millions of cells offering an almost limitless degree of freedom in optimizing material architecture. Recently, we made a ground-breaking discovery: 3D architected solids can exhibit remarkable damage tolerance violating the classical Griffith ideas of brittle fracture due to the inherent discreteness of the microstructure. Preliminary observations from in-situ fracture experiments in lab-based X-ray CT have shed initial light on this finding but the resolution and scan time preclude detailed study. It is now necessary to use a synchrotron facility to monitor the progress of fully embedded cracks in 3D as a function of loading and crack growth. The results, combined with numerical calculations, will lead to a revision of classical fracture mechanics to include architected metamaterials, enabling us to learn how to optimize the design lattice mechanical metamaterials for crack resistance.