3D crack images reveal complexity and toughness

3D images reveal link between crack complexity and material toughness

By capturing a rare glimpse into three-dimensional crack formation in brittle solids, EPFL researchers have found that complex cracks require more energy to advance than simple ones; a discovery that could improve materials testing and development.

Ttraditional mechanics approaches to analyzing crack formation assume that cracks are planar, i.e. that they form on the two-dimensional surface of a material. In fact, simple planar cracks are just the tip of the iceberg: most cracks – like those in everyday brittle solids like glass – propagate into three-dimensional networks of ridges and other complex features.

The researchers’ method involved creating very thin slices of four different hydrogels and an elastomer. Transparent and brittle, but easy to deform and measure without shattering, the hydrogels served as a proxy for understanding how cracks form in glass and brittle plastics. The elastomer was likewise a proxy for materials like rubber and silicone polymers.

Wei, X., Li, C., McCarthy, C. et al. Complexity of crack front geometry enhances toughness of brittle solids. Nat. Phys. (2024).