Tracing fracture in stretchy, disordered materials

Unlike crystalline solids, which are ordered and stiff, soft network materials are easily deformed, stretchable, and disordered at microscopic scales. These properties allow for essential movement and deformation in biological tissues, rubber, and textiles.

However, the multi-scale disorder in soft network materials makes studying their fracture challenging. Looking in microscopic detail can miss the damage beginning elsewhere in the material. But looking on a macroscopic scale will not catch the onset of the fracture process.

Tauber et al. now show that mesoscopic computer simulations can bridge the gap between these two scenarios, capturing the material’s disorder without enforcing every detail at the molecular scale.

“Because fracture is a problem that typically starts out at small scales and then expands, you can almost never do a computation that captures the entire process,” said author Justin Tauber. “Often damage accumulates very slowly, and then suddenly everything explodes and there’s a big crack. So, it’s a phenomenon that takes place over many length scales and many time scales.”

The team described insights into fracture in soft network materials developed within the last 20 years, and how other frameworks, such as disordered materials like concrete and elasticity models for biopolymer networks, can inform simulations.

They also identified open avenues for further research in the field. Comparing simulations to optical microscopy experiments — in which, for example, a breaking bond releases a photon for detection — could inform exactly when fracture begins and forecast catastrophic material failure. Meanwhile, it is also crucial to define and identify the defects and stresses that may instigate fracture in the first place.

Source: “Stretchy and disordered: Toward understanding fracture in soft network materials via mesoscopic computer simulations,” by Justin Tauber, Jasper van der Gucht, and Simone Dussi, Journal of Chemical Physics (2022). The article can be accessed at https://doi.org/10.1063/5.0081316 .