What's Inside the Box? - Length-Scales that Govern Fracture Processes of Polymer Fibers

摘要

The fracture strength of natural fibers remains a topic of intense debate, as it has not yet been possible to predict their fracture strength directly from an atomistic point of view. Here we show that the considerations of interatomic interactions alone cannot explain the fracture strength observed in biological fibers. Instead, the fracture strength of a fiber depends strongly on the length-scale of observation, and structures at multiple length-scales must be considered to explain their remarkable mechanical performance and resilience, including a fiber's sensitivity with respect to cracks (and other flaws). The impact of such stress concentrators on a material's performance was first quantified by Griffith and Weibull They developed strong theoretical arguments to explain the experimentally observed scaling of strength with specimen size, where smaller tends to be stronger, suggesting that the probability of having a critical flaw decreases with specimen size.