Fracture Diodes: Directional Asymmetry of Fracture Toughness

Abstract

Toughness describes the ability of a material to resist fracture or crack propagation. It is demonstrated here that fracture toughness of a material can be asymmetric, i.e., the resistance of a medium to a crack propagating from right to left can be significantly different from that to a crack propagating from left to right. Such asymmetry is unknown in natural materials, but we show that it can be built into artificial materials through the proper control of microstructure. This paves the way for control of crack paths and direction, where fracture -when unavoidable -can be guided through pre-designed paths to minimize loss of critical components.

'Guided' Fractures in Graphene Mechanical Diode-like Structures

“…Our results show that a robust diode-like behavior exists, thus validating that the phenomenon observed at the macroscale by Brodnik et al Brodnik et al [2021] still holds at the nanoscale for graphene membranes. Other topologies and/or defects can be also exploited to guide the fracture along engineering directions.…”

“…There are systems that do possess properties that are dependent on the direction and also on the propagation pathways, but they rely on the presence of interfacial effects Daniel et al [2004], Malvadkar et al [2010], Hancock et al [2012, Zambrano et al [2018], Xia et al [2012]. Recent works have demonstrated rectification effects and deflection of fractures by modifying only the microstructure with the creation of structural voids Hossain et al [2014], Brodnik et al [2021, Conway et al [2021] without any introduction of a different material. These strategies serve as a way to mitigate the damage of critical components when a fracture is unavoidable Brodnik et al [2021].…”

“…Recent works have demonstrated rectification effects and deflection of fractures by modifying only the microstructure with the creation of structural voids Hossain et al [2014], Brodnik et al [2021, Conway et al [2021] without any introduction of a different material. These strategies serve as a way to mitigate the damage of critical components when a fracture is unavoidable Brodnik et al [2021].…”

“…Once determined this direction, we tested the diode-like behavior considering just only one notch to determine which direction the fractures experience less resistance (tensile strength in the stress-strain curve). Although there are several works on electronic Dragoman et al [2010], Di Bartolomeo [2016], Wang et al [2021], Kim et al [2013b], Li et al [2016] and thermal Wang et al [2017], Liu et al [2021], Chen et al [2020], Melis et al [2015], Wang et al [2014] graphene-based diodes, to our knowledge mechanical graphene-based diode based on ideas proposed by Brodnik et al Brodnik et al [2021] has not been investigated and it is one of the goals of the present study.…”

What It’s Cracked Up To Be

“…But artificial materials containing asymmetric microstructures can be designed to break more easily along a certain path. Now, Kaushik Bhattacharya of the California Institute of Technology and colleagues have designed and tested an artificial material with an asymmetric pattern that makes it nearly twice as tough in one direction than in the other [1].…”