The phenomenon of interfacial fracture, as manifested by atom- istic cleavage, debonding and dislocation emission, provides a challenge for combined atomistic-continuum analysis. As a precursor for fully coupled atomi...The phenomenon of interfacial fracture, as manifested by atom- istic cleavage, debonding and dislocation emission, provides a challenge for combined atomistic-continuum analysis. As a precursor for fully coupled atomistic-continuum simulation of interfacial fracture, we focus here on the atomistic behavior within a nanoscopic core surrounding the crack tip. The inter-atomic potential under Em- bedded Atom Method is recapitulated to form an essential framework of atomistic simulation. The calculations are performed for a side-cracked disc configuration un- der a remote K field loading. It is revealed that a critical loading rate defines the brittle-to-ductile transition of homogeneous materials. We further observe that the near tip mode mixity dictates the nanoscopic profile near an interfacial crack tip. A zigzag interface structure is simulated which plays a significant role in the dislocation emission from an interfacial crack tip, as will be explored in the second part of this investigation.展开更多
The existence of a single topologically protected edge state in the first bulk bandgap for acoustic/elastic valley Hall insulators(VHIs)with zigzag interface configurations(ZICs)is well known.However,in this work,we s...The existence of a single topologically protected edge state in the first bulk bandgap for acoustic/elastic valley Hall insulators(VHIs)with zigzag interface configurations(ZICs)is well known.However,in this work,we show that an ultra-broadband edgestate pair in this bandgap can be created using the inverse design by topology optimization.The valley Hall insulator design increases the operational bandwidth 121%compared with an existing valley Hall insulator from recent literature and exhibits extreme field confinement,where more than 99%of the field intensity is concentrated within three unit-cells from the interface.One-way propagation and topological robustness towards small cavity defects are confirmed for the full bandwidth.The exploitation of such edge-state pairs of valley Hall insulators opens an avenue for realizing broadband confined edge modes.In tests for disorder and bend defects,we show that the additional ZIC,with a different operational frequency interval,encountered at the defects,degrades the transmission for bend and disorder defects which may prove significant for the application of VHIs.Through an alternative topology optimization method based on two ZICs,we further increase their common operational bandwidth.展开更多
基金The project supported by the National Natural Science Foundation of China
文摘The phenomenon of interfacial fracture, as manifested by atom- istic cleavage, debonding and dislocation emission, provides a challenge for combined atomistic-continuum analysis. As a precursor for fully coupled atomistic-continuum simulation of interfacial fracture, we focus here on the atomistic behavior within a nanoscopic core surrounding the crack tip. The inter-atomic potential under Em- bedded Atom Method is recapitulated to form an essential framework of atomistic simulation. The calculations are performed for a side-cracked disc configuration un- der a remote K field loading. It is revealed that a critical loading rate defines the brittle-to-ductile transition of homogeneous materials. We further observe that the near tip mode mixity dictates the nanoscopic profile near an interfacial crack tip. A zigzag interface structure is simulated which plays a significant role in the dislocation emission from an interfacial crack tip, as will be explored in the second part of this investigation.
基金supported by the China Scholarship Council(CSC)the Danmarks Grundforskningsfond(Grant No.DNRF147)。
文摘The existence of a single topologically protected edge state in the first bulk bandgap for acoustic/elastic valley Hall insulators(VHIs)with zigzag interface configurations(ZICs)is well known.However,in this work,we show that an ultra-broadband edgestate pair in this bandgap can be created using the inverse design by topology optimization.The valley Hall insulator design increases the operational bandwidth 121%compared with an existing valley Hall insulator from recent literature and exhibits extreme field confinement,where more than 99%of the field intensity is concentrated within three unit-cells from the interface.One-way propagation and topological robustness towards small cavity defects are confirmed for the full bandwidth.The exploitation of such edge-state pairs of valley Hall insulators opens an avenue for realizing broadband confined edge modes.In tests for disorder and bend defects,we show that the additional ZIC,with a different operational frequency interval,encountered at the defects,degrades the transmission for bend and disorder defects which may prove significant for the application of VHIs.Through an alternative topology optimization method based on two ZICs,we further increase their common operational bandwidth.
