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Asynchronous cracking with dissimilar paths in multilayer graphene
Jang, Bongkyun,Kim, Byungwoon,Kim, Jae-Hyun,Lee, Hak-Joo,Sumigawa, Takashi,Kitamura, Takayuki The Royal Society of Chemistry 2017 Nanoscale Vol.9 No.44
<P>Multilayer graphene consists of a stack of single-atomic-thick monolayer graphene sheets bound with π-π interactions and is a fascinating model material opening up a new field of fracture mechanics. In this study, fracture behavior of single-crystalline multilayer graphene was investigated using an<I>in situ</I>mode I fracture test under a scanning electron microscope, and abnormal crack propagation in multilayer graphene was identified for the first time. The fracture toughness of graphene was determined from the measured load-displacement curves and the realistic finite element modelling of specimen geometries. Nonlinear fracture behavior of the multilayer graphene is discussed based on nonlinear elastic fracture mechanics.<I>In situ</I>scanning electron microscope images obtained during the fracture test showed asynchronous crack propagation along independent paths, causing interlayer shear stress and slippages. We also found that energy dissipation by interlayer slippages between the graphene layers is the reason for the enhanced fracture toughness of multilayer graphene. The asynchronous cracking with independent paths is a unique cracking and toughening mechanism for single-crystalline multilayer graphene, which is not observed for the monolayer graphene. This could provide a useful insight for the design and development of graphene-based composite materials for structural applications.</P>
장봉균(Bongkyun Jang),이상주(Sang-Joo Lee),한승우(Seung-Woo Han),박정민(Jungmin Park),현승민(Seungmin Hyun),김재현(Jae-Hyun Kim),이학주(Hak-Joo Lee) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
The mechanical and electrical property of small-sized materials has been an important subject due to various applications such as semiconductors, MEMS devices, micro-nano sensors and flexible electronic devices. However, it has many difficulties because of not only fabrication and alignment of specimens, but also the measurement of strain and infinitesimal resistance of thin film. In this work, we used the real-time DIC strain measurement system in micro-tensile testing system. For measurement of electrical resistance, voltage/current sourcemeter is installed in the system. This system has advantages of real time strain monitoring up to 50 ㎚ resolution during micro-tensile test with the ability to measure a small amount of electrical resistance. For the measurement of electrical and mechanical properties, we fabricated micro-tensile specimens which are 200 ㎚ and 1.0 ㎛ thick and 70 and 200 ㎛ wide of gold thin film.