Yang Lu's blog

The extraordinary mechanical properties of graphene were measured on very small or supported samples. In our new paper published in Nature Communications, by developing a protocol for sample transfer, shaping and straining, we report the outstanding elastic properties and stretchability of free-standing single-crystalline monolayer graphene under in situ tensile tests.

Nanomechanics of Covalent Crystals and Elastic Strain Engineering

Yang Lu

Department of Mechanical Engineering, City University of Hong Kong

In our new paper published on Science Advances, we carefully measured the elastic mechanical properties of individual silicon nanowires by uniaxial tensile straining under both SEM and high-res optical microscope, and demonstrated that high quality VLS–grown single-crystalline Si nanowires with diameters of ~100 nm can be reversibly stretched at room temperature with 10% or more elastic strain, approaching the theoretical limit of silicon. 

Plastic deformation in metallic glasses is highly localized and often associated with shear banding, which may cause momentary release of heat upon fracture. Here, we report an explosive fracture phenomenon associated with momentary (∼10 ms) light emission (flash) in Lanthanum-based (LaAlNi) metallic glass microwires (dia. ∼50 μm) under quasi-static tensile loading.

In this study, the intrinsic viscoelastic mechanical behavior of a hierarchical bio-composite, structural bamboo material, was experimentally investigated and correlated with its microstructural constituents and molecular building blocks. The macroscopic viscoelastic responses of bulk bamboo at ambient temperature and dehydrated condition were evaluated through dynamic compression experiments with various loading frequencies, whereas the localized viscoelasticity of bamboo's microstructural phases, viz.

http://www.hindawi.com/journals/jnm/si/308678/cfp/

Journal of Nanomaterials special issue on

"In Situ Mechanical Characterization of Low-Dimensional Nanomaterials"

As one of the most renewable resources on Earth, bamboo has recently attracted increasing interest for its promising applications in sustainable structural purposes. Its superior mechanical properties arising from the unique functionally-graded (FG) hierarchical structure also make bamboo an excellent candidate for bio-mimicking purposes in advanced material design. However, despite its well-documented, impressive mechanical characteristics, the intriguing asymmetry in flexural behavior of bamboo, alongside its underlying mechanisms, has not yet been fully understood.

Bamboo, as a natural hierarchical cellular material, exhibits remarkable mechanical properties including excellent flexibility and fracture toughness. As far as bamboo as a functionally graded bio-composite is concerned, the interactions of different constituents (bamboo fibers; parenchyma cells; and vessels.) alongside their corresponding interfacial areas with a developed crack should be of high significance.

http://www.springerlink.com/content/y4228l3u78t38755/

Abstract

Adv. Funct. Mater.  DOI: 10.1002/adfm.201101224