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Compression Experiments (compression + experiment)
Selected AbstractsSize Independent Shape Memory Behavior of Nickel,Titanium,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Blythe G. Clark While shape memory alloys such as NiTi have strong potential as active materials in many small-scale applications, much is still unknown about their shape memory and deformation behavior as size scale is reduced. This paper reports on two sets of experiments which shed light onto an inconsistent body of research regarding the behavior of NiTi at the nano- to microscale. In situ SEM pillar bending experiments directly show that the shape memory behavior of NiTi is still present for pillar diameters as small as 200,nm. Uniaxial pillar compression experiments demonstrate that plasticity of the phase transformation in NiTi is size independent and, in contrast to bulk single crystal observations, is not influenced by heat treatment (i.e., precipitate structure). [source] Determination of Mechanical Properties of Copper at the Micron Scale,ADVANCED ENGINEERING MATERIALS, Issue 11 2006D. Kiener Using a focused ion beam workstation, micron-sized bending and compression samples were fabricated from a pure copper single crystal. The bending and compression experiments exhibited a strong size effect on the flow stress of copper, reaching values in the order of 1,GPa for the smallest test structures. Conventional strain gradient plasticity approaches are not capable of explaining this behaviour. The surface damage introduced by Ga+ ion implantation during focused ion beam preparation was investigated using Auger electron spectroscopy and its consequence on the mechanical response of the miniaturized test samples is addressed. [source] In situ Mechanical Testing Reveals Periodic Buckle Nucleation and Propagation in Carbon Nanotube BundlesADVANCED FUNCTIONAL MATERIALS, Issue 14 2010Shelby B. Hutchens Abstract Uniaxial compression studies are performed on 50-µm-diameter bundles of nominally vertical, intertwined carbon nanotubes grown via chemical vapor deposition from a photolithographically defined catalyst. The inhomogeneous microstructure is examined, demonstrating density and tube orientation gradients, believed to play a role in the unique periodic buckling deformation mechanism. Through in situ uniaxial compression experiments it is discovered that the characteristic bottom-to-top sequential buckling proceeds by first nucleating on the bundle surface and subsequently propagating laterally through the bundle, gradually collapsing the entire structure. The effects of strain rate are explored, and storage and loss stiffnesses are analyzed in the context of energy dissipation. [source] Advances in transmission electron microscopy: In situ straining and in situ compression experiments on metallic glassesMICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2009Jeff Th.M. De Hosson Abstract In the field of transmission electron microscopy (TEM), fundamental and practical reasons still remain that hamper a straightforward correlation between microscopic structural information and deformation mechanisms in materials. In this article, it is argued that one should focus in particular on in situ rather than on postmortem observations of the microstructure. This viewpoint has been exemplified with in situ straining and in situ compression studies on metallic glasses. In situ TEM straining of amorphous metals permits an evaluation of the thickness of the liquid-like layer (LLL) formed because of heat evolution after shear band development. The experimental evaluation confirms that the thickness of a LLL present at the last moment of fracture substantially exceeds the generally accepted thickness of a shear band. In situ TEM and in situ SEM compression experiments on metallic glass pillars lead to the conclusion that smaller sized pillars deform more homogeneously than larger sized pillars. Microsc. Res. Tech., 2009. © 2009 Wiley-Liss, Inc. [source] | ||||||||||