Research groups around the world have reached common and contradicting conclusions regarding the behavior and properties of nanostructured materials. The aim of this research is to affirm the common findings by previous research, and support one of the currently proposed concepts of mechanical behavior based on processing and characterization of consolidated nanocrystalline micropowders of high strength/precipitation hardenable aluminum alloy using combined PM/intense plastic straining via Equal Channel angular Extrusion (ECAE). This research work investigated the effect of (a) Cold and hot consolidation of nanocrystalline Al-2124 micropowders into compacts with 4.0 h/d ratio and (b) Canning material used for encapsulating the compact rods for subsequent extrusion within the ECAE channels, and (c) the effect of ECAE number of passes and routes on the green compact properties. The effect of the processing parameters (compaction condition, extrusion temperature, strain rate) on the sample density, grain, subgrain and subcell sizes, and hardness was studied. Pure wrought and cast Cu, and casts Al-cans as well as Al-2024 wrought cans were used for canning of the consolidated powders. Green and hot compact rods were produced from 40μm average particle size Al-2124 powders with 53nm internal structure. Highest density consolidated rods were produced for the double sided cold compaction at 6σ (450MPa) over duration of 30min, while single sided compaction at similar pressure over 60min duration time of compaction and at temperature of 480°C produced the most dense and highest hardness hot compacts. Pure wrought Cu and cast Al are the most suitable canning material for room temperature ECAE of the Al-2124 green compacts. Non-isothermal heating during extrusion hindered the uniform warm deformation of the green and hot compacts canned in wrought Al-2024. Loose powder particles of the green compacts results in particle rotation while passing though the 90° angle intersecting channels of ECAE, and hence prevents full consolidation and densification of the produced product.

A 1 cm × 1 cm biosensor chip for analyzing DNA hybridization is developed by CMOS process. The sensor chip has 6 measurement regions, each region with 3 pairs of parallel microcantilever of 125 × 60 × 0.75μm. The microcantilever is a 4-layer structure composed of an immobilized surface layer, a top insulation layer, an embedded piezoresistive layer, and a bottom insulation layer to measure the nano-deformation induced by the surface-assemble monolayer of alkanethiols on Au. By the Langmuir adsorption model, the estimated adsorption rate of the ssDNA is 0.005sec −1 . The design has intrinsic sensitivity needed in biochemical applications such as detecting nucleotide polymorphism and single base mutation to sequence DNA. The capability of in-situ, multipoint measurement promise many frontiers to be explored.

Nanostructured and conventional titania (TiO2) coatings were thermally sprayed using air plasma spray (APS) and high velocity oxy-fuel (HVOF) processes. The fatigue and mechanical properties of these coatings were investigated. The fatigue strength of coatings deposited onto low-carbon steel showed that the nanostructured titania coated specimens exhibited significantly higher fatigue strength compared to the conventionally sprayed titania. SEM analysis of fracture surfaces revealed valuable information regarding the influence of these coatings on the performance of the coated component. Analysis of surface deformation around Vickers indentations was carried out. This investigation gives new understanding to the nature of fatigue and deformation of these coatings.

Interlaminar fracture toughness for mode II deformation were investigated for carbon fiber (CF)/epoxy laminates toughened by carbon-nano-fiber/epoxy interlayer. Vapor grown carbon fiber (VGCF) and vapor grown carbon ‘nano’ fiber (VGNF) were chosen as the stiffeners for the interlayer. In order to illustrate the effect of the interlayer on the model II fracture toughness of the laminates, several types of CFRP/CNF hybrid laminates were fabricated, which are composed of unidirectional prepregs and carbon nano fiber varying the thickness of the interlayer. Mode II interlaminar fracture toughnesses of the hybrid composites were evaluated by end notched flexure (ENF) test using short-type beam specimens. The fracture toughnesses were calculated by traditional beam theory using the energy release rate of the crack. From the experimental results, it is confirmed that the mode II interlaminar fracture toughnesses for hybrid laminates are from 2.0 to 3.0 times higher than that of original CFRP laminates, and the optimal thickness (area density) of the CNF interlayer exists. The difference in the effect of the interlayer fracture properties under mode II deformation was discussed on the bases of fractographic observations derived from scanning electric microscope.

Tensile behavior of a carbon nanofiber reinforced vinyl ester polymer composite was studied using dog-bone shaped specimens to obtain its mechanical properties. Pyrograf III which is a very fine, highly graphitic and yet low cost carbon nanofiber was used as the fiber material. Vinyl ester with low molecular weight which was used as the matrix material is a thermoset with high tensile strength at room temperature. When small amounts of carbon nanofibers are combined with vinyl ester, the stiffness of the resulting composite can improve if the fiber-matrix adhesion is good. The mechanical properties can improve further after surface treatment (functionalization) of carbon nanofibers. This surface treatment adds some functional groups chemically to the nanofiber’s surface which increases the adhesion between nanofiber and matrix resin. Understanding the mechanical behavior of these composites is crucial to their effective application. In this research the stiffness, strength, and tensile deformation behavior of these nanocomposites were investigated. The effects of matrix curing systems and composition, strain rate, nanofiber concentration, nanofiber surface treatment and environment such as low and high temperatures and humidity were also characterized. Based on the mechanical properties simple models were used to represent tensile stress-strain and deformation behaviors of the nanocomposite. The experimental results were also applied to these models to examine their predictive capability.

The present work deals with a stress measure derived from a general atomic force field. Usually, stresses at atomic level are determined through the Clausius virial theorem for a fixed volume containing interacting particles. The present stress is derived on the basis of the first Brillouin zone, or equivalently the Voronoi cell, surrounding the atom. Thus, this is the smallest scale at which the stress measure makes sense. Obviously, the stress is discrete in nature since the Voronoi cells are discrete. In order for the stress to become continuous the finite element formalism is used in terms of interpolation functions from 3D Voronoi elements. The present stress measure is non-local, it is not necessarily symmetric in its indices and incorporates micro-deformations.

An atomic strain concept is formulated that allows calculation of continuum quantities directly within a discrete atomic (molecular) system. The concept is based on the Voronoi tessellation of the molecular system and calculation of atomic site strains, which connects continuum variables and atomic quantities when the later are averaged over a sufficiently large volume treated as a point of the continuum body. The atomic strain tensor is applied to investigate deformation of regular and disordered molecular systems. It is shown that disordered systems exhibit significant non-affine deformations which can be captured by a proper correction of the strain tensor.