Abstract: Stringer-stiffened plate-like structure is a typical engineering structure and its structural
integrity is critical. A guided Lamb wave-based damage identification scheme and an online structural
health monitoring (SHM) system with an integrated PZT-sensor network were developed. In the
previous studies, the specimens were relatively simple. In this paper, the abovementioned method was
extended to the stiffened plate-like structure—a flat plate reinforced by stringer. FE dynamic
simulation was applied to investigate the Lamb wave propagation characteristics due to the existence
of stringer with the consideration of its material and geometric configurations.
Abstract: Interfacial stress distribution of bonded quarter planes subjected a concentrated force was
re-investigated based on Bogy’s solution . It’s found that the characteristic length of the
singularity of interface end (δ), varies with the index of stress singularity at interface end from
millimeter to nanometer. This is a unique characteristic of stress singularity at interface end. How the
characteristic length of the singularity of interface end (δ) influences the initial de-bonding of the
interface end is a new question worth to pay attention. It’s found in the photoelasticity experiments
that usually the debonding initiated at the interface end with singularity, but as the index of stress
singularity, as well as the characteristic length of singularity of interface end, decrease to some extent,
the initial debonding moves to an inner point near the interface end. This phenomenon clearly shows
the index of stress singularity has obvious influence on the debonding of interface end.
Abstract: Highly-ordered titania nanotube array has been fabricated by a potentiostatic anodization
process in acidic fluoride electrolyte. Calcination at high temperature is followed to achieve
crystallization from amorphous to anatase phase. The approach of embedding bioactive enzymes
inside titania tubule channels has been applied for bioactivation modification of titania/titanium.
The electropolymerization process is applied by using conductive pyrrole monomer to achieve
surface immobilization of enzymes to improve interfacial connection. Characterizations including
field emission scanning electron microscopy, nano-indentation and linear sweep voltammetry
measurements have been performed to fully evaluate the surface morphology, nanomechanical and
electrochemical properties of this composite. Molecule detection application has been investigated
by applying such an enzyme-titania/titanium composite.
Abstract: The effects of component concentrations and addition order of the components, on the
final properties of ternary nanocomposites composed of amorphous poly (ethylene terephthalate)
matrix, organically modified clay, and an ethylene / methyl acrylate / glycidyl methacrylate (E-MAGMA)
terpolymer were studied. All formulations were prepared by melt compounding of the
components with a two-step mixing procedure in a corotating twin-screw extruder. Considering the
X-Ray Diffraction, SEM, impact and strain at break results, the best sequence of component
addition was the one in which PET was first compounded with E-MA-GMA, later this mixture was
compounded with the organoclay in a subsequent run. In this mixing order, the polymer-impact
modifier matrix mixture prepared in the first extrusion run has higher melt viscosity than pure PET,
thus this matrix can apply high shear stresses on the clay particles and delaminate the clay layers
resulting in the best mechanical properties.
Abstract: Nano-yttria powder can be synthesized by yttrium citrate-urea precursor, combusted at
600°C in air. The CVD SiC coated on graphite (CVD SiC/Graphite) infiltrated by the yttrium
citrate-urea precursor, combusted at of 600°C, and then sintered at 1450°C, the thin yttria film can
be achieved. The SEM morphology and EDS result of the thin yttria film show a mass of
needle-shaped pining into the CVD SiC layer, which improves the combination of CVD SiC
layer and wash yttria coating. Therefore, it is an effective transition layer between CVD SiC
coating and wash yttria layer.
Abstract: A number of micromechanical investigations have been performed to predict behaviour of
composite interfaces, showing that the detailed behaviour of the material at these interfaces
frequently dominates the behaviour of the composite as a whole. The interfacial interaction is an
extremely complex process due to continuous evolution of interfacial zones during deformation and
this is particularly true for carbon nanotubes since the interfacial interaction is confined to the
discrete molecular level. The atomic strain concept based upon Voronoi tessellation allows
analysing the molecular structure atom by atom, which may give a unique insight into deformation
phenomena operative at molecular level such as interface behaviour in nanocomposites.
Abstract: Mechanical properties of nanoclay/epoxy composites (NC) have been studied by various
experimental setups in bulk form recently. Creep mechanism of the NC is an important manufacturing
criterion for the aircraft industry. In this paper, nanoindentation was employed to investigate the
nano-mechanical creep effects on different wt. % of nanoclay contents in epoxy matrix. Creep
behaviors of the nanoclay/epoxy composites with different wt. % of nanoclay contents were modeled
by the power-law creep equation. Neglecting the temperature effects on creep, the stress exponents of
tested composites were estimated.