Abstract: The compatibility of various electrolyte and electrode combinations has been assessed
based on viewpoints of mechanics. The membrane-electrode assembly (MEA) was mainly comprised
of traditional ceramic-metal materials as well as solid electrolytes. Variations of key variables such as
size and coefficient of thermal expansion were incorporated into ABAQUS sensitivity analyses.
Accordingly, general design rules in manufacturing solid oxide fuel cell (SOFC) were proposed, and
these rules were beneficial to produce multilayer MEA in the future.
Abstract: Functionally gradient materials (FGMs) composed of 3YSZ and IN713LC were developed
in three different configurations. A linear-mode FGM had its compositions with a monotonic change
in coefficient of thermal expansion (CTE). Negative- and positive-deviated FGMs had their
compositions with lower and higher CTEs, respectively, on the ceramic sides. Fracture behaviors of
these three types of FGMs were evaluated with aids of residual stress analyses. FGMs with a
positive CTE deviation demonstrated the best performance in the experiment. The brittle ceramic
side was under high compressive stress, and high tensile stresses were primarily initiated in the
metal-rich gradient layers.
Abstract: As stress waves decay as they pass through the pile foundation system, it is extremely
challenging for all nondestructive testing methods to evaluate the pile integrity of a shaft underneath
a structure. In this study, time–frequency signal analysis (TFSA) is used for signal processing and
adopted to interpret the pile integrity testing signal. An experimental case with pile lengths of 58m
with caps, were tested by the low strain sonic echo method. Traditional time domain analyses can
not identify the pile tip response signals 58m lengths. After time-history curves are transformed into
a time–frequency domain distribution, the results indicate the pile tip can be located more easily and
clearly than the traditional time-domain analyses of pile integrity testing allowed for.
Abstract: Machining parameters such as speed (v), feed (f) and depth of cut (d) play an
important role in determining the residual stress as well as the surface roughness of a
material. The material used for the present study is a nickel based super alloy Udiment 720
which finds applications in the manufacture of gas turbine engine components. Residual
stress and surface roughness measured on this material showed different magnitudes for
different combinations of milling parameters but did not reveal any definite trend. Analytical
relationships developed between the magnitudes of residual stress, surface roughness and
milling parameters indicated that combined effects of the milling parameters influence both
residual stress and surface roughness.
Abstract: The recent results in constructing the mathematical basis of nonlinear acoustic techniques
for NDE of inhomogeneous materials are discussed. These include microstructural materials and
materials with weakly or strongly changing properties of specimens (structural elements) under
inhomogeneous prestress. The idea is to extract additional information from nonlinear and
dispersive effects of wave propagation. Novel concepts are introduced: (i) the analysis of dispersive
effects; (ii) the analysis of two counter-propagating nonlinear waves.
Abstract: Polypropylene/polyamide-6 and polypropylene/metallocene polyethylene blends containing 2.5 phr
of organophilic modified montmorillonite were prepared in a twin-screw extruder followed by
injection molding. In order to compare, blends without layered clay were also made. Styreneethylene-
butylene-styrene copolymer and polypropylene grafted with anhydride maleic were used
as compatibilizers in the ternary blends and in the PP nanocomposite preparation, respectively. The
presence of tactoids, intercalated and exfoliated structures was observed by TEM in some of the
samples containing layered clay and modified PP materials. Results showed that the compatibilized
blends prepared without clay are tougher than those prepared with the nanocomposite of PP as the
matrix phase and no significant changes in tensile moduli were observed between them. However,
the binary blend with a nanocomposite of PP as matrix and metallocene polyethylene exhibited
better tensile toughness and lower tensile modulus, than those prepared with a nanocomposite of PP
and polyamide-6 as dispersed phase. These results are related to the degree of clay dispersion in the
PP and to the type of morphology developed in the different blends. Differential scanning
calorimetry (DSC) showed that blends with a finer and homogeneously dispersed morphology
determined by SEM, the PA component exhibited fractionated crystallization exotherms in the
temperature range of 159-185°C. Also, nucleation of the PP component by PA phase and/or the
layered clay was observed in the blends with PA as dispersed phase.
Abstract: The results of experimental research of physical and chemical transformations in a
ferrous target, caused by intensive deformation mobility of its structural elements for times of
shock-wave treatment (∼10–3 sec), at simultaneous development of process of superdeep penetration
of lead microparticles are represented.
Abstract: A new configuration of smart structures which could be automatically adjusted according
to changes of forcing frequencies is proposed for vibration suppression. The new configuration is a
laminated beam-plate or wide beam composed of layers of piezoelectric sensors and actuators and
Shape Memory Alloy (SMA) wires embedded in the middle plane of the laminated structure. The
structural natural frequencies can be adjusted closely to the forcing frequencies by adjusting electric
heating for controlling temperature of SMA. In each layer, the piezoelectric sensors and actuators
whose electrode are trimmed to modal shapes in conjunction with proper control algorithm, to
achieve expected control effects. The sensors and actuators are connected with each other if they have
the same shapes and they are linked together by a controller to form a close loop feedback control.
Using active control algorithm to control behavior of the piezoelectric material can suppress the
structural vibration. Theoretical simulations are formulated and performed without physical
experimentation for evaluating its feasibility. The Hamilton's principle is used to derive the governing
equation and boundary conditions for the structure which is composed of PVDF and SMA materials.
Modal analysis is used to obtain the result of dynamical response.
Abstract: Mechanical sensitivity of a bossed and clamped layered isotropic circular plate with
pretension in large deflection is evaluated. The approach extends Von-Karman’s plate theory for
large deflection to a symmetrically layered plate with a center boss. The derived nonlinear
governing equations are solved using a finite difference method incorporating a numerical iteration
scheme in finding the lateral slope and radial force resultant. The obtained geometrical responses
are further manipulated to calculate the associated mechanical sensitivity. For a 3-layered plate
with nearly the same layer moduli, the results correlate well with those following available
formulation for a single-layer isotropic plate. The developed approach is then implemented for
various initial tensions, lateral pressures as well as different boss sizes and ratios between the layer
moduli. The obtained numerical results show that, initial tension appears to have the strongest
influence upon the radial variation of mechanical sensitivity over the top surface of the bossed
layered plate. While both the size of center boss and magnitude of lateral pressure can still have
a significant effect, the mechanical sensitivity seems to be insensitive to the change of the ratio
between layer moduli for a bossed and symmetrically layered plate.