Abstract: The creep properties for the Hastelloy-X alloy which is one of candidate alloys for a high
temperature gas-cooled reactor are presented. The creep data was obtained with different stresses at
950oC, and a number of the creep data was collected through literature surveys. All of the creep data
were combined together to obtain the creep constants and to predict a long-term creep life. In the
Norton’s creep law and the Monkman-Grant relationship, the creep constants, A, n, m, and m’ were
obtained. Creep master curves based on the Larson-Miller parameter were presented for the standard
deviations of 1σ, 2σ and 3σ. Creep life at each temperature was predicted for a longer-time rupture
above 105 hours. Failure probability was also estimated by a statistical process of all the creep rupture
Abstract: Before concrete structures are subjected to dynamic loadings such as earthquake, usually
they have already withstood static loads. Accordingly, the study on the strain-rate sensitivity of
concrete should also be closely related to the initial static loads that concrete structures experience.
But majority of the available documents concerning the dynamic properties of concrete do not take
initial static load into consideration. In this study, experiments were carried out to investigate the
effect of initial static load on the dynamic strength and deformation characteristics of concrete in
compression. A load was initially applied on the specimen at a very low speed to a specified value
and then the dynamic load was applied at a high strain rate up to the failure of the specimen. From
the test results it was revealed that the initial static load had significant influence on the dynamic
strength. The dynamic strength tended to decrease as initial static load increased. An exponential
function was proposed to formulate the relationship between the initial static load and the dynamic
Abstract: In this paper, an experimental verification has been conducted for a frequency response
function (FRF)-based structural damage identification method (SDIM) proposed in the previous
study . The FRF-based SDIM requires the natural frequencies and mode shapes measured in the
intact state and the FRF-data measured in the damaged state. Experiments are conducted for the
cantilevered beam specimens with one and three slots. It is shown that the proposed FRF-based
SDIM provides damage identification results that agree quite well with true damage state.
Abstract: In order to evaluate the damage evolution of rock under external loading, the surface
deformation field of a rectangle marble specimen is inspected and analyzed using digital speckle
correlation method (DSCM). Experimental results show that the damage evolution of rock
undergoes 3 stages: they are uniformly distributed damage, localized damage and catastrophic
failure stage. A statistic indicator, standard deviation of the strain field, can be used to quantitatively
express the damage localization level.
Abstract: The hot mill spindle assembly is the important component of the hot rolling process and
used for transmission of rotational power. The contact surface between end coupling and slipper
metal have high stress concentration due to operation interference. The life cycles of slipper metal
are reduced by the contact surface damage. In this study, the structural analysis and kinematics
simulation are performed by applying the various driving angle and dynamic boundary condition of
the mill spindle assembly. This study aims to minimize the contact damage which might happen in
the production process.
Abstract: As a typical model of steep-tilt or moderate-tilt bedding rock slopes, buckling failure
differs greatly from tensile or shear failure. The mechanical characteristic of buckling failure is
analyzed, and the geo-mechanics model of buckling failure is put forward. The process of buckling
failure includes three phases: slope terrane creep deformation, the lower of slope terrane bend
deformation, and terrane structure collapse. Using pressure bar failure theory, a formulation for
calculating critical load of buckling failure is developed, which shows that critical load decreases
with bend length increasing. The relationship between critical slope length and bend length is
analyzed. It is indicated that critical slope length decreases with bend length increasing, and that
critical slope length reaches minimal value while critical load is zero. The minimal slope length can
be considered as a limit value while analyzing buckling failure of bedding slope, and its calculation
equation is developed.
Abstract: The initiation and growth of micro-defects such as micro cracks and voids usually causes
the failure of long term operated structural components at high temperature. In this study, the creep
characteristics and void nucleation and growth characteristics of P92 steel which is used as main
steam pipe material in power plant were investigated at several temperatures and loading conditions.
The area fraction of void increased with increase of test temperature, stress, and load holding time.
In case of internal defect presence, micro-voids initiated in the early stage of loading period and
resulted in the increased load line displacement and crack growth rate. The microvoids were found
to form along the prior austenite grain boundaries and at the martensite packet boundaries.
Abstract: Stability limits of premixed microflames were experimentally and computationally studied
in order to understand the fundamental behavior of the flames when applied for micropower
generation. Single microflames were generated on microtubes with inner diameters of 300-420 μm
for methane-air mixtures at temperatures of 298-400 K and atmospheric pressure. For all the
microflames at normal temperature, the stability limits were observed in a fuel-rich region, which is
different from conventional macroflames exhibiting fuel-lean stability limits. Similar to the
macroflames, however, the stability limits of the microflames show C-shaped curves in a tube exit
Reynolds number (Re) – fuel equivalence ratio diagram, due to insufficient residence times and heat
losses. For elevated temperature that is realistic condition for micropower generation using a
heat-recirculation concept, the stability limits were extended toward the fuel-leaner conditions.
Numerically predicted structure of microflames near the critical point (that is defined as the
fuel-leanest condition among the C-shaped fuel-rich stability limits) showed significant fuel-dilution
immediately near the tube exit due to a low Re effect, explaining why the stability limits of
microflames are observed only in the fuel-rich region. Microcombustors for micropower generation
should be designed to completely consume fuel for better performance.
Abstract: Influence of the frequency to the temperature image obtained by an infrared
thermography was investigated using specimens of three kinds of materials at four kinds of
frequencies of the cyclic load. Then, the infrared hybrid method was developed to separate
individual stress components. However, the influence of heat conduction is inevitable in the infrared
stress measurement method. Therefore, an error arises in the infrared hybrid analysis. Then, the
system which corrects the error by the inverse analysis was developed. Thereby, the accuracy of the
stress intensity factor was able to be raised. Furthermore, the accuracy of hybrid method
considering to heat conduction was discussed in comparison with the 3-D finite element analysis
and 2-D hybrid method.
Abstract: Rotating components used in the hot sections of land-based gas turbine are exposed to
severe environment of several ten thousands operating hours above 1100. To protect such
components against high temperature oxidation an intermediate bond coat is applied, typical of a
MCrAlY-type metal alloy. Various processing methods have been studied for bond coat deposition.
This study is concerned with the cyclic oxidation behavior of CoNiCrAlY coatings. Coatings
were deposited by a vacuum plasma spray and high-velocity oxygen fuel method on a nickel-based
superalloy (GTD-111). Cyclic thermal oxidation test condition is at 1100 in ambient air for
various periods of time. Tests were used to evaluate the oxidation resistance of the spray-coated
specimens. The microstructure and morphology of as-sprayed and of tested specimens were
characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD).
The oxide phases formed on the coating surface are NiO, CoCr2O4, and Al2O3. The nickel oxide
of them was to be dominant with increasing cycles. The differences in microstructure and phase
composition in the interface with coating layer are reported. The influence of coating process
methods on coating characteristics and degradation mechanisms is discussed. The HVOF coating
with the splats was more resistant on the high temperature oxidation than the VPS coating.