Abstract: Rotating bending fatigue tests were carried out for maraging steels with different grain
size in moist air in order to investigate the effects of humidity, grain size and reversion austenite on
fatigue strength of the steel. Fatigue strength was decreased by humidity, and the decrease in fatigue
strength was large in larger grain sized steel. Both of the initiation and propagation of a crack were
promoted by humidity. Many cracks initiated at the specimen surface and intergranular cracks were
observed at specimen surface and on fracture surface when humidity was high. The decrease in
fatigue strength by humidity was suppressed by formation of reversion austenite.
Abstract: The paper presents a study on the tooth root, rim and web stresses of thin-rimmed spur
gear structure with symmetrical web, based upon 3D FEM calculations. In order to identify some
gear design directions, the effects of rim and web thickness on gear stress behaviour are
investigated, and maximum stresses resulting from actual rim and web contribution are compared.
Abstract: Electrochemical measurement techniques were applied to investigate the polarization and
hydrogen permeation behavior of Cu-bearing CrMo steel in a H2S saturated aqueous brine solution.
The observation on microstructure and precipitate phases of the steel was conducted by
transmission electron microscopy (TEM), and the corrosion product was investigated by using
X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron
microscopy (SEM). It is disclosed that copper addition could effectively influence the
electrochemical behavior of the investigated steel, and the dissolution behavior of iron matrix and
carbide precipitates in the H2S solution acts as a key role for the steel resistance to hydrogen sulfide
Abstract: Composite materials or generally materials with interfaces are nowadays used in many
varied engineering applications. In comparison with classical engineering materials the existence of
material interface causes locally different stress distribution, which can strongly influence behaviour
of whole structure and can have an important influence on failure mechanisms of such materials.
The paper presented is devoted to the investigation of stress singularity exponents of a crack
growing in a bimaterial body perpendicularly to the interface and touching the material interface.
Discrepancies between value of stress singularity exponent in the centre of bimaterial body and on
the free surface were found. The assumptions of linear elastic fracture mechanics (LEFM) and small
scale yielding (SSY) are considered. For numerical calculations finite element analysis was used.
Results obtained can contribute to a better understanding of failure of materials with interfaces.
Abstract: Magnesium alloy is the lightest metal that is used as a structural material. It has a higher
specific tensile strength and specific stiffness than Iron and Aluminum alloy, and the dent is not
caused easily from Iron and Aluminum alloy at the impact. Therefore, Magnesium alloy is widely
used in many areas, especially as an external shell of a mobile device and automotive parts which
replaces iron and plastic, etc., and its demand is expected to grow in the future. In this paper we
studied the hypervelocity impact with a ballistic range to clarify the characteristic of Magnesium
alloys which had such a characteristic. The effect of impact velocity, temperature and the size of
perforation hole were investigated experimentally. The perforation resistance of Magnesium alloys
and their impact behavior were characterized.
Abstract: Slurry coatings have been used for the protection of gas turbine materials in power plants
during the last years. These coatings can be applied by spaying, brushing or dipping. The main
constituent elements are silicon, chromium, potassium, borium, carbon and zirconium. They are
characterized by high hardness and very good resistance against corrosion, erosion, abrasive and
adhesive wear. To guarantee the reliability of coated steam turbines components used in power
plants, the lifetime assessment of the coatings and their failure prediction become very important.
Microhardness, scratch, adhesion and pin-on-disk sliding tests are commonly used for rapid
evaluation of the mechanical properties of these coatings [F. Loeffler: Thin Solid Films, Vol. 339
(1999), p. 181]. However, the above testing methods do not model the dynamic cyclic fatigue. In
this paper we evaluate the fatigue resistance of slurry coatings working under cyclic loading
conditions by the impact testing method. The coating failure mode and its extent were assessed by
SEM observations and EDX analysis. From the experimental results it was concluded that the
Si,Cr,O,B,C coatings deposited on P91 steel substrate showed an improved fatigue strength
compared to that of Si,Cr,O deposited on the same substrate.
Abstract: This paper presents a damage model dedicated to unsaturated brittle rocks. It mixes
phenomenological and micro-mechanical concepts, and is formulated based on the use of
independent state variables (net stress and suction). The expression of the liquid permeability is
modified in order to represent the influence of fracturing on interstitial fluid flows.
Abstract: The aim of this experimental investigation is to study the effect of various curing
temperatures on crack-front shape and crack growth life of centrally cracked aluminium panels in
mode-I condition with single-side glass/epoxy composite patches. The aluminium panels are made
of Al 2024-T3 with the thicknesses of 2.29 mm. Unidirectional four layers lay-up perpendicular to
the initial crack length were used for the patches of all specimens and the adhesive was Araldite
LY564. The cyclic remote stress of 118 MPa with the R-ratio of 0.05 was applied for all models.
The experiments were performed for different curing temperatures of room temperature, 50oC,
80oC, 100oC and 120oC. It is shown that the fatigue crack growth life of the repaired panels with
curing temperatures of 100oC and 120oC is considerably smaller than those obtained for specimens
cured at room temperature and 50oC.
Abstract: Based on experimental investigation under low cyclic reversed loading, the seismic
behaviors and seismic damage model for steel reinforced high strength and high performance
concrete (SRHSHPC) composite frame columns are studied. Several existing seismic damage models
are firstly presented and their characteristics are comparatively analyzed. From the test results of low
cyclic reversed loading, the variation history of cumulative dissipated hysteretic energy of the
SRHSHPC composite frame columns under different loading cycle levels is figured out, and the
influence of axial compression ratio, shear span ratio, stirrup ratio and concrete strength on the
cumulative dissipated hysteretic energy is also discussed. The damage index of the SRHSHPC
composite frame columns is compared according to the existing seismic damage models, and the
seismic damage model adapted for the SRHSHPC composite frame columns is established.
According to the variation history of the damage index under different loading cycle levels, the rule of
damage development for the SRHSHPC composite frame columns is proposed. The influence of axial
compression ratio, shear span ratio, stirrup ratio and concrete strength on the damage development is
also discussed. The results indicate that the seismic behaviors of the SRHSHPC composite frame
column are outstanding, and the seismic damage model could give a quantitative description for
damaging process of the samples, which is reference for establishing more rational damage criteria for
the SRHSHPC earthquake-resistant composite structure.
Abstract: The shear behaviors of steel reinforced high strength and high performance concrete
(SRHSHPC) composite frame columns are studied through the test on a number of SRHSHPC
specimens with grade of concrete strength varied from C80 to C120 subjected to constant axial
compression and cyclically varying horizontal load. Four influencing factors, namely, shear span
ratio, axial compression ratio, stirrup ratio and concrete strength, are taken into consideration in the
test, and strain gauges are respectively placed on steel web, stirrups as well as reinforcement bars to
study the shear mechanism of SRHSHPC composite columns. According to test results, the shear
failure patterns and shear mechanism of the specimens are discussed. By analyzing the contribution of
the steel web, concrete, stirrups and reinforcement bars to the shear capacity, the shear mechanism of
the SRHSHPC composite columns is figured out. Therefore, the influence of shear span ratio, axial
compression ratio, stirrup ratios and concrete strength on shear behaviors of the SRHSHPC frame
columns is clear. Finally, concrete truss model and principle of accumulation are applied to discuss
the shear capacity and a calculation model for shear strength of the SRHSHPC composite columns is
established. It is indicated that the shear behaviors of the SRHSHPC frame composite columns are
excellent, and the calculated results of shear strength have good conformity with test results.