Abstract: In this study, stress intensity factors were investigated and determined by photoelastic and
caustics methods to clarify the mechanical behavior of crack tips under various biaxiality ratios.
Polycarbonate (PC) plates with isotropic and anisotropic properties were used as specimens. The
results confirmed that regardless of biaxiality ratio or the material’s property only ‘KI’ was generated
in cases of a crack angle θ = 0º. It was also confirmed that only KI was generated in the isotropic PC
plate with crack angle θ = 45º under a biaxial load (1:1). When the biaxiality ratio is more than 1:1
with a crack angle θ = 45º, both KI and KII are simultaneously generated in the isotropic specimen.
Furthermore, KI, and KII values are influenced most by the extrusion direction in the anisotropic
specimens as the biaxiality load ratios increase.
Abstract: In order to investigate the influence of grain size on notch sensitivities in fatigue of a
fine-grained carbon steel, rotating bending fatigue tests were carried out using specimens with a
V-grooved circumferential notch of commercial fine-grained carbon steel with grain size of 6.5µm.
The results were compared with those of a larger grain sized carbon steel (grain size: 20 µm) and the
notch sensitivities were evaluated based on Linear notch mechanics proposed by Nisitani. Notch
sensitivities for both of fatigue limits for a crack initiation and its propagation of the fine grained
steel were high. The results were discussed from the view points of the size of area related to crack
initiation and the crack growth resistance.
Abstract: In order to study the hypervelocity impact of space debris on spacecraft through
hypervelocity impact on aluminum alloy multi-wall structure, a two-stage light gas gun was used to
launch 2017-T4 aluminum alloy sphere projectiles. The projectile diameters ranged from 2.74mm to
6.35mm and impact velocities ranged from 1.91km/s to 5.58km/s. Firstly, the advanced method of
multi-wall shield resisting hypervelocity impacts from space debris was investigated, and the effect
of amount and thickness of wall on shield performance was discussed. Finally, by regression
analyzing of experiment data, the experience equations for forecasting the diameter of the penetration
hole on the first wall and the diameter of the damaged area on the second wall of aluminum multi-wall
shield under hypervelocity normal impact of Al-spheres were obtained. The results indicated that the
performance of multi-wall shield with more amount of wall is excellent when area density is constant.
At the same time, intensity of the first wall and protecting space play the important roles.
Abstract: Polyurethane foam materials are widely used as cores in sandwich composites, for
packing and cushioning. This paper presents the experimental results obtained for the mechanical
properties of polyurethane foams in different loading conditions and the influence of impregnation
on the mechanical properties. A 200 kg/m3 density polyurethane foam was tested in tension,
compression and three point bending. The experimental results show that the impregnation layer has
no effect on the strength of the foam, but has considerable influence on the tensile and flexure
Abstract: A series of low-cycle fatigue experiments of axial-torsional loading of variable
amplitudes were performed on the tubular specimens of 304 stainless steel. Two models of
multiaxial low-cycle fatigue life, KBM and FS method, are evaluated based on the fatigue life data
of 304 stainless steel. Rainflow cycle counting and the Liner Damage Rule are used to calculate
fatigue damage. It was shown that the part prediction results are nonconservative for the two models.
The life prediction is done again based on the weight function critical plane method for the two
models. The prediction results are better by using the weight function critical plane method than the
previous results for KBM model. But the prediction results are improved little for FS model in spite
of the weight function critical plane method being used.
Abstract: A shape memory alloy (SMA) torsion actuator is designed by using SMA wires and a
thin-walled tube. A mechanical model, which predicts the thermo-mechanical behaviors of the
SMA torsion actuator, is developed based on the knowledge of solid mechanics and constitutive
relation of SMA. The relationship of the torsion-angle and temperature of the SMA torsion actuator
is numerically described by using the mechanical model coupled with Tanaka’s, Liang’s and Zhou’s
phase transformation models of SMA respectively. Results show the mechanical model well predict
the thermo-mechanical behaviors of the SMA torsion actuator.
Abstract: The stress singularity eigen-equation for V-notch in a bi-material plate is obtained. A new
definition of dynamic stress intensity factor of a crack perpendicular to bi-material interface is put
forward, and then is extended to any V-notch in bi-material plate. A formula of stress extrapolation
method to calculate dynamic stress intensity factors of V-notch in bi-material plate is obtained. As an
example, the three points bending sample with two materials is investigated.
Abstract: A quantitative life prediction method has been proposed to evaluate fatigue life during
morphological evolution of precipitates in Ni-based superalloys. The method is essentially based on
Eshelby’s equivalent inclusion theory and Mori-Tanaka’s mean field method. The shape stability
and life prediction are discussed when the external stress and matrix plastic strain are applied. The
calculated results show that the fatigue life is closely related with microstructures evolution of
precipitates. The magnitude and sign of the external stress and matrix plastic strain have an
important effect on fatigue life of Ni-based superalloys during the morphological evolution of
Abstract: The elastic finite element analysis (FEA) and the experimental method of testing the
cleavage strength of the joint were used to investigate the effect of the recessing as well as its length
on the stress distribution in both the mid-bondline and the adherend near the interface along the
bondline of adhesively bonded steel cleavage joint. The results from the FEA simulation showed
that the peak values of the stresses distributed in the mid-bondline were nearly the same when the
length of the arranged recessing was not greater than 10 mm except that the shear stress Sxy was
increased a little when the length of the recessing was increased. For the normal stress Sy near the
interface of the joint with a 16 mm length recessing, the peak stress in the adherend is about 49%
higher than the one in the adhesive at the left edge of the joint. And it is supported with the results
from the experiments that the ultimate load of the steel-to-steel cleavage joint decreased a little
when the gap length was less than 10 mm.
Abstract: Based on a ductile frames 15 level building, a non-linear analysis with increased
monotonically lateral loads (Push-Over) was made in order to determine its collapse and its
principal responses were compared against the elastic and inelastic time-history seismic responses
determined with the SCT-EW-85 record. The seismic-resistance design and faced to gravitational
loads was made according to the Complementary Technical Norms of Concrete Structures Design
(NTC-Concrete) and the NTC-Seismic of the Mexico City Code (RDF-04), satisfying the limit
service states (relative lateral displacement between story height maximum relations, story drifts ≤
0.012) and failure (seismic behavior factor, Q= 3). The compressible (soft) seismic zone IIIb and
the office use type (group B) were considered. The non-linear responses were determined with
nominal and over-resistance effects. The comparison were made with base shear force–roof lateral
displacement relations, global distribution of plastic hinges, failure mechanics tendency, lateral
displacements and story drift and its distribution along the height of the building, local and global
ductility demands, etc. For the non-linear static analysis with increased monotonically lateral loads,
it was important to select the type of lateral forces distribution.