Abstract: The microstructures of Cu-Cr alloys with 2.0-4.2wt%Cr have been studied. Very little
dendritic copper was found in supereutectic Cu-Cr alloy containing 2.4wt%Cr. When Cr content
reached to 4.2wt%, square-like section Cr fibers other than round fibers were observed besides
primary dendritic chromium in the Cu-Cr alloy. The fibrous Cr particles are eutectic chromium
Abstract: This paper proposes a novel atomistic-continuum mechanics (ACM) based on the finite
element method (FEM) to investigate the mechanical bulk behavior of atomic-level single crystal
silicon under uniaxial tensile loading. The ACM could be reduced efficiently the computational time
and maintained the simulation accuracy. A general form of Stillinger-Weber potential function was
used for interaction between the silicon atoms in the ACM simulations. Simulation results shows that
the Young’s modulus of single crystal silicon were 121.8, 153 and 174.6 GPa along the (100), (110)
and (111) crystallographic plane, respectively. These results are in reasonable agreement with the
experiment and simulation results reported in the literature.
Abstract: Firstly the tension experiment was undertaken to investigate the mechanic behaviors of
the flange repaired composite panels in this paper. Emphases were played on the damage initiation
and the failure strength for the repaired composite structure. Then numerical studies were conducted
by using finite element method. The effect of geometric non-linearity on the stress-strain response
was taken into account through quadrilateral, thick shell elements (S8R). A better agreement with
experiment could be obtained when geometric non-linearity was considered. In addition, a user
material subroutine (UMAT) was implemented into ABAQUS for studying damage initiation and
its progression in the composite structure. Finally, all the predicted strain distributions, damage
development and strength of the repaired laminate were compared with experiments. The
predictions and experiments were found to be in good agreement.
Abstract: Phase-stepping photoelasticity has been used to study the fragmentation of an E-glass
fibre in epoxy resin and examine quantitatively the effect of a transverse matrix crack on the stress
transfer at an interphase. Unsized glass fibre was coated by plasma polymerisation with a
crosslinked conformal film of 90% acrylic acid and 10% 1,7-octadiene. The micro-mechanical
response at the fibre-matrix interphase and in the adjacent matrix has been described in detail using
contour maps of fringe order. From these, the interfacial shear stress profiles at fibre-break have
Abstract: Spherical alumina powder and dispersant were mixed with distilled and deionized water, and ball
milled to make alumina slurry. The slurry was dried in a high magnetic field to make a compact.
Subsequently, the compact was cold-isostatic-pressed (CIP) to enhance the homogeneity in particle packing
density. Anisotropy of shrinkage during sintering was examined for the alumina compacts in detail. Particle
orientation existed in the spherical alumina powder compacts prepared in 10T, and made them shrink
anisotropically during sintering. Sintering shrinkage was larger in the direction parallel to magnetic field
direction (i.e., the c-axis direction of alumina crystal) than that in its perpendicular direction. The particle
orientation structure in the compacts was confirmed with the immersion liquid method of polarized light
microscope, and the grain alignment structure in the sintered bodies was also observed with X-ray diffraction,
the c-plane was perpendicular to the magnetic field direction. On the other hand, isotropic sintering shrinkage
occurred in the spherical alumina powder compacts prepared in 0T, which did not hold the particle orientation.
The experimental results indicate that sintering shrinkage of spherical alumina powder compact depends on
alumina crystal axis direction. Origin of the sintering shrinkage anisotropy for the spherical alumina powder
compacts can be attributed to the particle orientation caused by high magnetic field.
Abstract: The aim of this study is to evaluated the possibility of the in-situ synthesized (TiC+TiB)
reinforced titanium matrix composites (TMCs) for the application of structural materials. In-situ
synthesis and casting of TMCs were carried out in a vacuum induction melting furnace with Ti and
B4C. The synthesized TMCs were characterized using scanning electron microscopy, an electron
probe micro-analyzer and transmission electron microscopy, and evaluated through thermodynamic
calculations. The spherical TiC plus needle-like and large, many-angled facet TiB reinforced TMCs
can be synthesized with Ti and B4C by a melting route.
Abstract: Compressive experiments and finite element method (FEM) have been used to study the
mechanical behavior of composite laminate with plies drop-off. A user subroutine has been
implemented to ABAQUS to simulate the damage development of the laminate plate. This user
subroutine has taken consideration of the mechanical properties degradation according to
development of three types of damage. The load-strain curves can agree with each other between
experiments and FEM. The detail of damage development of the plies drop-off composite laminate
under compressive loading can be described as followed. Matrix cracking damage and fiber-matrix
shearing damage occur simultaneously at first, and then fiber buckling damage initiates. Matrix
cracking and fiber-matrix shearing are very dangerous to the carrying capacity of laminate and fiber
buckling intensifies further this effect. The initiation and development of fiber buckling indicates
that laminate loses carrying capacity at all.
Abstract: In this paper the relationship between CAI and compressive design allowables of
composite structures were discussed and it was pointed out that traditional CAI values could not
reflect the behavior of composite materials to withstand impact adequately and no relationship
between CAI values and compressive design allowables existed. Based on the integrity requirements
of composite structures, it was pointed out that the evaluation system of composite materials to
withstand impact should include both damage resistance and damage tolerance. Large numbers of test
data verified that the knee point phenomenon of composite laminates to withstand impact existed.
Based on failure mechanisms, it was proposed that the behavior evaluation system of composite
systems to withstand impact was based on the properties at the knee point, that is, the maximum
capability to keep integrity of the front plies (the maximum contact force) characterizing damage
resistance and the threshold of dent depth(or impact energy)~compressive strength(or failure strain)
curves characterizing damage tolerance.
Abstract: Iron-hercynite composite was synthesized from Al and Fe3O4 powders by reaction sintering
at ~1350oC, or by arc-melting. In reaction sintering, a three-step displacement reaction between Al
and Fe3O4 was identified. In arc-melting, we observed that molten iron and hercynite segregated from
each other readily. Magnetization of the extracted hercynite from the arc-melted sample was 4 emu/g,
smaller than those previously reported, and this can be explained by the variations of the
stoichiometric ratio and the degree of inversion of the spinel structure in the hercynite products.