Abstract: A system is developed on a 5-axes automatic scanning for ultrasonic test. It is a system
with the host-slave and open-loop mode that contains PC and a 5-axes drive card based on single
chip microcomputers. The system drives five stepper motors to carry the detector moving
paralleling the normal direction of the detected surface to complete the detect task.
Abstract: In order to obtain the projections with short cracks, a novel subvoxel model is proposed
for short crack simulation. Short cracks are modeled in subvoxel space. Giving an initial subvoxel
as an initial cracking point, a short crack is simulated according to the random growing mode. If
there are multiple initial cracking points, multi-cracks can be simulated easily, and short cracks are
visualized using CT. Limited by the resolution of real CT system, it is not possible to detect
individual short crack but a group of them. By pre-processing the reconstructed images, new images
are obtained, which are very close to actual conditions. The differences between the reconstructed
images without short cracks and the images with short cracks are analyzed. Experiment results
proved that it is feasible to detect short crack behavior by analyzing the grey level variance of the
Abstract: Femtosecond laser pulses are irradiated on a single-side polished single-crystalline silicon
wafer. Metamorphic zone appears around the ablated zone and the morphology changes gradually in
the metamorphic zone. Typical phenomena of thermal ablation such as melt-resolidification and
subtransparent glassy materials occur in the marginal area of the ablated zone. No apparent changes
are found among microscopic morphologies of the ablated, metamorphic and unirradiated zones.
There are flaws and spallations on the smooth back surface of the wafer, which are caused by the
stress inside the sample. Nanomechanical properties of the sample surface hardly change in the small
scope of the backside around the ablated zone. While regular changes occur in large scope, which is
the conjunct result of such stresses caused by many different collateral damages.
Abstract: By means of optical microscope(OM), scanning electron microscope(SEM), X-ray
diffraction(XRD) and shear test, the microstructure and mechanical property of 1Cr18Ni9Ti stainless
steel brazed joints with BNi-2 filler by electron beam brazing(EBB) and vacuum brazing(VB) are
investigated respectively. The results show that, the microstructures of brazed joint with BNi-2 by
EBB are mainly solid solutions of Ni. And the microstructures of brazed joint by VB are composed of
two parts: one part is a solid solution of Ni, which lies adjacent to base metal; another part is chemical
compound structures present in the centre zone of brazing seam. The shear strength of brazed joint by
EBB is higher than that of by VB. This is closely related with the microstructures of brazed joint.
Abstract: The photo-polymerization induced by Two-Photon Absorption (TPA) is tightly confined
in the focus because the efficiency of TPA is proportional to the square of intensity.
Three-dimensional (3D) micro-fabrication can be achieved by controlling the movement of the
focus. Based on this theory, a system for 3D-micro-fabrication with femtosecond laser is proposed.
The system consists of a laser system, a microscope system, a real-time detection system and a
3D-movement system, etc. The precision of micro-machining reaches a level down to 700nm
linewidth. The line width was inversely proportional to the fabrication speed, but proportional to
laser power and NA. The experiment results were simulated, beam waist of 0.413μm and TPA cross
section of 2×10-54cm4s was obtained. While we tried to optimize parameters, we also did some
research about its applications. With TPA photo-polymerization by means of our experimental
system, 3D photonic crystal of wood-pile structure twelve layers and photonic crystal fiber are
manufactured. These results proved that the micro-fabrication system of TPA can not only obtain
the resolution down to sub-micron level, but also realize real 3D micro-fabrication.
Abstract: Experiment setup of femtosecond laser pump probe was established, the time resolution
of time-delay setting reached 67fs. By use of femtosecond laser with width of 30fs and wavelength
is 796nm the dependence of transient change of reflectivity on delayed time in GaAs was measured
by pump-probe method. By calculating the change of complex index of refraction (%n), free-carrier
effect, lattice-temperature and carrier recombination contributions to relaxation curve was analyzed.
When the carrier density N is 1.44×1018/cm3, free-carrier contribution to refraction index %nFC is
-7.33×10-4, lattice-temperature %nLT is 0.85×10-4. Based on recombination rate equation,
recombination lifetime of 980ps was deduced.
Abstract: The connotation of ecological economic booster explosive has been defined firstly in this
paper. The ecological economic booster explosives green manufacturing process system
architecture and a general framework are provided. They are consisted of an assessing method for
manufacturing process, a modeling on rational proportioning for booster explosives, a modeling on
optimum control parameters of the manufacturing process and the rapid prototyping method of the
pellet used in the capability testing.
Abstract: Based on the metal cutting experiments, the forming model of feed direction burr is
proposed in the paper, a physical parameter of determining the generating of typeⅠ feed direction
burr — critical tool edge angle rI χ is given. And the main factors which influence rI χ are studied by
the experiment, and related theory analysis is made. Furthermore, some new controlling methods and
technology to restrain or decrease the feed direction burr in machining are developed.
Abstract: The structure and performance of the hardened layer in this paper has been researched by
means of transverse feed grinding 40Cr steel on a plane grinding machine, the result shows that
under the action of the grinding temperature field, there are different structural change rules and
distributing characteristics of micro-hardness. Although there is always a softened band, which is
made up of a transitional area and an unhardened area or a temper area in the hardened layer, the
reasonable softened band is conducive to the improvement of wear-resistant quality of a hardened
layer under the condition of oil lubrication.
Abstract: The purpose of this experimental research are investigation the growth behaviors of the
oxide layer at different pre-dressing conditions in ELID pre-dressing, effects of voltage and duty
ratio of the power supply, wheel speed on the oxide layer formation characteristics on the metal
bond diamond wheel surface. The results indicated that the oxide layer thickness on the wheel
surface increase with pre-dressing time. The oxide layer growth rate is faster in beginning period
time of pre-dressing process then slow down. Both the thickness and growth rate of oxide layer
increase with the increase of duty ratio and applied voltage. It takes longer time for oxide layer
growth rate to reach to stable state in lower duty ratio condition than in higher duty ratio condition.
There are no effects of wheel speed on oxide layer growth behaviors in the wheel speed range of
1000rpm to 4000 rpm.