Abstract: To improve the edge detecting effect of the pressed character, a novel method based on
facet model and topographic structures is proposed. Firstly, the discrete gray scale image is
approximated by a bivariate cubic function, then, the concerned features of the continuous function
are computed to describe the discrete image. After every pixel in the image has been defined to Peak,
Ridge, Saddle, Flat, Ravine, Pit or Hillside, the edge of the character is detected. To reduce the time in
computing the coefficients of cubic function, an efficient separable algorithm is presented. In addition,
an image enhancement method prior to edge detection is adopted to improve the detecting effect. The
tests show that the proposed method is more suitable for complex edge detecting problems than
Abstract: The effect of filler shape and volume fraction on the micromechanical damage behavior
of particulate-reinforced dental composites was investigated using the finite element method. Threedimensional
unit cell models for various filler volumes and shapes, using hydroxyapatite in Bis-
GMA as a model system, were used. Young’s modulus and stress concentration factor were
calculated. The effects of filler shape on the ease of initiation of strain damage in the matrix and
onset of particle-matrix debonding are discussed.
Abstract: Nanocrystalline diamond film is an excellent material for high-tech fields because of its
excellent properties. In this paper, research was carried out on the synthesis and deposition
mechanism of nanocrystalline diamond thick film in the self-made double bias hot filament
chemical vapor (HFCVD) deposited system. Double biases including positive bias on the grid
electrode on top of hot filaments and negative bias on the substrate were added to the HFCVD
system. During the deposition, nucleation and growth stages were applied alternately to control
crystalline size and improve quality. The mechanism of the deposition is discussed in detail in this
paper. The positive grid bias increases the active, decomposition and ionization of hydrogen and
methane molecules, while negative substrate bias helps positive carbon-containing ions bomb the
substrate that leads to the high nucleation density of the diamond. Raman results show that the film
prepared has high quality. And SEM results show that the film’s grain size is less than 100nm with
thickness of 50μm.
Abstract: Accurately material constitutive model is essential to understand and predict machining
process. High temperature split Hopkinson pressure bar (SHPB) test system is used to investigate
flow stress behavior and characteristics of 7050-T7451 aluminum alloy. Specimens are tested from
200°C to 550°C at intervals of 50°C and room temperature, at strain-rate of 2800s-1. The experimental
results show that flow stress is strongly dependent on temperature as well as strain rate, flow stress
decreases with the increase of temperature, while increase with the increasing of strain rate. The
material parameters are determined for both Johnson-Cook constitutive equation and modified
Johnson-Cook constitutive equation. The modified JC equation is more suitable for expressing the
dynamic behavior of 7050-T7451 aluminum alloy.
Abstract: The theory of composite material patch winding is proposed to determine the winding
trajectory by a meshed data model. The bridge condition on the concave surface is considered in
this work. This paper puts forward the judgmental principles and corresponsive solutions by
applying differential geometry theory and space geometry theory. To validate the feasibility of the
patch winding method, the winding control code is programmed. Furthermore, the airplane inlet
winding experiments are carried out.
Abstract: Magnetorheological finishing (MRF) is a novel precision optical machining technology.
MRF utilizes magnetic particles, nonmagnetic polishing abrasives in carrier fluid, and a magnetic
field to finish optical materials. Owing to its flexible finishing process, MRF eliminates subsurface
damage, corrects surface figure errors and the finishing process can be easily controlled by computer.
To achieve deterministic finishing, it’s necessary to know the mechanism of material removal.
Different magnetorheological fluids are used to finish optical glass on the same machining condition.
The material removal and surface quality are examined after finishing with no polishing abrasive,
aluminium oxide and cerium oxide. The results show that the hardness of polishing abrasive is not the
main factors to affect material removal.
Abstract: The laser shocking to the Al2O3 ceramics was proceeded, and the fracture microphology
that formed from the strong laser shock processing (LSP) was analyzed by the Scanning electron
microscopy (SEM). It was discovered that the feature of ceramics responds differently when the
laser energy was changed. The brittle fracture that consists of intergranular fracture and cleavage
fracture was the main mode under high energy laser shocking (laser pulse enegry: 42J); the
macroscopical fracture characteristic was the radial crack. When the laser energy reduced to a fit
level (25J), the brittle fracture of ceramics appears to the characteristic of plastic deformation, its
fracture microphology appears lots of slippage lines, and the macroscopical feature of radial crack
under 42J become subulate crack. While the energy reduced to 15J, the Al2O3 ceramics did not
fracture, its micro-hardness ascended, a feature of micro-plastic deformation was existed under the
low energy. The reason of the brittle materials appears to the feature of plastic deformation was
Abstract: Guide rolls play an important role in controlling both the ring circularity and the stability of
cold ring rolling process. However, it is difficult to predict and control the motion of the guide rolls
due to the complexity of process associated with the coupled effects of multi-factors. In this paper, a
reasonable controlling model of the guide rolls is proposed, and the functional relationship between
the motion track of the guide rolls and their setup parameters and process ones is established, by
which the guide rolls motion track can be determined. On this basis, a 3D-FE simulation model for
cold ring rolling is developed under the ABAQUS software environment and the effects of the initial
position and motion track of the guide rolls on the forming stability, ring circularity, rolling force, and
oscillating are investigated. Taking the forming stability and ring circularity as objects, the optimum
initial position and motion track of the guide rolls are obtained.
Abstract: Based on the magnetorheological (MR) effect of abrasive slurry, this paper presents an
innovative superfine machining method. In this technique, the particle-dispersed MR fluid is used as a
special instantaneous bond to cohere abrasive particles and magnetic particles so as to form a
dynamical tiny-grinding wheel. This tiny-grinding wheel can be used to polish the surface of brittle
materials in millimeter or sub-millimeter scale. The characteristics of the machined glass surfaces
examined by the scanning electron microscope (SEM) and the Talysurf roughness tester confirmed
the effectiveness of the finishing technique. The machined surface with convex center and concave
fringe demonstrates that the material removal process is dominated by the synergy of the applied
pressure and the relative velocity between the abrasives and workpiece. In the case of glass finishing,
the mode of material removal is found to be plastic, and controlled by the abrasive-wear mechanism.
Abstract: Cone spinning is an advanced but complex metal forming process under coupled effects
of multi-factors. Understanding the deformation mechanism, i.e., the stresses, strains, and metal
flow in the deformation zone during the process is of great significance for optimizing the spinning
process and controlling the product quality. In this paper, based on ABAQUS/Explicit, a reasonable
FEM model for cone spinning with a single roller has been established, and the features of stress,
strain and wall thickness during the process have been obtained. The results show the following: (1)
In the beginning, large stress, large strain and the acute thinning of wall thickness localize at the
small region below the roller, then the region extends into a small ring, further it becomes a large
ring, and finally the ring will become uneven if the wrinkling occurs in the flange. (2) After
spinning, the acute thinning region locates at the midst of the wall near the bottom of the workpiece.
(3) At earlier stage of cone spinning, as a result of the acute thinning of wall thickness in the wall
zone, the unevenness of wall thickness increases sharply to a value, then it almost keeps the value at
the stable stage, and finally it will slowly increase again if the wrinkling appears in the flange. The
results are helpful for determination and optimization of process parameters of cone spinning.