Applied Mechanics and Materials Vols. 201-202

Abstract: Some glass fiber/vinyl ester resin composite laminated panels were fabricated by varying levels of resin temperature, resin bleeding time and vacuum level. Interlaminar shear tests were performed to investigate the effects of process parameters on interlaminar shear strength (ISS) of laminated panel. The optimization of processing parameters was also conducted by employing the method of Artificial Neural Networks (ANN) in order to improve the ISS of laminated panel. The optimized test results are: resin temperature 30°C, resin bleeding time 7s, vacuum level 97KPa, and the result of ISS is 41.2MPa

Abstract: The filling capability is important for forging die design, which influences the quality and life of the die. To obtain the know-how of the deficiency for the filling capability, numerical simulation was performed to analyze the hot compression of Ti75 alloy with DEFORM-3D. In the simulation, the reducing height and work-piece dimensions remain the same. We obtained the results including the process of hot compression, the forming behavior of the work-piece and the effect of work-piece dimensions on the distribution of the stress and strain.

Abstract: The materials removal rate (V/VB) was selected to be objective function. It is comprehensive parameter about materials and tools wear. Through turning glass ceramics experimentation, the materials removal influence of cutting speed, cutting depth and feed speed were study. Based on least square method, the multiple regression prediction model of materials removal rate was built. And the model was tested. It was applied to predictive and control. The results indicated: this model was well to express materials removal law in turning glass ceramics. The multiple regression prediction model is high remarkable. The prediction value was coincident with measure value. This model is high reliability. So, expect materials removal rate can been obtained by this model, and choosing the technological parameter can been guided.

Abstract: In the face of the mechanical part of shape complex, the surface is difficult to be finished by the automatic and effective methods, but the magnetic fluid mixed with the polishing and cutting particles has motion characteristics in magnetic field. This paper introduces a kind of polishing technology which can rotate magnetic polishing fluid in the influence of magnetic field. The viscosity and hardness of magnetic polishing fluid change under the magnetic field, and the magnetic polishing fluid rotates in the fluence of the magnetic stirring apparatus, when machining magnetic in the liquid in polishing, and fixed in the liquid in proper position. When we select the best position in the magnetic polishing fluids and immerse the workpiece in the magnetic polishing fluids, the magnetic fluids rotate and move relatively to the workpiece. The friction between the magnetic fluid and the surface of workpiece has the finishing efficiency. The experiment is carried out to study the relation of the roughness and polishing and location on the home-made polishing laboratory platform in detail. The experimental results show that the rotating magnetic polishing liquid can be used for polishing the workpiece in super smooth processing, which is much better than polishing abrasive alone in reducing surface roughness. The study opens a new field for the application of the magnetic fluid. However, the direction of the field, the speed of the movement, and the polishing time of the process parameters still needs further research.

Abstract: The principles of jet electrodeposition orientated by rapid prototyping were introduced , The nanocrystalline nickel parts with simple shape were fabricated using jet electrodeposition oriented by rapid prototyping. The microstructure and phase transformation of nanocrystalline nickel were observed under the scanning microscope and X-ray diffraction instrument . The results show that the successful fabrication of metallic parts demonstrates the potential of the jet electrodeposition process for prototyping technology . The jet electrodeposition can greatly enhance the limited current density, fine crystalline particles and improve deposition quality. The nickel parts prepared by jet electrodeposition own a fine-grained structure( average grain size 25.6nm) with a smooth surface and high dimensional accuracy under the optimum processing parameters..The dimensional accuracy as well as the surface quality of metallic parts and tools manufactured using jet electrodeposition techniques still lag far behind those of conventionally machined parts.

Abstract: The in-situ synthesized TiC particle reinforced high chromium Fe-based ceramics composite coating was fabricated on the substrate of Q235 steel by plasma cladding process using Fe-Cr-Ti-C composite powder as reactive material. Microstructure of the coating was observed by scanning electron microscope (SEM), the phases were determined by X-ray diffraction (XRD), and the wear resistance was evaluated under dry sliding wear test conditions at room temperature. Results indicate that the composite coating consists of the reinforcing TiC carbide, (Cr,Fe)7C3 eutectic as well as austenite, and is metallurgically bonded to the Q235 steel substrate. The gradient distribution of TiC carbides is observed. TiC particles present in the granular shape in the fusion zone and central zone while present in the dendritic shape on the surface of the composite coating. Hardness of the coating from surface to fusion zone varies a little; the average hardness of the coating is about HV0.2750 which is 3.2 times as much as that of the base. The wear mass loss of Q235 base material is 13 times higher than that of the composite coating.

Abstract: In this paper, the forming limit of a body-centered cubic (BCC) sheet metal under non-proportional strain-path is investigated by using the Marciniak and Kuczynski approach integrated with a rate-dependent crystal plasticity model. The prediction model has been proved to be effective in predicting Forming Limit Diagram (FLD) of anisotropic sheet metal with FCC type of slip systems[1]. The same model has been used to study the FLD under non-proportional strain-path of BCC slip systems numerically and experimentally. The agreement between the experiments and simulations is good. With crystal plasticity model well describing the crystal microstructure effect, our model can be used to predict the FLD of BCC sheet metal under complicated strain path in plastic forming process with good accuracy.

Abstract: With equipment renewal of machining and people's demand on the green environmental protection sustainable development, green processing technology of mechanical processing process in mechanical field is becoming a development direction. The traditional method of processing hole removes a part of the general hole sheet metal, so that the depth of the hole is equal with the thickness of the board. In this paper, the new technological process to form deep hole on relative thin panel by friction heat not only saves material, but also saves man-hours, and the workpiece has a good piece of assembly. Because the processing technic is belong to local thermal processing, the microstructure and property (hardness) of heat affected zone are studied in this paper. The study results are useful to look for more appropriate machining parameters, and laid a foundation for further research on forming deep holes process on thin sheet metal by friction heat.

Abstract: Microstructure evolution is an effective means to improve the mechanical properties of products, shaft parts formed by cross wedge rolling is not only the shape of the formed parts, but more importantly it improves the comprehensive mechanical properties of the products by deformation. Therefore, the paper sets up the coupled rigid-plastic finite element model with deformation-heat transfer-microstructure by using nonlinear finite element method, and this model is adopted to make simulation calculation for the forming techniques of asymmetric shaft parts of cross wedge rolling based on parity wedge, specifically analyzes the rule of dynamic recrystallization and grain size distribution in the asymmetric rolled parts. The results show that the grain in the wedging place of asymmetric shaft parts of cross wedge rolling based on parity wedge can be obviously refined, and the research results of this paper may provide theoretical foundation for further improving the quality and mechanical properties of asymmetric shafts parts of cross wedge rolling.

Abstract: Metal vapor plume which induced during high power disc laser welding contains lots of information that related to the welding quality. Stainless steel 304 was taken as the experiment object for the high power disc laser welding experiment. A high-speed camera was used to capture the ultraviolet band and visible light band metal vapor plume images in the laser welding process. Image processing techniques such as median filtering, Wiener filtering, gray level threshold and image binarization were applied to get the images that only metal vapor plume was included. The ratio of the absolute value of coordinate difference between the centroid of plume and welding point was taken as the characteristic parameter. Welding experimental results and analysis of the changing of the ratio of the absolute value of coordinate difference between the centroid of plume and welding point confirmed that the welding quality could be monitored by the metal vapor plume during high power disc laser welding.