Applied Mechanics and Materials Vols. 633-634

Abstract: According to different printing materials, this paper has classified the types of 3D printers, discussed the characteristics and suitable material and application of various types of 3D printing technology, and put forward the future direction. Fund: Natural Science Foundation of Shandong Province (ZR2010EL015)

Abstract: Surface integrity, such as surface roughness and residual stress, is an aspect of surface quality on machined parts. Residual stress in the machined surface and subsurface is affected by materials, machining conditions, and tool geometry. These residual stresses could affect the service qualify and component life significantly. Residual stress can be determined by empirical or numerical experiments for selected configurations, even if both are expensive procedures. This paper presents a hybrid neural network that is trained using Simulated Annealing (SA) and Levenberg-Marquardt Algorithm (LM) in order to predict the values of residual stresses in cutting and radial direction after the MQL face turning process accurately. To verify the performance of the proposed approach, the predicted results are compared with the results obtained by training an ANN using SA and LM separately. The results have shown that the hybrid neural network outperforms SA and LM in predicting machining induced surface integrity that is critical to determine the fatigue life of the components.

Abstract: Surface roughness is an important outcome in the machining process and it plays a major role in the manufacturing system. Prediction of surface roughness has been a challenge to researchers because it is impacted by different machining parameters and the inherent uncertainties in the machining process. Prediction of surface roughness will benefit the manufacturing process to be more productive and competitive at the same time to reduce any pre-processing of the machined workpiece in order to meet the technical specifications. In this study, a hybrid GA-LM ANN is proposed for the prediction of surface roughness during roughing process in turning operation. To verify the performance of the proposed approach, the results are compared with the results obtained by training an ANN using GA or LM. The results have shown that the hybrid ANN outperformed the other two algorithms.

Abstract: The wood were treated by N₂,O₂ cold plasma with the processing power 300W, the treatment duration 5 min, then the treated wood was bonded with MUF to valve the bonding performance, the contact angles of the treated/untreated wood were tested. The chemical composition on the surface of wood with or without N₂ cold plasma treatment also was analyzed by X-ray photoelectron spectroscopy (XPS). The results showed: the contact angles of the surface decreased, the surface free energy increased evidently that treated by N₂ or O₂ cold plasma, and the average bonding performance of wood that treated by cold plasma (whether N₂ or O₂ ) increased obviously, more than 50% comparing with that untreated. The XPS analysis showed the atomic ratio O/C has increased, and more groups were oxidized or more peroxides were formed on the surface of wood, and the N element was introduced to the wood surface after nitrogen cold plasma treatment and it was guessed to the group of –NH₂.

Abstract: The importance of the axial rolling torque to design equipment and process is described. On the basis of the established formula of axial rolling force, the formula of axial rolling torque is derived by using the moving volume theory of energy method. The influence of processing parameters on the axial rolling torque is investigated. It is found that the axial rolling torque increases with the increase of the outer diameter of ring, and the axial rolling torque decreases with the increase of the inside diameter of ring. The greater the feed in axial direction, the greater the axial rolling torque. The correctness of the formula is verified by calculating actual examples.

Abstract: Taking the local parts of high-speed training service as the research object, the static form of the finite element model is established, and the dangerous parts of the stress distribution under different load form corresponding to loading and displacement conditions applied in experimental test is calculated. Fatigue life of the same welding parts of the different forms due to the state of the uniaxial tensile and the bending is respectively tested in the lab, the life distribution and characteristics of their statistics are obtained; Compared to the stress distribution of dangerous parts and data of the test, analysis that the similar parameters of life and failure forms can be received if it choose the reasonable load parameters in different form and loading in the test.

Abstract: The 2 mm sheet of 6082 - T6 aluminum alloy was carried to develop refill friction stir welding and withdrawing friction stir spot welding,the forming of solder joints , the cross-sectional microstructure and fracture morphology of welding joints were observed and analyzed, the cross-sectional microhardness of welding joints were tested. Tensile shear load and fracture mode were contrasted simultaneously. The results showed that smooth surface and free of macroscopic defects of welding joints could be obtained in both welding type. Tensile shear load of WFSSW was up to 10.28kN under the optimal process parameters greater than RFSSW’s 8.62kN.

Abstract: Instability criterion is an important factor to affect the accuracy of forming limit diagram (FLD), which signifies the strain state of metal material when material reaches forming limit. In this paper, conventional localized instability criteria during plastic forming of sheet metals are discriminated by various deduced methods based on plastic instability theory and experiment phenomena. The features, application in FLD of the instability criteria and challenges in future are described.

Abstract: In the course of ongoing development of riveting technologies, various methods were developed in the last years. Riveting is one of the most important joining methods. Nowadays, pre-hole riveting methods have been widely used in aviation, automobile and other fields because of its advantages of simple joining process, low cost and light weight. This paper mainly presents several typical pre-hole riveting methods. Their technical characteristics, working principles and research status are introduced. Also, this paper proposes the limitations and future focuses of typical pre-hole riveting methods.

Abstract: This paper studies the development of cutting strategy in the fabrication of freeform surface in ultra-precision raster milling (UPRM). The tasks of developing cutting strategy in freeform machining involve in the selection of cutting parameters and the planning of tool paths. An integrated system is built in this study to develop the cutting strategy, automatically generate NC program, simulate the tool paths and machining process, as well as make predictions for the machining time and the surface quality of the raster milled freeform surface. Experiment is conducted to verify the developed system and the experimental results show that the system is applicable for the machining of freeform surface in UPRM. This study therefore contributes to avoiding the need to conduct expensive and time consuming trial cutting tests to ensure the product quality in the freeform machining.