Single-point incremental forming （SPIF） is an innovational sheet metal forming method without dedicated dies, which belongs to rapid prototyping technology. In generalizing the SPIF of sheet metal, the deformation a...Single-point incremental forming （SPIF） is an innovational sheet metal forming method without dedicated dies, which belongs to rapid prototyping technology. In generalizing the SPIF of sheet metal, the deformation analysis on forming process becomes an important and useful method for the planning of shell products, the choice of material, the design of the forming process and the planning of the forming tool. Using solid brick elements, the finite element method（FEM） model of truncated pyramid was established. Based on the theory of anisotropy and assumed strain formulation, the SPIF processes with different parameters were simulated. The resulted comparison between the simulations and the experiments shows that the FEM model is feasible and effective. Then, according to the simulated forming process, the deformation pattern of SPIF can be summarized as the combination of plane-stretching deformation and bending deformation. And the study about the process parameters＇ impact on deformation shows that the process parameter of interlayer spacing is a dominant factor on the deformation. Decreasing interlayer spacing, the strain of one step decreases and the formability of blank will be improved. With bigger interlayer spacing, the plastic deformation zone increases and the forming force will be bigger.展开更多
We demonstrate an innovative preparation approach of diamond/Cu composites by powder-in-tube technique and rolling. A small copper tube was loaded with Ti- and Cu-coated diamond particles, mad then the diamond particl...We demonstrate an innovative preparation approach of diamond/Cu composites by powder-in-tube technique and rolling. A small copper tube was loaded with Ti- and Cu-coated diamond particles, mad then the diamond particles were combined with Cu matrix by composite rolling. The morphology and element distribution of the interface between diamond and Cu were determined by scanning electron microscopy and energy-dispersive spectrometer. Finite element method （FEM） simulation was used to analyze the rolling process associated with experiment by DEFORM-3D. The final experimental results showed that homogeneous distribution of diamond particles could be observed in the center layer of the composites. According to the contrast experiments, the sample, whose diamond particle size is 0.12-0.15 mm and thickness of pre-rolling is 1.2 mm, showed relatively complete morphologies and homogeneous distribution. Experimental results indicated a poor efficacy of excessive rolling reduction. The thermal conductivity of the composites is about 453 W （m K）-1 by theoretical calculation. For FEM simulation, roiling strain and temperature field of the composites were simulated by DEFORM-3D. Simulation results were interpreted, and numerical results verified the reliability of the model. The simulation predicted that the local area of large strain, indicative of the strain along the thickness direction, could be intensified by adding diamond particles.展开更多
This study reports the controllable surface roughening of Au-Ag alloy nanoplates via the galvanic replacement reaction between single-crystalline triangular Ag nanoplates and HAuC14 in an aqueous medium. With a combin...This study reports the controllable surface roughening of Au-Ag alloy nanoplates via the galvanic replacement reaction between single-crystalline triangular Ag nanoplates and HAuC14 in an aqueous medium. With a combination of experimental evidence and finite element method （FEM） simulations, improved electromagnetic field （E-field） enhancement around the surface-roughened Au- Ag nanoplates and tunable light absorption in the near-infrared （NIR） region （-800-1,400 nm） are achieved by the synergistic effects of the localized surface plasmon resonance （LSPR） from the maintained triangular shape, the controllable Au-Ag alloy composition, and the increased surface roughness. The NIR light extinction enables an active photothermal effect as well as a high photothermal conversion efficiency （78.5%）. The well-maintained triangular shape, surface- roughened evolutions of both micro- and nanostructures, and tunable NIR surface plasmon resonance effect enable potential applications of the Au-Ag alloy nanoplates in surface-enhanced Raman spectroscopic detection of biomolecules through 785-nm laser excitation.展开更多
基金supported by National Natural Science Foundation of China(No. 50175034).
文摘Single-point incremental forming （SPIF） is an innovational sheet metal forming method without dedicated dies, which belongs to rapid prototyping technology. In generalizing the SPIF of sheet metal, the deformation analysis on forming process becomes an important and useful method for the planning of shell products, the choice of material, the design of the forming process and the planning of the forming tool. Using solid brick elements, the finite element method（FEM） model of truncated pyramid was established. Based on the theory of anisotropy and assumed strain formulation, the SPIF processes with different parameters were simulated. The resulted comparison between the simulations and the experiments shows that the FEM model is feasible and effective. Then, according to the simulated forming process, the deformation pattern of SPIF can be summarized as the combination of plane-stretching deformation and bending deformation. And the study about the process parameters＇ impact on deformation shows that the process parameter of interlayer spacing is a dominant factor on the deformation. Decreasing interlayer spacing, the strain of one step decreases and the formability of blank will be improved. With bigger interlayer spacing, the plastic deformation zone increases and the forming force will be bigger.
基金supported by the National Nature Science Foundation of China (Nos. 51174028 and 51541406)
文摘We demonstrate an innovative preparation approach of diamond/Cu composites by powder-in-tube technique and rolling. A small copper tube was loaded with Ti- and Cu-coated diamond particles, mad then the diamond particles were combined with Cu matrix by composite rolling. The morphology and element distribution of the interface between diamond and Cu were determined by scanning electron microscopy and energy-dispersive spectrometer. Finite element method （FEM） simulation was used to analyze the rolling process associated with experiment by DEFORM-3D. The final experimental results showed that homogeneous distribution of diamond particles could be observed in the center layer of the composites. According to the contrast experiments, the sample, whose diamond particle size is 0.12-0.15 mm and thickness of pre-rolling is 1.2 mm, showed relatively complete morphologies and homogeneous distribution. Experimental results indicated a poor efficacy of excessive rolling reduction. The thermal conductivity of the composites is about 453 W （m K）-1 by theoretical calculation. For FEM simulation, roiling strain and temperature field of the composites were simulated by DEFORM-3D. Simulation results were interpreted, and numerical results verified the reliability of the model. The simulation predicted that the local area of large strain, indicative of the strain along the thickness direction, could be intensified by adding diamond particles.
基金This work was supported by the National Natural Science Foundation of China （Nos. 91323301, 21322105, and 51372025）, the Research Fund for the Doctoral Program of Higher Education of China （No. 2011101120016） and Program for New Century Excellent Talents in University （No. NCET-11-0793）. The authors would like to thank Prof. Chen Wang and Prof. Yanjun Guo of National Center for Nanoscience and Technology, China for AFM and SERS measure- ments and helpful discussions, respectively Dr. Haiwei Li for help on BET tests and helpful discussions.
文摘This study reports the controllable surface roughening of Au-Ag alloy nanoplates via the galvanic replacement reaction between single-crystalline triangular Ag nanoplates and HAuC14 in an aqueous medium. With a combination of experimental evidence and finite element method （FEM） simulations, improved electromagnetic field （E-field） enhancement around the surface-roughened Au- Ag nanoplates and tunable light absorption in the near-infrared （NIR） region （-800-1,400 nm） are achieved by the synergistic effects of the localized surface plasmon resonance （LSPR） from the maintained triangular shape, the controllable Au-Ag alloy composition, and the increased surface roughness. The NIR light extinction enables an active photothermal effect as well as a high photothermal conversion efficiency （78.5%）. The well-maintained triangular shape, surface- roughened evolutions of both micro- and nanostructures, and tunable NIR surface plasmon resonance effect enable potential applications of the Au-Ag alloy nanoplates in surface-enhanced Raman spectroscopic detection of biomolecules through 785-nm laser excitation.
