Applied Mechanics and Materials Vol. 159

Abstract: This paper presents a research progress on composition photoabsorber effect the solidification time and layer thickness of 3D structures fabrication using Liquid Crystal Display (LCD) projector as energy light source to initiate the photoreactive polymer. The polymer based material with composition of 1,6-Hexanediol dicrylate, Phenylbis(2,4,6-trimethylbenzoyl)- phosphine oxide with varied Sudan I concentrations was used to build 3D structures. The structure was fabricated using a three different photo absorber composition of Sudan I then the photoreactive polymer solidification phe¬nomena was evaluated. Based on the result obtained, higher exposed time of the photo absorber will reduced the surface roughness values and increased the solidification layer time. This work represents that photo absorber composition solution gave a different characteristics for 3D microstructure fabrication.

Abstract: There are multiple nonlinearities during the course of powder rolling and there is a difficulty for constructing its mechanical model and keeping the stability during the numerical calculation process. In addition, mechanical parameters determined by means of numerical simulation of rolling process are great significance both in theory and practical applications for the optimization of the process parameters and the design and manufacture of rolling equipment. Considering Material and Geometrical Nonlinearity during powder rolling, a constitutive model aiming to the powder rolling is constructed based on the Updated Lagrange (U.L.) formulation by which the basic theory of numerical simulation is deduced. The reasons are analyzed based on the experiments of powder rolling which led to the error during the numerical simulation and the effect of the different factors on powder rolling are analyzed. It is shown that the result of simulation is less than that of experiment and the whole result is dependable. The effect of various process factors is analyzed by the simulation of the rolling process and based on visual analysis of the simulation result, the primary and secondary factors affecting the relative density and the rolling force are obtained.

Abstract: Takes aluminum alloy ZL301 as an example, gets different surface roughness and cutting time under different cutter rotate speed and different overlapping rate with CNC engraving technique and analyses the reasons. The result is that the more of overlapping rate, the more cutting time, and the less of the surface roughness. While the overlapping rate≥50%, the roughness Ra≤6.3μm, while the overlapping rate≥70%, the cutting time increasing obviously. Consider the efficiency and the surface roughness, the best overlapping rate is from 50%～70%. The more of cutter rotate speed, the less of the surface roughness. While the overlapping rate≤70%, the cutter rotate speed almost no influence to the cutting time.

Abstract: In order to study the machine effects of using side-insulated electrode during the Micro electrochemical milling, a 704-silica material is firstly introduced to fabricate the side-insulation film on the micro ECM tool electrode by spin-coating technique. The 704-silica insulation film can effectively isolate the side of tool electrode with the electrolyte and eliminate the stray corrosion. With the side-insulated electrode, triangle, square and circle columns with vertical sidewalls were successfully machined in passivat sodium nitrate electrolyte. Moreover, the material removal rate is about 2.1×10⁴ μm³/s by using a tool electrode of Ф=100 μm in diameter.

Abstract: The aim of the work described in this paper is to investigate the implementation of Multi-core Parallel Genetic Algorithm (McPGA) for real-time turning of PID parameters based on it using OpenMP. The performance of our scheme is discussed in comparison with that of the Sequential Genetic Algorithm (SGA) program running on the same computer. Numerical experimental results clearly show that McPGA is much better than SGA on convergence, premature and optimized speed. It can be used for PID parameter real-time turning in Industry Process Control Computer (IPC).

Abstract: We report new results on a tunneling junction for tandem solar cells using a nano-structured amorphous silicon p⁺ layer (na-Si p⁺) as the recombination layer inserted between the n layer and the p layer. Devices were characterized by their dark current-voltage behavior (I-V), activation energy (E_a) and quantum efficiency (QE). The result shows that the tunnel junction with a na-Si p⁺ insertion layer has higher recombination rates with higher density of defect states of about 2.7×10¹⁹cm^-3 , lower resistance with activation energy of 22meV. The tunnel junction with a na-Si p⁺ insertion layer could be easily integrated into the tandem solar cell deposition process.

Abstract: As for the synthesis of polyester fibers based geopolymer, different fiber contents (0 %, 0.1 %, 0.2 %, 0.3 %, and 0.4 %) are investigated to obtain the optimum synthesis condition by flexural and compressive tests. X-ray diffraction analysis (XRD) and scanning electron microscope (SEM) are employed to explore the crystalline structure and microstructure of composites. Results show that the addition of 0.2 % fiber is considered as the most suitable proportion in polyester-geopolymers.

Abstract: The precision of ceramic component gotten by some Solid Freeform Fabirication processes based on paste extrusion is dependent to a considerable degree on paste extrudate. To get clearer understanding about paste extrudate, the experimental works were carried out to investigate some important extrudate features for ram extrusion process in this paper. The velocity, diameter, liquid content and mass of extrudate of alunima paste by ram extrusion were studied. The liquid content of extrudate tests show that the occurance liquid phase migration depends on the ram velocity. Without liquid phase migration, the extrudate velocities have a corresponding relations to extrusion force. The dilation of extrudate occurs in commonly used ram velocities. So extrudate velocities should not be calculated by nozzle diameter but by the average diameter of dilated extrudate. The mass of extrudate in the very end of extrusion is greatly reduced and should not be used.

Abstract: Based on unified strength theory, the equation for estimating the maximum reduction in thickness in a single sheet forming pass is obtained. Included the contribution of both intermediate principal shear stress and varying tension-compression-ratio to material mechanical property, the equation developed by this paper can reasonably apply to a wide range of material. It can be proved that the equation for estimating the maximum reduction based on unified strength theory becomes that based on unified yield criterion, when material has equal strength in tension and compression, i.e., the tension-compression-ratio of material is equal to units; and, that the values of the maximum reduction obtained previously based on Mises, or Tresca criterion, are all just special cases of those based on unified yield criterion. In addition, the maximum reduction in thickness for sheet drawing and extrusion is equal to one another.

Abstract: Blade is the key part of aeroengine. The main method for grinding blade is manual operation, which is inefficient. A new machine for grinding both sides of blade synchronically is proposed in this paper to improve the efficiency and machining accuracy. The modal analysis for the machine is demonstrated using ANSYS and the modal testing experiments verify the theoretical analysis.