Advanced Materials Research Vol. 510

Abstract: The nonlinear dynamics model of gearing system is developed based on RV transmission system. The influence of the nonlinear factors as time-varying meshing stiffness, backlash of the gear pairs and errors is considered. By means of the Lagrange equation the multi-degree-of-freedom differential equations of motion are derived. The differential equations are very hard to solve for which are characterized by positive semi-definition, time-variation and backlash-type nonlinearity. And linear and nonlinear restoring force are coexist in the equations. In order to solve easily, the differential equations are transformed to identical dimensionless nonlinear differential equations in matrix form. The establishment of the nonlinear differential equations laid a foundation for The Solution of differential equations and the analysis of the nonlinearity characteristics.

Abstract: The motion of amplification frame of dumper was simulated by multi-body dynamics simulation software ADAMS, and the danger working conditions of amplification frame were calculated. The stress of amplification frame was simulated and analyzed by Optistruct software. The results show that the stress distribution in amplification frame is not uniform and it is big in the middle and small in the edge zeros. The structure of amplification is optimized according to the simulation results. The utilization ratio of the material increases and the cost of production decreases after structural optimization.

Abstract: RNG (Renormalization Group) k-ε turbulent model was applied to the numerical simulation of turbulent mixing processes in the RQL gas turbine combustor, and SIMPLE algorithm was used to solve the finite difference equations. The calculated conclusions were used to analyze temperature distribution of the mixed flow field and near-wall region of the flow field, and then discuss the NO_x emissions. The results show that the effect of the injector zone geometry and the jet to crossflow momentum flux ratios on the NO_x emissions is obvious. The reasonable control of jet is beneficial to reduce the local high temperature area and is able to improve the distribution of the exit temperature. And then achieve the goal of reducing the environmental pollution.

Abstract: Based on VB platform, a stress redistribution and cutting simulation system of enlarging the hole of coal and rock is developed by using the computer technology, finite element analysis, the second development, combining with structure parameter selection and Object-Oriented Programming method as well as using VB to encapsulate ANSYS and writing APDL command to call the ANSYS calculation program. The soft provides a convenient parameters input and graphical interface, and has completed the preprocessor simulation solving of the model and analysis of the results. Even not capable of mastering the finite element theory and FEA soft, users can use the system to perform the stress analysis and simulation when enlarging the hole of coal and rock easily.

Abstract: In this article, L-ascorbic acid cellulose ester, a polymer with antioxidant properties, was synthesized using L-ascorbic acid and sodium carboxymethyl cellulose as feedstock. The whole reaction was divided into two parts: the preparation of carboxymethyl cellulose carbonyl chlorides and the synthesis of L-ascorbic acid cellulose ester. The optimal conditions of acyl chloride preparation: ratio (m/v) of CMCH to SOCl₂ was 1:3, proportion (m/v) of CMCH to DMF was 1:20, reaction temperature was 110-120°C, reaction time was 2h. The optimal conditions of L-ascorbic acid cellulose ester synthesis: ratio (m/v) of L-ascorbic acid to solvent was 1:3.5, proportion (Mol/Mol) of Carboxymethyl cellulose carbonyl chlorides to L-ascorbic acid was 1:1.3, reaction temperature was 20°C, reaction time was 22h. In this reaction conditions, the synthetic product not only saved the antioxidant activity of the groups, and added the safe and non-toxic ability of dietary fiber.

Abstract: The electron energy loss spectroscopy (EELS) of Ni in Ni₉₂TM₈ (TM=Ta, Nb, Mo, Cr, Mn) alloys and pure Ni has been collected. The d-electron occupancy of Ni is measured from the white-line intensity of EELS. It is found that the changes of d-electron occupancy of Ni is very small after alloying.

Abstract: In this paper, polyetheretherketone (PEEK) and polytetrafluoroethylene (PTFE) based composites reinforced with various amounts of potassium titanate whiskers (PTWs) or short carbon fibers (CF) were designed and fabricated respectively. The friction and wear properties of PEEK and PTFE based composites sliding under rigorous alkaline were comparatively investigated. Also, the morphologies of the worn and counterpart surfaces were studied by scanning electron microscopy (SEM). Because of the stable tunnel crystal structure and frame structure micro-reinforcement capacity, PTWs show outstanding performances in increasing the wear resistance and reducing the friction coefficients of both PEEK and PTFE based composites under alkaline. However, CF leads to the degradation of wear resistance and the increase of friction coefficient of PEEK based composites under alkaline. Furrows and abrasive wear were the main mechanisms for CF/PTFE/PEEK and CF/PTFE composites sliding in alkali. The results show that PTW/PTFE composites exhibit higher wear resistance under lower load, while PTW/PTFE/PEEK composite is more suitable for higher load under alkaline condition. Owing to the primary cooling and boundary lubricating effects of alkali, the wear rates and friction coefficients of PTFE composites and PTW/PTFE/PEEK composites decreased obviously, though the transfer films onto the counterpart steel surface were hindered considerably.

Abstract: TiO₂ samples with various shapes like flake, nanofiber and large grain were synthesized by template-free hydrothermal method with rutile TiO₂ or tetrabutyl titanate (Ti (OC₄H₉)₄, TBOT) as precursor. Photocatalytic degradation performances were investigated by using methyl orange (MO) as modeling pollutant. The results shown that pure mesoporous anatase TiO₂-Grain showed the highest photocatalytic activity (3.7 times higher than P25), which is due to a combinative effect of anatase phase and high specific surface areas. The bi-phase flaky TiO₂ also have higher activity than P25. While, nanofiber with TiO₂(B) phase has the lowest photocatalytic activity. The large sized TiO₂ grain can be separated and recycled easily after reaction.

Abstract: β-Ni (OH)₂ nanospheres have been successfully synthesized with nickel nitrate as nickel source and stronger ammonia water as precipitant by the hydrothermal method. The phase and the morphologies of the samples have been characterized and analyzed by X-ray diffraction (XRD) and Scanning electron microscope (SEM). XRD shows that the phase of the samples is β-Ni (OH)₂. SEM confirms that the increase of the reaction temperature is propitious to the synthesis of β-Ni (OH)₂ nanospheres, which are synthesized at at 180 °C for 48 h with pH=9 by the hydrothermal method.

Abstract: Linear low-density polyethylene (LLDPE)/nano-montmorillonite (nano-MMT) composites were prepared by melting method. Mechanical test, scanning electron microscope (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and small angle light scattering (SALS) measurements were used to characterize the mechanical properties and structure of the LLDPE composite. The results indicated that the impact strength of LLDPE decreased with the increase of nano-MMT content. However, the tensile strength firstly increased and then decreased. The aggregation of nano-MMT in LLDPE happened at larger content. The spherulite size and crystallinity of LLDPE reduced with the addition of nano-MMT. Furthermore, it was found that the structure of the spherulite was destroyed by the nano-MMT. The microcrystal size of LLDPE also decreased with the increase of nano-MMT content.