Advanced Materials Research Vols. 148-149

Abstract: A polymerization between 1,4-diaminobenzene (PPD) and acrylic acid catalyzed by Horseradish Perodxidase (HRP) in an water buffer will be described in this article. The effects of the concentration of H2O2, the ratio of the acrylic acid to PPD, the pH of the buffer, and the reaction time of polymerization were investigated. Compared with conventional methods, the synthesis is simple and the conditions are mild. The conductivity, UV-vis spectra, FT-IR spectra, X-ray photoelectron spectroscopy (XPS), and the thermo-gravimetric analysis (TGA) of the resulting polymer were investigated also. The results show that the synthesized polymer (PAnI) is a self-doped poly(1,4-diaminobenzene-acrylic acid) with 1,4-disubstituted aromatic ring, and a higher electro-activity, water-solubility, its decomposition temperature is 498.8 °C.

Abstract: Traditional feedback linearization approach (TFL) requires a priori knowledge of plant, which is difficult and the computational efficiency of controller is low due to complex dynamics of plant. In order to improve the tracking performance of hydraulic parallel machine tool and limit the drawbacks of TFL, a novel approximate feedback linearization approach is proposed in this paper. The mathematical models of hydraulic parallel machine tool are established using Kane method and hydromechanics. The approximate feedback linearization control is designed for the parallel machine tool in joint space, with the position and the stored data in the previous time step are employed, as a learning tool to yield improved performance. Under Lyapunov theorems, the stability of the presented algorithm is confirmed in the presence of uncertainties. Simulation results show the proposed control is readily and effective to realize path tracking, it exhibits excellent performance and high efficiency without a precision dynamics of plant. Moreover, the presented algorithm is well suitable for most industrial applications.

Abstract: Blades are the key parts of turbines. The materials used for making blades have many excellent performances such as high intensity, corrosion resistant and temperature resistant. They are of hard to machine materials. However, there is little information available in the literature related to abrasive belt grinding blades materials. And its mechanisms have not yet been fully explained. This paper aims to make a contribution to the understanding of the wear mechanisms of the abrasive belt and its influence factors. A series of tests were conducted on 1Cr13 stainless steel. The surface roughness and the surface topography of abrasive wear were observed. The influences of grinding force and grinding time on surface roughness were discussed. The wear mechanisms are revealed based on the model of abrasive grain’s wear. It revealed that existence of an optimum surface roughness reachable dependent of the grinding force and grinding time. It has also been shown that the type of abrasive and grinding depth have great influence on abrasive wear.

Abstract: This work aims to develop a physically based numerical model to predict the microstructure evolution and residual yield strength of high Cu/Mg ratio Al-Cu-Mg-Ag alloys after thermal exposure. Based on the established interfacial energy model and the classical nucleation and growth theories, a thermodynamically based precipitation model had been established to describe competitive precipitation of two phases, being of different stability, in under-aged and the subsequent thermally exposed Al-Cu-Mg-Ag alloys. And the strengthening model based on Orowan mechanism was deduced to predict the residual yield strength after thermal exposure. The microstructural evolution and yield strength predictions of the model in this work are generally in good agreement with the experimental result.

Abstract: Dynamic model and equation of a nonlinear flexible rotor-bearing system are established based on rotor dynamics. A local iteration method consisting of improved Wilson-θ method, predictor-corrector mechanism and Newton-Raphson method is proposed to calculate nonlinear dynamic responses. By the proposed method, the iterations are only executed on nonlinear degrees of freedom. The proposed method has higher efficiency than Runge-Kutta method, so the proposed method improves calculation efficiency and saves computing cost greatly. Taking the system parameter ‘s’ of flexible rotor as the control parameter, nonlinear dynamic responses of rotor system are obtained by the proposed method. The stability and bifurcation type of periodic responses are determined by Floquet theory and a Poincaré map. The numerical results reveal periodic, quasi-periodic, period-5, jump solutions of rich and complex nonlinear behaviors of the system.

Abstract: A searching strategy of Multidisciplinary Design Optimization (MDO) which is based on Orthogonal Design of Experiments is put forward. Through the optimization, the quality of piston decreased 4.6%. The stress by coupling thermal load and mechanical load was computed. The result shows that the mechanical load, which is affected mostly by height of fire field, is the major stress.

Abstract: Compared with the traditional vibration sensors, the micro-vibration sensor have many advantages, such as small size, high sensitivity and low noise which is based on micro-fabbrication.This paper introduced the micro-vibration sensors which sensitive structure are cilium and micro-elastic beams. The micro-vibration sensors were produced by the inductively coupled plasma technology (ICP), the maximal etching depth of which can be greater than 300μm, the thickness of beam is less than 20μm and the longth of cilium are more than 3000um.The sensitivity of the sensor is 102.5μV/g, the measurement range to +20g, and the resonant frequency is 2KHz.

Abstract: The parameters obtained in the study of single layer of laser cladding forming are not suitable for the forming of actual structures. The cooling condition varies with the height of clad layers, which result in instability and then failure of cladding. Therefore, the stability of laser cladding forming is of significance. In this paper, melt pool depth is used as a criteria for stability. And the effect of processing parameters such as laser power and laser velocity on melt pool depth, are investigated by numerical simulation method. The results unveil that there is a transition zone from the beginning to stable stage during laser cladding forming. In the transition zone, laser power should be decreased or laser velocity should be increased to maintain the constant melt pool depth and to ensure the former clad layer would not be remelt. The optimized processing parameters are obtained for stable processing for a thin flat wall and a cylindrical wall, which successfully guide the manufacturing of the real structures.

Abstract: The heat transfer in steel continuous casting process under mold oscillation was calculated, and temperature fluctuation phenomena was found in the initial solidification area, the maximum value was approximate 16 °C. The effect of different continuous casting parameters on temperature fluctuation were analyzed, and the temperature fluctuation was considered to be a key factor to the formation of oscillation marks. The Index of Temperature Fluctuation(ITF) was proposed to predict the effect of temperature fluctuation on the formation of billet surface defects.

Abstract: The kinematics model of planar closed-loop five-bar mechanism is established in this paper. The influence of mechanism’s input parameters on the output kinematics parameters is investigated by simulation. The five-bar mechanism is designed. The experimental system of hybrid actuators five-bar mechanism is established based PID control method. The experiment investigates the influence of mechanism’s input parameters on the output kinematics parameters. The results show that the mechanism’s output kinematics parameters depend on input parameters. The original angle of input bar is bigger, curves of kinematics parameters of output bar change more acutely. Applying PID control algorithm to control the hybrid actuators linkage, the real kinematics parameters of linkage are almost consistent with theory values and the error is less.