Applied Mechanics and Materials Vols. 52-54

Abstract: This paper presents an experimental investigation carried out to compare specific wear rate and surface morphology between Kenaf Epoxy Composite (KEC) and Carbon Fiber Reinforced Plastic (CFRP). Wear tests were carried out using Abrasion Resistance Tester (TR-600) in dry sliding conditions. These tests were performed at room temperature with different applied loads (5, 20 and 30N) and sliding velocity of 1.4m/s. Surface morphology of both materials was also examined before and after each test using an optical 3D surface measurement device. From the wear test, it was observed that the wear characteristics of KEC are comparative to those of CFRP. It was also found that the morphology of worn material composites in both cases exhibits a similar trend. This is a preliminary test for a future work on the enhancement of Kenaf Composites and the application.

Abstract: The paper analyzed the pressures and the temperatures in compression chambers to calculate the bending fatigue strength for small parameter scroll wraps, and a load model is proposed. For the small parameter scroll wraps, the pressure loads can be simplified on the mid-areas and the temperatures are equal to the temperatures of the mid-areas. The pressure loads are of π-region pressures which have a normal angle interval of π, the number of acting regions for pressure loads is equal to the number of scroll compression chamber pairs. Apart from the part situated in the center compression chamber, the temperatures of scroll wrap decrease linearly with the normal angle. Selecting the reasonable discharge, specifying the appropriate material and the parameters, and modifying the starting part of scroll wrap are significant methods to improve fatigue strength of scroll wraps in practice.

Abstract: In this paper, a novel studying-training algorithm of wavelet neural-network based on particle swarm optimization (PSO) was presented. Then it was compared with the traditional gradient descent algorithm by the fault classification experiment. The simulation result get a conclusion that the wavelet neural-network trained by PSO not only reduces the iterations, but also get the better convergence precision. It is further indicated that PSO algorithm is fit to train the wavelet neural-network and the optimized network has good signal classification ability.

Abstract: RETRACTED PAPER: A method of tool wear intelligence measure based on Discrete Hidden Markov Models (DHMM) is proposed to monitor tool wear and to predict tool failure. FFT features are first extracted from the vibration signal and cutting force in cutting process, and then FFT vectors are presorted and converted into integers by SOM. Finally, these codes are introduced to DHMM for machine learning and 3 models for different tool wear stage are built up. Pattern of HMM is recognised by calculating probability. The results of tool wear intelligence measure and pattern recognition of tool wear experiments show that the method is effective.

Abstract: Composite anodes made of NiO and SDC-(Li/Na)2CO3 were investigated in relation to their structure, morphology, and porosity. As a first step, the anode powder was prepared by mixing the NiO with SDC-(Li/Na)2CO3 via solid state reaction in weight percentage of 60 : 40 wt% and in various compositions of carbonates (20 and 30wt%), namely NiO-SDC8020 and NiO-SDC7030, respectively. The powder mixtures were then calcined at 680oC. The resultant powder was fine with surface area of about 13.10-13.70 m2/g and an average particle size of 0.32-0.37µm. The powders consist of two phases i.e. the cubic NiO and face-centered cubic structure SDC-(Li/Na)2CO3 as confirmed with x-ray diffraction. The microstructures were observed under scanning electron microscopy (SEM). The anode pellets were later compacted at different pressures (27, 32 and 37 MPa) and sintered at 600oC. The optimum porosity (20.99-24.78%) was achieved for samples of NiO-SDC8020 and NiO-SDC7030 sintered at 600oC and cold pressed at 32 and 37 MPa.

Abstract: In order to reduce workload of parameter identification for nonlinear mechanical model of metallic rubber, in this paper, based on parameters identification method of static experimental curves, experiments were designed, and data were processed, further aimed at hollow cylindrical metallic rubber, nonlinear dry-friction structural element model’ parameters were identified, what’s more, friction coefficient, radial stiffness, axial stiffness, and friction angle of stainless wire under room temperature were obtained. It was proved by simulation that parameters identification method in this paper was effective and accurate. Based on this, errors of simulation were analyzed elaborately.

Abstract: Simulation of sound wave propagation at the inlet of a jet engine is difficult due to the complex geometries of the propagation channel, so many simplifications are needed. A more realistic model is introduced in this paper to do the simulation. Dispersion-relation-preserving finite schemes are used in this paper where structured grids are designed by conformal mapping; the advanced perfectly matched layer absorbing boundary conditions are used to prescribe the input sound wave at the fan face of inlet. The advantages of the methods used in this paper are shown by two different cases.

Abstract: Using the signal amplitude domain, frequency domain, bearing shock pulse measurement of bearings, gear boxes, motors and other rotating machinery vibration parameters for key components, through the accumulation of historical data and diagnosis, to predict in advance of equipment failure, for maintenance work to help provide a reliable and assurance purposes. The results show that the system does for the routine maintenance of production equipment has played a guiding role.

Abstract: In this paper we have studied the streamfunction-vorticity formulation can be advantageously used to analyse steady as well as unsteady incompressible flow and heat transfer problems, since it allows the elimination of pressure from the governing equations and automatically satisfies the continuity constraint. On the other hand, the specification of boundary conditions for the streamfunction-vorticity is not easy and a poor evaluation of these conditions may lead to serious difficulties in obtaining a converged solution. The main issue addressed in this paper is the specification in the boundary conditions in the context of finite element of discretization, but approach utilized can be easily extended to finite volume computations.

Abstract: This study proposes a 3-axis AC servo motor parallel platform with intersecting rails. The 3-actuators are designed to be horizontally on the base platform with their extensions intersect in the base platform center. The forward kinematics, inverse kinematics and work space of this mechanism are established and the singularity distribution is investigated. Optimal maneuvering regions are recommended from the viewpoints of singularity and stiffness.