Applied Mechanics and Materials Vols. 148-149

Abstract: During bars manufacturing and using process, the use of bars with cracks influenced the service life and sustainable work, on the premise of certain detection system, the choose of signal de-noising method plays an important part in magnetic flux leakage testing process, for which determining the global performance of testing equipment. This paper studies on magnetic flux leakage signals characteristic of cracks on the bar, analyzed the advantages and disadvantages of wavelet analysis and wavelet packet threshold de-noising, and on this basis, in order to give consideration to both the low and high frequency interference signal removing, adopted an integration method that combines wavelet packet threshold de-noising, wavelet packet decomposition and wavelet reconstruction, which greatly improved signal processing results.

Abstract: The curves of true stress-strain of AZ80 Magnesium alloy had been tested with thermal simulation experiment, at the conditions of the experimental temperature being 260°C~ 410°C, and strain-rate being 0.001~ 10s-1, and the deformation degree being 50％. According the Arrhenius equation, a kind of constitutive equation of AZ80 Magnesium alloy which considered the strain had been put forward, and the relative errors between calculation results by the stress-strain model and experiment results are less than 10.5%.

Abstract: We explored a new type alloy EAM potential (CLI-EAM) that the value of atomic electron density and pair potential between distinct atoms are obtained by Chen’s lattice inversion based on first-principles calculations. The alloy CLI-EAM potential acquired from NiAl alloy can also apply in Ni3Al successfully and the results of basic properties agreed with the experiments. The results of formation energy of point defects of NiAl and Ni₃Al alloy indicate that the structural defects are anti-site defects of Al when enrichments of Al atoms.

Abstract: The research on automatic tracking solar concentrator photovoltaic system research has become one of issues of solar PV technology. Aiming at the problem of cell performance degradation which caused by the non-uniform illumination in the concentrating photovoltaic system. A dish-style concentrating photovoltaic system with second stage concentrator was designed and built in this article. The author measured the performance of three junction GaInP/GaInAs/Ge solar cell. According to experiment result, the Pmm of solar cell was increased from 1.54 W/cm2 to 1.88 W/cm2. The η of solar cell was increased from 32% to 34.1% separately that compared with the concentrating photovoltaic system which without the second stage concentrator at the same concentration ratio(150X)

Abstract: This paper presents the performance characteristics of two surfaces in line contact under isothermal mixed lubrication with non-Newtonian liquid–solid lubricant base on Power law viscosity model. The time dependent Reynolds equation, elastic equation and viscosity equation were formulated for compressible fluid. Newton-Raphson method and multigrid technique were implemented to obtain film thickness profiles, friction coefficient and load carrying in the contact region at various roughness amplitudes, applied loads, speeds and the concentration of solid lubricant. The simulation results showed that roughness amplitude has a significant effect on the film pressure, film thickness and surface contact pressure in the contact region. The film thickness decrease but friction coefficient and asperities load rapidly increases when surface roughness amplitude increases or surface speed decreases. When the concentration of solid lubricant increased, friction coefficient and asperities load decrease but traction and film thickness increase.

Abstract: In this paper, a kind of giant magnetostrictive material (GMM) model based on inverse magnetostritive effect was developed. Van de Pol nonlinear difference item was introduced to interpret the hysteresis phenomenon of the strain-magnetic field intensity (MFI) curve of GMM. The coupling relationship between strain and frequency was obtained in partial least-square regression method to describe the driftage phenomenon of the strain-MFI curves of GMM in different frequencies. Based on above, the final relationship among strain, MFI and frequency was set up. The result of significance test shows that the effects of all of the items in the final model are remarkable, and that of forecast test shows that the model can describe the characteristics of inverse magnetostritive effect of GMM in different frequencies well. The new GMM model is easy to be analyzed in theory, which is helpful to sensor design.

Abstract: For the past two decades, several design support tools have been developed for both research and commercial purposes. Most are stand-alone tools; few are comprehensive or collaborative design environments. Agent technology is an emerging field and agent-based application design is still a pioneering discipline. The agent-oriented design is a new generation method of programming design that mainly uses the script language as a basis for development and that is suitable to design the multi-agent application system. Some tools have adopted the notion of computational agency. In the urban design environment, suppose design objects such as pavements, lamps and plazas can look after themselves and have its own behavioral mechanism, where would a design object acquire the knowledge that allows it to interact intelligently This paper investigates the question through the notion of objects as agents in design and the purpose of this research is to propose a coordinative mechanism of agents of spatial objects by establishing this design agent.

Abstract: This paper presents experimental investigations on influences of cooling air temperature, as well as cutting velocity, on performance in milling of the 1Cr18Ni9Ti alloy with coated cemented carbide inserts. Cutting force, tool wear and surface roughness are experimentally studied to compare the effects of different cooling air temperatures. The results showed that minimum quantity lubrication (MQL) with cooling air significantly reduces cutting force, tool wear. Three different cooling air temperatures are used to investigate the effects of cooling air temperature on the machinability characteristics of 1Cr18Ni9Ti alloy. Based on the experimental results, MQL with cooling air of −50°C provides more favorable effects compared to the other two cooling air temperatures (−10°C, −30°C). However, different cooling air temperatures have a slight effect on cutting force under the same MQL condition.

Abstract: Significant changes have taken place in service pattern for equipment health management and health management plays an important role in the lifecycle management of complex equipment. To resolve the existing problems in health management of complex equipment, this paper proposes a lifecycle-oriented health management philosophy, summarizes the connotation and basic characteristics of the philosophy. A three-dimensional model consisting of lifecycle level, health management knowledge level and application model level is constructed to realize the philosophy, which elaborates the components, developments and applications of equipment lifecycle health management. On that basis, key technologies for philosophy implementation are analyzed, which lays the foundation of system construction for lifecycle-oriented health management.

Abstract: The stress field distribution and change law of the friction surface are analysed in order to get the mechanism and characteristics of the wear pairs. The theoretical stress model of pin-on-disc pairs are observed according to the model of elastic half-space and the finite element model of it is built using the software of ABAQUS. The boundary condition and load are set and the stress change of the stationary state ,running-in period and stable situation are analysed respectively. The Mises stress ,contact stress and friction in different period are described and compared according to the simulated result of the finite element model.The experiment result shows the same characteristics of the simulation, so the advise is given to improve the frictional performance of the pin-disc pairs.