Mechanical and Aerospace Engineering, ICMAE2012

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Authors: Tung Sheng Yang, Sheng Yi Chang, Jian Chang Chou
Abstract: Scratch test is mainly used to study mechanical properties of materials near their surface. This study applies the finite element method (FEM) in conjunction with an abductive network to predict the scratch character such as rear contact angle, shape ratio and hardness for strain hardening bulk material of scratch process. To verify the prediction of FEM simulation of scratch process, the experimental data are compared with the results of current simulation. A finite element analysis is also utilized to investigate the material properties on side view contour, rear contact angle, hardness and shape ratio. Additionally, the abductive network was applied to synthesize the data sets obtained from the numerical simulation. The prediction models are then established for the rear contact angle, hardness and shape ratio of nanoscratch process under a suitable range of material parameters.
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Authors: Adrian Olaru
Abstract: In the paper are shown one assisted method of the control orientation inertial mechanism of the small satellite. It is presented some of the general components of the small satellite and the possibility to orientation them between three axes using the inertial pulse of the electrical motors. The angular space position was determines by command of the final point and using the proper neural network to solve the inverse kinematics problem with the minimum of the errors. The precision of the space orientation position was increased by using in the proper controlling schema a direct kinematics module, direct and inverse dynamics, intelligent damper and one multiple inertial pulse method what was described in the paper. Finally was obtained one very good precision, before 2%.The neural network, the inertial pulse method, the results and the virtual LabVIEW instrumentation could be used in many other researches on the field.
665
Authors: Bouzouane Bélaid, Nacer Hamzaoui
Abstract: Various methods are implemented to identify the nature of a defect on a rotating machine, by using vibratory measures; they differ in their precision, simplicity of implementation and their sensitivity to errors measurement. The identification of several defects combination is still difficult to implement by conventional signal processing, as the vibration signal that emerges is disturbed, thus making any identification so hard. In this study, we proposed a method based on the neural networks to identify one defect or several combinations of mechanical defects. Thus we propose the neuronal method: the Radial Basis Function (RBF). We highlight their capacity to detect the defect and their sensibility with regard to a signal noise characterizing the other independent sources to the defects. This evaluation will be done with measurement will be carried out on a housing bearing and test bench made up of a toothed gearing on two floors, and without lubrication. Some provoked defects will be analyzed in this study.
674
Authors: Dao He Hao, Liang Wu
Abstract: The global stability properties was discussed for the neutral-type Hopfield neural networks with discrete and distributed time-varying delays .Based on the Lyapunov functional stability analysis and the linear matrix inequality approach, a new sufficient condition was derived to assure the global stability properties of the equilibrium. The criterion improved and extended the results of literature, and has less conservative.
682
Authors: Benmessaoud Abdelkader, Badaoui Mohamed, Hachi Brahim El-Khalil, Nehar Camellia Khaira, Guesmi Mohamed
Abstract: The aim of this paper is the determination of the evolution of the modal stress intensity factor (MSIF) for a non-propagating crack subjected to dynamic loading using the extended finite element method (X-FEM). The main advantage of this method coupled with the modal analysis is its capability in modeling cracks independently of the mesh and in a reduced computational time compared to the finite element method coupled with dynamic iterative method. The proposed procedure is applied to a reference problem (cracked plate). The MSIFs obtained agree well with those found by indirect boundary element (IBEM), weight function and Newmark’s explicit methods.
686
Authors: Elhefny Amr, Guo Zhu Liang
Abstract: Turbopump unit is a key component of the liquid rocket engine assembly and in this paper stresses of a turbopump turbine are investigated using finite element (FE) analysis. Three-dimensional solid modeling of a group of blades and a sector of the disc was first created on CAD software and subsequently exported to a FE package for analysis. The FE results reveals that the maximum stresses in the blades result from rotational and thermal loads owing to the relatively high operating speed and temperature of the turbine and they are located at the root of the blades. Also, the maximum stresses in the disc result from rotational and thermal loads, but with higher values than those in the blades and they are located at the center of the disc. The result of this study may serve as a guideline in the selection of the materials for both the disc and blades.
691
Authors: Muhammad Iqbal Sabir, Er Bao Liu, Zhen Li, Yu Feng Zheng, Li Li
Abstract: Biodegradable magnesium alloy stents have gained increasing interest in the past years due to their potential prospect. Magnesium alloy is brittle compared with stainless steel. This means it has less elongation than other stent materials and it may cause strut break under large deformation. In this paper, a finite element model for magnesium alloy stent is studied to simulate the mechanical behavior of the stent. It is composed of 1.5mm in inner diameter, 7mm length, 80µm thickness and 110µm in cross-sectional width. Six mechanical properties have been studied by mathematical modeling with determination of: (1) stent deployment pressure; (2) the intrinsic elastic recoil of the material used; (3) the stent foreshortening; (4) the stent coverage area, (5) the stent flexibility; and (6) the stress maps.
697
Authors: Yi Li, Dong Liu, Bo Wang, Xin Ming Li
Abstract: The concept of authentication network is proposed to solve the security problems of complex network. The basic idea of authentication network is to ensure that everything of network must be authenticated. The technologies about authentication node, including the trusted root and trusted chain are studied. The security technologies about authentication networks, including trusted transmission, distributed and tree authentication management, multistage and multilayer access control strategy are also researched. At last, the security abilities of authentication network are analyzed.
701
Authors: Adnan Muhammad, Bing Sun, Jian Wei Zhang, Dimitar Kamarinchev
Abstract: Mode-based, dynamic analysis of a Solid Rocket Motor (SRM), during transportation, is performed, while considering frequency-dependent modulus of viscoelastic materials. The modulus of viscoelastic materials depends on vibration frequency, which however cannot be modified during the mode-based response analysis. An iterative approach is proposed, to extract mode-based stress response of a SRM. The material modulus used to get response, is based on frequency that is the same as the motor’s eigenfrequency. In order to do modal summation of mode responses, two methods are used in the analysis. Results show that in both the Eigenfrequency extraction and in the subsequent stress response analysis, the used material evaluation frequency is in complete agreement with the eigenfrequency.
706
Authors: S.X. Wang, D. Lv, Z.Y. Liu, F. He
Abstract: For the geographical dispersion of wind farms, an effective and reliable platform of data transmission and storage based on VPN private tunnel and PI database is built to solve information sharing and centralized power forecasting. Then the real-time data which wind speed is predicted by ARMA model and predictive power through the wind-power model is built by neural networks is published. The simulation results indicate the forecasting system is conducive to ensuring the stable and secure running of the grid and improving the utilization rate of wind power.
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