Mechanical and Aerospace Engineering, ICMAE2012

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Authors: Akinlabi Esther Titilayo, Akinlabi Stephen Akinwale
Abstract: This paper reports the effects of processing parameters on defects formed during friction stir processing of 6082-T6 Aluminium Alloy. The plates were processed by varying the feed rate between 50 and 250 mm/min, while the rotational speed was varied between 1500 and 3500 rpm to achieve the best result. It was observed that the sheets processed at the highest feed rate considered in this research resulted in wormhole defect. These processed samples with defects were correlated to the tensile results and it was found that the Ultimate Tensile Strength (UTS) of these samples was relatively low compared to other samples without defects.
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Authors: Strzelecki Przemysław
Abstract: The paper presents accelerated methods for determining the fatigue curve in high cycle fatigue. The estimated fatigue characteristics using these algorithms always show an error, however the applicable literature does not seem to specify how accurate the methods are, which calls for their further examination. To verify the approximation methods, material C45+C was tested to provide reference characteristics. For the experimental results to be received, the test equipment developed applying own design was used. The analysis of the data has confirmed a good operation of the testing machine. To verify the accelerated methods, there was applied the statistics method to compare the coefficients of the regression curve from the experimental data and the coefficients of the analytical regression method. Using that comparison method, it can be assumed that only the estimated curve applying the algorithm by Strzelecki P. & Sempruch J. demonstrates the factors equal to the empirical line.
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Authors: Zbigniew Olszewski, Konrad J. Waluś
Abstract: Safe driving requires from the driver several visual-mental activities (perception, Proper selection of the tires depending on the season allows for optimizing the level of risk associated with driving in varying weather conditions. Properties tires used in the vehicle operational parameters show variability of depending on temperature, leading consequently to change the characteristics of the traction of the vehicle. Understanding the nature of these relationships is essential to determine the nature interaction. tires and road surface This paper presents experimental results hardness of tires under normal traffic using a mobile measuring equipment.
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Authors: Alexander Urbahs, Mukharbiy Banov, Vladislav Turko
Abstract: It is set on results the conducted experiments, that the appearance of multiple of fatigue cracks on specimens and design units with numerous concentrators takes place stochastically dependently. This stochastic relationship, both positive and negative, is observed in some zone, with certain dimensions. Positive cross-correlation relationship supposes that before there the fatigue crack will have been originated, the early the subsequent crack will be found out in direction perpendicular to the applied force. Such sequence of fatigue cracks’ originations assumes a mode as a propagation of the first crack, converting it to the only main spread out one. Such zone can be examined as a separate specimen or desigh element with probabilistic descriptions of endurance, fatigue strenght and other characteristics of reliability, that determines reliability of whole system. A physical proof of such zones existence and the description of reliability characteristics are shown as mathematical models.
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Authors: Zong Zhan Li, Jun Lin Tao, Yi Li
Abstract: This paper makes the acoustic emission of granite under uniaxial compression and splitting tensile test by electro-hydraulic testing machine and AE .We studied the relationship of uniaxial compressive strength and splitting tensile strength with the loading rate and AE characteristics of granite .The results show that uniaxial compressive strength and peak strain raise with loading rate, the AE energy gradually increases and get maximum in the 30% of the peak stress in the process of uniaxial compression test, and in the splitting tensile AE energy generates in the initial loading and gets maximum when the granite brittle fracture.
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Authors: Alexander Urbahs, Mukharbiy Banov, Vladislav Turko, Kristine Tsaryova
Abstract: The work is dedicated to the experimental study of micromechanics process of unidirectional composite materials’ specimens under static loading till its fracture using acoustic emission method compared with the strain-load deformation curve. An attempt is made to identify subtle effects of the failure process of the composite material which is impossible using the traditional methods of the strain measurement. The prospect of applying the method of acoustic emission (AE) for the development and improvement of existing methods of model tense- analysis is shown. The characteristic stages of the damage accumulation for unidirectional composites’ specimens and the effect of training on these processes are shown experimentally. It’s shown that the AE-deformation diagram have three stages in contrast to commonly used load-strain deformation curve with one stage. So it become possible to investigate the physical process of composite unit’s fracture under static load.
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Authors: Jia Guo, Yu Qiong Guan, Xing Wang, Chao Sun, Ye Luo
Abstract: The feasibility of preparing mesoporous activated carbons from bamboo, a fast growing plant in some Asian countries, particularly in China, was investigated. The effects of activation conditions, namely, activation temperature and retention time, on the characteristics of the activated carbons, i.e., specific surface area, pore size distribution and surface chemistry, were studied. The separation performance for Puerarin using the prepared bamboo activated carbon was compared to other adsorbents which included a commercial activated carbon and a macroporous resin. The experimental results showed that it was feasible to prepare mesoporous activated carbon from bamboo and to use it instead of the expensive resins presently used for Puerarin separation.
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Authors: Y. Şahin, K. Emre Öksüz
Abstract: Aluminium alloys (Al2014 and Al2124 alloy) and their composites containing 10wt.% Al2O3 with 3 µm and 43 µm sizes of particles have been produced by powder metallurgy (PM) method and the microstructure and hardness were investigated. Scanning electron microscopy (SEM) investigation showed a nearly uniform distribution of the Al2O3 particles within the Al2124 alloy matrix although some porosities were found in the Al2014 alloy matrix. Furthermore, it was found that the macrohardness of Al2124 alloy composite improved highly in comparison to that of Al2014 alloy due to fine of microstructure and increased hardness. The hardnesses of both MMCs increased with increasing the particle sizes.
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Authors: Salma Barboura, Salah Ramtani
Abstract: The present work tries to make an attempt to improve previous work which offers a simple but effective way to construct satisfied predicating model. Indeed, recent work due to Peng et al. [13] and dealing with a two-step homogenization scheme is revisited here by introducing an iterative process which allows us to take into account differently the porosity of the elastic media. Several homogenization schemes (dilute, Mori-Tanaka, self-consistent ...) are presented and compared with experimental data. One can say that the current approach provides reasonably accurate predictions for the effective moduli of multiphase composites without using the n parameter as proposed by Peng et al. [13]
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