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61.
The nature of localized deformation that occurs both in metal and polymer samples was examined under uniaxial tension by measuring the complete strain distribution of a deforming specimen at a constant crosshead speed. The development of localized deformation in 6111-T6 aluminium alloy and polycarbonate was recorded along both the longitudinal and lateral directions as the specimen was stretched until it fractured. Determination of the true strain at various points on the tensile specimens was made by using an automated, vision-based image processing method using a CCD camera to measure the deformation of a silk-screened grid on the specimen. This vision-based system produced accurate results, allowing for careful analysis of the entire necking process from initiation to propagation. It has been observed that localized deformation develops principally in the longitudinal direction. The major and minor true strain are uniform for the uniform section specimens, however, these strains peak in the centre of the hourglass specimens in the longitudinal direction for both materials. For both specimen geometries, the major strain is uniform while the minor strain is non-uniform in the lateral direction. The longitudinal true strain to lateral true strain ratio remains at about two for the uniform section specimens, but this ratio increases to between 3 and 5 for the hourglass specimens, due to the constraining effect of the sample geometry. 相似文献
62.
63.
Jae-Hee Han Su Hong Lee A.S. Berdinsky Yong Weon Kim Ji-Beom Yoo Chong-Yun Park Jin Ju Choi Taewon Jung In Taek Han Jong Min Kim 《Diamond and Related Materials》2005,14(11-12):1891
In this report, the FE characteristics of carbon nanotubes (CNTs) treated using both thermal annealing and mechanical coatings on the as-grown CNTs systematically studied. It was found that in the high temperature annealed samples, CNTs were attacked at its root during annealing due to a small amount of oxygen, and were pulled out of the substrate in places after FE measurements because of the contact resistance. However, for the mechanically coated samples both with spin on glass (SOG) and polymethyl methacrylate (PMMA), CNTs were found to be nearly intact after FE measurements and showed reliable FE characteristics over repeatable voltage scan. The reliability of CNTs during FE could be owing to the strong adhesion of CNTs to the substrate both by SOG and PMMA coatings. 相似文献
64.
Peng Lixia Yu Guoliang Ju Yinhong 《电气》2006,17(4):31-35
The firing is in the stable condition and the rate of oil saving comes up to 64%, after Fularji Power Plant adopted the technology of minimum gasified oil igniting pulverized lignite directly and the technology of multistage coal combustion with energy amplified stage by stage. 相似文献
65.
66.
实施开放式实验教学已成为当前高校实验教学改革的突破口。实施开放式实验教学,必须构建科学的运行体系,主要包括教学目标体系、内容体系、保障体系和效能考评体系四个方面。 相似文献
67.
根据中原油田地层高温、高盐、易塌、易漏失及水平井的特点,优选了适用于水平井的强抑制强封堵聚合物钻井液体系,并进行了现场应用.室内实验结果表明,优选的强抑制强封堵聚合物钻井液具有良好的井眼净化、摩阻控制、井壁稳定及油层保护等性能.现场应用时能满足钻井、录井、测井的需要,钻井施工顺利,取得了良好的经济和社会效益. 相似文献
68.
沿江圩区排涝水文计算实例 总被引:2,自引:0,他引:2
设计排涝模数的计算是圩区排涝规划的主要内容之一,它的大小决定了排涝站的装机容量和涵闸尺寸.本文推求了安徽省马鞍山市大公圩地区的排涝模数,是沿江圩区排涝水文计算的一个应用实例. 相似文献
69.
The main purpose of this paper is to find the mixed-mode stress intensity factors of composite materials using the crack opening displacement (COD). First, a series solution of the composite material with a crack was used to evaluate COD values. Then, the least-squares method was used to calculate mixed-mode stress intensity factors. This algorithm can be applied to any method that generates or measures COD values. The major advantage of this method is that COD values very near the crack tip are not necessary. Both finite element simulations and laboratory experiments were applied to validate this least-squares method with acceptable accuracy if the even terms of the series solution are removed. 相似文献
70.
Single-crystalline 3C-SiC nanowires have been synthesized in large scale through a one-step autoclave route by the reaction of SiCl4, (C5H5)2Fe and metallic Na at 500 °C. Electron microscopy investigations show that the nanowires have typical diameters of 15-50 nm, lengths up to several tens of micrometers and grow along the [111] direction. The possible growth mechanism of the nanowires is discussed. 相似文献