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991.
992.
Sung-Tae Hong Yuri Hovanski Curt A. Lavender K. Scott Weil 《Journal of Materials Engineering and Performance》2008,17(3):382-386
The die stress profiles during compaction of commercially pure titanium (Ti) and commercial lubricated iron (Fe) powders were
experimentally investigated using an instrumented die. The die was designed to simulate double-action pressing, and a detailed
stress profile was measured along the height of the die using multiple custom-made strain gage pins. The stress history shows
that residual stress remained in the die in the radial direction after the axial compaction stress was removed from the powder.
Also, the stress profile at the maximum axial stress and the residual stress profile were observed to be symmetric across
the height of the compact for both powders, but both have a unique shape for each powder. For both the stress profile at the
maximum axial stress and the residual stress profile, the unlubricated Ti powder produced a much higher radial stress at the
center of the compact with a steep pressure gradient on both top and bottom of the compact, while the lubricated Fe powder
produced a rather uniform radial stress distribution along the height of the compact.
This article was presented at Materials Science & Technology 2007, Automotive and Ground Vehicles symposium held September
16–20, 2007, in Detroit, MI. 相似文献
993.
Experience with use of pile foundations is described for the construction of five-, nine-, and 12-story buildings under complex soil conditions in Georgia with consideration given to the differing seismicity of the regions. Deformations are cited for residential buildings erected on reinforced-concrete friction piles in weak clayey soils, and also buildings on piles situated in soils prone to slump-type settlement. The range of application of pile foundations is presented for these conditions. 相似文献
994.
物质介入条件下摩擦学行为的工业试验 总被引:1,自引:1,他引:0
介绍我国铁路在运行中内燃机车柴油机上添加减摩修复物质的工业试验;历时5年、累计行程为115.2万公里所取得数据以及随机抽样统计分析结果证明了添加物的介入可以明显地改进气缸套-活塞摩擦副的表面特性;新的工程现象提出了研究"物质介入条件下的摩擦学行为"这一新命题的学术意义. 相似文献
995.
Zhongming Xu Lingyun Ding Ping Huang 《Frontiers of Mechanical Engineering in China》2008,3(3):276-282
An interfacial potential barrier theory to calculate friction and wear is proposed by considering the micro interaction of
frictional surfaces. The theory suggests that the performance of friction and wear depends on the magnitude and distribution
of the interfacial potential barrier on contact surfaces. The calculation methods of the interfacial potential barrier and
standard interfacial potential barrier are then studied and the formulas to calculate the friction force, friction coefficient,
and quantity of adhesion wear are derived based on the theory. With its independence and stability, the standard interfacial
potential barrier can be used as an index to describe the frictional performance of materials. The calculation results of
the friction force with some existing experimental data are consistent with the experimental results performed with an ultra
high vacuum atomic-force microscope, which proves that the theory and method are feasible.
__________
Translated from Tribology, 2007, 27(1): 54–59 [译自: 摩擦学学报] 相似文献
996.
A hydrodynamic numerical model and a tide-surge interaction model are described for the evaluation of storm surges and their
interaction with the tides in the Bay of Bengal. Numerical experiments are performed with the help of these models to simulate
the surges generated by three recent severe cyclonic storms which struck the east coast of India and Bangladesh. The predicted
peak sea-surface elevations compare well with the limited observed values. 相似文献
997.
高纯超细SrTiO3粉料的液相合成方法 总被引:4,自引:0,他引:4
本文研究了三种高纯超细SrTiO3粉料的液相合成方法:草酸盐沉淀法、过氧化物热分解法和液相直接沉淀法。通过在使用原料、制备流程、工艺条件、粉料收率及粉料性能等方面的对比得出:液相直接沉淀法具有原料便宜易得、工艺流程简单、操作方便、不需高温热分解和粉料收率高等优点,而且制得的粉料在粒度、粒度分布、颗粒形状及团聚状态等方面均优于另外两种方法制备出的粉料。 相似文献
998.
CF/CVD/树脂炭复合材料的摩擦性能 总被引:2,自引:0,他引:2
采用针刺炭纤维整体毡作为骨架,经CVD致密,树脂浸渍固化增密及炭化,石墨化后制得C/C复合材料,研究了CVD炭和树脂炭含量对摩擦性能的影响。实验结果表明:CVD炭具有典型显微组织是材料具有良好摩擦性能的保证;C/C复合材料中加入适量的树脂炭不会影响材料的摩擦性能;摩擦系数大小不一定和摩损率成对应关系。 相似文献
999.
Manuel Evaristo Tomas Polcar Albano Cavaleiro 《International Journal of Mechanics and Materials in Design》2008,4(2):137-143
W-S-C films were deposited by non-reactive sputtering from a carbon target incrusted with WS2 pellets in the eroded zone. This process allows depositing coatings with a wide range of compositions, with a precise control
of their carbon content. Before the deposition, a Ti interlayer was interposed between the film and the substrate to improve
the final adhesion. The carbon content in W-S-C system was varied from 29 at.% to 70 at.%, which led to an hardness enhancement
from 4 GPa up to 10 GPa where the maximum hardness was reached in films with a carbon content between 40 at.% and 50 at.%.
The tribological behaviour of the coatings was evaluated by pin-on-disk testing, in environments with different humidity levels.
Generally, the tribological performance of W-S-C coatings in environments with moderate to high humidity is better for coatings
with high carbon content. Friction coefficients, as 0.05 or lower could be reached at low humidity ranges (<7%) to all compositions.
However, for higher humidity values, friction coefficient increased up to 0.30 in the W-S-C film with low carbon content whereas
it was kept approximately constant for the others compositions. 相似文献
1000.
对三个工点岩石现场直剪试验结果和剪应力应变曲线进行分析 ,认为Ⅰ #岩石脆性较明显 ,Ⅱ #、Ⅲ #岩石的韧性 (延性 )特征明显 ,岩石抗剪强度指标建议值以大位移残馀强度为基准 ,对脆性岩石取值严格些 ,取低值 ,对韧性岩石取值偏高些。文中论述了上述认识和作法的依据 ,并对有关的其他问题进行了讨论。 相似文献