Inelastic constitutive equation of plasma-sprayed ceramic thermal barrier coatings

Ceramic thermal barrier coatings (TBCs) are a very important technology for protecting the hot parts of gas turbines (GTs) from a high-temperature environment. The coating stress generated in the operation of GTs brings cracking and peeling damage to the TBCs. Thus, it is necessary to evaluate precisely such coating stress in a TBC system. We have obtained a stress-strain curve for a freestanding ceramic coat specimen peeled from a TBC coated substrate by conducting the bending test. The test results have revealed that the ceramic coating deforms nonlinearly with the applied loading. In this study, an inelastic constitutive equation for the ceramic thermal barrier coatings deposited by APS is developed. The obtained results are as follows: (1) the micromechanics-based constitutive equation was formulated with micro crack density formed at splat boundary, and (2) it was shown that the numerical results for a nonlinearly deformed beam simulated by the developed constitutive equation agreed with the experimental results obtained by cantilever bending tests.     

重离子辐照模拟的实验验证(英文)

采用正电子湮没寿命技术研究了等效剂量的5.28×1016cm-2 85 MeV氟离子和3×1020cm-2En≥1 MeV中子辐照的α-Al2O3中产生的辐射损伤及其细致的热退火行为。实验结果表明重离子辐照的α-Al2O3中的正电子湮没寿命及其强度与中子辐照的α-Al2O3中的完全符合,从实验上验证了重离子辐照可以很好地模拟中子(质子)的辐照。     

QUADRANT ANALYSIS OF BUBBLE INDUCED VELOCITY FLUCTUATIONS IN A TRANSITIONAL BOUNDARY LAYER

Our previous study showed that the frictional drag decreases with increasing void fraction at Re > 1300, while it increases at Re < 1000. Decomposition of the Reynolds shear stress also implied that bubbles induce isotropy of turbulence. In order to confirm our previous analysis and to further investigate flow fields in the vicinity of bubbles, we analyze velocity fluctuations on the quadrant space in the streamwise and transverse directions ( u′ – v′ plane). Here, we focus on two specific Reynolds numbers ...     

PREVENTION OF THE INTERGRANULAR FRACTURE AT ELEVATED TEMPERATURES BY ADDITION OF PHOSPHORUS TO A HIGH PURITY Fe0 002% SALLOY

１．ＩｎｔｒｏｄｕｃｔｉｏｎＥｍｂｒｉｔｔｌｅｍｅｎｔｉｎｉｒｏｎａｎｄｓｔｅｅｌｓｉｓｃｌｏｓｅｌｙｒｅｌａｔｅｄｔｏｔｈｅｔｙｐｅ,ｔｈｅａｍｏｕｎｔ,ｔｈｅｅｘｉｓｔｉｎｇｓｔａｔｅ,ｅｓｐｅｃｉａｌｌｙｔｈｅｓｅｇｒｅｇａｔｉｏｎｏｆｉｍｐｕｒｉｔｉｅｓａｎｄａｌｌｏｙｉｎｇｅｌｅｍｅｎｔｓｔｏｂｏｕｎｄａｒｉｅｓ．Ｈｏｗｅｖｅｒ,ｔｈｅｒｏｌｅｏｆａｇｉｖｅｎｅｌｅｍｅｎｔｉｎｅｍｂｒｉｔｔｌｅｍｅｎｔｉｓｆｒｅｑｕｅｎｔｌｙａｆｆｅｃｔｅｄｂｙｔｈｅｅｘｉｓｔｅｎｃｅｏｆｏｔｈｅｒｅ…     

卧式振动沸腾床旧砂冷却的计算机数字模拟

本文建立了新的卧式振动沸腾床旧砂冷却系统的数学模型,并进行了计算机数字模拟。通过模拟,研究了几个工艺参数对旧砂冷却的影响,并应用能耗指数E和冷却效率η对工厂中使用的旧砂冷却装置进行了评价。     

有氧条件下氩弧焊钨电极表面的烧蚀

研究了在有氧条件下钨极氩弧焊的钨电极表面的烧蚀.研究结果表明,有氧条件下钨电极的钨基体烧蚀大大增加,主要原因是在一定温度范围内发生了氧和钨的反应;添加氧化钍的烧蚀主要是由于氧化钍的熔化和蒸发,采用纳米尺寸氧化钍的电极,氧化钍的烧蚀明显减轻,有助于提高钨电极的使用寿命.采用纳米氧化物添加钨电极以及保证保护惰性气体的纯度和流量可以降低钨电极的烧蚀,保证焊接质量.     

Effect of Cold-Rolling on Precipitation Phenomena in Sensitized Type 316L and 304L Austenitic Stainless Steels

Precipitation phenomena in Type 316L and 304L stainless steels were studied mainly by transmission electron microscopic (TEM) observations after cold-rolling ranging from 0% (as solution annealed) to 80% reduction in thickness,and then by sensitization treatment. Precipitates were identified by electron diffraction analysis and EDS analysis.Precipitates observed in sensitized 316L stainless steel were sigma and chi phases, whereas carbide and sigma were observed in sensitized 304L stainless steel. Recrystallized grains were formed in 30% cold-rolled and sensitized 304L.However, the tendency toward recrystallization in sensitized 316L was much lower than in 304L. Precipitation of sigma and chi phases was accelerated by cold-rolling and they were observed at grain boundaries in lower cold-rolling; they were also seen, in grain interiors in higher cold-rolling. Higher deformation induced partially recrystallization combined with precipitation, resulting in the formation of heterogeneous microstructures.     

NUMERICAL SIMULATION OF FORGING AND SUBSEQUENT HEAT TREATMENT OF A ROD BY A FINITE VOLUME METHOD

1.air-nonAtypicalindustrialmetalcoml,onentwouldoftenbemadeviatheforgingandheattreatm',ntoperationsintilenlarlufacturingstage.IntiledesignOfforgingprocesses,informationisllecesstllysuchasmaterialflowinthedies,levelofdiefill,del'ects,strain,stress,temperaturedistributioninthebarkpiecesaxltlthedies,andforgingforce.InthesubseqUentheattreatmentoperations,illf(,mlationoncolllbinationOfrnicrostructure,residualstressesanddiTocnsionalaccuracyintilel'illalproductalealsoveryimportant.Suchinformationmay…     

具有万向机构的蛇形机器人运动控制

设计了一种能够使蛇形机器人运动更灵巧、奇异点更少和运动能力更强的机构．对具有三个自由度的新型蛇形机器人单元进行了改进，在单元上增加被动轮机构，使其具有万向机构的特点。该单元不仅能够用被动轮驱动机器人运动．而且增加了类似于主动轮的驱动机构．克服了被动轮驱动能力弱的缺点，增强了机器人的运动能力。在分析非完整约束的基础上，对蛇形机器人的运动学和冗余度进行分析，提出了控制该类蛇形机器人运动的分解矩阵方法和分组交替运动法。     

单向纤维复合材料的偏轴实验方法开发与评价(英文)

This study presents an integrated method suitable for off-axis tension and compression testing in unidirectional composites,and its application to the testing of in-plane shear characterization.A new rotating-grip test fixture,incorporating the attractive features of the existing pinned-end fixture and hydraulic wedge grips,has been developed.The proposed gripping system consists of two sets of jaw faces,each with a pair of self-aligning bearings that allows for loading in the axial and radial directions.Fi...