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71.
Ling Yin Eric Y. J. Vancoille Kuppuswamy Ramesh Han Huang 《International Journal of Machine Tools and Manufacture》2004,44(6):607-615
Surface characterization of 6H-SiC (0001) substrates in indentation and abrasive machining was carried out to investigate microfracture, residual damage, and surface roughness associated with material removal and surface generation. Brittle versus plastic deformation was studied using Vickers indention and nano-indentation. To characterize the abrasive machining response, the 6H-SiC (0001) substrates were ground using diamond wheels with grit sizes of 25, 15 and 7 μm, and then polished with diamond suspensions of 3 and 0.05 μm. It is found that in indentation, there was a scale effect for brittle versus plastic deformation in 6H-SiC substrates. Also, in grinding, the scales of fracture and surface roughness of the substrates decreased with a decrease in diamond grit size. However, in polishing, a reduction in grit size of diamond suspensions gave no significant improvement in surface roughness. Furthermore, the results showed that fracture-free 6H-SiC (0001) surfaces were generated in polishing with the existence of the residual crystal defects, which were associated with the origin of defects in single crystal growth. 相似文献
72.
X2 0CrMoV12 1耐热合金钢广泛应用于热电厂主蒸汽管线等主要部件。经长期高温负荷运行后 ,材料性能明显退化。观察显微组织发现 ,材料性能下降是和晶界碳化物的粗化密切相关的。文章着重研究了损伤材料重新热处理后的性能和组织结构的变化 ,初步探讨了材料长期服役后通过热处理恢复其原始性能的可能性 相似文献
73.
讨论用数值模拟预测板材成形中发生拉深损伤破坏的两种不同的求解方法。第一种是采用完全耦合的弹塑性破坯模型的动力显式数值方法。基于状态参量的不可逆热力学过程 ,完全耦合的本构方程考虑各向同性强化和拉深。这些已引入有限元软件ABAQUS/E用于对金属成形的模拟。在数值技术方面 ,隐式积分方法被用来对本构方程的局部时间积分 ,动力显式技术用于求解总体平衡方程。第二种方案是采用简化的损伤模型的方法 ,被称为逆法 (InveseApprch)。I.A被限定在考虑各向同性强化和损伤的塑性全量理论基础上的简单的本构关系。做比例加载和临界损伤达到以后的损伤饱和假定 ,可以得到损伤演化方程的封闭解。这两种损伤模型在编程中的实施采用两种方式 :计算中考虑或不考虑损伤作用 ,也就是耦合的或非耦合的计算。文中给出一些算例来说明每种损伤模型的优点 相似文献
74.
桥梁健康监测中损伤特征提取的小波包方法 总被引:2,自引:0,他引:2
针对桥梁健康监测中结构损伤识别的特点,从模式识别的角度提出和分析了损伤特征提取问题.阐述了基于小波包分析的两种节点能量特征提取的方法.为了研究小波包系数节点能量和小波包信号成分节点能量对损伤信息进行特征提取的差异,通过对随机荷载激励下的连续梁进行数值模拟,得到了结构未损和损伤状态下的加速度时程信号.应用小波包变换,对不同结构状态下的加速度信号分别提取了两种小波包节点能量特征,并对它们作为结构损伤特征指标的敏感性进行了比较.认为两种特征指标的敏感性相差很小,而小波包系数节点能量特征指标的计算效率更高,更适合桥梁健康监测中损伤特征提取的要求. 相似文献
75.
Chung-Kuan Wu Ji-Fan Lin Tzong-Shyuan Lee Yu Ru Kou Der-Cherng Tarng 《International journal of molecular sciences》2021,22(7)
TRPA1, a nonselective cation channel, is expressed in sensory afferent that innervates peripheral targets. Neuronal TRPA1 can promote tissue repair, remove harmful stimuli and induce protective responses via the release of neuropeptides after the activation of the channel by chemical, exogenous, or endogenous irritants in the injured tissue. However, chronic inflammation after repeated noxious stimuli may result in the development of several diseases. In addition to sensory neurons, TRPA1, activated by inflammatory agents from some non-neuronal cells in the injured area or disease, might promote or protect disease progression. Therefore, TRPA1 works as a molecular sentinel of tissue damage or as an inflammation gatekeeper. Most kidney damage cases are associated with inflammation. In this review, we summarised the role of TRPA1 in neurogenic or non-neurogenic inflammation and in kidney disease, especially the non-neuronal TRPA1. In in vivo animal studies, TRPA1 prevented sepsis-induced or Ang-II-induced and ischemia-reperfusion renal injury by maintaining mitochondrial haemostasis or via the downregulation of macrophage-mediated inflammation, respectively. Renal tubular epithelial TRPA1 acts as an oxidative stress sensor to mediate hypoxia–reoxygenation injury in vitro and ischaemia–reperfusion-induced kidney injury in vivo through MAPKs/NF-kB signalling. Acute kidney injury (AKI) patients with high renal tubular TRPA1 expression had low complete renal function recovery. In renal disease, TPRA1 plays different roles in different cell types accordingly. These findings depict the important role of TRPA1 and warrant further investigation. 相似文献
76.
《中国稀土学报(英文版)》2022,40(6):906-915
Exploring an alternative strategy with high efficiency and low cost to abate formaldehyde (HCHO) in indoor environment, is of increasing significance for people's health. CeO2 catalysts prepared by hydrothermal, precipitation and calcination methods were investigated for HCHO removal at ambient temperature. It is found that indoor fluorescent light visibly boosts the catalytic performance of CeO2 catalysts for HCHO decomposition at ambient temperature. Among the CeO2 catalysts, CeO2 prepared from hydrothermal method (CeO2–H) exhibits a superior catalytic performance and an excellent durability by eight recycle times. Based on the characterization and analysis, the excellent catalytic performance of CeO2–H is mainly contributed by its abundance of surface oxygen vacancies, and photogenerated electrons and hole activated by fluorescent light. This work shows a potential practicability in HCHO pollution elimination by taking full advantage of the existing lighting in indoor environments. 相似文献
77.
78.
LI Zhengchao 《稀有金属(英文版)》2006,25(Z1)
A typical precipitation hardened alloy, Cu-Co dilute alloy was selected to study the precipitation behavior and irradiation effect on precipitates. It is found that the principal effect of ion irradiation on the coherent precipitates is loss of coherency, and TEM cross-section observations show that the fraction of the incoherent precipitates is dependent on dose but not on dose rate during heavy ion irradiation. 相似文献
79.
J. R. Tarpani W. W. Bose Filho D. Spinelli 《Journal of Materials Engineering and Performance》2002,11(5):563-570
The elastic-plastic fracture toughness and crack extension behavior under the quasi-static loading regimen of several thermally
embrittled conditions of a nuclear reactor pressure vessel (RPV) steel were assessed on the basis of microstructural parameters.
It was discovered that the bainite packet size is the fracture properties controlling parameter of single-phase quenched and
tempered microstructures. Results were found in close agreement to those obtained in a parallel study with dual-phase annealed
microstructures derived from the same low alloy steel. Similarly, it was concluded that a Hall-Petch type relationship correlates
J-fracture mechanics criteria to the grain size. 相似文献
80.
综述了堆内辐照对锆合金电化学性能影响的概况,浅析了堆内辐照损伤的机理,并重点探讨了主要的堆内辐照源——中子辐照对锆合金微观结构与氧化性能的影响。进一步阐述了堆外离子轰击模拟堆内中子辐照研究方法的进展概况,并就离子轰击实验参量的选择进行了较为深入的分析。 相似文献