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排序方式: 共有293条查询结果,搜索用时 15 毫秒
1.
High-cycle fatigue behaviour of titanium 5Al-2.5Sn alloy at room temperature has been studied. S-N curve characterization is performed at different stress ratios ranging from 0 to 0.9 on a subsized fatigue specimen. Both two-stress and three-stress level tests are conducted at different stress ratios to study the cumulative fatigue damage. Life prediction techniques of linear damage rule, double linear damage rule and damage curve approaches are applied, and results are compared with the experimental data. The agreement between prediction and experiment is found to be excellent. 相似文献
2.
Yuanxin Zhou Mohammed A. Baseer Hassan Mahfuz Shaik Jeelani 《Materials Science and Engineering: A》2006,420(1-2):63-71
This paper presents an analytical approach which combines the modified shear-lag model and Monte Carlo simulation technique to simulate the tensile failure process of unidirectional T700 carbon reinforced composite. Two kinds of matrix were investigated in the present paper, one is neat epoxy and the other one is SiC nano-particle filled epoxy. In the model, the strength of the fiber elements is randomly allocated by the Monte Carlo method, the elastic properties of the matrix elements and the friction after the interfaces breakage are definitely allocated. Using this model, the deformation, damage and failure process of the composite are simulated on the microscopic level, the tensile stress–strain relationship is well predicted. The relationship between mechanical properties of the fiber, matrix and composites was discussed. The analysis also shows that, compared with the neat system, nano-phased composite exhibits 10% improvement in tensile strength, which agrees with the experimental data. 相似文献
3.
Rao K. Srinivasa Madhuri T. Krishna Leela Sairam T. Manish Vali Shaik Shoukath Chand Ch. Gopi Sravani K. Girija 《Microsystem Technologies》2022,28(12):2697-2704
Microsystem Technologies - In this paper, we have designed and simulations of RF MEMS shunt switch. The electro-mechanical and electromagnetic analysis of the switch have been done using COMSOL... 相似文献
4.
A novel approach for extracting cellulose nanofibers from lignocellulosic biomass by ball milling combined with chemical treatment 下载免费PDF全文
Cellulose nanofibers (CNFs) were isolated from kenaf fibers and wheat straw by formic acid (FA)/acetic acid (AA), peroxyformic acid (PFA)/peroxyacetic acid (PAA), hydrogen peroxide (H2O2) treatment; and subsequently through ball milling treatment. Characterization of extracted cellulose and cellulose nanofibers was carried out through Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), and thermogravimetric analysis (TGA). TEM images showed that extracted cellulose nanofibers had diameter in the range of 8–100 nm. FTIR and XRD results implied that hemicellulose and lignin were mostly removed from lignocellulosic biomass with an increase in crystallinity, and isolation of cellulose nanofibers was successful. The TGA results showed that decomposition temperature of cellulose nanofibers increased by about 27°C when compared with that of untreated lignocellulosic biomass. No significant change was observed in the decomposition temperature of bleached celluloses after ball milling. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42990. 相似文献
5.
The thinning of the film beneath a liquid drop is often faster than predicted by radial drainage. This could be explained by asymmetrical drainage, but mathematical difficulties are then encountered. However, analytical solutions may be obtained for the two-dimensional case and expressions are derived here for the asymmetric viscous drainage of films trapped between convex and concave wedges. Solutions for the symmetrical drainage beneath wedges and parabolae are also presented which are analogous to the three-dimensional drainage beneath cones and paraboloids previously derived. 相似文献
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In a recent work, we demonstrated the usefulness of the Hilbert transform in identifying the in-plane rotation angle between two objects. Here we use the Hilbert-wavelet bases instead of the Hilbert transform in the determination of the exact angle of rotation. We describe the design of the two-dimensional Hilbert-wavelet filter based on the spectral-factorization method to generate a Hilbert-transform pair of orthogonal wavelet bases. We compare the relative performance of the Hilbert transform and the Hilbert wavelet to identify both in-plane and out-of-plane rotation angles. We demonstrate that the Hilbert wavelet offers better rotation-angle determination than the Hilbert transform. We present correlation based rotated and scaled object identification and tracking using Hilbert or Hilbert-wavelet transformed infrared image sequences. We also demonstrate reduced data handling and improved tracking of distorted objects using the Hilbert-wavelet transform. 相似文献
8.
Quantum mechanics has provided chemistry with two general theories, valence bond (VB) theory and molecular orbital (MO) theory. The two theories were developed at about the same time, but quickly diverged into rival schools that have competed, sometimes fervently, on charting the mental map and epistemology of chemistry. Three practitioners of MO and VB theory talk - fighting a little, trying to understand - of the past and present of these two approaches to describing bonding in molecules. 相似文献
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The life of a component subjected to a constant stress can be determined using the S-N diagram. Prediction of cumulative fatigue damage or fatigue life of a component subjected to a given stress sequence of varying
amplitude is difficult, if not impossible. Miner's rule and Kramer's equation can predict cumulative fatigue damage with a
reasonable degree of accuracy for limited cases. The development of Kramer's equation was studied and a modification suggested.
Cumulative fatigue data generated using aluminium alloys 2011-T3 and 2024-T4, were analysed using Miner's, Kramer's and the
modified equations. While Miner's rules and Kramer's equation predict cumulative fatigue damage with tolerable error for a
few cases, the modified equation has shown close agreement between the experimental and theoretical values of fatigue life
or cumulative fatigue damage for the materials studied in this investigation. 相似文献