排序方式: 共有28条查询结果,搜索用时 279 毫秒
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Shi Xunqing Wang Zhiping John HL Pang Zhang Xueren Nie Jingxu 《Acta Mechanica Sinica》2002,18(3):274-287
In this study, a new unified creep constitutive relation and a modified energy-based fatigue model have been established respectively
to describe the creep flow and predict the fatigue life of Sn−Pb solders. It is found that the relation successfully elucidates
the creep mechanism related to current constitutive relations. The model can be used to describe the temperature and frequency
dependent low cycle fatigue behavior of the solder. The relation and the model are further employed in part II to develop
the numerical simulation approach for the long-term reliability assessment of the plastic ball grid array (BGA) assembly.
The project supported by the National Natural Science Foundation of China (59705008) 相似文献
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C. C. O'Loughlin Ernst Bornemann Prettner R. Meyer Marcusson Albert Sommer Dietrich Lohmann Hermann W. Mahr Prévost Hubbard F. P. Pritchard Charles F. Reeve Pritchard Gary André Dubosc S. W. Parr Brainerd Mears D. L. Weatherhead Heinrich Loebell Clifford Richhardson Eickmann Meyerheim Landsberger A. von Skopnik A. Scheller E. Graefe F. Schwarz G. Halphen D. Spiess Holde F. Meister Nastjukow Severin Charitschkoff Leopold Barta A. P. Bjerregard 《Analytical and bioanalytical chemistry》1920,59(7):321-333
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D. Holde W. Stauf H. Mallison Albrecht Wolff E. Lazló Wo Ostwald R. Auerbacht C. E. Fawkes G. Gallo M. Tenani J. Duclaux J. Errera G. Meyerheim F. Frank H. Vogel S. Erk R. Ditmar R. Fischer E. P. Bauer K. Albert H. J. Schulz H. W. Klever E. Berl M. Isler A. Lange J. Traube J. Magasanik F. V. von Hahn D. Krüger E. C. Bingham R. F. Jackson E. von Mülendahl 《Analytical and bioanalytical chemistry》1930,82(4-5):163-176
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Temperature-dependent surface X-ray diffraction experiments have been performed on the K/Ag(001)-(2 × 1) adsorption system. The structure is characterized by a missing-row geometry in which alternate Ag rows along [1
0] are missing. The K atoms reside within the large grooves coordinated by six Ag atoms at a distance of 3.44(5) Å, corresponding to an effective K-radius of 2.00(5) Å. Large anisotropic disorder is observed for both the K-atoms and the top-layer (“ridge”) Ag atoms. The K-atom displacements are largest in the direction along the grooves, whereas for the Ag atoms the vibrations along [110] are significantly larger. The temperature dependence of the Ag vibrations is in accordance with Debye theory for the [110] direction, but deviates from it for the [1
0] vibrations at high temperature. In contrast to the K-atoms, the out-of-plane vibrations of the top-layer Ag atoms are larger than the in-plane vibrations. The inclusion of anharmonic contributions to describe the Ag disorder significantly improves the fits. It is shown that if anharmonicity is neglected the interlayer contraction is overestimated (Δd12/d12 only −3.2%, instead of −12.7% if anharmonicity is neglected). Due to the anharmonicity, different definitions of the atomic position arise (mean, mode and equilibrium position), which are discussed on the basis of the results. 相似文献
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Mironets O Meyerheim HL Tusche C Stepanyuk VS Soyka E Zschack P Hong H Jeutter N Felici R Kirschner J 《Physical review letters》2008,100(9):096103
Surface x-ray diffraction in combination with scanning tunneling microscopy and molecular dynamics calculations provide first quantitative evidence for unusually large relaxations in nanometer-sized Co islands deposited on Cu(001) at 170 K. These lead to sharply reduced interatomic Co distances as low as 2.36 A as compared to bulk Co (2.51 A) involving low symmetry Co adsorption sites. Our results prove the validity of the concept of mesoscopic mismatch which governs the strain relaxation of nanosized islands in general. 相似文献
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Meyerheim HL Sander D Popescu R Pan W Popa I Kirschner J 《Physical review letters》2007,99(11):116101
The x-ray structure analysis of the oxygen-surfactant-mediated growth of Ni on Cu(001) identifies up to 0.15 monolayers of oxygen in subsurface octahedral sites. This questions the validity of the general view that surfactant oxygen floats on top of the growing Ni film. Rather, the surfactant action is ascribed to an oxygen-enriched zone extending over the two topmost layers. Surface stress measurements support this finding. Our results have important implications for the microscopic understanding of surfactant-mediated growth and the change of the magnetic anisotropy of the Ni films. 相似文献
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Thamankar R Meyerheim HL Ernst A Ostanin S Maznichenko IV Soyka E Mertig I Kirschner J 《Physical review letters》2011,106(10):106101
Using scanning tunneling microscopy experiments in combination with first-principles calculations we have studied the geometric structure of the compressed c(7sqrt(2) × sqrt(2)) antiphase domain structure of CO on Cu(001). We find direct evidence for structural relaxations involving an inhomogeneous CO environment characterized by molecular tilting, bending, and nonterminal sites. Our analysis solves the long-standing problem of the adsorption structure of the compressed phase and is important for understanding the physical properties of this fundamental adsorption system. 相似文献