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801.
802.
Elastomeric materials show a wide range of different elastic and inelastic properties. Additionally, this class of materials
is subjected to large deformations. Considering all these effects, fracture mechanical investigations are very challenging
tasks and cannot be performed with standard approaches. Effects of inhomogeneities and discontinuities such as cracks can
be investigated with the so-called material force approach in an efficient and elegant way. For comprehensive investigations
of inelastic materials, the complete balance of the material motion problem has to be formulated. In this case, the material
volume forces depend on the internal history variables which are required for the inelastic constitutive model. This paper
derives a general formulation for rate-dependent and rate-independent inelastic materials based on a multiplicative split
of the deformation gradient to cover viscoelastic and elastoplastic materials at finite deformations. 相似文献
803.
NaGdF4:Eu3+, NaEuF4, and NaGdF4 nanocrystals were synthesized in the high‐boiling coordinating solvent N‐(2‐hydroxyethyl)‐ethylenediamine (HEEDA). Phase pure nanomaterials, crystallizing either in the cubic α‐phase or the hexagonal β‐phase, were obtained by adjusting one reaction parameter only, i.e., the molar ratio between metal and fluoride ions in the synthesis. The hexagonal β‐phase is formed, if this molar ratio is close to stoichiometric, whereas the cubic α‐phase is obtained in the presence of excess metal ions. The optical properties of the Eu3+ doped samples are different for the two crystal phases. The results indicate an increased number of oxygen impurities close to Eu3+ ions, if excess metal ions are used in the synthesis. 相似文献
804.
A. Gadisa W. Mammo L. M. Andersson S. Admassie F. Zhang M. R. Andersson O. Inganäs 《Advanced functional materials》2007,17(18):3836-3842
A new alternating polyfluorene copolymer poly[2,7‐(9,9‐dioctylfluoren)‐alt‐5,5‐(5′,8′‐di‐2‐thienyl‐(2′,3′‐bis‐(3′′‐octyloxyphenyl)‐quinoxaline))] (APFO‐15), which has electron donor–acceptor–donor units in between the fluorene units, is synthesized and characterized. This polymer has a strong absorption and emission in the visible range of the solar spectrum. Its electroluminescence and photoluminescence emissions extend from about 560 to 900 nm. Moreover, solar cells with efficiencies in excess of 3.5 % have been realized from blends of APFO‐15 and an electron acceptor molecule, a methanofullerene [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM). It has also been observed that electron and hole transport is balanced both in the pure polymer phase and in polymer/PCBM bulk heterojunction films, which makes this material quite attractive for applications in opto‐electronic devices. 相似文献
805.
Olli Salmela Klas Andersson Altti Perttula Jussi Särkkä Markku Tammenmaa 《Quality and Reliability Engineering International》2007,23(4):415-429
In this paper, the solder attachment fatigue model created by Werner Engelmaier is re‐calibrated in order to make it applicable in conjunction with leadless, lead‐free solder attachments. Sn3.8Ag0.7Cu solder attached ball‐grid‐array components are addressed to three thermal cycling test profiles. Based on the results, both physical and statistical parameters are obtained and compared with the values relevant to tin–lead solder assemblies. The validity of the statistical distribution selection (two‐parameter Weibull) is studied. Acceleration factors correlating different test profiles are obtained, and they are found to be only weakly dependent on the test vehicle type. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
806.
Ion beam etching based ultra precision surface finishing is a versatile technology with a high degree of predictability due to the high stability of state of the art ion sources and the acquired knowledge of the physics of beam surface interaction. The independent control of the ion energy and the ion current density over wide ranges and the possible additional use of chemical reactive species in combination with physical sputter removal allow solving tasks in a wide variety of applications. The paper summarizes the present status of more than 20 years of development of ion beam finishing technology in IOM. It gives an overview on the equipment and the components developed for production purposes and on the ion beam technologies developed to achieve nanometer and sub‐nanometer depth accuracies over the entire spectrum of spatial surface wavelength from the full aperture size down to the microroughness level of only micrometer lateral feature size. Results of the finishing of high‐end optical surfaces shown demonstrate the outstanding performances of the techniques with topography and roughness control on the atomic scale. 相似文献
807.
M. Khurshid Z. Barsoum I. Barsoum T. Däuwel 《Fatigue & Fracture of Engineering Materials & Structures》2016,39(10):1281-1298
In this study, the fatigue strength of inclined butt welds subjected to a proportional multiaxial stress state generated by uniaxial loading is studied in nominal and local stress concepts. The local methodologies studied included principal stress hypothesis, von Mises stress hypothesis and modified Wöhler curve method. Nominal methodologies included modified Gough–Pollard interaction equation, the design equation in Eurocode3 and the interaction equation in DNV standard. Results are evaluated along with data published in relevant literature. It is observed that both local and nominal stress assessment methods are able to estimate multiaxial fatigue strength. No obvious difference in fatigue strength is observed in the nominal stress concept, but the notch stress concept is able to capture a decrease in fatigue strength in shear‐dominated joints. It is concluded that modified Wöhler curve method is a suitable tool for the evaluation of fatigue strength in joints dominated by both normal and shear stresses. 相似文献
808.
Teet Örd Küllike Rägo Artjom Vargunin 《Journal of Superconductivity and Novel Magnetism》2016,29(12):3087-3091
The healing of two-band superconductivity near its interface is studied. It is demonstrated that the restoration of superconductivity gaps in the immediate vicinity of the interface is governed by two length scales: the first one diverges at critical temperature T c , while the second one diverges at T c+<T c . By moving away from the boundary, the temperature dependencies of characteristic lengths change so that singularity at T c+ becomes removed in the bulk by arbitrary weak interband coupling. The asymptotes for the spatial behavior of gaps have been found analytically near the surface and approaching the bulk state. 相似文献
809.
Subtissue Imaging and Thermal Monitoring of Gold Nanorods through Joined Encapsulation with Nd‐Doped Infrared‐Emitting Nanoparticles
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810.
Sylwia Nowakowska Aneliia Wäckerlin Ignacio Piquero‐Zulaica Jan Nowakowski Shigeki Kawai Christian Wäckerlin Manfred Matena Thomas Nijs Shadi Fatayer Olha Popova Aisha Ahsan S. Fatemeh Mousavi Toni Ivas Ernst Meyer Meike Stöhr J. Enrique Ortega Jonas Björk Lutz H. Gade Jorge Lobo‐Checa Thomas A. Jung 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(28):3757-3763