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11.
Summary A constitutive model is derived for the elastic behavior of rubbers at three-dimensional deformations with finite strains.
An elastomer is thought of as an incompressible network of flexible chains bridged by permanent junctions that move affinely
with the bulk medium. The constraints imposed by surrounding macromolecules on configurations of an individual chain are introduced
by combining the Flory–Erman and Erman–Monnerie approaches. To describe inter-chain interactions in a tractable way, the conventional
picture of a tube where a chain is confined is replaced by geometrical restrictions on the positions of its ends and center
of mass. The constraints on the chain ends are formulated within the traditional Flory concept, whereas those on the position
of center of mass are described following the Ronca–Allegra scenario. Stress–strain relations for a network of constrained
chains are derived by using the laws of thermodynamics. The constitutive equations involve four adjustable parameters with
transparent physical meaning. The material constants are found by fitting experimental data on elastomers at uniaxial and
equi-biaxial tensions and pure shear. It is demonstrated that (i) the model provides an acceptable prediction of stresses
in a test with one deformation mode, when its parameters are found by matching observations in an experiment with another
mode, and (ii) material constants are affected by chemical composition of elastomers in a physically plausible way. 相似文献
12.
Wafer Direct Bonding: From Advanced Substrate Engineering to Future Applications in Micro/Nanoelectronics 总被引:3,自引:0,他引:3
Christiansen S.H. Singh R. Gosele U. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2006,94(12):2060-2106
Wafer direct bonding refers to the process of adhesion of two flat mirror-polished wafers without using any intermediate gluing layers in ambient air or vacuum at room temperature. The adhesion of the two wafers occurs due to attractive long range van der Waals or hydrogen bonding forces. At room temperature the bonding energy of the interface is low and higher temperature annealing of the bonded wafer pairs has to be carried out to enhance the bonding energy. In this paper, we describe the prerequisites for the wafer-bonding process to occur and the methods to prepare the suitable surfaces for wafer bonding. The characterization techniques to assess the quality of the bonded interfaces and to measure the bonding energy are presented. Next, the applications of wafer direct bonding in the fabrication of novel engineered substrates such as "silicon-on-insulator" and other "on-insulator" substrates are detailed. These novel substrates, often called hybrid substrates, are fabricated using wafer bonding and layer splitting via a high dose hydrogen/helium implantation and subsequent annealing. The specifics of this process, also known as the smart-cut process, are introduced. Finally, the role of wafer bonding in future nanotechnology applications such as nanotransistor fabrication, three-dimensional integration for high-performance micro/nanoelectronics, nanotemplates based on twist bonding, and nano-electro-mechanical systems is discussed 相似文献
13.
The lubricant entrapment and escape phenomena in metal forming are studied experimentally as well as numerically. Experiments are carried out in strip reduction of aluminium sheet applying a transparent die to study the fluid flow between mesoscopic cavities. The numerical analysis involves two computation steps. The first one is a fully coupled fluid-structure Finite Element computation, where pockets in the surface are plastically deformed leading to the pressurization of the entrapped fluid. The second step computes the fluid exchange between cavities through the plateaus of asperity contacts with the plane tool, one cavity at a time. 相似文献
14.
15.
Nielsen Jacob Obitsø Christiansen Thomas Lundin Pantleon Karen 《Metallurgical and Materials Transactions A》2020,51(9):4880-4889
Metallurgical and Materials Transactions A - Fe-C coatings with a high amount of carbon were electrodeposited from an iron-sulfate electrolyte. Citric acid as an additive in the electrolyte not... 相似文献
16.
17.
Friction coefficients in cold forging: A global perspective 总被引:1,自引:0,他引:1
P. Groche P. Kramer N. Bay P. Christiansen L. Dubar K. Hayakawa C. Hu K. Kitamura P. Moreau 《CIRP Annals》2018,67(1):261-264
Worldwide, at least twenty different tribological tests have been proposed for the empirical determination of friction coefficients in cold forging processes. Due to the varying test setups, means of measurement, and level of abstraction, the comparability of the outcomes is, however, disputable. Within this work, six established test principles are compared using identical tribological systems. Large differences between the empirically determined friction coefficients are observed but can be explained under consideration of the respective tribological loads. Additional investigations of an extrusion process reveal that friction models also have to take into account the varying local thickness of the lubricant film. 相似文献
18.
O. Moutanabbir Y.J. Chabal M. Chicoine S. Christiansen R. Krause-Rehberg F. Schiettekatte R. Scholz O. Seitz S. Senz F. Süßkraut U. Gösele 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2009,267(8-9):1264-1268
The underlying physics and the role of H-defect interaction in H ion-induced splitting of GaN were investigated by transmission electron microscopy, high resolution X-ray diffraction, positron annihilation spectroscopy, ion channeling, elastic recoil detection, and infrared spectroscopy. A high concentration of void-like nanoscopic structures, nanobubbles, is detected immediately after implantation. Positron annihilation measurements demonstrate that the detected structures are vacancy clusters. FTIR data show that H-defect vibrational spectrum peaks at 3141 cm?1 mode attributed to VGa–H4. A large fraction of H was found to be trapped in higher frequency modes which we associate tentatively to N–H stretch modes in the internal surfaces of nanobubbles. These nanobubbles persist during annealing up to 450 °C. An increase of the strain is observed in this temperature range. This strain relaxes partially above 450 °C following the formation of the platelets which are embryos of the microcracks. 相似文献
19.
Henrik Andersson Arild Hoff Marielle Christiansen Geir Hasle Arne Løkketangen 《Computers & Operations Research》2010,37(9):1515-1536
This paper describes industrial aspects of combined inventory management and routing in maritime and road-based transportation, and gives a classification and comprehensive literature review of the current state of the research.The literature is contrasted with aspects of industrial applications from a constructive, but critical, viewpoint. Based on the status and trends within the field, future research is suggested with regard to both further development of the research area and industrial needs. By highlighting the industrial aspects, practitioners will hopefully see the benefit of using advanced decision support systems in complex situations related to combined inventory management and routing in their business. In addition, a classification and presentation of the research should help and motivate researchers to further focus on inventory management and routing challenges. 相似文献