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Extraction of a crack opening from a continuous approach using regularized damage models
Frédéric Dufour,Gilles Pijaudier-Cabot,Marta Choinska,Antonio Huerta 사단법인 한국계산역학회 2008 Computers and Concrete, An International Journal Vol.5 No.4
Crack opening governs many transfer properties that play a pivotal role in durability analyses. Instead of trying to combine continuum and discrete models in computational analyses, it would be attractive to derive from the continuum approach an estimate of crack opening, without considering the explicit description of a discontinuous displacement field in the computational model. This is the prime objective of this contribution. The derivation is based on the comparison between two continuous variables: the distribution if the effective non local strain that controls damage and an analytical distribution of the effective non local variable that derives from a strong discontinuity analysis. Close to complete failure, these distributions should be very close to each other. Their comparison provides two quantities: the displacement jump across the crack [U] and the distance between the two profiles. This distance is an error indicator defining how close the damage distribution is from that corresponding to a crack surrounded by a fracture process zone. It may subsequently serve in continuous/discrete models in order to define the threshold below which the continuum approach is close enough to the discrete one in order to switch descriptions. The estimation of the crack opening is illustrated on a one-dimensional example and the error between the profiles issued from discontinuous and FE analyses is found to be of a few percents close to complete failure.
Prospects of Nanoscience with Nanocrystals
Kovalenko, Maksym V.,Manna, Liberato,Cabot, Andreu,Hens, Zeger,Talapin, Dmitri V.,Kagan, Cherie R.,Klimov, Victor I.,Rogach, Andrey L.,Reiss, Peter,Milliron, Delia J.,Guyot-Sionnnest, Philippe,Konstan American Chemical Society 2015 ACS NANO Vol.9 No.2
<P>Colloidal nanocrystals (NCs, <I>i.e.</I>, crystalline nanoparticles) have become an important class of materials with great potential for applications ranging from medicine to electronic and optoelectronic devices. Today’s strong research focus on NCs has been prompted by the tremendous progress in their synthesis. Impressively narrow size distributions of just a few percent, rational shape-engineering, compositional modulation, electronic doping, and tailored surface chemistries are now feasible for a broad range of inorganic compounds. The performance of inorganic NC-based photovoltaic and light-emitting devices has become competitive to other state-of-the-art materials. Semiconductor NCs hold unique promise for near- and mid-infrared technologies, where very few semiconductor materials are available. On a purely fundamental side, new insights into NC growth, chemical transformations, and self-organization can be gained from rapidly progressing <I>in situ</I> characterization and direct imaging techniques. New phenomena are constantly being discovered in the photophysics of NCs and in the electronic properties of NC solids. In this Nano Focus, we review the state of the art in research on colloidal NCs focusing on the most recent works published in the last 2 years.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2015/ancac3.2015.9.issue-2/nn506223h/production/images/medium/nn-2014-06223h_0020.gif'></P>