Restrictions on the quasi-static extension, or healing, of Griffith cracks are developed in the framework of irreversible thermodynamics. It is emphasized that thermodynamics requires that (G − 2γ)ι ⩾ 0, where ι is crack speed, G the Irwin energy release rate, and 2γ the work of reversible separation of the surfaces to be fractured. Implications for ‘lattice trapping’ models of cracks and for thermally-activated crack motion are discussed, as are the effects on crack growth and healing of a surface-reactive environment, in which case γ must be given a definition appropriate to adsorption-altered surface properties.
In this chapter, the framework to analyze a multilayer stack of blanket films is presented. Emphasis is placed on stacks with piecewise-linear distributions of misfit, or ‘eigenstrain’, strain variations within each layer allowing for the possibility of discontinuities from layer to layer. In addition to being applicable to thermal problems with steady-state thermal distributions through the multilayer, the formulation encompasses layers with residual processing strains which vary from layer to layer and possibly within layers. The principle focus of this chapter is on computing the steady-state energy release rate for a semi-infinite crack. The results of the analysis are algebraic but nevertheless will usually require some computation. As the framework is applicable to any number of layers, it provides the basis to derive the results presented in Chapter 4 for bilayers.
The reaction of species in solutions flowing laminarly (without turbulent mixing) inside capillaries was used as the basis for a broadly applicable method of microfabrication. In this method, patterning occurs as a result of transport of reactive species to interfaces within the capillary by laminar flow. A wide range of chemistries can be used to generate structures with feature sizes of less than 5 micrometers and with spatial localization to within 5 micrometers. The method is applicable to the patterning of metals, organic polymers, inorganic crystals, and ceramics on the inner walls of preformed capillaries, using both additive and subtractive processes.
Technical Briefs On Optimal Arches B. Budiansky, B. Budiansky Harvard University, Cambridge, Mass. Search for other works by this author on: This Site PubMed Google Scholar J. C. Frauenthal, J. C. Frauenthal Division of Engineering and Applied Physics, Harvard University, Cambridge, Mass. Search for other works by this author on: This Site PubMed Google Scholar J. W. Hutchinson J. W. Hutchinson Harvard University, Cambridge, Mass. Search for other works by this author on: This Site PubMed Google Scholar Author and Article Information B. Budiansky Harvard University, Cambridge, Mass. J. C. Frauenthal Division of Engineering and Applied Physics, Harvard University, Cambridge, Mass. J. W. Hutchinson Harvard University, Cambridge, Mass. J. Appl. Mech. Dec 1969, 36(4): 880-882 (3 pages) https://doi.org/10.1115/1.3564790 Published Online: December 1, 1969 Article history Received: February 13, 1969 Online: September 14, 2011
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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHydrogenation of oriented monolayers of .omega.-unsaturated fatty acids supported on platinumMichael A. Richard, John Deutch, and George M. WhitesidesCite this: J. Am. Chem. Soc. 1978, 100, 21, 6613–6625Publication Date (Print):October 1, 1978Publication History Published online1 May 2002Published inissue 1 October 1978https://pubs.acs.org/doi/10.1021/ja00489a011https://doi.org/10.1021/ja00489a011research-articleACS PublicationsRequest reuse permissionsArticle Views175Altmetric-Citations24LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
This review focuses on experimental work on nonlinear phenomena in microfluidics, which for the most part are phenomena for which the velocity of a fluid flowing through a microfluidic channel does not scale proportionately with the pressure drop. Examples include oscillations, flow-switching behaviors, and bifurcations. These phenomena are qualitatively distinct from laminar, diffusion-limited flows that are often associated with microfluidics. We explore the nonlinear behaviors of bubbles or droplets when they travel alone or in trains through a microfluidic network or when they assemble into either one- or two-dimensional crystals. We consider the nonlinearities that can be induced by the geometry of channels, such as their curvature or the bas-relief patterning of their base. By casting posts, barriers, or membranes─situated inside channels─from stimuli-responsive or flexible materials, the shape, size, or configuration of these elements can be altered by flowing fluids, which may enable autonomous flow control. We also highlight some of the nonlinearities that arise from operating devices at intermediate Reynolds numbers or from using non-Newtonian fluids or liquid metals. We include a brief discussion of relevant practical applications, including flow gating, mixing, and particle separations.
