Thin films or coatings on a substrate are often under a state of residual biaxial tension. This paper analyzes the cut test wherein a straight cut which is long compared to the film thickness is made through the film down to the substrate. Depending on the elastic properties of the materials, the residual stress level, and the toughness of the interface bond between the film and substrate, the cut may induce extensive decohesion, limited decohesion or no decohesion at all. The main thrust of this paper is concerned with the shape and extent of the zone of decohesion when extensive decohesion occurs. The interface crack front at the boundary of the decohered region is subject to mixed mode conditions involving modes 1, 2 and 3. The shape of the decohesion region depends sensitively on the way in which the mode 3 contribution enters the decohesion criterion. Observations of shapes for a polyimide film on a glass substrate permit the relative importance of the mode 3 contribution to be inferred when the decohered film makes no contact with the substrate. Some experimental observations indicate that the decohesion process is quite complex when the decohered film makes contact with the substrate. A prototypical criterion for mixed mode interfacial fracture is proposed for cases in which the interfacial crack remains open.
Dynamic buckling is addressed for complete elastic spherical shells subject to a rapidly applied step in external pressure. Insights from the perspective of nonlinear dynamics reveal essential mathematical features of the buckling phenomena. To capture the strong buckling imperfection-sensitivity, initial geometric imperfections in the form of an axisymmetric dimple at each pole are introduced. Dynamic buckling under the step pressure is related to the quasi-static buckling pressure. Both loadings produce catastrophic collapse of the shell for conditions in which the pressure is prescribed. Damping plays an important role in dynamic buckling because of the time-dependent nonlinear interaction among modes, particularly the interaction between the spherically symmetric 'breathing' mode and the buckling mode. In general, there is not a unique step pressure threshold separating responses associated with buckling from those that do not buckle. Instead, there exists a cascade of buckling thresholds, dependent on the damping and level of imperfection, separating pressures for which buckling occurs from those for which it does not occur. For shells with small and moderately small imperfections, the dynamic step buckling pressure can be substantially below the quasi-static buckling pressure.
Abstract : Brief oxidation of low-density polyethylene film with chromic acid in aqueous sulfuric acid introduced carboxylic acid and ketone and/or aldehyde groups onto the surface of the film. The carboxylic acid moieties can be used to attach more complex functionality to the polymer surface. We are developing this surface-functionalized polyethylene (named 'polyethylene carboxylic acid,' PE-CO2H, to emphasize the functional group that dominates its surface properties) as a substrate with which to study problems in organic surface chemistry--especially wetting, polymer surface reconstruction, and adhesion--using physical-organic techniques. This document describes the preparation, characterization, and fluorescence properties of derivatives of PE-CO2H in which the Dansyl (5-dimethylaminonaphthalene-1-sulfonyl) group has been covalently attached by amide links to the surface carbonyl moieties. Keywords: Acidity; and Solvent effects.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRates of thiol-disulfide interchange reactions between mono- and dithiols and Ellman's reagentGeorge M. Whitesides, Jennifer E. Lilburn, and Richard P. SzajewskiCite this: J. Org. Chem. 1977, 42, 2, 332–338Publication Date (Print):January 1, 1977Publication History Published online1 May 2002Published inissue 1 January 1977https://pubs.acs.org/doi/10.1021/jo00422a034https://doi.org/10.1021/jo00422a034research-articleACS PublicationsRequest reuse permissionsArticle Views2098Altmetric-Citations200LEARN 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
Two-dimensional ridge structures are induced by equibiaxial compression with a large equi-biaxial pre-stretch in a thin film, using a microfluidics technique. Whereas wrinkles tend to be uniformly distributed, the ridges are localized. The wrinkle-to-ridge transition and the evolution of a ridge network are studied by experiments and numerical simulations on page 4061 by A. Takei and co-workers.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTtrans,trans-1,5-CyclooctadieneGeorge M. Whitesides, Gerald L. Goe, and Arthur C. CopeCite this: J. Am. Chem. Soc. 1967, 89, 26, 7136–7137Publication Date (Print):December 1, 1967Publication History Published online1 May 2002Published inissue 1 December 1967https://pubs.acs.org/doi/10.1021/ja01002a065https://doi.org/10.1021/ja01002a065research-articleACS PublicationsRequest reuse permissionsArticle Views237Altmetric-Citations15LEARN 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
Calculations are reported for the mixed mode toughness of an interface joining an elastic-plastic solid to a solid which does not yield plastically. A potential function of the components of the crack face displacements is used to generate the tractions along the interface where the fracture processes causing separation occur. The two main parameters characterizing this potential are the work of separation per unit area and a peak normal stress. This description of the interface separation process is embedded within the continuum description as a boundary condition on the interface linking the adjoining solids. Small-scale yielding in plane strain is considered with the remote field specified by the magnitude and phase of the mixed mode stress intensity factors. Crack growth resistance curves are computed for a range of the most important nondimensional material parameters and for various combinations of remote mixed mode loading. Particular emphasis is placed on the ratio of the steady-state interface toughness to the “intrinsic” work of separation as it depends on plastic yielding and on the combination of modes 1 and 2. Plasticity enhances the interface toughness for all modes of loading, but substantially more so in the presence of a significant mode 2 component of loading than in near-mode 1 conditions.
A higher baseline arginine/asymmetric dimethylarginine ratio was associated with lower CVD incidence in a high cardiovascular risk population. The intervention with the MD did not change 1-year levels of these metabolites.
Technical Briefs On the Estimation of a Crack Fracture Parameter by Long-Wavelength Scattering B. Budiansky, B. Budiansky Division of Applied Sciences, Harvard University, Cambridge, Mass. Search for other works by this author on: This Site PubMed Google Scholar J. R. Rice J. R. Rice Division of Engineering, Brown University, Providence, R.I. Search for other works by this author on: This Site PubMed Google Scholar Author and Article Information B. Budiansky Division of Applied Sciences, Harvard University, Cambridge, Mass. J. R. Rice Division of Engineering, Brown University, Providence, R.I. J. Appl. Mech. Jun 1978, 45(2): 453-454 (2 pages) https://doi.org/10.1115/1.3424331 Published Online: June 1, 1978 Article history Received: December 1, 1977 Revised: February 1, 1978 Online: July 12, 2010
