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This paper is a study of the theoretical foundations of constitutive relations at finite strain for a class of solids exhibiting inelasticity as a consequence of specific structural rearrangements, on the microscale, of constituent elements of material. Metals deforming plastically through dislocation motion are of this class and form the primary application of the theory. The development is in terms of a general internal-variable thermodynamic formalism for description of the microstructural rearrangements, and it is shown how metal plasticity may be so characterized. The principal result is in the normality structure which is shown to arise in macroscopic constitutive laws when each of the local microstructural rearrangements proceeds at a rate governed by its associated thermodynamic force. This provides a theoretical framework for time-dependent inelastic behavior in terms of a “flow potential”, and reduces to statements on normality of strain increments to yield surfaces in the time-independent case. Conventional characterizations of the stress-state dependence of metallic slip are noted to be in accord with this concept of associated forces governing rates, so that the resulting normality structure may be considered directly applicable to metal plasticity.
Microtransfer molding is a new technique for rapidly fabricating micrometer‐scale structures over large areas (3.5 cm × 0.8 cm). This new technique, which involves the solidification of a liquid precursor in an elastomeric mold, can generate microstructures of organic polymers and ceramics such as that shown in the Figure on both planar and contoured surfaces and is able to make three‐dimensional structures layer by layer. magnified image
We present an analysis of inelastic off‐fault response in fluid‐saturated material during earthquake shear rupture. The analysis is conducted for 2‐D plane strain deformation using an explicit dynamic finite element formulation. Along the fault, linear slip‐weakening behavior is specified, and the off‐fault material is described using an elastic‐plastic description of the Drucker‐Prager form, which characterizes the brittle behavior of rocks under compressive stress when the primary mode of inelastic deformation is frictional sliding of fissure surfaces, microcracking and granular flow. In this part (part 1), pore pressure changes were neglected in materials bordering the fault. In part 2, we more fully address the effects of fluid saturation. During the rapid stressing by a propagating rupture, the associated undrained response of the surrounding fluid‐saturated material may be either strengthened or weakened against inelastic deformation. We consider poroelastoplastic materials with and without plastic dilation. During nondilatant undrained response near a propagating rupture, large increases in pore pressure on the compressional side of the fault decrease the effective normal stress and weaken the material, and decreases in pore pressure on the extensional side strengthen the material. Positive plastic dilatancy reduces pore pressure, universally strengthening the material. Dilatantly strengthened undrained deformation has a diffusive instability on a long enough timescale when the underlying drained deformation is unstable. Neglecting this instability on the short timescale of plastic straining, we show that undrained deformation is notably more resistant to shear localization than predicted by neglect of pore pressure changes.
<title>Abstract</title> OBJECTIVE AND METHODS: We have developed a novel Bayesian Linear Structural Equations Model (BLSEM) with variable selection priors (available as an R package) to build directed acyclic graphs to delineate complex variable associations and pathways to BMI development. Conditional on standard assumptions used in causal inference, the model provides interpretable estimates with uncertainty for natural direct and indirect (mediated) effects. RESULTS: We showcase our method using data on 4 119 offspring followed from the pre-pregnancy period to age 46 years(y) in a Finnish population-based birth cohort. The BLSEM enabled efficiently to analyse all available data over the long-time span, identifying factors to distil potential causal pathways contributing to adult BMI development. All of the associations between early childhood and adolescence variables with adult BMI at 46y (BMI46) were indirect via multiple paths. For example, maternal prepregnancy BMI, smoking and socioeconomic position associated with BMI46 through 35, 31 and 26 paths. Another notable feature was that the contribution of very early life factors, particularly prenatal, was captured by growth patterns along the childhood which were the strongest early predictors of middle age BMI46 (the age at adiposity rebound (AgeAR), early growth parameters between the AgeAR to 11y). BMI and blood pressure measured 15y earlier also predicted BMI46, all other factors held constant. Genetic predisposition by the polygenic risk score for BMI, showed an indirect effect that became apparent at AgeAR and thereafter. CONCLUSIONS: The Bayesian approach we present and BLSEM software developed advances methodologies for the analysis of complex, multifaceted life-course data prior to the estimation of potential causal pathways. Our results, although exploratory in nature, suggest that the effective interventions to tackle adverse BMI development could be designed throughout childhood though period by AgeAR maybe paramount. We feature the importance of integrated life-course analyses that help to understand the contribution of life-stage factors of development.
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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPreparation of deuterated organic compounds from activated organic halides by reduction with zinc-deuterium oxideLarry S. Trzupek, Erwin R. Stedronsky, and George M. WhitesidesCite this: J. Org. Chem. 1972, 37, 21, 3300–3303Publication Date (Print):October 1, 1972Publication History Published online1 May 2002Published inissue 1 October 1972https://pubs.acs.org/doi/10.1021/jo00986a023https://doi.org/10.1021/jo00986a023research-articleACS PublicationsRequest reuse permissionsArticle Views651Altmetric-Citations11LEARN 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
