The Mode III Crack Problem in Microstructured Solids Governed by Dipolar Gradient Elasticity: Static and Dynamic Analysis

Georgiadis, HG

dc.contributor.author	Georgiadis, HG	en
dc.date.accessioned	2014-03-01T01:19:37Z
dc.date.available	2014-03-01T01:19:37Z
dc.date.issued	2003	en
dc.identifier.issn	0021-8936	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/15612
dc.subject	Microstructures	en
dc.subject	Static and Dynamic Analysis	en
dc.subject.classification	Mechanics	en
dc.subject.other	Boundary value problems	en
dc.subject.other	Elastic moduli	en
dc.subject.other	Elasticity	en
dc.subject.other	Fracture mechanics	en
dc.subject.other	Integration	en
dc.subject.other	Microstructure	en
dc.subject.other	Stiffness	en
dc.subject.other	Stresses	en
dc.subject.other	Dipolar gradient elasticity	en
dc.subject.other	Cracks	en
dc.title	The Mode III Crack Problem in Microstructured Solids Governed by Dipolar Gradient Elasticity: Static and Dynamic Analysis	en
heal.type	journalArticle	en
heal.identifier.primary	10.1115/1.1574061	en
heal.identifier.secondary	http://dx.doi.org/10.1115/1.1574061	en
heal.language	English	en
heal.publicationDate	2003	en
heal.abstract	This study aims at determining the elastic stress and displacement fields around a crack in a microstructured body under a remotely applied loading of the antiplane shear (mode III) type. The material microstructure is modeled through the Mindlin-Green-Rivlin dipolar gradient theory (or strain-gradient theory of grade two). A simple but yet rigorous version of this generalized continuum theory is taken here by considering an isotropic linear expression of the elastic strain-energy density in antiplane shearing that involves only two material constants (the shear modulus and the so-called gradient coefficient). In particular, the strain-energy density function, besides its dependence upon the standard strain terms, depends also on strain gradients. This expression derives from form II of Mindlin's theory, a form that is appropriate for a gradient formulation with no couple-stress effects (in this case the strain-energy density function does not contain any rotation gradients). Here, both the formulation of the problem and the solution method are exact and lead to results for the near-tip field showing significant departure from the predictions of the classical fracture mechanics. In view of these results, it seems that the conventional fracture mechanics is inadequate to analyze crack problems in microstructured materials. Indeed, the present results suggest that the stress distribution ahead of the tip exhibits a local maximum that is bounded. Therefore, this maximum value may serve as a measure of the critical stress level at which further advancement of the crack may occur. Also, in the vicinity of the crack tip, the crack-face displacement closes more smoothly as compared to the classical results. The latter can be explained physically since materials with microstructure behave in a more rigid way (having increased stiffness) as compared to materials without microstructure (i.e., materials governed by classical continuum mechanics). The new formulation of the crack problem required also new extended definitions for the J-integral and the energy release rate. It is shown that these quantities can be determined through the use of distribution (generalized function) theory. The boundary value problem was attacked by both the asymptotic Williams technique and the exact Wiener-Hopf technique. Both static and time-harmonic dynamic analyses are provided.	en
heal.publisher	ASME-AMER SOC MECHANICAL ENG	en
heal.journalName	Journal of Applied Mechanics, Transactions ASME	en
dc.identifier.doi	10.1115/1.1574061	en
dc.identifier.isi	ISI:000185676500007	en
dc.identifier.volume	70	en
dc.identifier.issue	4	en
dc.identifier.spage	517	en
dc.identifier.epage	530	en