Piezomagnetic and piezoelectric poling effects on mode I and II crack initiation behavior of magnetoelectroelastic materials

Sih, GC; Jones, R; Song, ZF

dc.contributor.author	Sih, GC	en
dc.contributor.author	Jones, R	en
dc.contributor.author	Song, ZF	en
dc.date.accessioned	2014-03-01T01:19:25Z
dc.date.available	2014-03-01T01:19:25Z
dc.date.issued	2003	en
dc.identifier.issn	0167-8442	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/15485
dc.subject	Distortion and dilatation	en
dc.subject	Mode I and II crack extension	en
dc.subject	Piezomagnetic and piezoelectric pole	en
dc.subject.classification	Engineering, Mechanical	en
dc.subject.classification	Mechanics	en
dc.subject.other	Continuum mechanics	en
dc.subject.other	Crack initiation	en
dc.subject.other	Magnetoelectric effects	en
dc.subject.other	Microstructure	en
dc.subject.other	Piezoelectric materials	en
dc.subject.other	Piezoelectricity	en
dc.subject.other	Electric energy	en
dc.subject.other	Magnetic materials	en
dc.subject.other	fracture mechanics	en
dc.subject.other	piezoelectricity	en
dc.title	Piezomagnetic and piezoelectric poling effects on mode I and II crack initiation behavior of magnetoelectroelastic materials	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/S0167-8442(03)00044-2	en
heal.identifier.secondary	http://dx.doi.org/10.1016/S0167-8442(03)00044-2	en
heal.language	English	en
heal.publicationDate	2003	en
heal.abstract	The ferrite and ferroelectric phase of magnetoelectroelastic (MEE) material can be selected and processed to control the macroscopic behavior of electron devices using continuum mechanics models. Once macro- and/or microdefects appear, the highly intensified magnetic and electric energy localization could alter the response significantly to change the design performance. Alignment of poling directions of piezomagnetic and piezoelectric materials can add to the complexity of the MEE material behavior to which this study will be concerned with. Appropriate balance of distortional and dilatational energy density is no longer obvious when a material possesses anisotropy and/or nonhomogeneity. An excess of the former could result in unwanted geometric change while the latter may lead to unexpected fracture initiation. Such information can be evaluated quantitatively from the stationary values of the energy density function dW/dV. The maxima and minima have been known to coincide, respectively, with possible locations of permanent shape change and crack initiation regardless of material and loading type. The direction of poling with respect to a line crack and the material microstructure described by the constitutive coefficients will be specified explicitly with reference to the applied magnetic field, electric field and mechanical stress, both normal and shear. The crack initiation load and direction could be predicted by finding the direction for which the volume change is the largest. In contrast to intuition, change in poling directions can influence the cracking behavior of MEE dramatically. This will be demonstrated by the numerical results for the BaTiO3-CoFe2O4 composite having different volume fractions where BaTiO3 and CoFe2O4 are, respectively, the inclusion and matrix. To be emphasized is that mode I and II crack behavior will not have the same definition as that in classical fracture mechanics where load and, crack extension symmetry would coincide. A striking. result is found for a mode II crack. By keeping the magnetic poling fixed, a reversal of electric poling changed the crack initiation angle from theta(0) = +80degrees to theta(0) = -80degrees using the line extending ahead of the crack as the reference. This effect is also sensitive to the distance from the crack tip. Displayed and, discussed are results for r/a = 10(-4) and 10(-1). Because the theory of magnetoelectro-elasticity used in the analysis is based on the assumption of equilibrium where the influence of material microstructure is homogenized, the local space and temporal effects must be interpreted accordingly. Among them are the maximum values of (dW/dV)(max) and (dW/dV)(min) which refer to as possible sites of yielding and fracture. Since time and size are homogenized, it is implicitly understood that there is more time for yielding as compared to fracture being a more sudden process. This renders a higher dW/dV in contrast to that for fracture. Put it differently, a lower dW/dV with a shorter time for release could be more detrimental. (C) 2003 Elsevier Ltd. All rights reserved.	en
heal.publisher	ELSEVIER SCIENCE BV	en
heal.journalName	Theoretical and Applied Fracture Mechanics	en
dc.identifier.doi	10.1016/S0167-8442(03)00044-2	en
dc.identifier.isi	ISI:000185041900006	en
dc.identifier.volume	40	en
dc.identifier.issue	2	en
dc.identifier.spage	161	en
dc.identifier.epage	186	en