88 research outputs found
WORKSHOP 2 EXPANDING HORIZONS. New strategies for multifield fracture problems across scales in heterogeneous systems for energy, health and transport
Crack onset and growth at the fibre–matrix interface under a remote biaxial transverse load. Application of a coupled stress and energy criterion
A theoretical model for prediction of the critical load generating a crack onset at the fibrematrix
interface under a remote biaxial transverse load is presented. In particular, this work is
focused on the tension dominated failure.
After an abrupt onset the crack grows unstably up to achieving an arrest length. A simple plane strain
model of a single circular inclusion surrounded by an unbounded matrix allows to obtain conclusions
approximately valid for a dilute fibre packing. Linear isotropic elastic behaviour is assumed for both
inclusion and matrix. Two classical elastic solutions for both perfectly bonded and partially debonded
circular inclusions are used together with a coupled stress and energy criterion, proposed recently in
the framework of Finite Fracture Mechanics, and a phenomenological law for fracture toughness of
interface cracks growing in fracture mixed mode. The obtained analytical and semi-analytical
expressions make easy to study the influence of all the dimensionless parameters governing the fibrematrix
system behaviour: Dundurs elastic bimaterial constants and , the interface
brittleness number , the load biaxiality parameter , and the fracture mode-sensitivity
parameter . A size effect of the inclusion radius on the critical load is predicted, smaller
inclusions being stronger and less dependent on the secondary load. Finally, an experimental
procedure for measurement of the fibre-matrix interface fracture and strength properties is
proposed.Ministerio de Ciencia e InnovaciónJunta de AndalucíaMinisterio de Educació
Formulación simétrica de las ecuaciones integrales de contorno para materiales elásticos anisótropos en 2D
II CONGRESO NACIONAL DE MATERIALES COMPUESTOS. Celebrado en Madrid, 25 al 28 de noviembre, 1997El estudio presente forma la base teórica de la implementación de un código
del Método de los Elementos de Contorno (MEC) Simétrico para el análisis tensional de
materiales anisótropos homogéneos en estados de defomación plana generalizada o tensión
plana. Se discuten algunas ventajas que tiene el MEC Simétrico frente al enfoque convencional.
Se desarrolla un planteamiento débil y simétrico de las Ecuaciones Integrales de
Contorno (EIC) para un problema elástico mixto. Se introducen expresiones explícitas para
los núcleos integrales que aparecen en estas EIC. Se desarrolla un procedimiento simple para
la regularización de la integral hipersingular que se precisa para un cálculo eficaz de la forma
cuadrática. correspondiente.The present study providcs the theorclical basis for an implementation of a
Symmetrical Boundary Element Method (SBEM) code for stress analysis of anisotropic ho·
mogeneous materials subjected to a generalised plane deformation or plane stre~s state.
Sorne advantages of SBEM over the conventional approach are discussed. A weak symmetrical
formula.tion of Boundary Integral Equations for a mixed clastic problem is given. Explicit
expressions of the integral kcrnels are introduced. A simple procedure of regularization of
the hypersingular integral, required for an efficient evaluation of the corresponding quadratic
form, is develope
Formulación de la identidad de Somigliana de tensiones en la elasticidad anisótropa bidimensional
CONGRESO NACIONAL DE MATERIALES COMPUESTOS. Celebrado en Málaga en 1999El desarrollo de las aplicaciones de los materiales compuestos requiere
cada vez más aplicaciones de los métodos numéricos, y en particular del Método de
los Elementos de Contorno (MEC), al análisis tensional de los materiales
anisótropos elásticos, para modelar desde un punto de vista macroscópico los
materiales compuestos. El MEC se aplica a la resolución numérica de la Ecuaciones
Integrales de Contorno (EIC) correspondientes a un problema elástico. El presente
trabajo desarrolla una formulación general de una de estas EIC, llamada Identidad
de Somigliana de Tensiones, considerándola no sólo en los puntos de contorno
suaves sino también en las esquinas. Resultado de un análisis asintótico es la
formulación de esta EIC en forma de suma de términos libres y una integral en el
sentido de Parte Finita de Hadamard. Las fórmulas analíticas que se presentan de
los tensores coeficientes de los términos libres pueden implementarse con facilidad
en códigos basados en el MEC
Interface crack onset at a circular cylindrical inclusion under a remote transverse tension. Application of a coupled stress and energy criterion
The plane strain problem of a single circular cylindrical inclusion embedded in an unbounded matrix subjected to a remote uniform uniaxial transverse tension is studied. A theoretical model for the simultaneous prediction of \emph{the initial size of a crack originated at the inclusion/matrix interface} (or equivalently the initial polar angle of this crack) and of \emph{the critical remote tension required to originate this crack} is developed. Isotropic and linear elastic behaviour of both materials, with the inclusion being stiffer than the matrix, is assumed. The interface is considered to be strong (providing continuity of displacements and tractions across the interface surface) and brittle. The model developed is based on the classical analytic solutions for the above-mentioned inclusion problem without and with a crack situated at the inclusion/matrix interface and a recently introduced coupled stress and energy criterion of failure by Leguillon (\emph{Eur. J. Mech. A/Solids, 21, pp. 61--72, 2002}). A new dimensionless structural parameter , depending on bimaterial and interface properties together with the inclusion radius , which plays a key role in characterizing the interface crack onset, is introduced. Asymptotic behaviour of the predicted critical remote tension and the interface crack length/polar angle at the onset are characterized for small and large values of and . A size effect inherent to this problem is predicted and analysed. The following asymptotic characteristics of this size effect are noteworthy: \emph{i)} for small inclusion radii , the polar angle of the crack at onset is constant (independent of ), whereas the critical remote tension increases with decreasing , being inversely proportional to the square root of ; \emph{ii)} for large inclusion radii , the length of the crack at onset and the critical remote tension are approximately constant.Ministerio de Educación, Cultura y DeporteJunta de Andalucí
Coupled stress and energy criterion for multiple matrix cracking in cross-ply composite laminates
The authors are indebted to Professors Federico París and Antonio Blázquez (University of Seville) for inspiring discussions. The authors wish to thank the Royal Society (UK) International Exchanges Scheme (award # IE141234), the Spanish Ministry of Economy and Competitiveness and European Regional Development Fund (Projects MAT2012-37387 and MAT2015-71036-P) for supporting this research.Peer reviewedPostprin
Workshop 2 Expanding Horizons: New strategies for multifield fracture problems across scales in heterogeneous systems for energy, health and transport
NewFrac Workshop-2 is especially focused on Phase Field and Finite Fracture Mechanics. It is open to senior researchers and PhD students in fracture mechanics.Horizonte 2020 (Unión Europea) 86106
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