Influence of a neighbour fibre on the onset and growth of a fibre-matrix debond under biaxial loading. A study by Finite Fracture Mechanics at linear elastic interfaces

A recently proposed criterion is used to study the behavior of debonds produced at a fiber–matrix interface. The criterion is based on the Linear Elastic–(Perfectly) Brittle Interface Model (LEBIM) combined with a Finite Fracture Mechanics (FFM) approach, where the stress and energy criteria are suitably coupled. Special attention is given to the discussion about the symmetry of the debond onset and growth in an isolated single fiber specimen under uniaxial transverse tension. A common composite material system, glass fiber–epoxy matrix, is considered. The present methodology uses a two-dimensional (2D) Boundary Element Method (BEM) code to carry out the analysis of interface failure. The present results show that a non-symmetrical interface crack configuration (debonds at one side only) is produced by a lower critical remote load than the symmetrical case (debonds at both sides). Thus, the non-symmetrical solution is the preferred one, which agrees with the experimental evidences found in the literature.

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A numerical implementation of the Coupled Criterion of Finite Fracture Mechanics for elastic interfaces

Theoretical and Applied Fracture Mechanics ◽

10.1016/j.tafmec.2020.102607 ◽

2020 ◽

Vol 108 ◽

pp. 102607 ◽

Cited By ~ 1

Author(s):

M. Muñoz-Reja ◽

L. Távara ◽

V. Mantič ◽

P. Cornetti

Keyword(s):

Fracture Mechanics ◽

Numerical Implementation ◽

Finite Fracture Mechanics ◽

Elastic Interfaces ◽

Coupled Criterion

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Non-local criteria for the borehole problem: Gradient Elasticity versus Finite Fracture Mechanics

Meccanica ◽

10.1007/s11012-021-01376-6 ◽

2021 ◽

Author(s):

A. Sapora ◽

G. Efremidis ◽

P. Cornetti

Keyword(s):

Stress Concentration ◽

Fracture Mechanics ◽

Elastic Material ◽

Fracture Criterion ◽

Biaxial Loading ◽

Gradient Elasticity ◽

Energy Conditions ◽

Material Behaviour ◽

Finite Fracture Mechanics ◽

Non Local

AbstractTwo nonlocal approaches are applied to the borehole geometry, herein simply modelled as a circular hole in an infinite elastic medium, subjected to remote biaxial loading and/or internal pressure. The former approach lies within the framework of Gradient Elasticity (GE). Its characteristic is nonlocal in the elastic material behaviour and local in the failure criterion, hence simply related to the stress concentration factor. The latter approach is the Finite Fracture Mechanics (FFM), a well-consolidated model within the framework of brittle fracture. Its characteristic is local in the elastic material behaviour and non-local in the fracture criterion, since crack onset occurs when two (stress and energy) conditions in front of the stress concentration point are simultaneously met. Although the two approaches have a completely different origin, they present some similarities, both involving a characteristic length. Notably, they lead to almost identical critical load predictions as far as the two internal lengths are properly related. A comparison with experimental data available in the literature is also provided.

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Revisiting the Problem of Debond Initiation at Fibre-Matrix Interface under Transversal Biaxial Loads - A Comparison of Several Non-Classical Fracture Mechanics Approaches

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.713.232 ◽

2016 ◽

Vol 713 ◽

pp. 232-235 ◽

Cited By ~ 2

Author(s):

L. Távara ◽

I.G. García ◽

Roman Vodička ◽

C.G. Panagiotopoulos ◽

Vladislav Mantič

Keyword(s):

Fracture Mechanics ◽

Cohesive Zone Model ◽

Failure Criteria ◽

Transverse Load ◽

Zone Model ◽

Interface Model ◽

Matrix Interface ◽

Linear Elastic ◽

Energetic Approach ◽

Fibre Matrix

Understanding matrix failure in LFRP composites is one of the main challenges when developing failure criteria for these materials. This work aims to study the influence of the secondary transverse load on the crack initiation at micro-scale. Four non-classical approaches of fracture mechanics are used to model the onset of fibre-matrix interface debonds: Linear Elastic Brittle Interface Model (LEBIM), an Energetic Approach for the Linear Elastic Brittle Interface Model (EA-LEBIM), an Energetic Approach for the bilinear Cohesive Zone Model (EA-CZM) and the Coupled Criterion of the Finite Fracture Mechanics (CC-FFM). Results obtained by these approaches predict that, for brittle fibre-matrix configurations, a secondary transverse compression reduces the critical value of the main transverse tension leading to the debond onset. This fact is not taken into account by the currently used failure criteria

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Brittle Failure of Nanoscale Notched Silicon Cantilevers: A Finite Fracture Mechanics Approach

Applied Sciences ◽

10.3390/app10051640 ◽

2020 ◽

Vol 10 (5) ◽

pp. 1640 ◽

Cited By ~ 2

Author(s):

Pasquale Gallo ◽

Alberto Sapora

Keyword(s):

Fracture Mechanics ◽

Brittle Failure ◽

Process Zone ◽

Single Crystal Silicon ◽

Crystal Silicon ◽

Linear Elastic ◽

Finite Fracture Mechanics ◽

Generalized Stress Intensity Factors ◽

Fracture Tests ◽

Elastic Fracture

The present paper focuses on the Finite Fracture Mechanics (FFM) approach and verifies its applicability at the nanoscale. After the presentation of the analytical frame, the approach is verified against experimental data already published in the literature related to in situ fracture tests of blunt V-notched nano-cantilevers made of single crystal silicon, and loaded under mode I. The results show that the apparent generalized stress intensity factors at failure (i.e., the apparent generalized fracture toughness) predicted by the FFM are in good agreement with those obtained experimentally, with a discrepancy varying between 0 and 5%. All the crack advancements are larger than the fracture process zone and therefore the breakdown of continuum-based linear elastic fracture mechanics is not yet reached. The method reveals to be an efficient and effective tool in assessing the brittle failure of notched components at the nanoscale.

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