Theoretical Modelling of the Effect of the Interfacial Shear Strength on the Longitudinal Tensile Strength of Unidirectional Composites

Shih, G.C.; Ebert, L. J.

doi:10.1177/002199838702100302

Cited by 30 publications

(7 citation statements)

References 12 publications

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“…A strong adhesion however can also be detrimental, as it tends to localise the fractures in the same plane. Therefore, the general belief is that an intermediate interfacial strength leads to the best tensile properties [143][144][145].…”

Section: Interfacial Propertiesmentioning

confidence: 99%

A review of input data and modelling assumptions in longitudinal strength models for unidirectional fibre-reinforced composites

Swolfs

Verpoest

Gorbatikh

2016

Composite Structures

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Fibre-reinforced composites are rapidly increasing their market share in structural applications. Nevertheless, this increase would be much stronger if reliable failure predictions were available. These predictions are not only insufficiently reliable for complex loading of multidirectional composites, but even for longitudinal tensile failure of unidirectional (UD) composites. Since composite failure usually coincides with longitudinal failure of a 0° ply, the reliability often hinges on longitudinal failure predictions of UD composites. Despite great progress in the state-of-the-art models, significant obstacles remain in collecting the necessary input data and understanding the influence of the modelling assumptions. This review therefore surveys the mechanics, chemistry and physics involved in tensile failure of UD composites and highlights potential areas for improvement. Specific proposals are made to advance the state-of-the-art strength models, which could catalyse the use of composites in structural applications.

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Section: Interfacial Propertiesmentioning

confidence: 99%

A review of input data and modelling assumptions in longitudinal strength models for unidirectional fibre-reinforced composites

Swolfs

Verpoest

Gorbatikh

2016

Composite Structures

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“…The magnitudes and length scale of overloads in fibres adjacent to a cluster of contiguous breaks, combined with the strength statistics of the fibres at this characteristic length scale, determine the transverse growth of the cluster. The stress distribution at a break depends on the existence and growth of fibre/matrix debonding, which is often the precursor to longitudinal splitting [8][9][10]. While several theoretical studies have attempted to explain these phenomena [11][12][13][14][15], little has been substantiated experimentally about the constitutive behaviour and the mechanisms of debonding at the length scale of a fibre break, especially in the presence of other closely spaced fibres.…”

Section: Introductionmentioning

confidence: 99%

Experiments on shear deformation, debonding and local load transfer in a model graphite/glass/epoxy microcomposite

1991

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Recent statistical theories for the failure of polymer matrix composites depend heavily on details of the stress redistribution around fibre breaks. The magnitudes and length scales of fibre overloads as well as the extent of fibre/matrix debonding are key components in the development of longitudinal versus transverse crack propagation. While several theoretical studies have been conducted to investigate the roles of these mechanisms, little has been substantiated experimentally about the matrix constitutive behaviour and mechanisms of debonding at the length scale of a fibre break. In order to predict the growth of transverse and longitudinal cracks using the same micromechanical model, we microscopically observed the epoxy shear behaviour around a single fibre break in a three-fibre microcomposite tape. The planar specimens consisted of a single graphite fibre placed between two larger glass fibres in an epoxy matrix. The interfibre spacing was less than one fibre diameter (< 6 I~m) in order to reflect the spacing between fibres found in typical composites. The epoxy constitutive behaviour was modelled using shear-lag theory where the epoxy had elastic, plastic, and debond zones. The criteria for debonding were modified from conventional shear-lag approaches to reflect the orientational hardening in the epoxy network structure. The epoxy, which is brittle in bulk, locally underwent a shear strain of about 60% prior to debonding from the fibre.

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“…Certain restrictive assumptions accompany various analyses in order to make them mathematically tractable. The interphase region is often considered to be isotropic and homogeneous [5,6,7], yet, has been modeled as a multiphase region with each subphase possessing its own properties [8,9,10]. Each interphase interface is &dquo;perfect&dquo; in the sense that continuity of displacements and tractions are assumed to exist across the boundary.…”

Section: Idealizations Of the Interphasementioning

confidence: 99%

“…The constituents have uniform properties. 6. The effect of the local stress concentrations on strength is not considered.…”

Section: Uniaxial Tensile Strengthmentioning

confidence: 99%

Interface/Interphase Concepts in Composite Material Systems

Swain

Reifsnider

Jayaraman

et al. 1990

Journal of Thermoplastic Composite Materials

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The influence of interfaces and interphases on the mechanical behavior of composite materials has been widely discussed in the literature, particularly in the last few years. Several books have been devoted to the subject. Despite this fact, the systematic representation of the mechanics of this subject remains grossly incomplete, and because of this, no consistent approach has been developed towards the determination of the influence of the interphase on the properties and performance of composite materials and laminates.The present paper advances a fundamental approach to this subject. The approach is based on the premise that the "composite effect"—that which defines the difference between the mechanical response of constituents acting without interaction and the response when they are bonded rigidly together — is the proper definition of the mechanical effect of the interphase. Within these two bounds, the "real" situation is determined by the extent of this interaction. The present paper attempts to specify these two bounds for typical loading and material situations. The nature of the boundary value problems associated with the two extremes as well as the intermediate cases is discussed.The incorporation of an interphasial region into micromechanical analyses of composite stiffness and strength will necessitate a reevaluation of the boundary value problem. The anisotropic, inhomogeneous, time-dependent quality of the interphase demands a more thorough treatment in existing micromechanical models. Yet, the level of complexity modeled is limited by our ability to measure interphasial properties. The interphase offers a wealth of opportunity on both analytical and experimental aspects of the problem.

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Theoretical Modelling of the Effect of the Interfacial Shear Strength on the Longitudinal Tensile Strength of Unidirectional Composites

Cited by 30 publications

References 12 publications

A review of input data and modelling assumptions in longitudinal strength models for unidirectional fibre-reinforced composites

A review of input data and modelling assumptions in longitudinal strength models for unidirectional fibre-reinforced composites

Experiments on shear deformation, debonding and local load transfer in a model graphite/glass/epoxy microcomposite

Interface/Interphase Concepts in Composite Material Systems

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