Ductile–brittle transitions in the fracture of plastically-deforming, adhesively-bonded structures. Part I: Experimental studies

Sun, Ce; Thouless, M.D.; Waas, Anthony M.; Schroeder, J.A.; Zavattieri, Pablo

doi:10.1016/j.ijsolstr.2008.01.011

Cited by 45 publications

(42 citation statements)

References 15 publications

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“…In these studies, plastic deformation of the steel always accompanied fracture. The mode-I studies (Sun et al, 2008a) exhibited crack growth that was contained completely within the adhesive layer. The mode-I properties of the adhesive layer were determined to be essentially rate-independent, except in one important regard: as the crack velocity increased, there was an increased tendency for a catastrophic transition to a relatively brittle mode of fracture.…”

Section: Background and Motivationmentioning

confidence: 98%

“…There was a considerable range of crack velocities for the quasi-static mode after transitions to dynamic fracture occurred, but it should be noted that quasistatic crack growth did occur at a velocity very comparable to the average specimen velocity, even at the fastest rate. It was noted that transitions to dynamic fracture were not as prevalent for these mode-I "adhesive" failures at the interface as they had been for mode-I "cohesive" crack growth within the adhesive layer (Sun et al, 2008a). Figure 13, shows that when the crack was growing in a quasi-static mode, the distance between the crack tip and the wedge was in the range of 6 to 10 mm with no correlation to crack velocity (outside specimen-to-specimen variation), but increased to between 16 and 24 mm immediately after a transition to dynamic fracture.…”

Section: Asymmetric Wedge Geometry and The Toughness Of The Brittle Modementioning

confidence: 98%

“…The essential aspect of these geometries are that they are almost completely mode-I, but with enough asymmetry to drive the crack along one interface. In this paper, three geometries were used that were based on geometries of the symmetrical mode-I tests (Sun et al, 2008a;2008b): asymmetrical tensile tests, asymmetrical double-cantilever beam tests, and asymmetric wedge tests. A wide range of loading rates was obtained by using a servo-hydraulic testing machine that could provide displacement rates of up to 250 mm/s, and a drop-tower facility that could provide displacement rates of up to 5 m/s.…”

Section: Interfacial Mode-i Cohesive Parameters For Mixed-mode Fracturementioning

confidence: 99%

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Rate effects for mixed-mode fracture of plastically-deforming, adhesively-bonded structures

Sun

Thouless

Waas

et al. 2009

International Journal of Adhesion and Adhesives

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Mixed-mode fracture of an adhesively-bonded structure made from a commercial adhesive and a dual-phase steel has been studied under different rates. Since mixedmode fracture occurs along the interface between the steel and adhesive, the cohesiveparameters for the interface were required. The mode-II interfacial properties were deduced in earlier work. In this paper the mode-I interfacial toughness and the mode-I interfacial strength were determined at different rates. The mode-I interfacial strength was not affected by rate up to crack velocities at levels associated with impact conditions, and was essentially identical to the cohesive strength appropriate for crack growth within the adhesive layer. The mode-I toughness was reduced by about 40% when the crack propagated along the interface rather than within the adhesive. Furthermore, transitions to a brittle mode of failure occurred in a stochastic fashion, and were associated with a drop in interfacial toughness by a factor of about five. The mode-I interfacial parameters were combined with the previously-determined mode-II interfacial parameters within a cohesive-zone model to analyze the mixed-mode fracture of the joints which exhibited both quasi-static and unstable fracture. The mixed-mode model and the associated cohesive parameters for both quasi-static and unstable crack propagation provide bounds for predicting the behavior of the bonded joints under various rates of loading, up to the impact conditions that could be appropriate for automotive design. (August 15, 2008) 2

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Section: Background and Motivationmentioning

confidence: 98%

Section: Asymmetric Wedge Geometry and The Toughness Of The Brittle Modementioning

confidence: 98%

Section: Interfacial Mode-i Cohesive Parameters For Mixed-mode Fracturementioning

confidence: 99%

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Rate effects for mixed-mode fracture of plastically-deforming, adhesively-bonded structures

Sun

Thouless

Waas

et al. 2009

International Journal of Adhesion and Adhesives

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“…The results showed good agreement with experiments with respect to the stiffness and the peak load but overestimated the crack propagation load. The cohesive parameters for both tough and brittle modes of crack growth were determined in the work of Sun et al [22,23] by comparing numerical predictions from cohesive zone simulations to the experimental results obtained using DCB specimens and tensile tests. Li et al [24] used a cohesive--zone approach to model the mode I fracture of adhesively bonded composite joints.…”

Section: Application Of the Czm To Adhesive Jointsmentioning

confidence: 99%

Effects of bond gap thickness on the fracture of nano-toughened epoxy adhesive joints

Cooper

Ivanković

Karač

et al. 2012

Polymer

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Publication information Polymer, 53 (24): 5540-5553Publisher Elsevier Item record/more information http://hdl.handle.net/10197/5950 Publisher's statementThis is the author's version of a work that was accepted for publication in Polymer. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Polymer (53, 24, (2012)) DOI: http://dx.doi/org/10.1016/j.polymer.2012.09.049Publisher's version (DOI) http://dx.doi.org/10.1016/j.polymer.2012.09.049 NotesOther RMSIDs: 316516744Some rights reserved. For more information, please see the item record link above. Bosnia and Herzegovina AbstractThe current work is a combined experimental--numerical study of the fracture behaviour of a nano--toughened, structural epoxy adhesive. The mode I fracture toughness of the adhesive is measured using tapered double--cantilever beam ( IntroductionThe accurate and efficient determination of the fracture toughness and the associated fracture mechanisms of a structural adhesive are of fundamental importance to adhesive manufacturers and end users alike. The ability to predict the behaviour of such joints can lead to better designs, increased performance, reduced costs and enhanced safety. Better understanding of the structure--property relationship will ultimately lead towards improved adhesives with tailored properties. However, the behaviour of joints in real structures is difficult to predict since their behaviour, including the failure mechanisms, are complex to measure and model. The testing of prototypes and trial structures is costly and time--consuming. Consequently, there has been a growing motivation for the development of theoretical models for predicting the damage and failure of adhesive joints. These models require geometry independent material parameters, which are usually obtained from tests with simpler geometries and subsequently applied in the analysis of more complexgeometries.An important parameter in adhesive joint design is the bond gap thickness (BGT) which needs to be accurately controlled in order to obtain a consistent and reliable joint strength. In the current work, the mode I fracture behaviour of a nano--toughened, structural epoxy adhesive was examined using low--rate TDCB tests with various bond gap thicknesses. The Application of the CZM to adhesive jointsCohesive zone models are widely used to model the fracture of adhesive joints. In general, the substrates are modelled as elastic--plastic continua while two main approaches are adopted for the modelling of the adhesive layer: i) CZM is used to represent the entire adhesive layer, ii) the adhesive layer is modelled as a continuum while CZM is used to describe the local fracture process. A number of authors have used a single row of cohesive zone elements to represent the adhesive layer, e.g. ...

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“…Rate-dependent CZMs have been used extensively to model the fracture of ratedependent materials in general [e.g. [19][20][21][22][23][24][25][26][27][28][29].However, only a few authors have reported the use of rate-dependent CZMs to study the fracture of adhesive joints [15,[30][31][32][33][34][35]. For example, to capture the rate-dependency of failure in adhesive bonds of the double cantilever-beam test specimen, Xuet.…”

Section: Introductionmentioning

confidence: 99%

Modelling the fracture behaviour of adhesively-bonded joints as a function of test rate

Karač

Blackman

Cooper

et al. 2011

Engineering Fracture Mechanics

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Tapered-double cantilever-beam joints were manufactured from aluminium-alloy substrates bonded together using a single-part, rubber-toughened, epoxy adhesive. The mode I fracture behaviour of the joints was investigated as a function of loading rate by conducting a series of tests at crosshead speeds ranging from 3.33 x10 -6 m/s to 13.5 m/s. Unstable, (i.e. stick-slip crack) growth behaviour was observed at test rates between 0.1 m/s and 6 m/s, whilst stable crack growth occurred at both lower and higher rates of loading. The adhesive fracture energy, G Ic , was estimated analytically, and the experiments were simulated numerically employing an implicit finite-volume method together with a cohesive-zone model. Good agreement was achieved between the numerical predictions, analytical results and the experimental observations over the entire range of loading rates investigated. The numerical simulations were able very readily to predict the stable crack growth which was observed, at both the slowest and highest rates of loading. However, the unstable crack propagation that was observed could only be predicted accurately when a particular rate-dependent cohesive zone model was used. This crack-velocity dependency of G Ic was also supported by the predictions of an adiabatic thermal-heating model (ATM).

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Ductile–brittle transitions in the fracture of plastically-deforming, adhesively-bonded structures. Part I: Experimental studies

Cited by 45 publications

References 15 publications

Rate effects for mixed-mode fracture of plastically-deforming, adhesively-bonded structures

Rate effects for mixed-mode fracture of plastically-deforming, adhesively-bonded structures

Effects of bond gap thickness on the fracture of nano-toughened epoxy adhesive joints

Modelling the fracture behaviour of adhesively-bonded joints as a function of test rate

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