Interlaminar shear fracture of laminated composites

Chai, Herzl

doi:10.1007/bf00036181

Cited by 66 publications

(22 citation statements)

References 13 publications

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“…Therefore, it is not clear whether the measured G IIc value represents FRP's delamination resistance. Some evaluation has been conducted using specimens with multidirectional fibres, but the results were inconsistent with each other, that is, some angle ply specimens showed higher delamination resistance [12][13][14][15][16], while the others lower [17] than that of the unidirectional specimens. There was even a study showing no significant effect on G IIc value by the fibre orientation [18].…”

Section: Introductionmentioning

confidence: 93%

A New Method to Quantify Delamination Resistance of Fibre Reinforced Polymers (FRP) under Transverse Loading

et al. 2005

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A test method, with specimen design similar to that proposed by ) but under 3-point bending, is proposed to measure the critical strain energy release rate (G c ) for delamination in fibre-reinforced polymers (FRP) under out-of-plane (transverse) loading. Unlike end-notch-flexure (ENF) test or double-cantilever-beam (DCB) test that are currently used, the new method does not require an insert film or a pre-crack to initiate delamination. Instead, the delamination was initiated from a FRP layer of the same composition but with different fibre orientation. Difference of the fibre orientation used in this study was 90 • , i.e. one 90 • layer in the mid-thickness and the rest 0 • layers. Under 3-point bending, matrix shear cracking was firstly initiated in the 90 • layer, mimicking the mechanism for delamination initiation in the FRP when subjected to transverse loading. The matrix shear cracking led to delamination in the adjacent interlaminar regions, of which area can be measured after the test. Calculation of G c was based on "area method", that is, dividing the total energy loss by the delamination area. The G c was compared with that from plate specimens of the same composition and fibre lay-up but subjected to transverse point loading. The comparison suggests that very similar G c values were produced from the two types of testing, even though unstable crack growth occurred under 3-point bending and stable crack growth under transverse point loading. Therefore, the proposed method has the potential of quantifying delamination resistance of FRP under the transverse loading conditions.

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Section: Introductionmentioning

confidence: 93%

A New Method to Quantify Delamination Resistance of Fibre Reinforced Polymers (FRP) under Transverse Loading

et al. 2005

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“…This usually leads to increases in the interlaminar fracture toughness, as parts of the stresses in the interlaminar zone are carried by the fibers. 35,36 Hence, the observed values have to be read with caution.…”

Section: Figure 11mentioning

confidence: 96%

Environmental effects on thermoplastic and elastomer toughened cyanate ester composite systems

Hillermeier

Seferis

2000

J. Appl. Polym. Sci.

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ABSTRACT:The effects of temperature and moisture on thermal and mechanical properties of high-temperature cyanate ester composite materials were investigated. A resin transfer molding process was used to impregnate glass fiber fabrics with matrices that underwent thermoplastic or elastomeric toughness modifications. The elastomer-modified material obtained the highest mode I fracture toughness values primarily because the toughener did not phase separate. Extended exposure to 200°C, however, deteriorated initial toughness improvements regardless of the modifier utilized. Although the thermal stability was increased by using thermoplastic modifiers in comparison to the elastomer-modified material, the degradation was mainly governed by the cyanate ester network. Gaseous degradation products caused delaminations and therefore reduced strength when the materials were exposed to 200°C for 1000 h. Also, upon immersion in water at 95°C, the matrices absorbed up to 3.3 wt % more than previous values reported in the literature. Fiber/matrix interfacial phenomena were responsible for this behavior because fiber/matrix adhesion also was reduced drastically as shown by the strong reduction in flexural strength.

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“…5 shows that the resistance to fracture increased with decreasing epoxy thickness. However, since decreasing the adhesive layer thickness is usually expected to decrease the resistance to fracture (Chai 1988(Chai , 1990, the effect of fracture modemix on toughness for this epoxy (Chai and Liechti 1992) is considered in the next section as a potential contributing factor. In addition, the three quantities defined for each resistance curve, J 0 , J SS , and a ss , will be used to determine the key parameters of the traction-separation relations in the cohesive zone model.…”

Section: Beam On Elastic Foundationmentioning

confidence: 99%

On determining mixed-mode traction–separation relations for interfaces

Gowrishankar

Huang

et al. 2016

Int J Fract

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Traction-separation relations can be used to represent the adhesive interactions of a bimaterial interface during fracture. In this paper, a direct method is proposed to determine mixed-mode tractionseparation relations based on a combination of global and local measurements including load-displacement, crack extension, crack tip opening displacement, and fracture resistance curves. Mixed-mode interfacial fracture experiments were conducted using the end loaded split (ELS) configuration for a silicon-epoxy interface, where the epoxy thickness was used to control the phase angle of the fracture mode-mix. Infrared crack opening interferometry was used to measure the normal crack opening displacements, while both normal and shear components of the crack-tip opening displacements were obtained by digital image correlation. For the resistance curves, an approximate value of the J-integral was calculated based on a beamon-elastic-foundation model that referenced the measured load-displacement data.sive zone model with mixed-mode traction-separation relations was then adopted in finite element analyses, with the interfacial properties determined directly from the experiments. With the mode-I fracture toughness from a previous study, the model was used to predict mixed-mode fracture of the silicon/epoxy interfaces for phase angles ranging from −42 • to 0 • . Results from experiments using ELS specimens with phase angles that differed from those employed in parameter extraction were used to validate the model. Additional measurements would be necessary to further extend the reach of the model to mode-II dominant conditions.

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Interlaminar shear fracture of laminated composites

Cited by 66 publications

References 13 publications

A New Method to Quantify Delamination Resistance of Fibre Reinforced Polymers (FRP) under Transverse Loading

A New Method to Quantify Delamination Resistance of Fibre Reinforced Polymers (FRP) under Transverse Loading

Environmental effects on thermoplastic and elastomer toughened cyanate ester composite systems

On determining mixed-mode traction–separation relations for interfaces

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