Study of the interface in Kevlar 49-epoxy composites by means of microbond and fragmentation tests: effects of materials and testing variables

Wagner, H. Daniel; Gallis, H. E.; Wiesel, E.

doi:10.1007/bf00367590

Cited by 74 publications

(37 citation statements)

References 15 publications

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“…The interfacial shear strength can be affected by the type of fiber and matrix as well as the condition of the fiber surface treatment [1,2]. Some test methods, such as the pull-out test [3,4], microdroplet test [5][6][7], microdebond test [8,9] and fragmentation test [10,11] have been used to evaluate the interfacial shear strength.…”

Section: Introductionmentioning

confidence: 99%

The interfacial shear strength of Kevlar fiber/epoxy composite measured by the microdroplet test

Caichilan²

2010

Materialwissenschaft Werkst

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Epoxy chloropropane (ECP) grafting modification method was used for the surface treatment of Kevlar fiber to improve the interfacial adhesion of the Kevlar fiber reinforced epoxy composite. The surface characteristics of untreated and treated Kevlar fiber were characterized by Fourier transform infrared (FT-IR) spectroscope. The interfacial shear strength between epoxy and Kevlar fiber was analyzed by measuring from microdroplet specimens adhered onto a single carbon fiber. Microdroplet specimens exhibited different results of the interfacial strength due to the Kevlar fiber surface treatment. The results showed that a larger shear stress concentration arose along the interface for the surface treated model than for the untreated one.

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Section: Introductionmentioning

confidence: 99%

The interfacial shear strength of Kevlar fiber/epoxy composite measured by the microdroplet test

Caichilan²

2010

Materialwissenschaft Werkst

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“…The interfacial shear strength of composites can be measured by tests on single fibre systems [1][2][3][4][5][6][7][8][9][10][11][12][13]. It is noticeable, however, that the various tests give different results even when used to characterise the same system [14][15]. Of the single fibre methods the most commonly used has been the pull-out technique [1][2][3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Investigation of the micromechanics of the microbond test

Day¹,

Rodrigez²

1998

Composites Science and Technology

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The microbond test is a method which is sometimes used for measuring interfacial shear strength. In the analysis of the data it is often assumed that the interfacial shear stress is constant and thus, by implication, that the strain in the fibre along the embedded fibre decreases linearly from the point of entry to the point of exit. In this paper the results of conventional microbond tests and simulated microbond tests performed under a Raman microscope on a Kevlar-49/epoxy system are reported. The conventionally performed tests show that the calculated interfacial shear strength for this system is approximately 16 MPa regardless of the position of the supporting knife edges. The strain distribution along the fibre during simulated microbond tests was studied as a function of knife edge position, interfacial area and level of load by means of Raman spectroscopy. It was found that the interfacial shear stress was not constant, as is frequently assumed, but was strongly dependent upon distance through the droplet, knife-edge position and applied load. At low loads the strain was a maximum at the point where the fibre entered the droplet and then dropped off sharply through the embedded length. This effect was enhanced when the knife-edge separation was reduced. The variation of the shape of the stress distribution was similar to that predicted by a linear finite element analysis. At higher load levels the onset of failure in the region closest to the point where the fibre entered the droplet could be observed. M1 7HS AbstractThe microbond test is a method which is sometimes used for measuring interfacial shear strength. In the analysis of the data it is often assumed that the interfacial shear stress is constant and thus, by implication, that the strain in the fibre along the embedded fibre decreases linearly from the point of entry to the point of exit. In this paper the results of conventional microbond tests and simulated microbond tests performed under a Raman microscope on a Kevlar 49/epoxy system are reported. The conventionally performed tests show that the calculated interfacial shear strength for this system is approximately 16 MPa regardless of the position of the supporting knife edges. The strain distribution along the fibre during simulated microbond tests was studied as a function of knife edge position, interfacial area and level of load using Raman spectroscopy. It was found that the interfacial shear stress was not constant, as is frequently assumed, but was strongly dependent upon distance through the droplet, knife edge position and applied load. At low loads the strain was a maximum at the point where the fibre entered the droplet and then dropped off sharply through the embedded length. This effect was enhanced when the knife edge separation was reduced. The variation of the shape of the stress distribution was similar to that predicted by a linear finite element analysis. At higher load levels the onset of failure in the region closest to the point where the fibre entered the drople...

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“…Shearing plates play a critical role in the micromechanical test as they make direct contact with the matrix. Various configurations of shearing plates can be found in the literature [8,[13][14][15]. We chose the configuration of a pair of shear plates with polished edges.…”

Section: Design and Manufacture Of The Microvicementioning

confidence: 99%

“…Consequently, individual laboratories tend to create their own methods with essentially the same idea but different procedures. Although the application of MBT to thermosetting composites has attracted a great deal of attention over the years [4,[12][13][14][15], it has been, to a lesser extent, considered for thermoplastic systems [16][17][18]. As a result, the procedure for using this method with thermoplastic polymers needs to be further improved.…”

Section: Introductionmentioning

confidence: 99%

Development and application of micromechanical techniques for characterising interfacial shear strength in fibre-thermoplastic composites

Yang

Thomason

2012

Polymer Testing

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a b s t r a c tThe development of single fibre pull-out and microbond tests for characterising interfacial strength in thermoplastic composites is reviewed in detail. Manufacture of an experimental jig and sample preparation regimes for both tests are described. The challenges addressed in the sample preparation include the measurement of embedded fibre length for pull-out samples and the low yield rate of axisymmetric resin droplets obtained during sample preparation under nitrogen. The applications of these laboratory developed techniques are demonstrated by characterisation of the interfacial shear strength (IFSS) of glass fibre-polypropylene (GF-PP) and natural fibre-polylactic acid (NF-PLA). The comparison of the IFSS between neat and modified GF-PP showed that both methods were sensitive to the interfacial performance change despite the poor agreement between them for the absolute IFSS values from the same composite. The effect of the material modification was also reflected in load-displacement curves with different behaviour of the frictional motion after complete debonding. When a high level of fibre-matrix adhesion was realised in the composites with weak fibres, the microbond test showed higher feasibility for characterising the IFSS. This was clearly shown in its application to NF-PLA.

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Study of the interface in Kevlar 49-epoxy composites by means of microbond and fragmentation tests: effects of materials and testing variables

Cited by 74 publications

References 15 publications

The interfacial shear strength of Kevlar fiber/epoxy composite measured by the microdroplet test

The interfacial shear strength of Kevlar fiber/epoxy composite measured by the microdroplet test

Investigation of the micromechanics of the microbond test

Development and application of micromechanical techniques for characterising interfacial shear strength in fibre-thermoplastic composites

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