The Reliability of Fragmentation Test

2006 ◽  
Vol 312 ◽  
pp. 155-160
Author(s):  
Ying Dai ◽  
Xing Ji ◽  
Lin Ye ◽  
Yiu Wing Mai
Keyword(s):  
Shear Strength ◽  
Failure Modes ◽  
Interfacial Shear Strength ◽  
Stress Singularity ◽  
Singularity Analysis ◽  
Interfacial Shear ◽  
Matrix Cracking ◽  
Fragmentation Test ◽  
Matrix Cracks ◽  
Fiber Breaks

The single fiber fragmentation test has been continuously used to determine the interfacial shear strength. However, the results of the tests were still suspected by some researchers. To evaluate the reliability of the fragmentation test, the stress singularity near the interface end of fragmentation is investigated. According to the local failure modes near the interface end of a fiber fragment, there are three cases of the interface end conditions to be considered for the fragmentation tests: (A) fiber breaks only, without matrix cracking and de-bonding, (B) fiber breaks and matrix cracks, without interface de-bonding, (C) fiber breaks and interface de-bonds, with or without matrix cracking. After the singularity analysis of stress field near the interface end was depicted, it is obvious, that the interfacial shear strength given by the fragmentation test is not proper, because of that a stress singularity exists near the interface end.

Interfacial shear strength and failure modes in sPP/CF and iPP/CF microcomposites by fragmentation

Polymer ◽  
2001 ◽  
Vol 42 (1) ◽  
pp. 129-135 ◽  
Author(s):  
Chang-Mou Wu ◽  
Ming Chen ◽  
József Karger-Kocsis
Keyword(s):  
Shear Strength ◽  
Failure Modes ◽  
Interfacial Shear Strength ◽  
Interfacial Shear

scholarly journals Effect of Tow Size and Interface Interaction on Interfacial Shear Strength Determined by Iosipescu (V-Notch) Testing in Epoxy Resin

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1786 ◽  
Author(s):  
Filip Stojceveski ◽  
Andreas Hendlmeier ◽  
James D. Randall ◽  
Chantelle L. Arnold ◽  
Melissa K. Stanfield ◽  
...  
Keyword(s):  
Shear Strength ◽  
Carbon Fiber ◽  
Epoxy Resin ◽  
Failure Modes ◽  
Interfacial Shear Strength ◽  
Interfacial Shear ◽  
Single Filament ◽  
Time Investment ◽  
Beam Shear ◽  
Surface Modified

Testing methodologies to accurately quantify interfacial shear strength (IFSS) are essential in order to understand fiber-matrix adhesion. While testing methods at a microscale (single filament fragmentation test—SFFT) and macroscale (Short Beam Shear—SBS) are wide spread, each have their own shortcomings. The Iosipescu (V-notch) tow test offers a mesoscale bridge between the microscale and macroscale whilst providing simple, accurate results with minimal time investment. However, the lack of investigations exploring testing variables has limited the application of Iosipescu testing to only a handful of studies. This paper assesses the effect of carbon fiber tow size within the Iosipescu tow test for epoxy resin. Tow sizes of 3, 6, and 9 k are eminently suitable, while more caution must be shown when examining 12, and 15 k tows. In this work, tows at 18 and 24 k demonstrated failure modes not derived from interfacial failure, but poor fiber wetting. A catalogue of common fracture geometries is discussed as a function of performance for the benefit of future researchers. Finally, a comparison of commercial (T300), amine (T300-Amine), and ethyl ester (T300-Ester) surface modified carbon fibers was conducted. The outcomes of this study showed that the Iosipescu tow test is inherently less sensitive in distinguishing between similar IFSS but provides a more ‘real world’ image of the carbon fiber-epoxy interface in a composite material.

Interfacial studies of carbon fibre / polycarbonate composites using dynamic mechanical analysis

e-Polymers ◽  
2005 ◽  
Vol 5 (1) ◽  
Author(s):  
Maria C. Paiva ◽  
João F. Mano
Keyword(s):  
Shear Strength ◽  
Carbon Fibre ◽  
Dynamic Mechanical Analysis ◽  
Interfacial Shear Strength ◽  
Mechanical Analysis ◽  
Interfacial Shear ◽  
Carbon Fibres ◽  
Matrix Interaction ◽  
Fragmentation Test ◽  
Fibre Matrix

AbstractUnidirectional composite material samples with ultrahigh modulus carbon fibres, treated and untreated by oxygen plasma, and a polycarbonate matrix were prepared and tested. Dynamic mechanical analysis (DMA) was used to study interfacial fibre/matrix interaction and the fragmentation test method was applied to determine interfacial shear strength. For the composite samples with treated carbon fibres, analyzed by DMA, a consistent shift of the loss modulus peak toward higher temperature was observed. The damping ratio was highly affected by residual stresses along the carbon fibre direction due to the large difference of thermal expansion coefficients of matrix and fibres. Critical fibre length and interfacial shear strength, obtained from the fragmentation test, showed substantial improvement for treated fibres as compared to the untreated ones. Plasma oxidation of the fibre surface improved considerably the fibre-matrix interaction. Care must be taken interpreting the DMA results, due to specific characteristics of the system studied.

Study on 2-D Multi-Fiber Arrange Model Composites

2005 ◽  
Vol 297-300 ◽  
pp. 219-224
Author(s):  
Chang Kwon Moon ◽  
Ki Woo Nam
Keyword(s):  
Shear Strength ◽  
Surface Treatment ◽  
Interfacial Shear Strength ◽  
Fiber Surface ◽  
Interfacial Properties ◽  
Interfacial Shear ◽  
Two Dimensional ◽  
Fragmentation Test ◽  
Fiber Fragmentation ◽  
Fiber Surface Treatment

The effect of interfiber distance on the interfacial properties in two dimensional multi-Eglass fiber/epoxy resin composites has been investigated using fragmentation test. In additions, the effect of the fiber surface treatment on the interfacial properties has been studied. We found that the interfacial shear strength decreased with the decreasing of the interfiber distance at the range of under 50µm and the extent of the decreasing was more serious as the increasing of the number of adjacent fiber. This is probably that the interface between the fiber and the resin was damaged by the adjacent fiber breaks and the damage increased with closing the interfiber spacing and the number of adjacent fiber. We can guess from this interfacial shear strength in real composites is much smaller than that of multi-fiber fragmentation sample with touched fiber. It was seen that the interfacial shear strengths saturated when the interfiber distance was over 50µm, the ones were saturated regardless of fiber surface treatment and the ones were in close agreement with those of the single fiber fragmentation test. Finally, the interfacial shear strength evaluated using two dimensional fragmentation tests are shown as real values in-site regardless of fiber surface treatment, interfiber distance and existing of matrix cracks.

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