A method to measure fracture toughness of the fiber/matrix interface using the single-fiber fragmentation test

2009 ◽  
Vol 40 (6-7) ◽  
pp. 679-686 ◽  
Author(s):  
F.A. Ramirez ◽  
L.A. Carlsson ◽  
B.A. Acha
Keyword(s):  
Fracture Toughness ◽  
Single Fiber ◽  
Matrix Interface ◽  
Fragmentation Test ◽  
Fiber Matrix Interface ◽  
Fiber Matrix ◽  
Fiber Fragmentation

The Use of a Single-Fiber Fragmentation Test to Study Environmental Durability of Interfaces/Interphases Between Epoxy and a Glass Fiber

1993 ◽  
Vol 304 ◽  
Author(s):  
Carol L. Schuute ◽  
Walter McDonough ◽  
Masatoshi Shioya ◽  
Donald L. Hunston
Keyword(s):  
Glass Fiber ◽  
Fiber Surface ◽  
Critical Length ◽  
Single Fiber ◽  
Resin Matrix ◽  
Matrix Interface ◽  
Model Composite ◽  
Fragmentation Test ◽  
Fiber Matrix ◽  
Fiber Fragmentation

AbstractThis work examines the usefulness of the single-fiber fragmentation test in studying the durability of fiber/matrix interfaces/interphases. This test measures the critical length/diameter ratio (L/D) of the fiber fragments formed in the test and relates this length to the interface's strength, or ability to transfer load. In the work reported here, we immersed samples of epoxy containing a single-glass fiber - that was previously sized with an epoxy-compatible coating - in either 65 or 75 °C water and tested after different times of exposure. In general, this ratio increased as a function of time of exposure to water. During exposure at 75 °C, the fibers' L/D in the samples did not increase significantly until after the sample reached its “apparent” equilibrium content of water ∼ (3.0 wt%). Because there was no significant measurable change in the tensile modulus between wet and dry samples, we cannot attribute these differences in L/D to changes in the resin's properties due to plasticizing by water. A small percentage of samples exposed at 65 °C did not show a significant increase in L/D, and in these cases the moisture produced a marked roughening of the fiber surface along the fiber/matrix interface. One possible explanation is that the attack by moisture degrades the interface, thus reducing its strength with a corresponding increase in the L/D. To varying degrees, however, the attack by moisture also degrades the E-glass fiber. This attack by moisture roughened the surfaces of the fibers and increased the distribution and/or size of the critical flaws, thus reducing both the strength of the fiber and the L/D. Based on our preliminary results, it appears that the singlefiber test has the potential to be useful for studying the durability of the resin/matrix interface providing that the influence of the environmental agent on all of the components of the model composite: resin, fiber, and interface/phase, is considered.

scholarly journals Multiscale Characterization of Nanoengineered Fiber-Reinforced Composites: Effect of Carbon Nanotubes on the Out-of-Plane Mechanical Behavior

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Carlos Medina ◽  
Eduardo Fernandez ◽  
Alexis Salas ◽  
Fernando Naya ◽  
Jon Molina-Aldereguía ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Fracture Toughness ◽  
Shear Strength ◽  
Mechanical Behavior ◽  
Matrix Interface ◽  
Short Beam ◽  
The Matrix ◽  
Fiber Matrix Interface ◽  
Fiber Matrix

The mechanical properties of the matrix and the fiber/matrix interface have a relevant influence over the mechanical properties of a composite. In this work, a glass fiber-reinforced composite is manufactured using a carbon nanotubes (CNTs) doped epoxy matrix. The influence of the CNTs on the material mechanical behavior is evaluated on the resin, on the fiber/matrix interface, and on the composite. On resin, the incorporation of CNTs increased the hardness by 6% and decreased the fracture toughness by 17%. On the fiber/matrix interface, the interfacial shear strength (IFSS) increased by 22% for the nanoengineered composite (nFRC). The influence of the CNTs on the composite behavior was evaluated by through-thickness compression, short beam flexural, and intraply fracture tests. The compressive strength increased by 6% for the nFRC, attributed to the rise of the matrix hardness and the fiber/matrix IFSS. In contrast, the interlaminar shear strength (ILSS) obtained from the short beam tests was reduced by 8% for the nFRC; this is attributed to the detriment of the matrix fracture toughness. The intraply fracture test showed no significant influence of the CNTs on the fracture energy; however, the failure mode changed from brittle to ductile in the presence of the CNTs.

scholarly journals Finite Element Modeling of the Fiber-Matrix Interface in Polymer Composites

2020 ◽  
Vol 4 (2) ◽  
pp. 58 ◽  
Author(s):  
Daljeet K. Singh ◽  
Amol Vaidya ◽  
Vinoy Thomas ◽  
Merlin Theodore ◽  
Surbhi Kore ◽  
...  
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Polymer Composites ◽  
Parametric Study ◽  
Single Fiber ◽  
Interface Debonding ◽  
Matrix Interface ◽  
The Matrix ◽  
Fiber Matrix Interface ◽  
Fiber Matrix

Polymer composites are used in numerous industries due to their high specific strength and high specific stiffness. Composites have markedly different properties than both the reinforcement and the matrix. Of the several factors that govern the final properties of the composite, the interface is an important factor that influences the stress transfer between the fiber and matrix. The present study is an effort to characterize and model the fiber-matrix interface in polymer matrix composites. Finite element models were developed to study the interfacial behavior during pull-out of a single fiber in continuous fiber-reinforced polymer composites. A three-dimensional (3D) unit-cell cohesive damage model (CDM) for the fiber/matrix interface debonding was employed to investigate the effect of interface/sizing coverage on the fiber. Furthermore, a two-dimensional (2D) axisymmetric model was used to (a) analyze the sensitivity of interface stiffness, interface strength, friction coefficient, and fiber length via a parametric study; and (b) study the shear stress distribution across the fiber-interface-matrix zone. It was determined that the force required to debond a single fiber from the matrix is three times higher if there is adequate distribution of the sizing on the fiber. The parametric study indicated that cohesive strength was the most influential factor in debonding. Moreover, the stress distribution model showed the debonding mechanism of the interface. It was observed that the interface debonded first from the matrix and remained in contact with the fiber even when the fiber was completely pulled out.

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