Interlaminar shear strength of C/C-composites: the dependence on test methods

Li, M.; Matsuyama, R.; Sakai, Mototsugu

doi:10.1016/s0008-6223(99)00049-4

Cited by 36 publications

(17 citation statements)

References 10 publications

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“…The main characterisation for ILSS is the shortbeam-shear test (ASTM D-2344-00), the four-point shear test, the Iosipescu test (ASTM D-5379-98), the tensile test (ASTM D-3518-94) and the double notch compression test (ASTM D-3846-94). However, it was demonstrated by Li et al [5] how the ILSS depends on the test method: for example in the short-beam test a nonuniform bending moment along the shear plane and stress concentrations under the loading rollers may yield undesirable errors while the distribution of the shear stresses over the shear planes (laminar planes) introduces a difficulty to analysis [6]; a compression test leads to lower shear strength as the failure consistently occurs in a well-defined single shear plane [7], yielding a rather conservative estimate for safety design. Consequently, it can be guessed that also the relation between smallscale test methods and a real on-the-field fracture test yields different results due to variations in stress conditions and test geometries.…”

Section: Introductionmentioning

confidence: 91%

Fracture Assessment of Carbon Fibre/Epoxy Reinforcing Rings through a Combination of Full-Scale Testing, Small-Scale Testing and Stress Modeling

Samyn

Schepdael²,

Paepegem

et al. 2006

Appl Compos Mater

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Carbon fibre/epoxy rings are used as radial reinforcement for polymer bearing elements with nominal diameter 250 mm functioning under 150 MPa. Fullscale static and dynamic testing revealed no catastrophic failure for loading to 400 MPa, although there was circumferential splitting of carbon fibres at the machined top edge causing counterface wear under sliding. A combined numericalexperimental analysis was applied for design improvement with a representative small-scale qualification test on the real ring geometry, inducing additional stress concentrations compared to ASTM standards. Full-scale modelling revealed high radial-axial shear stresses (33 MPa) in non-hydrostatically loaded zones, while it increased towards 104 MPa under hydrostatic load conditions. The former is the most critical and should be simulated either on a small-scale unidirectional compression test or on a representative short beam shear test, respectively, measuring the radial-axial or radial-tangential shear strength. A relation between both smallscale states of stress was experimentally and numerically studied, experiencing that the composite ring has lower radial-tangential shear stress compared to radial-axial shear stress as a different hydrostatic stress state is observed in the bulk of the composite ring. As a compressive test is however more difficult to perform than a short-beam-shear test, a representative design criterion for shear fracture is determined from failure at 27 kN normal load in a short-beam-shear test. Finally, Appl Compos Mater (2006) 13: 57-85 fracture is avoided by optimising the cross-sectional geometry of the composite reinforcing ring and close control of the processing parameters.

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Section: Introductionmentioning

confidence: 91%

Fracture Assessment of Carbon Fibre/Epoxy Reinforcing Rings through a Combination of Full-Scale Testing, Small-Scale Testing and Stress Modeling

Samyn

Schepdael²,

Paepegem

et al. 2006

Appl Compos Mater

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“…[2,4,5,[10][11][12][13] The micro-mechanical test mainly includes single-fiber pull-out and single-fiber push-out test. [4,5,10,11] For macro-mechanical test, several testing methods are available for measuring the interlaminar shear strengths (ILSS), such as the short-beam shear test (three-point bend of short beam), [2,[12][13] four-point flexural test. [13] In the case of single-fiber pull-out test, most of studies have been done by using model composites reinforced with single or few fibers.…”

Section: Introductionmentioning

confidence: 99%

“…[4,5,10,11] For macro-mechanical test, several testing methods are available for measuring the interlaminar shear strengths (ILSS), such as the short-beam shear test (three-point bend of short beam), [2,[12][13] four-point flexural test. [13] In the case of single-fiber pull-out test, most of studies have been done by using model composites reinforced with single or few fibers. [4,5,10] Owing to the presence of the neighboring fibers, the residual thermal stress and polymer morphology in real composites can differ significantly form those model composites.…”

Section: Introductionmentioning

confidence: 99%

Influence of carbon fiber’s surface state on interlaminar shear properties of CFRP laminate

Sha

Dai

et al. 2013

Composite Interfaces

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In order to investigate the influence of carbon fiber's surface state on the interlaminar shear properties of carbon fiber-reinforced plastic (CFRP) laminate, the carbon fiber's surface state was modified by thermal treatment at elevated temperatures. The interlaminar shear strength (ILSS) of CFRP laminates reinforced with treated fibers was measured by means of short-beam shear test, and the surface state of fiber was characterized by Electron Spectroscopy for Chemical Analysis (ESCA) analysis to reveal the dominate factor for controlling the ILSS. Combining the ILSS measurement with the ESCA analysis, the results indicated that: (1) the ILSS is strongly dependent on the oxygen-containing functional groups on the surface of carbon fiber; (2) the fiber treated at 600°C has the highest oxygen-containing functional groups that lead to the highest ILSS of CFRP; and (3) at temperatures beyond 600°C, the oxygen-containing functional groups decrease with increasing the heat treatment temperature, resulting in a low ILSS of CFRP laminates. Furthermore, from the microstructure observation, it was found that the CFRP mainly failed in the mode of multi-interlaminar shear. The multi-interlaminar shear failure in the CFRP laminates with low ILSS is more severe due to a weak fiber-matrix interface.

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“…Several attempts have been made to measure the interfacial shear strength (IFSS) of C/Cs, for example, fiber push-in, push-out, and pull-out tests. [12][13][14][15] However, the IFSS of C/Cs has not been successfully determined, especially for the 3D-C/Cs.…”

Section: Introductionmentioning

confidence: 99%

Real-time observation of damage nucleation in three-dimensionally reinforced carbon/carbon composites and role of bundle/matrix interface

Wei¹,

Meng

et al. 2013

Advanced Composite Materials

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Carbon/carbon composites (C/Cs) are widely used as thermal protection materials in aviation and aerospace field. Most of the fracture processes of C/Cs have been found to be profoundly affected by their interfacial properties. Specially arranged fiber bundle push-out test was utilized to determine the fiber bundle/matrix interface shear strength of one threedimensionally reinforced C/Cs. In order to reveal the link between the interfacial properties and the failure behavior, the micromechanisms of damage initiation at the notch tip on the C/Cs was investigated in real-time during the flexural fracture tests through scanning election microscopy. Real-time fracture observation revealed that the damage was nucleated in the fiber bundle/matrix interfaces around the notch tip and the failure crack was successfully observed along the fiber bundle/matrix interface. Fiber yarns acted as an obstacle to crack propagation hence it was necessary to increase the load to propagate the crack through the next fiber yarn.

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Interlaminar shear strength of C/C-composites: the dependence on test methods

Cited by 36 publications

References 10 publications

Fracture Assessment of Carbon Fibre/Epoxy Reinforcing Rings through a Combination of Full-Scale Testing, Small-Scale Testing and Stress Modeling

Fracture Assessment of Carbon Fibre/Epoxy Reinforcing Rings through a Combination of Full-Scale Testing, Small-Scale Testing and Stress Modeling

Influence of carbon fiber’s surface state on interlaminar shear properties of CFRP laminate

Real-time observation of damage nucleation in three-dimensionally reinforced carbon/carbon composites and role of bundle/matrix interface

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