Measurement and analysis of fiber-matrix interface strength of carbon fiber-reinforced phenolic resin matrix composites

Abstract

Since fiber-matrix interface strength is critical to properties of carbon fiber-reinforced composites, measurement and analysis of interface strength are crucial steps in tailored design of composites. In the present work, the single fiber push-out test and the short-beam shear test were applied to measure the fiber-matrix interface strength in uni-directionally and two-directionally carbon fiber-reinforced phenolic resin matrix composites. The technical difficulties in processing the specimen and in realizing the fiber push-out were also discussed and clarified. For obtaining the successful test, typically, the thickness of the specimen should be smaller than 100 mm. During the fiber push-out, the de-bonding and fiber sliding at the interface were analyzed from the load-displacement curve features. The results indicated that both methods could be applied to determine the interface strength. The single fiber push-out and the short-beam shear tests resulted in a similar phenomenon in regard to the interface strength of uni-directionally and two-directionally carbon fiber-reinforced phenolic resin matrix composites, but expressed different values. The low interface strength measured from the short-beam shear test could be associated with multiple interlaminar shear failures. Furthermore, it was found that the interface strength of uni-directionally carbon fiber-reinforced phenolic resin matrix composites is somewhat higher than that of two-directionally carbon fiber-reinforced phenolic resin matrix composites. The difference in the interface strength could be attributed to the thermally induced residual stresses caused by the coefficient of thermal expansion mismatch of fiber and matrix. The approaches applied in the current work can be used for the evaluation of the interface strength of carbon fiber-reinforced phenolic resin matrix composites with different fiber-matrix bonding properties.

Combination of Nitrogen Plasma Modification and Waterborne Polyurethane Treatment of Carbon Fiber Paper Used for Electric Heating of Wood Floors

“…Carbon fiber (CF)-based paper is regarded as the most promising material for electric heating wood floors. Carbon fibers (CFs) exhibit high tensile strength, good conductivity, excellent thermal and chemical stability, and have been successfully applied in many fields (Wei et al 2013;Yuan et al 2013;Sha et al 2014). CFs are also good heating elements (Pang et al 2013), and the conversion efficiency from electricity into caloric energy of CF-based materials can be as high as 97% (Li 2002).…”

Influence of plastic deformation on single-fiber push-out tests of carbon fiber reinforced epoxy resin

“…In contrast to ceramic matrix composites, a further increase of the indenter displacement results in a gradual change to non-linear behavior in the majority of cases. The onset of this non-linearity is often interpreted as crack initiation followed by crack growth [7][8][9][10][11]. Various models were proposed to deduce the interfacial shear strength based on this non-linear behavior [9][10][11][12].…”

“…For carbon fiber reinforced polymers, however, the appearance of a plastic energy contribution is likely, since polymers typically show significant plastic deformation before failure. After the onset of non-linear behavior in CFRP, an increase of force up to peak load is observed [8,10,13,16].…”

“…In some approaches the interfacial shear strength is evaluated based on a simple balance of force at the moment of push-out [8,15,17,20]. The values of indenter displacement and force at push-out are also required for energy based approaches, e.g.…”

“…To ensure a reliable interpretation of a single-fiber push-out experiment contact between indenter and the matrix surrounding the fiber has to be avoided, since such contact to the matrix causes a superposition of different loading effects [8,14,15,20]. In the force-displacement curves a strong increase of load at indenter-matrix contact is observed (cf.…”