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

Abstract

Please cite this article as: Jäger, J., Sause, M.G.R., Burkert, F., Moosburger-Will, J., Greisel, M., Horn, S., Influence of plastic deformation on single-fiber push-out tests of carbon fiber reinforced epoxy resin, Composites: Part A (2015), doi: http://dx. AbstractIn our study we present a procedure to measure and analyze single-fiber push-out force-displacement curves on carbon fiber reinforced polymers using a cyclic loading-unloading scheme. The measured cyclic force-displacement curves allow an energy-based evaluation of the interfacial failure, taking into account elastic, plastic and other dissipative energy contributions. Experimental and modeling results demonstrate that a deviation of the push-out curve from linear behavior does not correspond to crack opening but to a plastic deformation of the matrix. Evaluating the plastic energy yields a linear increase of the total plastic energy after a certain indenter displacement. This linear increase is attributed to stable crack propagation.Back-extrapolation of the linear part to zero total plastic energy using a linear regression yields the initiation of crack growth. It is concluded that for ductile matrix materials like polymers, a reliable interpretation of push-out data has to take into account plastic material deformation.

Quantification of crack area in ceramic matrix composites at single-fiber push-out testing and influence of pyrocarbon fiber coating thickness on interfacial fracture toughness

“…6(b) illustrates the more general case with a neighboring fiber breaking the cylindrical symmetry of the arrangement with respect to the loaded fiber. This configuration results in a higher stress concentration in the narrow region between the fibers and, consequently, leads to stable crack growth along the interface in that region at an early stage of the experiment [19]. With increased loading, the crack propagates in fiber axis direction until it reaches the back surface of the sample.…”

“…Recently, this approach was expanded to samples with a more ductile matrix, e.g. for carbon-fiber reinforced polymers, leading to substantial plastic matrix deformation during the test and to crack initiation without a distinct signature in the load-displacement curve [17][18][19].…”

Failure of Fiber-Reinforced Composites

“…In recent years, some approaches used fracture mechanics concept as hybrid approaches [50,58] or in their pure form [76] to describe damage progression within laminates. Similar to the strength based failure criteria, there is still room for improvement of the experimental methods to determine microscopic fracture toughness values for various load conditions [15,77,78].…”

Essential Properties of Fibres for Composite Applications

“…Hence, the conditions of a real composite material are maintained. Moreover, even a detailed investigation of the composite's mechanical properties and crack propagation is possible [52]. The sample preparation (thin sections of approx.…”