Theoretical and Experimental Investigation of Failure and Damage Progression of Graphite-Epoxy Composites in Flexural Bending Test

Abstract

Predicting failure stress and failure modes in composite laminates is very difficult. The choice between failure criteria is complex and there is a lack of experimental study to validate the results obtained. In this paper, a theoretical and experimental study of damage progression and failure modes of graphite-epoxy laminates in three points bending tests is presented. A quasi-isotropic [(± 45/9010)]5 graphite-epoxy composite is investigated. C-scan method and microscopic sectioning permit to monitor damage progression and failure modes during the experiment. Specimens at different failure levels are used to determine damage progression and the effect of geometrical parameters on the successive failures and on failure modes is studied. The progression of damage has been followed experimentally and identified in detail. The theoretical study is based on the classical laminate theory in the case of in-plane loads. A software program has been elaborated for post-failure treatment and experimental results are compared with numerical predictions.

Variational solutions to stresses in cracked cross-ply laminates under bending

“…Experimental investigations in this area have been reported by Echaabi et al (1996) and Adolfsson and Gudmundson (1999). Smith and Ogin (1999) have obtained estimates of the reduced flexural modulus as a function of crack density based on the shear-lag approach.…”

On the Decreasing Flexural Modulus of Glass/Vinylester Composite Beams Up to Failure State

“…So a more accurate simulation of the load carrying of the composite laminates under bending is accomplished using progressive damage analysis (PDA). By considering of material nonlinearity and more accurate simulation of the boundary conditions, the presented results in the recent researches are more accurate than those, obtained by the earlier numerical researches (Echaabi et al, 1996;Smith and Ogin, 1999). Of course, PDA of the composite laminates has a great background in the literature.…”

Variational analysis of cracked general cross-ply laminates under bending and biaxial extension

“…Schoepner and Pagano, 1999), model based on considering the role of the crack face relative displacements Varna, 2005, 2011), continuum damage mechanics approach (Barbero et al, 2013;Talreja, 1985;Voyiadjis et al, 2007), discrete damage mechanic (Barbero et al, 2011), synergistic damage mechanic (Singh and Talreja, 2010;Varna et al, 2004), multiscale models (Ladeve`ze et al, 2006;Lubineau, 2010), numerical methods such as finite element (Yuan and Selek, 1993), state-space method (Ye and Zhang, 2012), etc. Contrary to the symmetric laminates under in-plane loading, few works have contributed to nonsymmetric laminates under out-of-plane bending, which also belong to the recent years. Experimental investigations of cracked laminates under flexural loading have been reported by Adolfsson and Gudmundson (1999), Echaabi et al (1996), and Ogi and Smith (2002). Li et al (1994) have implemented the finite strip method as a seminumerical approach for analyzing cracked laminates which is capable of handling laminates under out-of-plane bending.…”