This paper discusses the problem of interlaminar delamination in composite materials, with particular attention focused on the important role played by the resin properties. A DCB (Double Cantilever Beam) specimen has been modelled for finite element analysis assuming that the crack is situated inside a thin pure resin layer, similar to the models proposed by Ozdil and Crews. A numerical model for the ERR (Energy Release Rate) evaluation based on energy balance is described. In the energetic approach proposed, an expression for G has been used, that holds in general conditions of elasto-plastic materials. For an accurate estimate of the energy stored in the resin, its constitutive relationships are required. A test program has been carried out on the thermoset resin EPON 828, achieving a monoaxial curve and Poisson coefficient, to be used for the assessment of G. Results show that the material behaviour is non-linear elastic because the residual strain is negligible after unloading. The non-linear relationship has been introduced in the bidimensional finite element model for the DCB specimen analysis. The stress and strain fields are used for the evaluation of the ERR by means of the numerical model. The results show a considerable dependence on the constitutive relationship and give the opportunity of a more accurate evaluation of the toughness for experimental results from DCB specimen.
Influence of the constitutive characteristics of resins on the composite materials delamination
Einfluß der konstitutiven Eigenschaften von Kunstharz auf die Schichtablösung von Verbundwerkstoffen
Engineering Fracture Mechanics ; 55 , 6 ; 1001-1012
1996
12 Seiten, 11 Bilder, 4 Tabellen, 22 Quellen
Aufsatz (Zeitschrift)
Englisch
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