COMPARISON OF AXISYMMETRICAL AND PLANAR FRACTURE-MECHANICS MODELS FORFIBER-REINFORCED COMPOSITES

Many fracture mechanics models based on either 3D-axisymmetric or 2D-p lanar models are used to predict mechanical parameters of composites, such as their fracture toughness, matrix crack initiation stress and s tiffness. In this study, fracture mechanics models for a composite geo metry with a matrix crack under uniform crack pressure are developed u sing both 3D-axisymmetric and 2D-planar assumptions. Three critical pa rameters, namely the stress intensity factor at the crack tips, the ma ximum crack-opening displacements and the stress ratios at the interfa ce, which are used to quantify the above mechanical parameters of a co mposite, are compared for the two models. The results for the stress r atios at the interface, which are used to predict the path of crack pr opagation near a fiber-matrix interface, are close to each other. Howe ver, the results for the stress intensity factor and the crack-opening displacements, which are used to quantify matrix crack initiation str ess and damaged composite longitudinal stiffness, differ considerably.