Inelastic Response of Porous, Hybrid Fiber Composites

Abstract

Abstract A methodology is presented for a micromechanics model of the inelastic response of porous, hybrid fiber composites. The composite, designated A-PA/IC50, consists of porous hybrid fibers (Nextel 610 alumina filaments in a porous alumina binder) in a nickel alloy matrix (IC50 nickel aluminide). Using Aboudi’s Generalized Method of Cells (GMC), the elastic and inelastic response of the composite is modeled in a three step process. The first step uses the 3-D version of GMC to predict the elastic properties of the porous alumina binder as a function of the percent porosity. These properties of the porous binder are then used in a 2-D analysis of the hybrid with the filaments taken to be linear elastic. Properties of the hybrid fiber are thus available as a function of the present porosity as well as the percent of filaments in the hybrid fiber. Finally, the elastic properties and inelastic response of the composite are predicted using 2-D GMC with the hybrid fiber taken to be elastic and the nickel matrix inelastic. The inelastic matrix is modeled using the Bodner-Portom unified visco-plasticity theory. Input properties of the constituents were determined from laboratory measurements. Representative predictions showing the influence of percent porosity (of the alumina binder in the hybrid fiber) and percent hybrid fiber in the composite on the axial and transverse responses of the composite are shown in the figures below. Clearly, both the porosity and the percent hybrid fiber have an influence on the elastic modulus, the proportional limit, and inelastic response. Details of the methodology and additional results for axial, transverse and shear properties will be presented in the full paper.