Damage progression analyses of transverse stitched T-joints under flexure and tensile loading

Abstract

The progressive damage of a new type of composite T-joint with transverse stitching using a fiber insertion process was modeled using numerical methods. T-joints modeled herein were fabricated from dry fabric preforms using resin transfer molding. Fiber tows were inserted into the dry fabric preforms prior to consolidation. Experiments were conducted to determine the load–displacement and strain–load history under Flexure and Tensile loading. Linear, nonlinear, and damage progression finite element models were developed to predict the mechanical behavior under each load condition. Experimental observations of initial failure were marked by a discrete drop in the load–displacement behavior and the initiation and propagation of an interfacial matrix crack at the web-to-flange interface. Fiber insertion bridging and fiber insertion breakage were observed at T-joint ultimate failure. The linear and nonlinear analyses show good correlation with experimental results through T-joint initial failure. An effective stress failure criterion was applied to predict damage initiation at the T-joint web-to-flange interface. The damage progression finite element analyses showed good agreement with experimentally determined load–displacement values through ultimate failure. The predictive models developed herein are used in future parametric design studies.