Effect of non-uniform roving-matrix-CSM architecture on the flange-web interface behavior of pultruded GFRP composite members

Abstract

Pultruded glass fiber reinforced polymer (PGFRP) composites are heterogenous compositions of glass roving, continuous strand mat (CSM) and resin matrix. Nonetheless, PGFRPs are considered to be idealized homogeneous materials for structural design. Unintended variation of roving-matrix-CSM (RMC) architecture can result in a reduction in PGFRP flexural member capacity. The objective of this study is to investigate the effect of non-uniform RMC architecture on the performance of PGFRP members subject to flexure, focusing on the failure mode characterized by cracking at the flange-web junctions of such members. This study considers five PGFRP shapes – box, I, C, T and L – and quantifies non-unform RMC architecture for 18 sections. A robust FE model capturing the individual roving and CSM layers of the PGFRP was developed, and both non-uniform and idealized uniform RMC architectures were modeled in every case allowing the effect of RMC architecture variation to be investigated. Three-dimensional Hashin damage criterion was implemented to predict the progressive failure of PGFRP materials in an accurate and repeatable manner. A parametric study varying fiber volume ratio, CSM proportion and shear span resulted in 360 separate FE models. Study conclusions demonstrate the increased sensitivity of box shapes to variations in RMC architecture with reductions in capacity compared to idealized RMC architecture exceeding 20% in some cases.