Influence of different structural parameters of 3D woven honeycomb composites on three-point bending behavior

Abstract

In this study, various honeycomb preforms with different cell geometries were woven by changing the cell size, opening angle, free wall length, bonded wall length, and the number of layers keeping cell shape constant and composite thickness constant. The shape of the cells was altered by altering the pick numbers. E-glass tows of 600 Tex were used to produce fabric samples. All the constituent walls have the same construction and are woven with 2D plain fabric. Composite samples were created from honeycomb fabric and epoxy resin (matrix) using the VARIM (vacuum-assisted resin infusion method) technology. Three-point bending test was carried out for different cell geometries of 3D woven honeycomb composites. It was found that specific bending load is higher for a honeycomb structure with an opening angle of 60°, smaller cell sizes, small wall length, and for more layers keeping thickness and cell shape constant. Face wrinkling causes specimen failure in the following ways: localized buckling of the compressed face, debonding of the face sheet, and Mode 1 cell wall collapse in the region between the fixed support and load application.