Abstract:

Two combined beam models are developed to represent respectively the meso structures of inner and surface fiber bundles in 3D woven composites. The periodicities of meso structures and meso deformation are contained in the models. The effects of local bending/shearing coupling and local off axial tension of fiber bundles are taken into account. An isotropic visco-elastic constitution, used to describe resin matrix, is calibrated by a resin creep experiment. Based on it, a transverse isotropic visco-elastic constitution is suggested for characterizing the creep behaviors of fiber bundles. These two visco-elastic constitutions are employed in the combined beam models to predict the overall visco-elastic responses of 3D woven composites. This visco-elastic combined beam model is applied to a 3D woven epoxy resin/glass fiber composite. The local stresses and average elastic constants are predicted and creep elastic recovering curves are simulated. Model predictions are in good agreement with experiment data.

Key words: 3D woven composites, meso mechanics, local bending/shearing coupling effect, local off axial tension effect, combined beam element, visco-elasticity