Multiple scale viscoelastic analysis of 3D woven composite materials

A multiple scale viscoelastic model for the 3D woven composites was suggested. Firstly, the repeated unit cells, representing periodic distributions of fibers in a yarn and periodic weave architecture in composite, were constructed. They are named micro scale cell and meso scale cell respectively. Elastic constants of the yarn were obtained by analysis of the micro scale cell model, and then they were used in the meso scale cell model for calculating those of 3D woven composites. The periodic boundary conditions were applied to the two scales cell models; therefore both displacements and stresses on the two cells boundaries satisfy continuum conditions. Then two viscoelastic models for the resin and fiber yarn respectively were suggested. The viscidity parameters of the resin model were determined by creep experiment for the pure resin material, and then they were adopted in the micro scale cell to rectify the viscoelastic model of the yarn. Finally, the two viscoelastic models were adopted in the meso scale cell to simulate the creep test of 3D woven composites numerically. The predictions of both elastic constants and creep curves agree well with experimental data.