Compression properties of fabric fibers under dry and wet conditions

The experiments of carbon fabrics and glass fiber fabrics under both dry and wet conditions were conducted for exploring the compression characteristic. By using the viscoelastic theory model, the viscoelastic curves and viscoelastic model parameters of the compression, stress relaxation and rebound stages under the two aforementioned conditions were analyzed. The deformation mechanism at three compression stages of the yarn was analyzed, and the corresponding explanations for these differences were presented. The results show that the forming thickness of wet fabrics is slightly larger than dry fabrics when the same maximum forming pressure is loaded at the compression stage. The compression time of wet fabrics is shorter than that of dry fabrics, and the yarn specification is much smaller. Besides, the difference of the time is not obvious. The time constant at the compression stage for wet fabrics is less than the corresponding value for dry fabrics. At the stress relaxation and rebound stage, a small amount of media penetrates into the fabric gaps, while the change process of the fabrics is basically the same. The forming thickness difference and rebound thickness difference under the two conditions are very close. Correspondingly, the rebound thickness of wet fabrics is finally slightly larger than that of dry fabrics. The time constants of stress relaxation and rebound are basically the same. These results provide important guidance for the forming process of fiber reinforced resin matrix composites.