Effects of stitch yarns on interlaminar shear behavior of three-dimensional stitched carbon fiber epoxy composites at room temperature and high temperature

Effects of four kinds of stitch yarns (carbon fiber (CF), aramid fiber, PBO fiber, and silk fiber (SF)) on interlaminar shear strength (ILSS) and failure behavior of the three-dimensional stitched composites (3DSCs) were investigated by double-notch shear test at room temperature (RT) and 100 degrees C. The failure process was recorded by the high-speed camera system. The interfacial strength of stitch yarns/resin at 100 degrees C was quantitatively measured for the first time. The results revealed that the mechanical properties of stitch yarns play a dominant role in determining the ILSS of composites at RT, and 3DSCs stitched with PBO stitch yarn show the best ILSS at RT, which can reach about 82.6 MPa. At 100 degrees C, the stitch yarns/resin interface performance is the decisive factor to the ILSS of composites, 3DSCs stitched with CF stitch yarn show the best interlaminar shear performance, and the ILSS is about 52.4 MPa. Moreover, the improvement of the ILSS by stitching was more obviously at 100 degrees C, increasing by at least 42%. The low-cost SF has a great advantage in replacing CF at RT on the premise of guaranteeing mechanical properties.

Automated summary

The effects of four types of stitch yarns on the interlaminar shear strength and failure behavior of 3D stitched composites were investigated at room temperature and 100 degrees C. The study found that the mechanical properties of the stitch yarns play a dominant role in determining the interlaminar shear strength at room temperature, with PBO stitch yarns showing the best performance. At 100 degrees C, the stitch yarns/resin interface performance becomes the decisive factor, with CF stitch yarns showing the best interlaminar shear performance. The use of stitching significantly improves the interlaminar shear strength at 100 degrees C, and silk fiber has the advantage of replacing carbon fiber at room temperature while maintaining mechanical properties.