Experimental investigation of stitched laminates subjected to low-velocity impact and compression after impact

Both impact and compression after impact tests were carried out to research the impact damage and post-impact residual strength of stitched laminates in various types. The results indicate that the matrix damage and delamination are the main damage mode of stitched and unstitched laminates after impact. Compared with the unstitched laminates, stitching improves the damage resistance of impact and the compressive strength of after impact. The impact damage and the post-impact residual strength increase with the stitch density increasing. The stitch laminates with 0° direction have better damage resistance and higher compressive strength of after impact. Adding ply 0° while reducing the ply 45°,-45° can improve the damage resistance of impact and the compressive strength of after impact.