Strength of RTM single lap joints with transverse stitching

An experimental investigation is presented to show the effect of appropriate transverse stitching on the static strength of RTM carbon/epoxy lap joints. Tackifier was used to stabilise the dry preform which was then stitched using a zigzag stitch scheme at the ends of the overlap and a straight stitch pattern in the central region of the overlap. It was found that this technique improved the quality of stitches at the ends of the overlap. Static strength tests were carried out, and the test results showed that the static strength of the stitched joints can be improved by up to 46 % over the unstitched joints, and that the stitched joints can sustain larger axial displacement than the unstitched joints.