Study on stiffness of stitched laminates

An analytical model was developed to determine the effective elastic constants of stitched laminae. The effects of stitch parameters on effective elastic constants were analyzed by considering the nortuniformity and in-plan fiber waviness induced by stitching. Based on the model, the constitutive relationship of stitched laminates was presented and the effects of stitch parameters on stiffness of stitched laminates were investigated. Tension and compression tests were conducted to validate the predictions. The experimental results were in good agreement with predictions based on the analytical model.