Failure strength of composite T-joints prepared using a new 1-thread stitching process

Abstract

The interlaminar or through-thickness strength of composite materials is lower than their 2-D plane strengths, which can cause failure of the composite structure. Z-pinning and stitching are two typical methods to increase through-thickness material strength. Z-pinning is a technique that inserts reinforcing pins or fibers along the thickness direction of composite materials, which improves their z-directional properties. Stitching, on the other hand, is typically carried out using aramid or carbon fibers. However, the strength of aramid fibers is relatively low, while carbon fibers fracture easily during the stitching process due to their high stiffness. In this study, a new 1-thread stitching process is proposed to minimize bending of carbon fibers and prevent their fracture. Composite T-joints were made, stitched using the new stitching process, and their strength compared to that of T-joints made using the Z-pinning method. (C) 2017 Elsevier Ltd. All rights reserved.