Development and Testing of Open Architecture Composite Structures and Composite Yarns for Compressive Strength
Type of DegreeMaster's Thesis
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Open Architecture Composite Structures (O-ACS) are truss structures formed by braid- ing specially designed hybrid yarns, made of high strength bers, on convex shaped mandrels. Previous studies on them have shown that they exhibit high sti ness to weight characteris- tics under axial, bending and torsion loading conditions when compared to traditional metal structures. The light weight nature of the structures nds them many potential applications in highly competitive aerospace, automotive and other industries. This research focuses on improving the load bearing capacity of O-ACS under axially compressive loading. It can be achieved by improving the compressive properties of the axial yarns which are the primary load bearing members of the structure, by using more axial yarns or by optimizing the geometry of structures. Hybrid yarns with di erent cores (24k, 48k, 84k and 96k carbon ber towpreg) and di erent braided jackets (Nylon, polypropelene and carbon ber towpreg) were manufactured and studied for their compatibility to make O-ACS on conventional maypole braiders. A suitable method which uses acorn nuts to hold the cured yarn samples between them was developed to test the yarns under axial compression. All the manufactured yarns were tested for their compressive strength and their compressive e ciencies were studied to understand how much of the load carrying capacity of the raw bers is carried over into their hybrid form. Triaxial structures of di erent architectures and di erent axial yarns were manufactured. They were tested under axial compression. The structural e ciencies were studied to understand how the architecture of the structures is e ecting their load bearing capacity.