|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.