Mechanics of non-orthogonally interlaced textile composites

The present paper focuses on geometric and micromechanical modelling of non-orthogonal structures. Braided structure and sheared woven structures have similar interlacement geometry. However, tow wavelength in a woven fabric remains constant during in-plane shear, where as, in the case of a braid, tow wavelength deceases with an increase in interlacement angle. In the present work, lenticular geometry has been used for describing the unit cell geometry, and relations for various geometrical parameters have been derived. Three braided composite tubes with angles of 31°, 45° and 65° were prepared for experimental validation of geometric and mechanical models. Almost all the published work was based on orthogonal repeating unit cells suitable only for un-sheared woven structures. In this work, we identified a non-orthogonal representative volume element (RVE) that can deal with any interlaced tow architecture. Experimental results for three braided tubes were compared with the data obtained using modified laminate theory and finite element analysis.