Size-influenced mechanical isotropy of singly-plied triaxially woven fabric composites

Mechanical isotropy of triaxially woven fabric composite is investigated analytically, numerically using beam lattice models, and experimentally under tension and bending loads, due to evidence suggesting that its commonly regarded quasi-isotropy is shattered by size effects. Models verification has found that the sawtooth configuration best fits the observation. Employing therefore this configuration and varying model size, it is remarked that the mechanical behaviors are sensitive when loads are perpendicular to the tows direction while no obvious perturbation is seen when loads align with the tows. For practical convenience, time-saving universal equations that are mechanically meaningful are formulated, catering both loading directions for both pre- and post-straightening states for arbitrary size.