A Novel Elastomeric Composite Skin for Polymorphing Wing Applications

Morphing wings require skins that are highly compliant in plane yet resistant to deleterious lateral contraction and out of plane distortion. This study introduces a novel elastomeric composite skin (ECS) that embeds discontinuous, aligned carbon fiber lamina tapes within an Ecoflex 0010 matrix to tailor in plane anisotropy and suppress major Poisson contraction while preserving large recoverable strain. Three tape architectures with different fiber volume fractions and strip widths/separations are fabricated using a vacuum assisted casting protocol. The mechanical response is quantified via uniaxial tensile tests with DIC, complemented by micro CT porosity assessment and SEM fractography. The results indicate that, for loading transverse to the fibers (1 direction), the effective stiffness E_11 remains comparable to that of neat Ecoflex, with relative deviations of -23.5%, +9.73%, and -10.6% at fiber volume fractions of 6.67%, 10%, and 13.3%, respectively. While the minor Poisson’s ratio ν_12 decreases markedly with fiber content (up to −67.7%). For loading along the fibers (2 direction), stiffness gains are substantial approximately +142%, +350%, and +615% for the same three architectures accompanied by a reduction in the major Poisson’s ratio ν_21. Tensile cyclic tests reveal large first cycle hysteresis with rapid stabilization; aligned fiber coupons require more cycles to stabilize than transverse ones, consistent with progressive interfacial rearrangement. Micro CT indicates porosity increasing with fiber volume fraction and strip width, and SEM confirms matrix cracking–dominated failure transversely and fiber pull out/interfacial debonding along the fibers. Collectively, the ECS attains the targeted combination of directional stiffness, reduced Poisson coupling, and large strains attributes essential for 2D morphing skins.