Multiaxial mechanical characterization of latex skin for morphing wing application

A morphing aircraft continuously adjusts its wing geometry to achieve optimal flight characteristics for a wide range of flight conditions. Research on morphing aircraft has focused on developing wings with 1 morphing degree of freedom "monomorphing". However, nowadays the focus is on developing wings with multiple morphing degrees of freedom "polymorphing". One of the key design challenges for morphing aircraft technology is the development of skin capable of facilitating morphing whilst maintaining the aerodynamic shape of the wing. Soft polymeric materials represent a potential candidate to act as morphing skin because of their ability to undergo large deformation in multiaxial directions. In this study, latex skin is characterized under all possible deformation modes such as uniaxial, pure shear, biaxial, and equibiaxial to account for monomorphing and polymorphing applications. The effects of strain rate, thickness, and aspect ratio on hysteresis loss, stress relaxation and, stiffness are also studied. The outcomes of this study provide a comprehensive understanding of the mechanical viscoelastic behavior of latex skin under various deformation modes.