Elastic load coupling with tailored elastomer composites

ABSTRACT This study identifies a unique performance benefit in flexible composite laminates through evaluation of the load-coupling potentials once an external stimulus triggers extensional loadings. A combination of soft elastomers with stiff fibers can be used to develop a composite with distinct direction-dependent properties. Unique exponential flexibility changes in some directions and extreme linear stiffness in others are observed. These tunable multidirectional flexibilities can be achieved at different flexibility ratios tailored to a wide range of applications, such as extension-twist coupling in composite laminates. To this end, the conflicting design requirements such as decoupling ratio between deformation modes, i.e. extension and twist, and torsional flexibility are studied for laminates with different ply thicknesses, stacking directions, constituent materials, and numbers of plies. A design space is then introduced and used to evaluate the capability of laminates for effective load-coupling behaviors. It is also demonstrated that significant differences in the (linear) stiffness of the constituent materials result in highly nonlinear mechanics in hyperelastic fiber-reinforced composites, mainly owing to the contributions of the matrix-fiber mechanical interaction.