Structural materials combining high stiffness and damping capabilities are in high demand for passive damping applications in vibration control, precision manufacturing, and resilient buildings. However, the development of enhanced passive damping materials with high stiffness at low weight has been hindered by the mutually excluding nature of these mechanical properties. Motivated by the mechanical performance of biological materials such as bone and nacre, we exploit a simple casting and magnetically assisted manufacturing process to fabricate platelet-reinforced polymers with a stiff and damping staggered architecture. Dynamic mechanical analysis of our staggered architectures reveals an increase in the stiffness of the composites by a factor up to 4.5 while maintaining the strong damping response of the host polymer. Using an established micromechanical model, we can predict the damping figure of merit of such composites and provide guidelines for the creation of stiff and damping bio-inspired structures while considering boundary conditions of the manufacturing process. By reaching mechanical performance superior or comparable to bone and nacre, our bio-inspired strategy proves to be a promising pathway for the further development of low-power passive damping materials.

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Structural materials such as metals and fibre-reinforced plastics are stiff engineering materials used in many industrial fields. However, their high stiffness leads usually to the inability to dissipate energy via vibration damping. Contrarily, compliant materials such as rubbers and soft polymers exhibit an excellent damping behaviour, but lack in stiffness. Natural composites, such as wood, bone and seashells possess both high stiffness and high damping and thus combine properties that are generally mutually exclusive. In this study, the design principles of two biological composites, i.e. nacre and wood, were studied to design composites out of engineering materials which display a damping behaviour like the natural systems and are producible on a larger scale. The dynamic properties of nacre-inspired epoxy and flax fibre-reinforced composites were investigated and compared to structural engineering materials and to the biological materials served for the inspiration.@en