Mineralized bio-composite materials are typically structured as assemblies of bulk mineralized elements, separated by thin organic interfaces. Common examples of such mineralized bio-composites are the spicules of sea sponges, the nacreous and prismatic layers of various sea shells, and various bone tissues. The mineral phase of the bio-composite is typically elastic, while the organic interfaces exhibit significant viscoelastic characteristics. The viscoelastic nature of these organic interfaces grant the bio-composite various extraordinary functional capabilities compared to that of the isolated bulk minerals, such as increased force-to-failure, enhanced fracture toughness, and magnified impact-resistance. Thus, quantifying the viscoelastic properties of these thin interfaces is critical step toward understanding the fundamental mechanics of various bio-composite systems.
In this study, we propose an indirect analytical-experimental method to measure the viscoelastic properties of thin interfaces in biocomposite materials. We introduce closed-form analytical relations between the dynamic modulus of the isolated viscoelastic interfaces and those of the whole biocomposite. We used these analytical expressions to back-calculate the net viscoelastic properties of isolated organic interfaces from large-scale DMA (dynamic mechanical analysis) experiments on whole biocomposite. We preformed validation of these analytical expressions by using Finite elements simulations. We finally demonstrated the method implementation via a numerical case study of a sea shells biocomposite model .