Effect of interface strength on the mechanical behaviour of bio-inspired composites: A molecular dynamics study

S Mathiazhagan and S Anup, MECHANICS OF MATERIALS, 132, 93-100 (2019).

DOI: 10.1016/j.mechmat.2019.02.016

Nanoscale composites inspired from biological materials such as nacre and bone are excellent candidates for improving the mechanical properties of ceramic matrix composites (CMC) or in general any brittle- matrix composites. These composites are based on the regularly staggered model (RSM) and on the stair-wise staggered model (SSM), and consist of stiffer platelets embedded in a compliant matrix. The interface between the platelets and the matrix plays a key role as an enormous amount of interfacial area exists in the nanocomposite materials. We investigate the influence of interface strength on the overall mechanical properties and deformation mechanisms of bio-inspired brittle-matrix nanocomposites. Atomistic simulations are used for this purpose and the interface strength is controlled by varying the binding energy between the platelet atoms and the matrix atoms. We found that the mechanical properties of both models initially increase with the interface strength. However, above a critical value, the trend changes drastically between the two models. The RSM model continues to maintain the flow stress and toughness at higher interface strengths, due to the persistence of deformation mechanisms such as bulk matrix plasticity and platelet pullout. In contrast, in the SSM model the flow stress and toughness are deteriorated as softening of stress and fracturing of platelets occur at higher interface strengths. The knowledge gained from this study paves new way for the development of bio-inspired ceramic- matrix composites with improved mechanical properties.

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