Microcontact Interactions in Architected Interfaces: A Fine-Scale Finite Element Modeling
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Architected interfaces provide a powerful framework to tailor macroscopic contact and frictional responses through controlled micro-scale geometries. In such structures, the collective behavior of discrete microcontacts plays a central role. Indeed, the macro-scale response remains difficult to predict due to strong elastic interactions, geometric nonlinearity, and finite-size effects. In this work, we present a three-dimensional finite element model of architected interfaces composed of arrays of spherical micro-asperities with prescribed heights and spatial arrangements. The proposed fine-scale model resolves multi-contacts, large deformations, and multiple interacting contact zones, while accounting for finite substrate thickness. This approach enables a critical assessment of the validity of assumptions made in existing experimental architected interfaces and their impact on design performance. The numerical results first confirm the validity of the experimental strategy used in the literature. Then, we show that, for reference patterns with well-separated asperities and sufficiently thick substrates, classical multicontact assumptions provide accurate predictions of the global response. However, significant deviations arise when asperities are spatially clustered or when the substrate thickness becomes comparable to the asperity size. In these cases, elastic interactions between neighboring microcontacts strongly influence the activation sequence of contacts and modify the resulting macroscopic behavior. This study highlights how fine-scale elastic interactions can be exploited as design parameters in architected interfaces. It provides critical insights into the robustness and practical limitations of the architected interfaces design strategy and guidelines for its future improvements.
