Monolithic additive manufacturing of a fluid-structure coupled architected cellular mechanical system for...

Passive damping systems combining high dissipation capacity, rate-adaptivity and cyclic durability remain unrealised in conventional architected materials (purely structural damping mechanism), while conventional fluid dampers require complex assembly. Here, we present a novel cellular mechanical system (CMS), in which orifice-governed viscous dissipation is activated by the coupling of compliant cellular deformation, while the encapsulated fluid generates velocity-dependent hydraulic resistance in parallel with structural viscoelasticity. Unlike conventional fluid dampers, the CMS is fabricated monolithically via single-step additive manufacturing without post-processing or assembly. Flow regime analysis confirms viscous flow conditions for the silicone oil configurations (Re < 1), establishing the applicability of linear viscous orifice resistance across the full tested parameter space. Under quasi-static compression (10-1000 mm min^-1), the fluid filled CMS achieves a specific energy dissipation of 68.5 J kg^-1 at 1000 mm min^-1, 116% higher than that of the empty configuration, while both give nearly identical dissipation at 10 mm min^-1, confirming a speed threshold for hydraulic contribution. The loss factor reaches 0.062 at 1000 mm min^-1, 121% above the empty structure. A parametric study shows that raising viscosity from 0.1 Pa s to 1.0 Pa s increases specific energy dissipation by 92% and reducing orifice diameter from 3.0 to 1.5 mm increases it by 62%. Under dynamic cycling testing at 1.0-2.5 Hz over 400 cycles, the filled CMS sustains a loss factor that is 85-107% higher than that of the empty configuration, with a cyclic stability index of 88-91% and no leakage or structural failure. This design establishes a cyclically stable, rate-adaptive, and geometrically tunable platform for additively manufactured cellular hydraulic dampers.