Mechanical performance of sinusoidally architected concrete enabled by robotic additive manufacturing

Concrete additive manufacturing (AM) is an emerging technology that enables the fabrication of complex and efficient geometries with intricate features. Here, the mechanical performance of bio-inspired sinusoidally architected concrete is investigated in comparison to monolithic, cast counterparts. A robotic additive manufacturing process was utilized to fabricate sinusoidal architectures in three orientations (denoted X, Y, and Z) and two rectilinear architectures and compared to conventionally cast specimens of equivalent geometries. Single-edge bend and single-edge-notched bend experiments were performed to test the strength and fracture toughness, respectively. Unlike rectilinear architectures, the X and Z-Sinusoidal architected concrete elicited a flexural strength and fracture toughness statistically equivalent to cast counterparts, whereas the Y-Sinusoidal architecture exhibited a 71 % increase in flexural strength as compared to the cast counterparts. Finite element simulations were carried out to evaluate the effect of sinusoidal frequency and amplitude on stress distribution through the test specimens. In addition, a theoretical analysis of stress concentration was conducted to understand the role of sinusoidal perturbation from surface to core. The sinusoidal architectures were observed to produce stress concentrations and non-uniform stress profiles (depending on two design variables, i.e., amplitude, A, and wavelength, λ), which led to outperforming rectilinear additively manufactured and cast counterparts.