Vibration Characteristics of 3D Printed Rigid Photopolymer Metamaterials Infiltrated with Biodegradable Shear Thickening Fluid

Background: Hybrid metamaterials, obtained by infiltrating biodegradable shear-thickening fluids (STFs) into a porous structure, hold great promise for applications requiring enhanced sustainability and vibration reduction capabilities. However, research into the mechanical behavior of such hybrid materials remains limited. Objective: The study aims to explore the vibration characteristics of 3D-printed hybrid metamaterials, investigating the effect of topology variation and providing experimental evidence supporting the effectiveness of biodegradable STF filler for vibration damping enhancement. Methods: The dynamic properties of beam-like specimens integrating different types of metamaterials were evaluated through experimental modal analysis (EMA). Two distinct unit cell topologies, YRS (Y re-entrant structure) and FBCCZ (face and body-centered cell with vertical struts along the z-axis), were tested to observe the effect of geometric variation on the material’s dynamic properties. Additionally, each specimen was analyzed with and without a biodegradable STF filler. Results: YRS specimens generally achieved better infiltration than FBCCZ specimens, likely due to the easier fluid flow within the structure. Analysis of Variance confirmed that cell topology and STF infiltration had a major influence on the damping behavior of the specimens. The damping ratio of the YRS specimens was, on average, 20% higher than that of the FBCCZ specimens. After STF infiltration, the damping ratio increased by an average of 14% for the FBCCZ specimens and 9% for the YRS specimens. Conclusions: Results highlighted the superior performance of the hybrid auxetic metamaterial infiltrated with the biodegradable non-Newtonian fluid, offering a sustainable solution for adaptive structural vibration control by utilizing the shear-rate sensitivity of the STF.