Superior compressive performance of alveolar biomimetic interlaced hollow lattice metastructures

Description

Advancements in additive manufacturing have significantly enhanced the designability of lattice structures for superior compression resistance. Inspired by the sac-like morphology of alveolar tissues, an alveolar biomimetic interlaced hollow lattice metastructure with superimposed double pipes is proposed. This metastructure features customizable geometric parameters, offering strong designability, unique compression deformation behavior, and distinct mechanical responses. Specimens with different geometric dimensions are fabricated from Inconel 718 by selective laser melting. Detailed surface morphology evaluations using scanning electron microscopy and X-ray scanning reveal high-fidelity manufacturing outcomes. A novel refined finite element model, based on X-ray data, accurately predicts the mechanical behavior of millimeter-scale lattice structures, validated through rigorous experiments. Compressive performance of the metastructures under different size parameters is investigated using both experimental testing and finite element simulations, revealing that the 45° metastructure exhibits the highest energy absorption efficiency of 90%. The enhancement of self-supporting effect is significant, especially the 30° double-cell structure energy absorption capacity is increased by 51% compared to single-cell case. Additionally, gradient metastructures are designed and tested, demonstrating effective suppression of shear band formation and increasing energy absorption capacity up to 26.29%. The proposed hollow lattice metastructure holds great potential for load bearing and energy absorption applications. Keywords: Lattice metastructures; Alveolar biomimetic design; Refined finite element model; Compressive behavior; Energy absorption

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For morphological characterization of the printed alveolar biomimetic metastructures, X-ray scanning (XRM) and tungsten filament scanning electron microscopy (SEM) are employed. The XRM analysis, conducted using an Xradia 610 Versa (Carl Zeiss), is utilized for assessing geometric deviations between the as-designed and as-built metastructures. Meanwhile, the SEM evaluation, performed with an EVO10 (Carl Zeiss), focuses on surface quality assessment of the printed samples. Quasi-static compression tests of the printed lattice metastructures are carried out on a hydraulic loading system (WAW-2000CG). The experimental loading rate is 1 mm/min, corresponding to a nominal strain rate of 5.2×10-4 s-1. Compressive loading is exerted by the upper platen, with the lower platen fixed. A digital video is set at the front side of the samples to record the deformation process of metastructures. The nominal compressive strain is calculated as the ratio of the loading displacement and the height of samples; while the nominal compressive stress is calculated as the ratio of loading force and interface contour area of the sample. In the experiments, for each set of parameters, three samples are prepared and tested. It has been established that the compressive responses for the metastructure specimens in each set are quite repeatable.

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