Flexural Properties and Failure Mechanics of Morphology-Driven Mechanical Metamaterials Fabricated Using Acrylonitrile Butadiene Styrene Material on Fused Deposition Modeling Process

Abstract

Mechanical metamaterials (MMs) have revolutionized the structural performance through geometric design and are increasingly fabricated using additive manufacturing. Their flexural performance is important to investigate for their use in bending applications. This article presents the effect of several designed polymeric MM morphologies on their effective flexural performance. Twelve MM designs, along with a solid beam, are modeled with the same volume ratio of 32% and manufactured from acrylonitrile butadiene styrene material using fused deposition modeling. They are tested with the three-point bending technique using a flexure instrument, an Instron 3367 universal testing machine. The experiment data, including peak force, maximum displacement, effective flexural modulus, and effective flexural stress, were acquired for these designs. In addition, the specific load capacity (SLC) and specific energy absorption (SEA) were evaluated to determine their energy absorption (EA) and structural efficiency. The results showed a profound MM morphological dependency, affecting the effective flexural performance, that is, peak force, effective flexural modulus, effective flexural stress, and maximum displacement, with a 37% weight reduction, approximately, compared with a solid beam. Cubic-based MM D1 maximized structural rigidity, achieving an SLC of up to 5.95 N/g and a flexural modulus of 379 MPa. Conversely, the octahedral-based MM D11 excelled in compliance and crashworthiness, exhibiting maximum displacements of over 13 mm and maximizing SEA to 0.07 J/g. The results highlight the significant role of the MMs morphology in governing flexural performance and demonstrate that they may be programmed to achieve a desired balance between loading capacity and EA for lightweight structural applications.