Session: 07-07-03: Computational Modeling in Biomedical Applications III

Paper Number: 166333

Characterization of Auxetic Meta-Biomaterials: Investigating the Impact of Lattice Structure and Geometric Parameters on Mechanical and Biological Properties 

Auxetic meta-biomaterials exhibit exceptional mechanical and biological properties, which includes energy absorption, negative Poisson’s ratio, biocompatibility, bioactivity and bio-functionality. Such qualities make them ideal for biomedical engineering applications. Applying additive manufacturing (AM) techniques enhances mechanical performance, while material selection enhances biological characteristics. Current lattice structures fabricated with an AM technique exhibit relatively high strength but can be further improved by refining and hybridizing topological features of lattice geometry. This research focuses on enhancing auxetic biomaterials' biological and mechanical performance through numerical and experimental analyses of energy absorption and local buckling using compressive and tensile testing.  

Past research has shown that hybrid in-plane lattice structures on energy absorption and buckling properties of auxetic materials have a significant impact. Several factors, such as axial placement of struts, strut thickness, re-entrant angle, relative density, and unit cell size could affect the mechanical properties of polymer-based auxetic materials. Recent studies have shown that re-entrant arrowhead (RAH) hybrid lattice structure exhibits higher mechanical performance in comparison to different classic and hybrid lattice structures from other past studies. Although the hybrid RAH lattice structure performed better than other unit cell designs, improvements could be made to decrease the negative Poisson’s ratio to exhibit higher auxetic behavior. Different geometrical patterns and sizes should be further researched to optimize the failure of mechanical performance of the materials. 

The purpose of this research is to: 1) investigate the failure mechanisms of auxetic tubular stents, 2) study the effects of geometric parameters by modifying lattice structures and compositions, and 3) examine the short-term and long-term behavior of additive manufacturing (AM)-based auxetic metamaterials. The authors will utilize additive manufacturing with fused deposition modeling (FDM) to create the unit cell and lattice structures for experimental analysis. To fabricate both planar solid and tubular auxetic structures, the authors will introduce a new topology for an auxetic unit cell. For numerical analysis, the researchers will employ Ansys software, version 2024 R2, to conduct finite element analysis and quantify the theoretical characteristics of mechanical properties under tensile, compressive, and bending stresses. To ensure reliable quantitative characterization of long-term elastic and viscoelastic behavior, the finite element model will account for heterogeneity, damage, and anisotropic behavior of the auxetic material. Additionally, the study will analyze the local and global buckling and energy absorption capacity of the novel auxetic unit cell and tubular stent. The researchers will employ Scanning Electron Microscopy and Digital Image Correlation techniques to study the micro and macro mechanics of damage and Poisson's ratio at the structural scale. 

Presenting Author: April Nguyen California Polytechnic State University - San Luis Obispo

Presenting Author Biography: My name is April Nguyen and I am a 4th-year biomedical engineering major at California Polytechnic State University, San Luis Obispo, with a concentration in mechanical design. My research interests include continuity in biomechanics, atomic force microscopy, and finite element analysis.

Authors:

April Nguyen California Polytechnic State University - San Luis Obispo
Masoud Yekani Fard California Polytechnic State University - San Luis Obispo