Session: IMECE Undergraduate Research and Design Exposition

Paper Number: 118722

118722 - Mechanical Behavior and Material Modeling of Additively Manufactured Architectured Lattices: A Comparative Study 

Investigations into architectured lattices’ mechanical and morphological properties have surged due to advancements in additive manufacturing, which allows the fabrication of complex structures. These architectured lattices can be categorized using their unit cells’ geometry and arrangement, namely, stochastic (foams), periodic (lattices), and pseudoperiodic. To analyze and predict the mechanical behavior and failure mechanisms of these structures in a faster, cost-effective, and reasonably accurate manner, Finite Element Analysis (FEA) serves as a valuable tool for computer-aided engineering. FEA involves following certain steps such as designing a geometric model, discretization, or division of the model into small elements (finite elements), assigning material models to those elements, and application of forces and boundary conditions. The incorporation of a proper material model plays a vital role in predicting the mechanical behavior and failure mechanism of these structures during computational analysis. Several material models have been proposed to correctly predict the mechanical behavior of these polymer-based structures including the classical rubber elasticity model, the Ogden model, and the polynomial model each having a limitation of their own. As such, in this research, we aim to address the limitations by comparing various material models, including Asymptotic Homogenization (AH), the Arruda-Boyce model (AB), Yeoh Hyperelastic model (YH), Johnson Cook model (JC), and Three Network Viscoelastic model (TNV). The objective is to simulate and predict the response of polymer-based lattice structures more effectively. Experimental verification of the results was conducted using experimental uniaxial compression testing. The data for the material model was calibrated using Mcalibration software (PolymerFEM LLC 2023, Dover, MA). In this study, we have focused on two types of lattice structures, Schoen Gyroid, and Diamond, which belong to the category of triply periodic minimal surface (TPMS) lattices. To conduct our analysis, we modeled 10 mm lattice structures with gyroid and diamond unit cells, each having pore sizes of 0.5 mm and 0.6 mm, and a porosity of 50%. The modeling process was performed using nTopology software (nTopology Inc., New York, USA). The computational analysis was conducted in Abaqus/Standard 2023, USA. The selected material models were assigned to the lattice structures and a uniaxial compression test was simulated.  For this purpose, we applied encastre boundary conditions at the bottom plate and a 2 mm displacement on the top plate. To ensure the reliability of our results, we conducted a mesh sensitivity analysis on a single unit cell to verify the independence of the outcomes on the mesh size and choice. The selected mesh size was 0.2 mm C3D4 tetrahedral. This study is primarily focused on investigating the mechanical properties of the lattice structure in the elastic region, and as a result, the Asymptotic Homogenization model was chosen for the analysis. For the gyroid unit cell, the elastic modulus was calculated as 276.22 MPa (0.5 mm pore size) and 278.37 MPa (0.6 mm pore size). For the diamond unit cell, the elastic modulus was found to be 286.3 MPa (0.5 mm pore size) and 326.83 MPa (0.6 mm pore size). Our findings verified that the morphological features of the unit cells, such as cell topology and pore size, play a crucial role in influencing the mechanical behavior of the lattice structures. Moreover, the computational analysis tended to yield mechanical behavior estimates that were higher than the experimental results. This discrepancy may be attributed to manufacturing defects and the material models used for simulation purposes. In conclusion, this research aims to offer a more profound understanding of the mechanical behavior and failure mechanisms of lattice structures. Additionally, it seeks to identify a suitable material model that accurately predicts these behaviors.

Presenting Author: Holly Fulcomer George Mason University

Presenting Author Biography: My name is Holly Fulcomer. I am a junior at George Mason University pursuing an undergraduate degree in mechanical engineering. I also trying to get a minor in mathematics. My interests are fixing electronics, art, and materials. In my free time, I do technical drawings of different objects.

Authors:

Kunal Gide George Mason University
Holly Fulcomer George Mason University
Shaghayegh Bagheri George Mason University