Engineers at the University of Maine are developing a new method to more accurately predict the strength of light-weight 3D printed objects. This research, conducted at the university’s Advanced Structures and Composites Center (ASCC), will enable designers to create more robust and reliable components by controlling strength when lightweighting virtually any plastic component.
The research team was made up of Philip Bean, research engineer at the ASCC, and Senthil Vel, professor of mechanical engineering, alongside Roberto Lopez-Anido, professor of civil engineering. Their study, recently published in Progressive Additive Manufacturing, integrates advanced computer modeling with physical experiments to provide a more comprehensive understanding of how these parts will perform under stress.
They focused on gyroid infill, an intricate, repeating internal structure commonly employed in 3D printing to minimize weight while preserving structural integrity. By utilizing computer simulations to analyze the gyroid’s response to various forces, the team validated these predictions through experiments on 3D-printed prototypes. The findings offer insights into how this complex in-ternal pattern contributes to a part’s overall performance; a fac-tor often not possible with conventional analytical methods.
“This work allows us to design 3D printed parts with greater confidence and efficiency,” says Bean, one of the lead re-searchers. “By understanding the precise strength of these gyroid-infilled structures, we can reduce material use and im-prove performance across industries.”
This method is anticipated to significantly benefit sectors demanding strong, lightweight materials, including aero-space, automotive, and medical device manufacturing.
The full publication, “Investigation of the nonlinear response of gyroid infills for prediction of the effective yield strength,” provides more details on the method.
For more information, contact Roberto Lopez-Anido at
Overview
This document presents a comprehensive study on the nonlinear mechanical response of gyroid infill structures used in additive manufacturing (AM), specifically focusing on their effective yield strengths across a full range of relative densities. Gyroids, a type of triply periodic minimal surface, are a common periodic infill pattern in AM due to their continuous, smooth geometry and favorable mechanical properties. Despite wide use, there is limited data on their structural behavior, especially under nonlinear loading conditions.
The research extends prior linear elastic analyses by incorporating elastic–perfectly-plastic finite element analysis (FEA) models that apply periodic boundary conditions on single unit-cell representative volume elements (RVEs). These models capture the yielding behavior of gyroids under compression and shear loads for both polymer materials and across relative densities from 0.25 to 1. The study shows that linear models inadequately predict yield strength, thus necessitating nonlinear simulation to capture plastic deformation onset and progression.
Base material characterization tests are performed on two common AM polymers—toughened polylactic acid (tPLA) and polyethylene terephthalate glycol (PETG)—including tensile and shear experiments following ASTM standards. Results reveal anisotropic elastic and strength properties tied to printing direction and layering effects, underscoring the importance of accurate material inputs for FEA. Shear properties are experimentally determined as well to support shear strength predictions.
The nonlinear FEA results are used to develop semi-empirical predictive equations for normalized compressive and shear yield strengths as functions of relative density and base material yield strength. These equations facilitate rapid strength estimations useful in design and topology optimization workflows. Prediction curves show good agreement with experimental data from this study and literature for lower density gyroids, though some underestimation occurs at higher densities likely due to differences in compressive vs. tensile material strengths and possible internal contact effects within the gyroid.
Experimental validation is performed through compression testing of large gyroid specimens and shear testing of hybrid sandwich panels with gyroid cores, revealing significant scatter that partially reflects the variability inherent in fused filament fabrication (FFF) processes. The authors note that alternative AM methods like selective laser sintering (SLS) may provide more repeatable results.
The document concludes that the semi-empirical nonlinear models provide a useful framework for predicting gyroid infill yield strengths over a wide density range, advancing the capability to incorporate such infills reliably into structural designs and AM optimization. Future work is suggested to address internal contact effects, explore more advanced homogenization methods, and validate results with other AM technologies.
References and standards used in modeling and experimental validation are cited, emphasizing reproducibility and alignment with existing literature.
