Abstract

The study aims to compare mechanical properties of polymer and metal honeycomb lattice structures between a computational model and an experiment. Specimens with regular honeycomb lattice structures made of Stratasys Vero PureWhite polymer were produced using PolyJet technology while identical specimens from stainless steel 316L and titanium alloy Ti6Al4V were produced by laser powder bed fusion. These structures were tested in tension at quasi-static rates of strain, and their effective Young’s modulus was determined. Analytical models and finite element models were used to predict effective Young’s modulus of the honeycomb structure from the properties of bulk materials. It was shown, that the stiffness of metal honeycomb lattice structure produced by laser powder bed fusion could be predicted with high accuracy by the finite element model. Analytical models slightly overestimate global stiffness but may be used as the first approximation. However, in the case of polymer material, both analytical and FEM modeling significantly overestimate material stiffness. The results indicate that computer modeling could be used with high accuracy to predict the mechanical properties of lattice structures produced from metal powder by laser melting.

Highlights

  • Functional properties of products manufactured by classic subtractive methods can be predicted with high accuracy as there is extensive engineering knowledge on the mechanical behavior of materials and the effect of their processing

  • The samples made of titanium alloy Ti6Al4V were produced using the 3D printer M2 cusing (Concept Laser GmbH, Lichtenfels, Germany) from Concept Laser CL 42Ti Grade 2 powder consisting of particles with sizes ranging from 20 to 50 μm

  • Our results indicate that the Finite element analysis (FEA) model is more accurate than an analytical model of the honeycomb lattice structure

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Summary

Introduction

Functional properties of products manufactured by classic subtractive methods can be predicted with high accuracy as there is extensive engineering knowledge on the mechanical behavior of materials and the effect of their processing. The imperfections, which can occur during such complex AM processes, namely pores, part distortion, or lack of fusion defects, should not be neglected in the design process [2] but they cannot be predicted explicitly It has been shown in numerous studies that the properties of AM products largely depend on the orientation of the structure during the manufacturing process, size of the structure, or set of process parameters [3]. Such structures are characterized by a high surface area to volume ratio that makes them prone to surface imperfections during the building process [6] It is the aim of this study to provide a direct comparison between the computer model of honeycomb lattice structure and its mechanical properties. Material defects may close up and do not have a significant impact on behavior under compression modes of loading [12]

Honeycomb Lattice Specimen
Analytical Model
Numerical Model
Additive Manufacturing of Specimens
Experimental Testing
Results
Discussion
Conclusions
Full Text
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