Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2023 Feb 26;15(5):1178.
doi: 10.3390/polym15051178.

Impact Performance of 3D Printed Spatially Varying Elastomeric Lattices

Charles M Dwyer  1 , Jose G Carrillo  2 , Jose Angel Diosdado De la Peña  3 , Carolyn Carradero Santiago  1 , Eric MacDonald  4 , Jerry Rhinehart  5 , Reed M Williams  6 , Mark Burhop  6 , Bharat Yelamanchi  1 , Pedro Cortes  1
Affiliations

Impact Performance of 3D Printed Spatially Varying Elastomeric Lattices

Charles M Dwyer et al. Polymers (Basel). .

Abstract

Additive manufacturing is catalyzing a new class of volumetrically varying lattice structures in which the dynamic mechanical response can be tailored for a specific application. Simultaneously, a diversity of materials is now available as feedstock including elastomers, which provide high viscoelasticity and increased durability. The combined benefits of complex lattices coupled with elastomers is particularly appealing for anatomy-specific wearable applications such as in athletic or safety equipment. In this study, Siemens' DARPA TRADES-funded design and geometry-generation software, Mithril, was leveraged to design vertically-graded and uniform lattices, the configurations of which offer varying degrees of stiffness. The designed lattices were fabricated in two elastomers using different additive manufacturing processes: (a) vat photopolymerization (with compliant SIL30 elastomer from Carbon) and (b) thermoplastic material extrusion (with Ultimaker™ TPU filament providing increased stiffness). Both materials provided unique benefits with the SIL30 material offering compliance suitable for lower energy impacts and the Ultimaker™ TPU offering improved protection against higher impact energies. Moreover, a hybrid lattice combination of both materials was evaluated and demonstrated the simultaneous benefits of each, with good performance across a wider range of impact energies. This study explores the design, material, and process space for manufacturing a new class of comfortable, energy-absorbing protective equipment to protect athletes, consumers, soldiers, first responders, and packaged goods.

Keywords: additive manufacturing; elastomers; functionally graded; impact energy management; lattices; volumetrically varying.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

Figures

Figure 1
Figure 1
Rendering and photos of the lattice structures investigated in this work based on the Kelvin unit cell (designed in Siemens Mithril software); (a) vertically-graded SIL30, and (b) non-graded SIL30.
Figure 2
Figure 2
Representation of the impact testing and data analysis. The area enveloped by the force vs. displacement curve is the energy absorbed by the lattice and is shaded above.
Figure 3
Figure 3
None-graded lattice full mesh with bottom plate and impactor.
Figure 4
Figure 4
Force versus time of SIL30 and ULTI at different impact energies; (a) SIL30-NG (non-graded), (b) SIL30-VG (vertically-graded), (c) ULTI-NG, and (d) ULTI-VG with peak force values labeled for comparison.
Figure 5
Figure 5
Force versus displacement of SIL30 and ULTI at different impact energies; (a) SIL30-NG, (b) SIL30-VG, (c) ULTI-NG, (d) ULTI-VG. Densification points are labeled; however, ULTI-NG does not show densification in these graphs due to its stiffness.
Figure 6
Figure 6
Absorbed energy at the densification point of impact force for the SIL30 and ULTI materials based on the vertically-graded and non-graded configurations, normalized by mass (bars). Elastic Young’s Modulus is shown by the dashed circles and dashed axis on the right side to compare material stiffness as well.
Figure 7
Figure 7
Deformation versus time for intermediate layers of the hybrid approach at a 14.3 J impact. Note that the bottom metal plate thickness is included here and is 10 mm.
Figure 8
Figure 8
Force response of double stacked vertically-graded configurations; (a) 2.6 J, (b) 9.6 J.
Figure 9
Figure 9
Impact energy response at the densification point for the double stacked vertically-graded systems; (a) densification energy, (b) densification specific impact energy. The compromise resulting from combining materials is evident here.
Figure 10
Figure 10
Peak energy absorption from double stacking vertically-graded systems at different impact energies.
Figure 11
Figure 11
Acceleration response of all three double-stacked vertically-graded configurations; (a) 2.6 J, (b) 9.6 J.
Figure 12
Figure 12
Micrographs of the SIL30 sample (a) before impact, (b) after impact and (c) high magnification view post impact.
Figure 13
Figure 13
Non-graded lattice numerical results: (a) impact force–displacement curve comparison and (b) maximum compression under simple impact.
See this image and copyright information in PMC

References

    1. Munford M., Hossain U., Ghouse S., Jeffers J.R.T. Prediction of Anisotropic Mechanical Properties for Lattice Structures. Addit. Manuf. 2020;32:101041. doi: 10.1016/j.addma.2020.101041. - DOI
    1. Dong G., Tang Y., Li D., Zhao Y.F. Design and Optimization of Solid Lattice Hybrid Structures Fabricated by Additive Manufacturing. Addit. Manuf. 2020;33:101116. doi: 10.1016/j.addma.2020.101116. - DOI
    1. Carneiro V.H., Rawson S.D., Puga H., Meireles J., Withers P.J. Additive Manufacturing Assisted Investment Casting: A Low-Cost Method to Fabricate Periodic Metallic Cellular Lattices. Addit. Manuf. 2020;33:101085. doi: 10.1016/j.addma.2020.101085. - DOI
    1. Flores I., Kretzschmar N., Azman A.H., Chekurov S., Pedersen D.B., Chaudhuri A. Implications of Lattice Structures on Economics and Productivity of Metal Powder Bed Fusion. Addit. Manuf. 2020;31:100947. doi: 10.1016/j.addma.2019.100947. - DOI
    1. McGregor D.J., Tawfick S., King W.P. Mechanical Properties of Hexagonal Lattice Structures Fabricated Using Continuous Liquid Interface Production Additive Manufacturing. Addit. Manuf. 2019;25:10–18. doi: 10.1016/j.addma.2018.11.002. - DOI

LinkOut - more resources