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Search Publications by: Jonathan Seppala (Fed)

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Displaying 1 - 25 of 35

Characterization of Die-Swell in Thermoplastic Material Extrusion

July 5, 2023
Austin Colon, David Kazmer, Amy Peterson, Jonathan Seppala
Die-swell is a flow effect that occurs in polymer extrusion whereby the material experiences rapid stress and dimensional changes upon exiting the nozzle orifice. Material extrusion additive manufacturing is no exception, and this effect influences the

Simulated stress mitigation strategies in embedded 3D bioprinting

August 30, 2022
Leanne Friedrich, Ross Gunther, Jonathan Seppala
Extrusion-based 3D bioprinting is a powerful tool for fabricating complex cell-laden constructs. Embedded Ink Writing (EIW) is an extrusion-based printing technique wherein a nozzle embedded into a support bath writes continuous filaments. Because it

Suppression of filament defects in embedded 3D printing

July 5, 2022
Leanne Friedrich, Ross Gunther, Jonathan Seppala
Embedded 3D printing enables the manufacture of soft, intricate structures. In the technique, a nozzle is embedded into a viscoelastic support bath and extrudes filaments or droplets. While embedded 3D printing expands the printable materials space to low

Solvent-cast 3D Printing of Biodegradable Polymer Scaffolds

October 22, 2021
John Tolbert, Diana Hammerstone, Nathaniel Yuchimiuk, Jonathan Seppala, Lesley Chow
Three-dimensional (3D) printing is a popular technique to fabricate scaffolds for tissue engineering because of its ability to produce complex tissue-like architectures. Scaffolds are often 3D printed using biodegradable polymers like poly(caprolactone)

Simulated filament shapes in embedded 3D printing

July 22, 2021
Leanne Friedrich, Jonathan Seppala
Embedded 3D printing, wherein fluid inks are extruded into a bath, has enabled the manufacture of complex, custom structures ranging from cell-laden tissue analogues to soft robotics. This method encompasses two techniques: embedded ink writing (EIW)

Fabrication of 3D Printed Hydroxyapatite Composite Scaffolds for Bone Regeneration

May 19, 2021
Yoontae Kim, Eun-Jin Lee, Albert Davydov, Stanislav Frakhtbeyen, Jonathan Seppala, Laurence Chow, Tagaki Shozo, Stella Alimperti
Additive biomanufacturing has been adapted in a wide variety of biomedical and tissue engineering applications, including orthopedics. The ability to print biocompatible, patient-specific geometries with controlled porosity, mechanical strength has made

Estimations of the effective Young's modulus of specimens prepared by fused filament fabrication

April 5, 2021
Lichen Fang, Yishu Yan, Ojaswi Agarwal, Jonathan Seppala, Kalman D. Migler, Thao D. Nguyen, Kevin Hemker, Sung Hoon Kang
The elastic response of homogeneous isotropic materials is most commonly represented by their Young's modulus (E), but geometric variability associated with additive manufacturing results in materials that are neither homogeneous nor isotropic. Here we

AMB2018-03: Benchmark Physical Property Measurements for Material Extrusion Additive Manufacturing of Polycarbonate

October 29, 2020
Daniel P. Cole, Frank Gardea, Todd C. Henry, Jonathan Seppala, Edward Garboczi, Kalman D. Migler, Christopher M. Shumeyko, Jeffery R. Westrich, Sara Orski, Jeffery L. Gair
Material extrusion (MatEx) is finding increasing applications in additive manufacturing of thermoplastics due to the ease of use and the ability to process disparate polymers. Since part strength is anisotropic and frequently deviates negatively with

Effects of Environmental Temperature and Humidity on the Geometry and Strength of Polycarbonate Specimens Prepared by Fused Filament Fabrication

October 3, 2020
Lichen Fang, Yan Yishu, Ojaswi Agarwal, shengyu Yao, Jonathan Seppala, Sung Hoon Kang
It is widely known that the printing quality of fused filament fabrication (FFF) is heavily affected by environmental temperature and humidity, as the case of warping and porosity. However, there is little understanding about the quantitative relations

3D printed optical concentrators for LED arrays

July 19, 2020
Behrang H. Hamadani, Jonathan E. Seppala, Clarence J. Zarobila
Additive manufacturing methods based on photopolymerization offer a great potential for fabrication of high quality, highly transparent optical components. One appropriate use of these technologies is related to fabrication of parts that can be used in

Outcomes and Conclusions from the 2018 AM-Bench Measurements, Challenge Problems, Modeling Submissions, and Conference

February 13, 2020
Lyle E. Levine, Brandon M. Lane, Jarred C. Heigel, Kalman D. Migler, Mark R. Stoudt, Thien Q. Phan, Richard E. Ricker, Maria Strantza, Michael R. Hill, Fan Zhang, Jonathan E. Seppala, Edward J. Garboczi, Erich D. Bain, Daniel Cole, Andrew J. Allen, Jason C. Fox, Carelyn E. Campbell
The Additive Manufacturing Benchmark Test Series (AM-Bench) was established to provide rigorous measurement test data for validating additive manufacturing (AM) simulations for a broad range of AM technologies and material systems. AM-Bench includes

Compressive deformation analysis of large area pellet-fed material extrusion 3D printed parts in relation to in situ thermal imaging*

February 8, 2020
Eduardo M. Trejo, Xavier Jimenez, Kazi M. Billah, Jonathan Seppala, Ryan Wicker, David Esplain
In large area pellet extrusion additive manufacturing, the temperature of the substrate just before the deposition of a new subsequent layer affects the overall structure of the part. Warping and cracking occur if the substrate temperature is below a

Measuring & Predicting Crystal Morphology in Fused Deposition Modeling

June 19, 2019
Claire McIlroy, Jonathan Seppala, Anthony Kotula
Semi-crystalline polymer melts are commonly used in fused deposition modeling. Although flows have a profound effect on polymer crystallization, the relationship between typical fused deposition modeling (FDM) deformation rates and printed-part crystal

Polymer Additive Manufacturing: Confronting Complexity

June 19, 2019
Anthony P. Kotula, Jonathan E. Seppala, Chad R. Snyder
Since its development and commercialization in the 1980s, polymer additive manufacturing (AM) has become a disruptive technology. In this chapter we describe the ever-increasing demands for polymer AM in industry, academia, and government, as well as the


June 19, 2019
Jonathan E. Seppala, Anthony P. Kotula, Chad R. Snyder

Weld formation during material extrusion additive manufacturing

August 11, 2017
Jonathan E. Seppala, Seung Hoon Han, Kaitlyn E. Hillgartner, Chelsea S. Davis, Kalman D. Migler
Material extrusion (ME) is a layer-by-layer additive manufacturing process that is now used in personal and commercial production where prototyping and customization are required. However, parts produced from ME frequently exhibit poor mechanical