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Search Publications by Jonathan Seppala

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Displaying 1 - 25 of 28

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 E. 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 E. 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 E. Seppala, Anthony P. 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

Cure temperature influences electrical properties via carbon nanotube-rich domain formation

July 27, 2016
Chelsea S. Davis, Nathan D. Orloff, Jeremiah W. Woodcock, Christian J. Long, Kevin A. Twedt, Bharath NMN Natarajan, Jonathan E. Seppala, Jabez J. McClelland, Jan Obrzut, James A. Liddle, Jeffrey W. Gilman
Carbon nanotube (CNT) nanocomposites are enticing materials that enable engineers to tailor structural and electrical properties for applications in the automotive and aerospace industries. CNT mass fraction and the matrix cure temperature are two ways to

An azeotropic cross-linked styrene-methacrylate network formed through rapid visible-light photo- polymerization

July 15, 2016
Yin Yang, Aaron A. Urbas, Andres Gonzalez-Bonet, Richard J. Sheridan, Jonathan E. Seppala, Kathryn L. Beers, Jirun Sun
A system containing well-defined functional material, a clinically practical procedure to make the material in situ, and proper analytical tools for chemical structure and kinetic studies is appealing, but currently unavailable. Herein, we introduce an all

Thermography and Weld Strength Characterization of Thermoplastic Extrusion 3D Printing

May 23, 2016
Jonathan E. Seppala, Kaitlyn E. Hillgartner, Chelsea S. Davis, Kalman D. Migler
In fused filament fabrication (FFF), a material extrusion additive manufacturing (AM) method, thermoplastic filament is extruded though a rastering nozzle on prior layers building a 3 dimensional object. The resulting strength of the FFF produced part is

Rapid Fabrication of Poly(DL-lactide) Nanofiber Scaffolds with Tunable Degradation for Tissue Engineering Applications by Air-brushing

April 28, 2016
Adam M. Behrens, Jeffrey J. Kim, Nathan A. Hotaling, Jonathan E. Seppala, Peter Kofinas, Wojtek J. Tutak
Polymer nanofiber based materials have been widely investigated for use as tissue engineering scaffolds. While promising, these materials are typically fabricated through techniques that require significant time or cost. Here we report a cost effective

Characterization of clay composite ballistic witness materials

July 29, 2015
Jonathan E. Seppala, Yoonae Heo, Paul E. Stutzman, John R. Sieber, Chad R. Snyder, Kirk D. Rice, Gale A. Holmes
Mechanical and thermal properties of Roma Plastilina Clay #1 (RP1) were studied through small-amplitude oscillatory shear (SAOS), large-amplitude oscillatory shear (LAOS), and differential scanning calorimetry (DSC), supplemented with thermogravimetric