I will be collaborating with Palo Alto Research Center (formerly Xerox PARC) on a Department of Energy (DOE) grant shooting for enhanced properties in lead-free piezoelectric materials.  We will apply high-throughput (HT) processing and characterization techniques on piezoceramics. This unique HT data will enable materials informatics approaches to guide our experiments towards higher performance systems.  Figure.  […]

Croom, Brendan P; Keles, Ozgur; Flores, Mark D, Prediction Of Crack Propagation Along Non-Uniform Raster Patterns In Am Composites, ASC 35th Technical (Virtual) Conference, 2020.https://asc2020.nyc/program Figure 9. Damage progression in specimens with different α. (a-d) Damage at four increasing load steps. Specimens with α=0°,5°,10°,15°,20° and 30° are stacked from front to back in each panel; matrix […]

Effect of recycling on the mechanical behavior and structure of additively manufactured acrylonitrile butadiene styrene (ABS) Alex K. Cress 1, Jimmy Huynh1, Eric H. Anderson1, Ryan O’neill1, Yanika Schneider2, Özgür Keleş 1*1Chemical and Materials Engineering Department, San Jose State University, San Jose, CA, 95192, USA2EAG Laboratories, 810 Kifer Rd Sunnyvale, CA 94086, USA AbstractFused deposition […]

A predictive failure framework for brittle porous materials via machine learning and geometric matching methods  Alp Karakoç1, Özgür Keleş2,* 1Aalto University, Department of Bioproducts and Biosystems, Vuorimiehentie 1, Espoo, Finland 2San Jose State University, Chemical and Materials Engineering Department, One Washington Square, San Jose, CA 95192, USA https://link.springer.com/article/10.1007/s10853-019-04339-1 ABSTRACT Brittle porous materials are used in […]

J.R. Seibert, O. Keles, J. Wang, F. Erogbogbo, Data on Thermal Conductivity and Dynamic Mechanical Properties of Graphene Quantum dots in epoxy, Data in Brief,  https://doi.org/10.1016/j.dib.2019.105008. Fig. 2. TEM images of bird charcoal at 2500x (A) and at 50000x (B), and GQDs at 50000x (C) and 500000x (D) GQDs are indicated by the red circles. […]

“Multi-Scale Structure Control for Advanced Functional Materials” Ozgur Keles, Ph.D.Assistant ProfessorChemical and Materials Engineering DepartmentSan Jose State University Thursday, December 5, 20194:00 PMTien Room, 6101 Etcheverry Hall  ABSTRACTEconomic growth demands better products; hence, better materials. Specifically, product space in energy, defense, aerospace, and automotive industries requires materials that are multi-functional, lightweight, reliable, and tough. In addition, environmental regulations […]

Joel R Seibert, Ozgur Keles, Jun Wang, and Folarin Erogbogbo, “Infusion of Graphene Quantum Dots to Modulate Thermal Conductivity and Dynamic Mechanical Properties of Polymers,” Polymer, Accepted.  https://www.sciencedirect.com/science/article/pii/S0032386119309954?via%3Dihub Abstract  Graphene quantum dots are small fragments of graphene that may be advantageous to transferring properties to polymers because of their small size, molecular like interactions, surface […]

We will be installing a new EOS M 100 metal additive manufacturing system. Our research is targeting unexplored hierarchical structural spaces that can be achieved using the unique capabilities of the selective laser melting system. I would like to thank my co-PIs, collaborators, NSF officials,  and reviewers, including Birsen Sirkeci, Feruza Amirkulova, Raymond K. Yee, […]

See our new work at the International Mechanical Engineering Congress and Exposition, IMECE2019 November 11-14, 2019. Joseph Dei Rossi, Ozgur Keles, and Vimal Viswanathan, Fused deposition modeling with added vibrations: a parametric study on the accuracy of the printed parts, Proceedings of the ASME 2019 International Mechanical Engineering Congress and Exposition, IMECE2019 November 11-14, 2019, Salt Lake City, […]

I thank the SPE club for the nomination and committee for the Advisor of the Year award at SJSU. Posted 6th June 2019 by Ozgur Keles

I will be presenting our work on: Mechanics of additively manufactured hierarchical materials Abstract: Additive manufacturing (AM) is increasingly used for biomedical, automotive, space, defense, transportation, and consumer product applications. Fused deposition modeling (FDM) is most common AM technique that can produce polymer, composite, metal, and ceramic materials. Extrusion-based FDM allows structure control at macro- […]

Title: Additively Manufactured Biomimetic Polymers Özgür Keleş Date: 5/11/2019Time: 10:30 AM – 11:30 AMLocation: San Jose State University Second Floor – Student Union buildingStudent Union building on map: “SU” at grid 3 – B/C              Campus map:  http://www.sjsu.edu/map/     ABSTRACT: Additive manufacturing (AM) is increasingly used for biomedical, automotive, space, defense, transportation, and consumer product applications.  […]

Group member Eric Anderson ([email protected]) got the Donald Beall Award for Engineering Accomplishment. Eric investigated the effects of lattice density on stochastic fracture of 3D printed composites. He also manufactured composites via vibration-assisted fused deposition modeling (VA-FDM), which we developed to reduce inherent porosity in extrusion 3D-printed materials. Eric also processed biomimetic porous polymers with […]

New paper in Composites Part B: Engineering “A hierarchical approach for creating electrically conductive network structure in polyurethane nanocomposites using a hybrid of graphene nanoplatelets, carbon black and multi-walled carbon nanotubes” by Pashupati Pokharel, Dequan Xiao, FolarinErogbogbo, OzgurKeles, Dai Soo Lee (2018). Please check https://www.sciencedirect.com/science/article/pii/S1359836818327203?fbclid=IwAR2N4HlXlIjn63GmBJT4LXOmxS6zuZcQ74nvyuQHyBpb2ZzQcO_jNeX96mw# Posted 22nd October 2018 by Ozgur Keles

Ozgur Keles, Eric Anderson, Jimmy Huynh, Jeff Gelb, Jouni Freund, and Alp Karakoc, “Stochastic fracture of additively manufactured porous composites,” Scientific Reports, (2018). Online access:https://www.nature.com/articles/s41598-018-33863-4  Figure. X-ray computed tomography images of a) infill=100 % composite showing inter-bead porosity as red shaded areas, b) beads with inter- and inner-bead porosity, c) carbon fibers and pores at the fiber […]

Title: Effect of lattice density on the mechanical behavior of FDMed composites Özgür Keleş, Eric Anderson, Jimmy Huynh, Jeff Gelb, Jouni Freund, Alk Karakoc Date: 10/17/2018Time: 2:30 PM – 2:50 PMLocation: Greater Columbus Convention Center – A222 Consumer level fused deposition modeling (FDM) systems have been used for production of open-source free designs that contain intentional porosity. Despite the […]

Synthesis and characterization of graphene quantum dot containing ceria-zirconiaÖzgür Keleş, Andrew C. Dina, Daniel Fok Abstract: Zirconia-based nanoparticles are used in various applications, such as catalyst, filter, oxygen storage, and sensor. Among many synthesis methods to produce zirconia-based nanoparticles, aqueous sodium borohydride (NaBH4) coprecipitation produces zirconia containing nano-pores. In this work, we extended the NaBH4 coprecipitation […]

Title: Mechanical reliability of fused deposition modeled materials Date: Monday, July 30Time: 2:00pmLocation: NASA Ames N229/R215 Abstract: Additive manufacturing (AM) is increasingly used for space, defense, transportation, and consumer product applications. Among various AM techniques, fused deposition modeling (FDM) is most common one that can produce polymer, composite, metal, and ceramic materials. However, FDMed materials […]

S. Swaminathan, T. Shah, B. Sirkeci-Mergen, and O. Keles, “MachineLearning Models for Predicting Fracture Strength of Porous Ceramics and Glasses,” Proceedings of the 2018 International Conference on Data Science, (2018) pp. 147–150. Abstract – One of the crucial factors that determine the quality of a material is its ability to withstand stress. Classical methods to analyze fracture […]

Mechanical reliability of fused deposition modeled polymers and composites Özgür Keleş* and Eric H. Anderson* * Biomedical, Chemical and Materials Engineering Department, San Jose State University San Jose, CA, 95192, USA; [email protected] Fused deposition modeling (FDM) is the most widely- used additive manufacturing technique for the production of cost-effective polymers and composites. FDM offers design […]

I will talk about our work on the “Mechanical behavior of 3D printed continuous glass-fiber-reinforced nylon” in the symposium Metal and Polymer Matrix Composites IV.  Two of my MS and another undergraduate student have been working on this project. Abstract Title: Mechanical behavior of 3D printed continuous glass-fiber-reinforced nylonAuthors: Ozgur Keles, Stephanie Luke, David Soares, Afrah […]

I will be presenting at the 2018 TechConnect World Innovation Conference. Title:  Mechanical reliability of fused deposition modeled polymers and compositesAuthors: O. Keles, E.H. Anderson Day: Wednesday, May 16Time: 11:10 AM Venue: Anaheim Convention Center, Anaheim, California, U.S.A. This title may be found in the general online program, or you may find it in the […]

Mechanical reliability of short carbon fiber reinforced ABS produced via vibration assisted fused deposition modelingÖzgür Keleş, Eric H. Anderson, and Jimmy HuynhBiomedical, Chemical and Materials Engineering Department, San Jose State University, San Jose, California, USARapid Prototyping JournalStructured Abstract:Purpose — Mechanical reliability (variations in mechanical properties) of fused deposition modeled (FDMed) short-fiber-reinforced composites are unknown, which […]

I will also present a poster about our recent research on mechanical reliability of additively manufactured composites. For more information please click. Image showing our hierarchical simulation approach to reveal the origins of the mechanical reliability in additively manufactured lattice structures. Posted 8th November 2017 by Ozgur Keles