Research Projects


Ceramic On-Demand Extrusion (CODE) for Additive Manufacturing of Ceramics and Ceramic Composites

Sponsor(s): Department of Energy (National Energy Technology Laboratory), S&T Intelligent Systems Center

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This research investigates using the ceramic on-demand extrusion (CODE) process to fabricate complex 3D parts made of ceramics and ceramic composites, with applications to aerospace, energy, and biomedical industries. CODE is a novel freeform extrusion fabrication process recently developed at Missouri S&T. This process uses layer-by-layer extrusion of aqueous pastes followed by uniform radiation drying between successive layers. The parts that we have fabricated using this process include aerospace structural components with high-temperature and ultra-high-temperature materials (e.g., alumina, zirconium diboride, and partially stabilized zirconia). This process has also been used to fabricate smart parts with embedded sensors, e.g., smart lining blocks with embedded optical fiber sensors that can used for in situ temperature and stress monitoring. Our current research focuses on fabricating composite structures made of two or more materials that can be distinct materials or graded in compositions continuously as programmed to created parts with functionally graded materials. The current research tasks include: (1) design of parts with optimal material distribution, (2) development of colloidal pastes from ceramic powder (3) simultaneous control of flow rates of multiple pastes and homogeneous mixing of pastes, and (4) evaluating the mechanical properties of fabricated parts with functionally graded materials.

Publication(s):
  1. A novel extrusion-based additive manufacturing process for ceramic parts,” Ghazanfari, Amir, Wenbin Li, Ming C Leu, and Gregory E Hilmas. Austin, TX, 2016.
  2. Properties of Partially Stabilized Zirconia Components Fabricated by the Ceramic On-demand Extrusion Process,” Li, Wenbin, Amir Ghazanfari, Devin McMillen, Ming C Leu, Gregory E Hilmas, and Jeremy Watts. Austin, TX, 2016.
  3. Designed Extrudate for Additive Manufacturing of Zirconium Diboride by Ceramic On-demand Extrusion,” McMillen, Devin, Wenbin Li, Ming C Leu, Gregory E Hilmas, and Jeremy Watts. Austin, TX, 2016.
  4. Advanced ceramic components with embedded sapphire optical fiber sensors for high temperature applications ,” Ghazanfari, Amir, Wenbin Li, Ming C. Leu, Yiyang Zhuang, and Jie Huang 112 (2016): 197-206.
  5. Methods of extrusion on demand for high solids loading ceramic paste in freeform extrusion fabrication,” Li, Wenbin, Amir Ghazanfari, Ming C Leu, and Robert G Landers. Austin, TX, 2015.
  6. Composition Optimization for Functionally Gradient Parts Considering Manufacturing Constraints,” Ghazanfari, Amir, and Ming C. Leu, Vol. 2. Detroit, MI, 2014.
  7. Modeling, Analysis, and Simulation of Paste Freezing in Freeze-Form Extrusion Fabrication of Thin-Wall Parts,” Li, Mingyang, Robert G. Landers, and Ming C. Leu, 2014.
  8. Development of Freeze-Form Extrusion Fabrication With Use of Sacrificial Material,” Leu, Ming C, and Diego A Garcia, 2014.
  9. Extrusion Process Modeling for Aqueous-Based Ceramic Pastes-Part 1: Constitutive Model,” Li, Mingyang, Lie Tang, Robert G. Landers, and Ming C. Leu, 2013.
  10. Extrusion Process Modeling for Aqueous-Based Ceramic Pastes-Part 2: Experimental Verification,” 2013.
  11. Hybrid Extrusion Force-Velocity Control Using Freeze-Form Extrusion Fabrication for Functionally Graded Material Parts,” Deuser, Bradley K., Lie Tang, Robert G. Landers, Ming C. Leu, and Greg E. Hilmas, 2013.
  12. Freeze-form extrusion fabrication of functionally graded materials ,” Leu, Ming C., Bradley K. Deuser, Lie Tang, Robert G. Landers, Gregory E. Hilmas, and Jeremy L. Watts 61, no. 1 (2012): 223-26.

Modeling, Control, Characterization, and Optimization of Selective Laser Melting (SLM)

Sponsor(s): Honeywell Federal Manufacturing & Technologies

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The aim of this project is to perform fundamental research aimed at understanding the selective laser melting (SLM) process, which is an additive manufacturing technique that bonds successive layers of powder to produce metal parts with any complex 3D geometry. The main research objectives are: to characterize powder material, relate it to part properties and assess its viability for reuse/recycling; to improve part properties through optimization of process parameters; to control the microstructure of manufactured parts with sensing using an infrared camera; to tune the chemistry of input powder for the SLM process. To address these objectives, the project consists of the following tasks: (1) powder characterization, (2) material property characterization, (3) temperature effects on material properties, (4) controlling microstructure and mechanical properties, and (5) chemistry specifically for additive manufacturing.

Publication(s):
  1. Powder characterization techniques and effects of powder characteristics on part properties in powder-bed fusion processes,” Sutton, Austin T., Caitlin S. Kriewall, Ming C. Leu, and Joseph W. Newkirk 11, no. 4 (2016): 1-27.
  2. Powder Characterization in Additive Manufacturing: Characterization Techniques and Effects on Part Properties,” Austin, TX, 2016.
  3. Investigation of Heat-affected 304L SS Powder and its Effect on Built Parts in Selective Laser Melting,” Kriewall, Caitlin S., Austin T. Sutton, Ming C. Leu, Joseph W. Newkirk, and Ben Brown. Austin, TX, 2016.
  4. Investigation of Tensile Properties of Bulk and SLM Fabricated 304L Stainless Steel Using Various Gage Length Specimens,” Karnati, Sreekar, Frank F. Liou, Joseph Newkirk, and Izach Axelsen. Austin, TX, 2016.
  5. Elevated temperature microstructure stability of SLM 304L stainless steel,” Amine, Tarak, and Joseph Newkirk. Austin, TX, 2016.

Laser Foil Printing (LFP) for Additive Manufacturing

Sponsor(s): Department of Energy

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The objective of the project is to develop a new additive manufacturing (AM) technology, called Laser Foil Printing (LFP), for fabricating three-dimensional (3D) metal parts. Instead of using metal powders as in most existing AM technologies, the new method uses metal foils as feed stock. The procedure consists of two alternating processes: foil welding by a high-power continuous-wave laser and foil cutting by a Q-switched ultraviolet laser. The foil welding process involves two sub-processes: laser spot welding and laser raster-scan welding. The reason for using two lasers is to achieve simultaneously the high-speed and high-precision manufacturing. The results on laser foil-welding and foil-cutting show that complete and strong welding bonds can be achieved with selected parameters, and that clean and no-burr/distortion cut of foil can be obtained. Several 3D AISI 1010 steel parts fabricated by the proposed AM technology are obtained, and the micro-hardness and tensile strength of the as-fabricated parts are both significantly greater than those of the original foil. The LFP can also be used for fabricating sensor-embedded parts and for outer space manufacturing under low gravity, vacuum and low temperature environments.

Publication(s):
  1. “Foil-Based Additive Manufacturing System and Method,” Tsai, Hai-Lung, Chen Chen, and Yiyu Shen, filed on October 13, 2015.
  2. A Foil-Based Additive Manufacturing Technology for Metal Parts,” Chen, Chen, Yiyu Shen, and Hai-Lung Tsai, 2016.

Low-Cost Rapid Tooling by Fused Deposition Modeling (FDM)

Sponsor(s): Boeing, Stratasys, Steelville Manufacturing, S&T Center for Aerospace Manufacturing Technologies, America Makes

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The objective of this research project is to investigate low-cost rapid tooling with Ultem (9085 & 1010) using the fused deposition modeling (FDM) process, an additive manufacturing technique that built a part layer-by-layer by extruding thermoplastic material that is supplied in the filament form. The tooling can be used in manufacturing of composites with the autoclave, vacuum assisted resin transfer molding and other processes, as well as in stamp forming applications. In this project, Ultem specimens are fabricated using the FDM process and then their mechanical properties are measured in compression, tension, and flexure tests at room and elevated temperatures. The test specimens include solid coupons and sparse-build coupons with varying build parameters including air gap, wall thickness, and cap thickness, as well as different internal lattice structures. Modeling and simulation with finite element analysis is used to predict the mechanical properties of sparse-build FDM tools and compare the predicted results with data obtained from experimental testing. The project is conducted jointly by Missouri S&T and Boeing Research & Technology.

Publication(s):
  1. “Investigation of Ultem 1010 FDM Sparse-Build Parts Using Design of Experiments and Numerical Simulation,” Taylor, G., X. Wang, L. Mason, M. C. Leu, and K. Chandrashekhara. Anaheim, CA, 2016.
  2. Effects of Build Parameters on Compression Properties for ULTEM 9085 Parts by Fused Deposition Modeling,” Motaparti, Krishna P., Gregory Taylor, Ming C. Leu, K. Chandrashekhara, James Castle, and Mike Matlack. Austin, TX, 2016.
  3. Effect of Sparse-build Internal Structure on Performance of Fused Deposition Modeling Tools Under Pressure,” Meng, Shixuan, Leah Mason, Gregory Taylor, Xin Wang, Ming C. Leu, K. Chandrashekhara, Mike Matlack, and James Castle. Austin, TX, 2016.
  4. Modeling and characterization of fused deposition modeling tooling for vacuum assisted resin transfer molding process,” Li, H., G. Taylor, V. Bheemreddy, O. Iyibilgin, M. Leu, and K. Chandrashekhara 7 (2015): 64-72.
  5. “Modeling and Characterization of Fused Deposition Modeling Tooling for Autoclave Process,” Taylor, G., X. Wang, K. P. Motaparti, S. Meng, M. C. Leu, and K. Chandrashekhara. Dallas, TX, 2015.
  6. Investigation of sparse-build rapid tooling by fused deposition modeling,” Iyibilgin, O, MC Leu, G Taylor, H Li, and K Chandrashekhara. Austin, TX, 2014.

3D Printing for Bone Tissue Engineering

Sponsor(s): Missouri Research Board, MO-SCI Corporation, S&T Intelligent Systems Center, Keith and Pat Bailey Professorship Fund

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In this research, we first investigated the fabrication of scaffolds with engineered porosity from 13-93 bioactive glass using the selective laser sintering (SLS) process and an extrusion-based process. The SLS process is a powder-bed based additive manufacturing technique that fabricates a scaffold layer-by-layer by controlling laser scans to sinter the mixture of ceramic and binder particles in a powder bed. Pore geometry in the scaffold is shown to play a crucial role as it affects not only the mechanical properties and degradation over time as well as the amount of bone regeneration upon implantation. In the extrusion-based process, aqueous-based bioactive glass paste was deposited layer-by-layer using a micro-sized nozzle. The fabricated green scaffolds are then heat treated to remove the binder. Our sintered scaffolds demonstrated an average compressive strength of 136 MPa, which is the highest reported in additive manufacturing of bioactive glass. To improve the toughness of the scaffold, titanium fibers were added to the paste to increase the fracture toughness and flexure strength of the scaffold. Because a major limitation of synthetic bone repair is insufficient vascularization in the interior of the porous implant, our current research focuses on 3D bioprinting of mesenchymal stem cells (MSCs) suspended in the hydrogel and polymer-bioactive glass composite. Bioprinting a scaffold with these materials would offer a 3D environment for complex and dynamic interactions that govern the MSCs behavior in vivo. Bioactive glass is added to a mixture of polymer and an organic solvent to make an extrudable paste. Porous polymer-glass composite scaffolds are fabricated by extruding this paste using a syringe, and MSCs suspended in the hydrogel is deposited using another syringe. In vitro assessment indicates the viability of the process to print MSCs suspended in Matrigel. Fluorescence images from the live-dead assay indicate that cells are alive and actively moving in the scaffold.

Publication(s):
  1. Freeform extrusion fabrication of titanium fiber reinforced 13–93 bioactive glass scaffolds ,” Thomas, Albin, Krishna C.R. Kolan, Ming C. Leu, and Gregory E. Hilmas 69 (2017): 153-62.
  2. 3D bioprinting of stem cells and polymer/bioactive glass composite scaffolds for tissue engineering,” Murphy, Caroline, Krishna Kolan, Wenbin Li, Julie Semon, Delbert Day, and Ming Leu 3, no. 1 (2017): 1-11.
  3. 3D Printing of a Polymer Bioactive Glass Composite for Bone Repair,” Murphy, C, KCR Kolan, M Long, W Li, MC Leu, JA Semon, and DE Day, 2016.
  4. Freeform Extrusion Fabrication of Titanium Fiber Reinforced Bioactive Glass Scaffolds,” Thomas, A., Krishna C. R. Kolan, M. C. Leu, and G. E. Hilmas, 2015.
  5. In vitro assessment of laser sintered bioactive glass scaffolds with different pore geometries,” Kolan, Krishna C R, Albin Thomas, Ming C Leu, and Greg Hilmas 21, no. 2 (2015): 152-58.
  6. The effects of 3D bioactive glass scaffolds and BMP-2 on bone formation in rat femoral critical size defects and adjacent bones,” Liu, Wai-Ching, Irina S Robu, Rikin Patel, Ming C Leu, Mariano Velez, and Tien-Min Gabriel Chu 9, no. 4 (2014).
  7. Effect of architecture and porosity on mechanical properties of borate glass scaffolds made by selective laser sintering,” Kolan, Krishna CR, Ming C Leu, Gregory E Hilmas, and T Comte, 2013.
  8. Effect of material, process parameters, and simulated body fluids on mechanical properties of 13-93 bioactive glass porous constructs made by selective laser sintering ,” Kolan, Krishna C.R., Ming C. Leu, Gregory E. Hilmas, and Mariano Velez 13 (2012): 14-24.
  9. In Vivo Evaluation of 13-93 Bioactive Glass Scaffolds Made by Selective Laser Sintering (SLS),” Velez, M., S. Jung, K. C. R. Kolan, M. C. Leu, D.E. Day, and T-M.G. Chu, 237:91-99, 2012.
  10. Freeze extrusion fabrication of 13-93 bioactive glass scaffolds for bone repair,” Doiphode, Tieshu, Nikhil D.and Huang, Ming C. Leu, Mohamed N. Rahaman, and Delbert E. Day 22, no. 3 (2011): 515-23.
  11. Fabrication of 13-93 bioactive glass scaffolds for bone tissue engineering using indirect selective laser sintering,” Kolan, Krishna C R, Ming C Leu, Gregory E Hilmas, Roger F Brown, and Mariano Velez 3, no. 2 (2011).
  12. Porous and strong bioactive glass (13–93) scaffolds fabricated by freeze extrusion technique,” Huang, T.S., M.N. Rahaman, N.D. Doiphode, M.C. Leu, B.S. Bal, D.E. Day, and X. Liu 31, no. 7 (2011): 1482-89.
  13. Freeze extrusion fabrication and selective laser sintering of 13-93 bioactive glass: A comparison,” Kolan, Krishna CR, ND Doiphode, and MC Leu, 2010.
  14. Selective laser sintering of 13-93 glass,” Kolan, Krishna CR, Leu MC, Hilmas GE, and Velez M, 2010.

Cyber-Physical Sensing, Modeling, and Control with Augmented Reality for Smart Manufacturing Workforce Training and Operations Management

Sponsor(s): National Science Foundation

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Smart manufacturing integrates information, technology, and human ingenuity to inspire the next revolution in the manufacturing industry. Manufacturing has been identified as a key strategic investment area by the U.S. government, private sector, and university leaders to spur innovation and keep America competitive. However, the lack of new methodologies and tools is challenging continuous innovation in the smart manufacturing industry. This award supports fundamental research to develop a cyber-physical sensing, modeling, and control infrastructure, coupled with augmented reality, to significantly improve the efficiency of future workforce training, performance of operations management, safety and comfort of workers for smart manufacturing. Results from this research are expected to transform the practice of worker-machine-task coordination and provide a powerful tool for operations management. This research involves several disciplines including sensing, data analytics, modeling, control, augmented reality, and workforce training and will provide unique interdisciplinary training opportunities for students and future manufacturing engineers.

Publication(s):
  1. American Sign Language alphabet recognition using Microsoft Kinect,” Dong, Cao, M. C. Leu, and Z. Yin, 44-52, 2015.

Scalable Cyber-Physical Manufacturing Systems

Sponsor(s): National Science Foundation

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This is a collaborative research project between Missouri S&T and the University of Arkansas. This project is dedicated to the development of a framework including architecture and protocols for communication among various manufacturing resources and management of manufacturing services for cyber-physical systems in cloud manufacturing. The practical aim is of the cyber-physical system to increase the productivity and efficiency of industrial enterprises by managing and sharing geographically dispersed manufacturing resources and connecting customers with manufacturing companies. The research consists of the following tasks: (1) scalable service-oriented architecture for scalable cyber-physical manufacturing, (2) network architecture and plug-and-play protocols, (3) methods for virtualization of manufacturing resources (e.g., CNC machines, 3D printers, CMMs), and (4) development of a testbed to evaluate the developed architecture, protocols, and methods.

Publication(s):
  1. Implementation of MTConnect for open source 3D printers in cyber-physical manufacturing cloud,” Liu, Frank, S. M. Nahian Al Sunny, Md Rakib Shahriar, Ming C. Leu, Maggie Cheng, and Liwen Hu, 2016.
  2. Design and Implementation of Cyber-Physical Manufacturing Cloud Using MTConnect,” Liu, Frank, Md Rakib Shahriar, S. M. Nahian Al Sunny, Ming C. Leu, Maggie Cheng, and Liwen Hu, 2016.