Mechanical Engineering Commons^™

Revealing Particle-Scale Powder Spreading Dynamics In Powder-Bed-Based Additive Manufacturing Process By High-Speed X-Ray Imaging, Luis I. Escano, Niranjan D. Parab, Lianghua Xiong, Qilin Guo, Cang Zhao, Kamel Fezzaa, Wes Everhart, Tao Sun, Lianyi Chen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Powder spreading is a key step in the powder-bed-based additive manufacturing process, which determines the quality of the powder bed and, consequently, affects the quality of the manufactured part. However, powder spreading behavior under additive manufacturing condition is still not clear, largely because of the lack of particle-scale experimental study. Here, we studied particle-scale powder dynamics during the powder spreading process by using in-situ high-speed high-energy x-ray imaging. Evolution of the repose angle, slope surface speed, slope surface roughness, and the dynamics of powder clusters at the powder front were revealed and quantified. Interactions of the individual metal powders, with …

Ultra-Thin Coating And Three-Dimensional Electrode Structures To Boosted Thick Electrode Lithium-Ion Battery Performance, Jie Li, Yan Gao, Xinhua Liang, Jonghyun Park

Chemical and Biochemical Engineering Faculty Research & Creative Works

This paper reports a multiscale controlled three‐dimensional (3D) electrode structure to boost the battery performance for thick electrode batteries with LiMn_1.5Ni_0.5O₄ as cathode material, which exhibits a high areal capacity (3.5 mAh/cm²) along with a high specific capacity (130 mAh/g). This excellent battery performance is achieved by a new concept of cell electrode fabrication, which simultaneously controls the electrode structure in a multiscale manner to address the key challenges of the material. Particles with ultrathin conformal coating layers are prepared through atomic layer deposition followed by a nanoscale‐controlled, thermal diffusion doping. The particles …

Explosive Dust Test Vessel Comparison Using Pulverized Pittsburgh Coal, Jacob Miller, Jay Schafler, Phillip R. Mulligan, Robert Eades, Kyle A. Perry, Catherine E. Johnson

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Explosions of coal dust are a major safety concern within the coal mining industry. The explosion and subsequent fires caused by coal dust can result in significant property damage, loss of life in underground coal mines and damage to coal processing facilities. The United States Bureau of Mines conducted research on coal dust explosions until 1996 when it was dissolved. In the following years, the American Society for Testing and Materials (ASTM) developed a test standard, ASTM E1226, to provide a standard test method characterizing the “explosibility” of particulate solids of combustible materials suspended in air. The research presented herein …

Ultrafast X-Ray Imaging Of Laser-Metal Additive Manufacturing Processes, Niranjan D. Parab, Cang Zhao, Ross Cunningham, Luis I. Escano, Kamel Fezzaa, Wes Everhart, Anthony D. Rollett, Lianyi Chen, Tao Sun

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The high-speed synchrotron X-ray imaging technique was synchronized with a custom-built laser-melting setup to capture the dynamics of laser powder-bed fusion processes in situ. Various significant phenomena, including vapor-depression and melt-pool dynamics and powder-spatter ejection, were captured with high spatial and temporal resolution. Imaging frame rates of up to 10 MHz were used to capture the rapid changes in these highly dynamic phenomena. At the same time, relatively slow frame rates were employed to capture large-scale changes during the process. This experimental platform will be vital in the further understanding of laser additive manufacturing processes and will be particularly …

Deformation Of A Ferrofluid Droplet In Simple Shear Flows Under Uniform Magnetic Fields, Md Rifat Hassan, Jie Zhang, Cheng Wang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We numerically investigate the deformation and orientation of a ferrofluid droplet in a simple shear flow under a uniform magnetic field. The numerical simulation is based on the finite element method and couples the magnetic and flow fields. A level set method is used to model the dynamic motion of the droplet interface. Systematic numerical simulations are used to assess the effects of the direction and the strength of the magnetic field. Focusing on low Reynolds number flows (Re ≲ 0.02), the numerical results indicate that at a small capillary number (Ca ≈ 0.02), the magnetic field dominates over the …

Locomotion Of A Cylindrical Rolling Robot With A Shape Changing Outer Surface, Michael G. Puopolo, Jamey D. Jacob, Emilio Gabino

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A cylindrical rolling robot is developed that generates roll torque by changing the shape of its flexible, elliptical outer surface whenever one of four elliptical axes rotates past an inclination called trigger angle. The robot is equipped with a sensing/control system by which it measures angular position and angular velocity, and computes error with respect to a desired step angular velocity profile. When shape change is triggered, the newly assumed shape of the outer surface is determined according to the computed error. A series of trial rolls is conducted using various trigger angles, and energy consumed by the actuation motor …

Shape-Based Separation Of Micro-/Nanoparticles In Liquid Phases, Behrouz Behdani, Saman Monjezi, Mason J. Carey, Curtis G. Weldon, Jie Zhang, Cheng Wang, Joontaek Park

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The production of particles with shape-specific properties is reliant upon the separation of micro-/nanoparticles of particular shapes from particle mixtures of similar volumes. However, compared to a large number of size-based particle separation methods, shape-based separation methods have not been adequately explored. We review various up-to-date approaches to shape-based separation of rigid micro-/nanoparticles in liquid phases including size exclusion chromatography, field flow fractionation, deterministic lateral displacement, inertial focusing, electrophoresis, magnetophoresis, self-assembly precipitation, and centrifugation. We discuss separation mechanisms by classifying them as either changes in surface interactions or extensions of size-based separation. The latter includes geometric restrictions and shape-dependent transport …

The Influence Of Build Parameters On The Compressive Properties Of Selective Laser Melted 304l Stainless Steel, Okanmisope Fashanu, Mario F. Buchely, R. Hussein, S. Anandan, Myranda Spratt, Joseph William Newkirk, K. Chandrashekhara, H. Misak, M. A. Walker

Materials Science and Engineering Faculty Research & Creative Works

Process parameters used during Selective Laser Melting (SLM) process have significant effects on the mechanical properties of the manufactured parts. In this study, the influence of two build parameters (build orientation and hatch angle) on the compressive properties of 304L stainless steel was evaluated. SLM 304L samples were manufactured using three hatch angles, 0°, 67°,105° and two orientations, z-direction and x-direction, and tested using a compression frame according to ASTM E9-09. Bulk density was measured according to ASTM C373-17 before compression. Properties evaluated were the bulk density, yield strength, strength at 15% plastic-strain and strength at 30% plastic-strain. Results showed …

General Rules For Pre-Process Planning In Powder Bed Fusion System -- A Review, Tan Pan, Sreekar Karnati, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Powder bed fusion (PBF) is one of the current additive manufacturing techniques that can fabricate almost fully dense functional metal components. Through a layer by layer fabrication methodology, complex geometries to meet the requirements of aerospace, automotive, biomedicine industries, etc. can be produced. The success of a build largely depends on having a flawless pre-process planning, including build orientation selection, support structure optimization, process parameter chosen, etc., which closely relates to the quality of the final products. Geometric inaccuracy and poor surface quality can occur due to a bad build plan. This review presents the crucial general planning rules for …

Additive Manufacturing Of Metal Functionally Graded Materials: A Review, Yitao Chen, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Functionally graded materials (FGMs) have attracted a lot of research interest due to their gradual variation in material properties that result from the non-homogeneous composition or structure. Metal FGMs have been widely researched in recent years, and additive manufacturing has become one of the most important approaches to fabricate metal FGMs. The aim of this paper is to review the research progress in metal FGMs by additive manufacturing. It will first introduce the unique properties and the advantages of FGMs. Then, typical recent findings in research and development of two major types of metal additive manufacturing methods, namely laser metal …

Incorporation Of Automated Ball Indentation Methodology For Studying Powder Bed Fabricated 304l Stainless Steel, Sreekar Karnati, Jack L. Hoerchler, Aaron Flood, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Automated Ball Indentation (ABI) is a viable method for estimating the ductility, yield stress, and ultimate stress, among other metrics, in different metallic materials. Currently, ABI data analysis utilizes Holloman’s Power Law to model the plastic region of the true stress-true strain curve. While this formulation is accurate for some materials, its relevance for additively manufactured austenitic stainless steels, such as 304L, needed investigation. The deviation of the material’s plastic behavior from the Power Law was investigated. In order to better model this behavior, both the Voce and Ludwigson formulation were investigated. These formulations were tested for both wrought and …

Experimental Characterization Of A Direct Metal Deposited Cobalt-Based Alloy On Tool Steel For Component Repair, Xinchang Zhang, Tan Pan, Wei Li, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Die casting dies made of tool steel is subject to impact, abrasion and cyclic thermomechanical loading that delivers damage such as wear, corrosion, and cracking. To repair such defects, materials enveloping the damage need to be machined and refilled. In this study, V-shape defects with varied sidewall inclination angles were prepared on H13 tool steel substrates and refilled with cobalt-based alloy using direct metal deposition (DMD) for superior hardness and wear resistance. The microstructure of rebuild samples was characterized using an optical microscope (OM) and scanning electron microscope (SEM). Elemental distribution from the substrate to deposits was analyzed using energy …

Effects Of Thermal Camera Resolution On Feature Extraction In Selective Laser Melting, Xin Wang, Cody S. Lough, Douglas A. Bristow, Edward C. Kinzel, Robert G. Landers

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Selective Laser Melting (SLM) is a common additive manufacturing process which uses a laser energy source to fuse metal powder layer by layer. Engineering properties and microstructure are related to the part’s thermal history. It is important to measure the thermal history in-situ to qualify parts and provide the sensing which is necessary for process control. A common measurement tool for this purpose is a thermal camera that records the thermal emission of the part’s surface.

This study investigates the effects of spatial sampling resolution of thermal cameras when monitoring the temperature in SLM processes. High-fidelity simulation of an SLM …

Development Of Pre-Repair Machining Strategies For Laser-Aided Metallic Component Remanufacturing, Xinchang Zhang, Wenyuan Cui, Leon Hill, Wei Li, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Remanufacturing worn metallic components can prolong the service life of parts that need frequent replacement but are extremely costly to manufacture, such as aircraft titanium components, casting dies. Additive manufacturing (AM) technology enables the repair of such valuable components by depositing filler materials at the worn area layer by layer to regenerate the missing geometry. In general, damaged parts would be inspected and pre-machined prior to material deposition to remove oil, residue, oxidized layers or defects located in inaccessible regions. Therefore, the motivation of this paper is to introduce pre-repair machining strategies for removing contaminated materials from damaged components and …

Recyclability Of 304l Stainless Steel In The Selective Laser Melting Process, Austin T. Sutton, Caitlin S. Kriewall, Ming-Chuan Leu, Joseph William Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

During part fabrication by selective laser melting (SLM), a powder-bed fusion process in Additive Manufacturing (AM), a large amount of energy is input from the laser into the melt pool, causing generation of spatter and condensate, both of which have the potential to settle in the surrounding powder-bed compromising its reusability. In this study, 304L stainless steel powder is subjected to five reuses in the SLM process to assess its recyclability through characterization of both powder and mechanical properties. Powder was characterized morphologically by particle size distribution measurements, oxygen content with inert gas fusion analysis, and phase identification by X-ray …

Additive Manufacturing Of Metal Bandpass Filters For Future Radar Receivers, Bradley Grothaus, Dane Huck, Austin T. Sutton, Ming-Chuan Leu, Ben Brown

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Selective laser melting (SLM) is a powder-bed fusion (PBF) process that bonds successive layers of powder with a laser to create components directly from computer-aided design (CAD) files. The additive nature of the SLM process in addition to the use of fine powders facilitates the construction of complex geometries, which has captured the attention of those involved in the design of bandpass filters for radar applications. However, a significant drawback of SLM is its difficulty in fabricating parts with overhangs necessitating the use of support structures, which, if not removed, can greatly impact the performance of bandpass filters. Therefore, in …

Mechanical Properties Of Zr-Based Bulk Metallic Glass Parts Fabricated By Laser-Foil-Printing Additive Manufacturing, Yingqi Li, Ming-Chuan Leu, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The application of bulk metallic glasses (BMGs) has been traditionally limited to parts with small dimensions and simple geometries, due to the requirement of fast cooling during the conventional process of casting. This research exemplifies a promising additive manufacturing method, i.e., laser-foil-printing (LFP), to fabricate high-quality BMG parts with large dimensions and complex geometries. In this study, Zr_52.5Ti₅Al₁₀Ni_14.6Cu_17.9 BMG parts were fabricated by LFP technology in which MG foils are laser welded layer-by- layer upon a substrate. The mechanical properties of the fabricated BMG parts were measured using micro-indentation, tensile test …

Effects Of Identical Parts On A Common Build Plate On The Modal Analysis Of Slm Created Metal, Tristan Cullom, Troy Hartwig, Ben Brown, Kevin Johnson, Jason Blough, Andrew Barnard, Robert G. Landers, Douglas A. Bristow, Edward C. Kinzel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The frequency response of parts created with Additive Manufacturing (AM) is a function of not only process parameters, powder quality, but also the geometry of the part. Modal analysis has the potential to evaluate parts by measuring the frequency response which are a function of the material response as well as the geometry. A Frequency Response Function (FRF) serves as a fingerprint of the part which can be validated against the FRF of a destructively tested part. A practical scenario encountered in Selective Laser Melting (SLM) involves multiple parts on a common build plate. Coupling between parts influences the FRF …

Effect Of Environmental Variables On Ti-64 Am Simulation Results, Aaron Flood, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In metal AM the environment is critical and therefore care should be taken to ensure that the simulation matches reality. This paper will investigate the effect that various environmental factors have on the results of the simulation. This will help to determine their importance in the simulation setup. The material properties which relate to this are the convective coefficient and the emissivity. These material properties will be investigated to determine their effect on the outcome of the simulation. In addition to these properties, the size of the substrate will be investigated to determine if any results are altered. Lastly, the …

Characterization Of Impact Toughness Of 304l Stainless Steel Fabricated Through Laser Powder Bed Fusion Process, Sreekar Karnati, Atoosa Khiabhani, Aaron Flood, Frank W. Liou, Joseph William Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this research, the impact toughness of powder bed based additively manufactured 304L stainless steel was investigated. Charpy specimens were built in vertical, horizontal and inclined (45⁰) orientations to investigate the variation in toughness with build direction. These specimens were tested in as-built and machined conditions. A significant difference in toughness was observed with varying build directions. The lowest toughness values were recorded when the notch was oriented in line with the interlayer boundary. The highest toughness was recorded when the notch was perpendicular to the interlayer boundary. A significant scatter in toughness values was also observed. The variation and …

Additive Manufacturing Of Liners For Shaped Charges, Jason Ho, Cody Lough, Phillip R. Mulligan, Edward C. Kinzel, Catherine E. Johnson

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

A Shaped Charge (SC) is an explosive device used to focus a detonation in a desired direction, and has applications in oil extraction, weaponry and demolition. The focusing relies on a void in the explosive mass, shaped by a metal liner that becomes a super-heated projectile during detonation. Additive Manufacturing (AM) allows greater design freedom and geometric complexity for the liner portion of the SC. Specifically, hierarchical structuring and functional grading can potentially provide greater velocity, directionality, and efficiency. In this work, Selective Laser Melting (SLM) is used to explore different geometries for an SC liner made out of SS …

Fabricating Functionally Graded Materials By Ceramic On-Demand Extrusion With Dynamic Mixing, Wenbin Li, Austin J. Martin, Benjamin Kroehler, Alexander M. Henderson, Tieshu Huang, Jeremy Lee Watts, Greg Hilmas, Ming-Chuan Leu

Materials Science and Engineering Faculty Research & Creative Works

Ceramic On-Demand Extrusion (CODE) is an extrusion-based additive manufacturing process recently developed for fabricating dense, functional ceramic components. Presented in this paper is a further development of this process focusing on fabrication of functionally graded materials (FGM). A dynamic mixing mechanism was developed for mixing constituent ceramic pastes, and an extrusion control scheme was developed for fabricating specimens with desired material compositions graded in real time. FGM specimens with compositions graded between Al₂O₃ and ZrO₂ were fabricated and ultimately densified by sintering to validate the effectiveness of the CODE process for FGM fabrication. Energy dispersive spectroscopy …

Effect Of Wall Thickness And Build Quality On The Compressive Properties Of 304l Thin-Walled Structures Fabricated By Slm, Myranda Spratt, Sudharshan Anandan, Rafid M. Hussein, Joseph William Newkirk, K. Chandrashekhara, Heath Misak, Michael Walker

Materials Science and Engineering Faculty Research & Creative Works

The specific strength of lightweight lattice structures built with SLM is of interest to the aerospace industry. Honeycombs were manufactured with increasing wall thicknesses (which increases density) and tested under compression. The optimal strength to density ratio was determined from the resulting data. The build quality was also evaluated to determine how/if the results were influenced by the specimen quality. Differences between the nominal and as-built geometry were identified, but considered to be minimal. Microstructural evaluation of the specimens revealed a possible dependence on the ‘border scan’ properties, as the thickness of the specimens was such that the board scan …

Fiber-Fed Printing Of Free-Form Free-Standing Glass Structures, John M. Hostetler, Jason E. Johnson, Jonathan T. Goldstein, Douglas A. Bristow, Robert G. Landers, Edward C. Kinzel

Materials Science and Engineering Faculty Research & Creative Works

Additive Manufacturing (AM) of low-profile 2.5D glass structures has been demonstrated using a fiber-fed laser-heated process. In this process, glass fibers with diameters 90-125 μm are supported as they are fed into the intersection of the workpiece and a CO₂ laser beam. The workpiece is positioned by a four-axis CNC stage with coordinated rotational/transitional kinematics. The laser energy at λ = 10.6 μm is coupled to phonon modes in the glass, locally heating it above its working point. The rapid heating and cooling process allows for the deposition of various glasses into free-standing three-dimensional structures such as trusses and …

Fast Prediction Of Thermal History In Large-Scale Parts Fabricated Via A Laser Metal Deposition Process, Lei Yan, Tan Pan, Joseph William Newkirk, Frank W. Liou, Eric E. Thomas, Andrew H. Baker, James B. Castle

Materials Science and Engineering Faculty Research & Creative Works

Laser metal deposition (LMD) has become a popular choice for the fabrication of near-net shape complex parts. Plastic deformation and residual stresses are common phenomena that are generated from the intrinsic large thermal gradients and high cooling rates in the process. Finite element analysis (FEA) is often used to predict the transient thermal cycle and optimize processing parameters; however, the process of predicting the thermal history in the LMD process with the FEA method is usually time-consuming, especially for large-scale parts. Herein, multiple 3D FEA models with simple assumptions on the heat source and its loading methods are compared and …

Mechanical Properties Evaluation Of Ti-6al-4v Thin-Wall Structure Produced By A Hybrid Manufacturing Process, Lei Yan, Wenyuan Cui, Joseph William Newkirk, Frank W. Liou, Eric E. Thomas, Andrew H. Baker, James B. Castle

Materials Science and Engineering Faculty Research & Creative Works

The hybrid manufacturing (HM) process combines the precision of computer numerical control (CNC) and the freeform capability of additive manufacturing to expand the versatility of advanced manufacturing. The intent of this paper is to explore the relationship between HM processing parameters and mechanical properties of the final parts manufactured by one type of HM process that combines laser metal deposition (LMD) and CNC milling. The design of experiment (DOE) is implemented to explore the Ti-6Al-4V thin-wall structure fabrication process with different HM build strategies. Vickers hardness, tensile test, and microstructure analyses are conducted to evaluate the mechanical property variance within …

Development Of An Engineering Diagram For Additively Manufactured Austenitic Stainless Steel Alloys, Zachary T. Hilton, Joseph William Newkirk, Ronald J. O'Malley

Materials Science and Engineering Faculty Research & Creative Works

Austenitic stainless steels are the most widely applied types of stainless steels, due to their good weldability and high corrosion resistance. A number of engineering diagrams exist for the purpose of providing insight into the behavior of these steels. Examples of these diagrams are constitution diagrams (aka Schaeffler Diagrams) which are used to approximate the solidification path of the alloy and the amount of retained ferrite in the solidified matrix. Other diagrams are the Suutala diagram, which approximates cracking susceptibility, and microstructural maps, which predict the solidification path by varying a processing parameter, such as cooling rate. By combining these …

Frequency Response Inspection Of Additively Manufactured Parts For Defect Identification, Kevin Johnson, Jason Blough, Andrew Barnard, Troy Hartwig, Ben Brown, David Soine, Tristan Collum, Edward C. Kinzel, Douglas A. Bristow, Robert G. Landers

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The goal of this paper is to evaluate internal defects in AM parts using dynamic measurements. The natural frequencies of AM parts can be identified by measuring the response of the part(s) to a dynamic input. Different excitation methods such as a modal impact hammer or shakers can be used to excite the parts. Various methods exist to measure the parts' responses and find the natural frequencies. This paper will investigate the use of Doppler lasers, accelerometers and Digital Image Correlation (DIC). The parts evaluated in this work include sets of parts that are still attached to the AM build …

Use Of Swir Imaging To Monitor Layer-To-Layer Part Quality During Slm Of 304l Stainless Steel, Cody S. Lough, Xin Wang, Christopher C. Smith, Olaseni Adeniji, Robert G. Landers, Douglas A. Bristow, Edward C. Kinzel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper evaluates using in-situ SWIR imaging to monitor part quality and identify potential defect locations introduced during Selective Laser Melting (SLM) of 304L stainless steel. The microstructure (porosity, grain size, and phase field) and engineering properties (density, modulus, and yield strength) depend on the thermal history during SLM manufacturing. Tensile test specimens have been built with a Renishaw AM250 using varied processing conditions to generate different thermal histories. SWIR imaging data is processed layer-to-layer to extract features in the thermal history for each process condition. The features in the thermal history are correlated with resulting part engineering properties, microstructure, …

In-Situ Optical Emission Spectroscopy During Slm Of 304l Stainless Steel, Cody S. Lough, Luis I. Escano, Minglei Qu, Christopher C. Smith, Robert G. Landers, Douglas A. Bristow, Lianyi Chen, Edward C. Kinzel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper demonstrates the potential of in-situ Optical Emission Spectroscopy (OES) to monitor the Selective Laser Melting (SLM) process. A spectrometer is split into the beam path of a home-built SLM system to collect visible light emitted from the melt pool and plume. The inline configuration allows signal collection regardless of the laser scan location. The spectral data can be used to calculate the temperature of the vapor plume and correlated with the melt-pool size. The effects of varying the atmosphere and pressure on the OES signal are also explored. These results demonstrate that OES can provide useful feedback to …