bluuebunny/crossref_metadata_2025 huggingface dataset:
Improved Local Mean Decomposition for Vibration-Based Machinery Fault Diagnosis
Authors: Wang Lingyan , Lu Hong , Qiao Yu , Wu Wan , Li Le , Liu Qiong , Wang Shaojun
Published: January 2021

The rotor stand vibration signals carry abundant dynamic information of the machinery and are sometimes very useful in the machinery fault diagnosis. Due to the difficulty of recognition for the non-stationery signals, many traditional ways have been discussed and made the comparison to analyze the pros and cons of the methods. Then this paper proposed an improved LMD time-frequency method to solve the shortcuts, so as to obtain the better results during the machinery fault diagnosis. The LMD time-frequency method helps to reduce the appearance of the singular points and glitches and it has better precision in the PF component, so that the characteristics of the original signal can fully be reflected.

And the simulated rotor signal along with actual fault signals are used to demonstrate, test, verify the accuracy and the effectiveness of the improved LMD method with the support of the established test rig and NI device. Through the Time-Frequency Analysis Time Spectrum, the newly proposed method has been proved its accuracy, efficiency in the time-frequency analysis and its stableness in the machinery fault diagnosis.
A Simplified Approach to Tolerance Verifications for Cylindrical Surfaces Using Point-Set Data
Authors: Ko Hua-Wei , Kapoor Shiv G. , Ferreira Placid M.
Published: January 2021

Cylindrical surface and its tolerance verification play important role in machining process. Although there exists many approaches that can fit the maximum, minimum and minimum zone cylinders, the cylinder fitting problems can even be further simplified. The methodology developed in this paper seeks to reduce the number of parameters used in cylinder fitting model using the projection model. The model evaluates 3-D tolerance specifications by introducing the optimal direction of projection such that the 2-D point projected onto this direction has optimal tolerance specifications (maximum, minimum and minimum zone circles). Besides, a global optimum solver, Particle Swarm Optimization (PSO) is applied to avoid the problem of finding local optimum. The proposed simplified method shows consistent results when compared with the results from literature.
Edge Computing Accelerated Defect Classification Based on Deep Convolutional Neural Network With Application in Rolling Image Inspection
Authors: Huang Jiayu , Sergin Nurretin , Dua Akshay , Tavakoli Erfan Bank , Yan Hao , Ren Fengbo , Ju Feng
Published: January 2021

This paper develops a unified framework for training and deploying deep neural networks on the edge computing framework for image defect detection and classification. In the proposed framework, we combine the transfer learning and data augmentation with the improved accuracy given the small sample size. We further implement the edge computing framework to satisfy the real-time computational requirement. After the implement of the proposed model into a rolling manufacturing system, we conclude that deep learning approaches can perform around 30–40% better than some traditional machine learning algorithms such as random forest, decision tree, and SVM in terms of prediction accuracy. Furthermore, by deploying the CNNs in the edge computing framework, we can significantly reduce the computational time and satisfy the real-time computational requirement in the high-speed rolling and inspection system. Finally, the saliency map and embedding layer visualization techniques are used for a better understanding of proposed deep learning models.
Advanced Sensing Development to Support Accuracy Assessment for Industrial Robot Systems
Authors: Qiao Guixiu , Garner Jonathan
Published: January 2021

Manufacturers currently struggle with the assessment of a machine/robots’ accuracy degradation that limits the efficiency of machine/robots in high precision applications. Current best practice in industry is to inspect the final products or add redundancies (local calibration, etc.) during the process to determine the machine’s accuracy and performance. These create complexities in the process and increase the maintenance costs of applications such as high precision robot operations (welding, robotic drilling/riveting, and composite material layout), in-process metrology, and machines in mobile applications. A higher speed, more precise control of position and orientation is required to remedy these complexities. A novel smart target was designed at the National Institute of Standards and Technology (NIST) to integrate with a vision system to acquire high-accuracy, real-time 6-D (six-dimensional x, y, and z position, roll, pitch, and yaw orientation) information. This paper presents the development of the smart target and the image processing algorithm to output 6-D information. A use case is presented using the smart target on universal robots (UR3 and UR5) to demonstrate the feasibility of using the smart target to perform the robot accuracy assessment.
Analysis of Anisotropic Surface Topography Effects on Metal Flow: Warm and Hot Working Processes
Authors: Crowley Ross , Domblesky Joseph
Published: January 2021

The results of an experimental study that analyzed how anisotropic tool topography influences friction and metal flow under warm and hot working conditions are presented. Six sets of H-13 steel platens having different roughnesses were used to compress AA 6061-T6, AA 2024-T4, and AISI 1018 specimens. The platens were machined to have a unidirectional lay while the specimens were prepared to have a constant roughness with an isotropic surface texture. Rectangular specimens were placed at different angular orientations relative to the surface lay of the graphite-lubricated platens and then side-pressed at die temperatures ranging from 149–204°C (300–400°F). Ring tests were also performed in order to determine interface shear friction factors for each experimental condition. Results showed that surface roughness had little effect on planar metal flow whereas specimen orientation showed a strong correlation. An explanation for this behavior is presented based on evidence gathered with a laser measuring microscope. While further investigation is needed, the results indicate that an oriented surface texture has the potential to be used as a tool to optimize flow patterns in bulk forming processes.
The Impact of Material Aging on Stereolithography Reliability: An Experimental Study
Authors: Zhao Jing , Yang Yiran , Li Lin
Published: January 2021

Additive manufacturing as an emerging technique, however, delivers relatively low reliability compared to traditional manufacturing. Unlike in traditional manufacturing systems that manufacturers mainly focus on the machine reliability by adopting failure rates of equipment, in additive manufacturing systems the performance of reliability is often evaluated by the consistency of measurement results. In addition, the reliability of additive manufacturing systems is not only affected by the failure rates of machine elements, the condition of the photo-sensitive raw material could also lead to variations on the overall performance of the additive-manufactured products and thus affect the reliability. In this work, the impact of raw material condition with respect to the material aging time on the reliability of the stereolithography manufactured products is evaluated experimentally. More specifically, the liquid resin is sampled and stored in a laboratory environment for 2, 6, 8, and 12 days of aging, respectively. A series of specimens are printed with the aged raw materials as well as the fresh raw material. By computing the standard deviation and correlation of the measurements among specimens, the results indicate that material aging time has a negligible impact on the geometric dimension of the specimens while it does significantly affect the hardness. In other words, the results of the work imply that the reliability of stereolithography is significantly affected by raw material aging time.
Fused Filament Deposition of Silicone Blends With Tunable Mechanical Properties
Authors: Jaipean Bryson , Estelle Kevin , Tandel Ruchira , Gozen B. Arda
Published: January 2021

Addition-cured silicones are widely used in emerging soft robotics and wearable device technologies which can benefit greatly from the customizability offered by versatile 3D printing methods such as fused filament deposition (FFD). However, precursors of addition-cured silicones, particularly the ones with high compliance, are generally incompatible with 3D printing due to their rheological properties. Several silicones with rheological properties suitable for 3D printing lacks the compliance necessary for many application. This paper explores FFD of composite silicone inks consisting of two types of addition cured silicone precursors with different rheology and mechanical properties: inherently 3D-printable Dow SE-1700 with low compliance and non-printable Smooth-On EcoFlex 00-10 with high compliance. Specifically, blended ink rheology, morphology and the mechanical properties of the printed structures are experimentally studied. It was shown that 3D printable rheology was maintained in inks that contained up to 33% EcoFlex 00-10, even though the reduction in the elastic moduli and the yield stress were noted. Inclusion of EcoFlex 00-10, led to smoother side walls of the printed structures at an optimal composition. Through varying the relative composition of the two components, 100% tensile moduli of the printed structures can be controlled between 959–347 kPa. Several issues are noted associated with the transient behavior of the blended inks due to short pot life of the EcoFlex 00-10.
Fabrication of a Graded Micropillar Surface for Guided Cell Migration
Authors: Krishnamoorthy Srikumar , Xu Changxue
Published: January 2021

The migration of cells is caused by the interaction of cells and the local microenvironment around them, such as changes in stiffness, chemical gradients etc. The local topography of substrates in contact with cells is a key factor that regulates the migration of cells. The interaction between the topography of the substrate and cells is crucial for the understanding of tissue development and regeneration. In this paper, the fabrication of a graded micropillar substrate for studying topography-based cell migration is described in detail. The fabrication protocol comprises of the utilization of dynamic maskless lithography system, capillary molding, and corona arc surface treatment. The fabricated micropillar substrate has been shown and the cells have been successfully seeded on the substrate. Guided cell migration on the substrate with graded microtopography has been demonstrated to occur from the sparser zone to the denser zone. Moreover, some examples of potential applications are provided.
Demand Response for Sustainable Manufacturing Systems Considering Buffer Content Utilization
Authors: Zhou Xue , Zhao Jing , Yun Lingxiang , Sun Zeyi , Li Lin
Published: January 2021

Due to the rapidly rising energy price and increase in public awareness of environmental protection, the manufacturers are facing the ever-increasing moral and economic pressures from the community, government, and society. Hence, the significance of energy related studies in manufacturing systems has gradually become recognized in recent years. In most cases, the techniques to reduce the energy consumption are either renewable energy methods (solar, tidy and wind) or improving energy efficiency for existing energy modes. The approach to cut the energy related costs for manufacturing plants has not been comprehensively considered, although the same methods such as demand response and load shedding have been widely studied in the building research. In this paper, a brief analysis of the unique challenges to the application of the demand response technique in manufacturing systems is presented. The feasibility and profitability of demand response in manufacturing systems under the constraint of system throughput are studied and explored. An initial study about customer side decision making on demand response is introduced, and a numerical case of a section of a manufacturing system is used to show the benefits of the proposed idea, which illustrates over 6% bill reduction and over 5% consumption reduction during a billing cycle without sacrificing system throughput.
Spatially-Constant Material Removal Control Under Variable-Speed Robotic Sanding
Authors: Devine Cameron , Garbini Joseph , Devasia Santosh
Published: January 2021

During manufacturing, minor flaws in the surface of commercial airplane interior panels are often corrected using hand sanding, sometimes leading to repetitive stress injuries. Robotic sanding is an attractive option to mitigate these injuries. However, in preprogrammed automated sanding, both the sander path and the speed along that path are predetermined. Such fixed automation has limited effectiveness due to the part-to-part variability of surface condition. In addition, in typical fixed automation, a constant contact force and path speed are used to maintain constant material removal depth. Teleoperated robotic sanding allows a skilled operator to monitor the process and the condition of the surface in real time to correct the individual flaws. However, during teleoperated sanding, the path and speed along the path are inherently both time-varying and unknown a priori. The principal contribution of this work is to facilitate precision teleoperated sanding by developing a process model and control strategy that ensures constant material removal depth along the sanding path. Experimental results, with and without the proposed contact-force adjustments, for the same variable speed motion of the sander, shows 65% improvement in spatial variation of material removal with the proposed approach.
Study of Aging Heat Treatment Parameters for 7050 and 7075 Aluminum Alloys
Authors: James Sagil , Roy Ambarneil
Published: January 2021

Among the different commercially used Aluminum (Al) alloys, the 7000 series offers some of the highest mechanical properties making them the material of choice for several critical engineering applications. These Al alloys often required to undergo a heat treatment (HT) process to enhance their mechanical and metallurgical properties to the desired levels. Currently, there is a growing need to find the optimal operational parameters for the HT process of Al 7000 series alloys. The operators have to resort to a start/stop approach, while intermittently evaluating and testing the mechanical properties until the desired level is reached. Among the various steps, aging is the final and often the longest step in the HT process. Consequently, the age soak time parameter needs to be narrowed to the smallest possible operating range for industrial applications. This study aims to experimentally optimize the age soak time of Al 7000 series alloys (7050-T74 and 7075-T73) by measuring its hardness, electrical conductivity (EC), fatigue properties. The study found that the optimal age soak times for 7050-T74 and 7075-T73 Al alloys are between 24–27 hours and 22–24 hours, respectively. The results of the study are subsequently confirmed using the grain flow and grain direction analysis. The results of this study are crucial in extending the applications of Al 7000 series alloys in several critical engineering industries.
Human Point Cloud Inpainting for Industrial Human-Robot Collaboration Using Deep Generative Model
Authors: Wang Le , Xie Shengquan , Xu Wenjun , Yao Bitao , Cui Jia , Liu Quan , Zhou Zude
Published: January 2021

In complex industrial human-robot collaboration (HRC) environment, obstacles in the shared working space will occlude the operator, and the industrial robot will threaten the safety of the operator if it is unable to get the complete human spatial point cloud. This paper proposes a real-time human point cloud inpainting method based on the deep generative model. The method can recover the human point cloud occluded by obstacles in the shared working space to ensure the safety of the operator. The method proposed in this paper can be mainly divided into three parts: (i) real-time obstacles detection. This process can detect obstacle locations in real time and generate the image of obstacles. (ii) the application of the deep generative model algorithm. It is a complete convolutional neural network (CNN) structure and introduces advanced generative adversarial loss. The model can generate the missing depth data of operators at arbitrary position in the human depth image. (iii) spatial mapping of the depth image. The depth image will be mapped to point cloud by coordinate system conversion. The effectiveness of the method is verified by filling hole of the human point cloud occluded by obstacles in industrial HRC environment. The experiment results show that the proposed method can accurately generate the occluded human point cloud in real time and ensure the safety of the operator.
Numerical Simulation and Experimental Validation of Pure Water Jet Machining of Ti-6Al-4V
Authors: Pasken Greg , Ma J. , Jahan Muhammad P. , Lei Shuting
Published: January 2021

The most common problem when machining titanium using traditional metal cutting processes is that tools rapidly wear out and need to be replaced. This study examines the ability of a pure water jet to machine Ti-6Al-4V via simulations using ABAQUS’s Smoothed Particle Hydrodynamics (SPH). These simulations are then validated experimentally at two pressures, 138 MPa and 317 MPa. Using a Maxiem water jet built by Omax, experiments are conducted by creating a series of 5 lines that are 5 inches (127 mm) long placed 0.5 inches (12.7 mm) apart on a 1 mm thick Ti-6Al-4V workpiece. Predictive modeling is also conducted using the two additional pressures 400 MPa and 621 MPa as well as three orifice diameters 0.254 mm, 0.3556 mm, and 0.4572 mm. The simulations are validated at both pressures and had a percent error less than 2.6% which were within the standard deviation of the experimental results. The predictive modeling indicates that the pressures above 317 MPa create a near identical percent increase from the orifice diameter but the kerf has a more noticeable decrease in width of cut as the pressure increases. The 138 MPa has the smoothest surface profile compared to the other pressures. The volume of removed material decreases as the pressure increases but the material removal rate (MRR) increases as the pressure increases. This is due to the velocity of the water increasing as the pressure increases causing a lower run time. The 621 MPa is the best pressure to machine Ti-6Al-4V as it has a better MRR than the other pressures used in the predictive modelling.
Friction Stir Forward Extrusion: Small Scale Tooling Development and Preliminary Test Results
Authors: Emblom William J. , Huval Dillon J. , Oustalet Dylan J. , Rubi Jacob , Olayinka Ayotunde , Wagner Scott W. , Wahab Muhammad A.
Published: January 2021

Preliminary work on a new research project frequently entails proof-of-concept tests and modeling. The current project is investigating friction stir processing to produce small macroscale aluminum solid cylinders. The tooling was designed to be used in a 2-HP Bridgeport Mill for initial proof of concept tests and then later used in a CNC mill. The work pieces for these first tests were A1100 annealed ½ in. (12.7 mm) diameter work pieces, the final diameters were ¼ in (6.35 mm), and 3/18 inches (9.53 mm). The nominal speeds of the mill were 850 and 1000 RPM and were limited by the power available and the age of the mill. The paper discusses tooling design, instrumentation, preliminary results, and analysis. Temperature was measured during the tests but force was not measured due to limits to the available instrumentation. The future directions of this project are discussed.
Numerical Simulation of Pulsed Water Jet Machining of Al 6061-T6 and Ti-6Al-4V
Authors: Pasken Greg , Ma J. , Jahan Muhammad P. , Lei Shuting
Published: January 2021

Aluminum, known for its low density and its ability to resist corrosion through passivation, is vitally important to the aerospace industry, transportation, and building industries. The most common problem when machining titanium using traditional metal cutting processes is that tools rapidly wear out and need to be replaced since the variation of chip thickness, high heat stress, high-pressure loads, spring back, and residual stress result in higher tool wear and worse machined surface integrity. Thus, a technique that allows high precision machining of titanium that preserves the integrity of the machined material, reduces tool wear or even eliminates tooling entirely is an important advance. This study examines the ability to machine Al 6061-T6 and Ti-6Al-4V using a pulsed water jet by simulation using ABAQUS Smoothed Particle Hydrodynamics (SPH). The aluminum results showed that between the three diameters the 0.4572 mm orifice is a better choice based upon the percent increase from the orifice diameter; but based off of the kerf, the 0.3556 mm is the better choice. The results show that the 621 MPa has the highest MRR for Al 6061-T6, 232.1 mm3/s. For the four pressure simulations for the titanium, the 138 MPa pressure has the smoothest surface. Even though the volume removed decreased as the pressures increased for the titanium, the MRR increased due to the shorter machining times with 621 MPa pressure having the second highest MRR, 170.051 mm3/s. The results show that overall the 621 MPa is the best choice from the parameters chosen for machining Al 6061-T6 and Ti-6Al-4V.
Embedded Sensing Capabilities in an FDM Printed Object
Authors: McGrady Garrett , Jain Neel , Jackson Douglas , Walsh Kevin
Published: January 2021

The objective of this paper is to demonstrate the flexure properties of ABS plastic in a 3D printed object as a process to enable embedded pressure sensing capabilities. Developing the potential for non-static 3D parts broadens the scope of the fused deposition modeling (FDM) process to include printing ‘smart’ objects that utilize intrinsic material properties to act as microphones, load sensors, accelerometers, etc. In order to demonstrate a strain-based pressure transducer, strain gauges were embedded either directly on top or in the middle of a flexible ABS diaphragm.

Securing a strain gage directly on top of the diaphragm traced a reference pressure more closely than diaphragms with the strain gage embedded halfway into the diaphragm. To prevent temperature-related drift, an additional strain gage was suspended above the secured gage, inside the 3D printed cavity. The additional gage allowed for a half-bridge circuit in lieu of a quarter-bridge circuit, which minimized drift due to temperature change. The ABS diaphragm showed no significant signs of elastic hysteresis or nonlinear buckling. When sealed with 100% acetone, the diaphragm leaked ∼50x slower than as-printed sensors. After pressurizing and depressurizing the devices multiple times, they output pressure readouts that were consistent and repeatable for any given pressure within the operational range of 0 to 7psi.

The repeatability of each of the final generation sensors indicates that ‘smart’ objects printed using an FDM process could be individually calibrated to make repeatable recordings. This work demonstrates a concept overlooked previous to now — FDM printed objects are not limited to static models, which lack dynamic motion of the part as an element of design. Altering FDM’s bottom-up process can allow for easily embedding sensing elements that result in printed objects which are functional on the mesoscale.
Order Fulfilment Progress Estimation for Collaborative Manufacturing Enabled by Industrial Internet of Things
Authors: Peng Chen , Zhang Zheng , Peng Tao , Tang Renzhong , Zhao Xiaoliang
Published: January 2021

It has been recognized by manufacturing companies that working collaboratively is the way to advance their competiveness. Order fulfillment estimation addresses the issue of uncertainty from vendors. It is significant for collaborative manufacturing, which enhances companies’ responsiveness to market dynamics. In a data-rich scenario, order fulfillment estimation can be performed based on information extracted from data acquisition devices, such as smart sensors. The analysis result should serve the decisions-making of the production planning, and an indicator should be passed along the production chain even to its end customer for collaborative purpose. In the meanwhile, the manufacturer’s sensitive or confidential information is excluded to avoid risks. This article studies a method to effectively evaluate the order fulfillment process in an Industrial Internet of Things (IIoT) facilitated make-to-order production system. An order fulfilment progress (OFP) indicator is proposed to dynamically represent the fulfillment progress, and its estimation mathematical models are proposed. To improve the practicability of the OFP indicator in production, the influence of abnormal event scenarios are discussed to modify the OFP. A case study presented in this research demonstrates the proposed indicator with consideration of job in process (JIP) is promising comparing to conventional indicators that are represented by the proportion of finished over total products.
Parametric Study and Multi-Criteria Optimization in Laser Directed Energy Deposition of 316L Stainless Steel
Authors: Kersten Samuel , Praniewicz Maxwell , Elsayed Omar , Kurfess Thomas , Saldana Christopher
Published: January 2021

Directed Energy Deposition (DED) is an additive manufacturing technique in which a heat source is used to generate a small pool of molten material while powder feedstock is fed into the melt pool to create tracks of raised material on the surface of a part. Given the appropriate process parameters for the chosen material system and process conditions, fully dense complex geometric features are able to be constructed. In order to generate a high quality clad, two main criteria must be met: sufficient bonding with the substrate with minimized dilution of the clad by the base material and minimal porosity. Track shape is a key indicator in determining the quality of the process.

This paper evaluates the influence of several of the key processing parameters — laser power, scanning speed, and powder mass flowrate — on single-clad track morphology. An analysis of variance (ANOVA) is performed to evaluate the significance of the main input parameters and the interactions between multiple parameters. A second-order polynomial model is then fit to the data to allow for predictive modelling of track shape based on a set of inputs. Finally, a multi-criteria cost function is generated, and sequential quadratic programming is performed to solve the objective function. Through these operations, the correct combination of processing parameters can be selected in order to generate a cladded track with desirable geometric traits.
Human-Robot Collaboration in Smart Manufacturing: Robot Reactive Behavior Intelligence
Authors: Nicora Matteo Lavit , Ambrosetti Roberto , Wiens Gloria J. , Fassi Irene
Published: January 2021

To enable safe and effective human-robot collaboration (HRC) in smart manufacturing, seamless integration of sensing, cognition and prediction into the robot controller is critical for real-time awareness, response and communication inside a heterogeneous environment (robots, humans, equipment). The specific research objective is to provide the robot Proactive Adaptive Collaboration Intelligence (PACI) and switching logic within its control architecture in order to give the robot the ability to optimally and dynamically adapt its motions, given a priori knowledge and predefined execution plans for its assigned tasks. The challenge lies in augmenting the robot’s decision-making process to have greater situation awareness and to yield smart robot behaviors/reactions when subject to different levels of human-robot interaction, while maintaining safety and production efficiency. Robot reactive behaviors were achieved via cost function-based switching logic activating the best suited high-level controller. The PACI’s underlying segmentation and switching logic framework is demonstrated to yield a high degree of modularity and flexibility. The performance of the developed control structure subjected to different levels of human-robot interactions was validated in a simulated environment. Open-loop commands were sent to the physical e.DO robot to demonstrate how the proposed framework would behave in a real application.
Corrosion Evolution in Al/Steel Dissimilar Joints
Authors: Wen Weiling , Liu Tian , Banu Mihaela , Simmer Joseph , Carlson Blair , Hu S. Jack
Published: January 2021

Al/steel joints are increasingly used in the automotive industry to meet the requirement of energy saving and emission reduction. Among various joining technologies, self-pierce riveting (SPR) and resistance spot welding (RSW) are two promising technologies to fabricate dissimilar joints with stable and high mechanical performance. However, corrosion will occur in these joints inevitably due to different electrochemical properties, which can degrade the surface quality and the mechanical performance, including strength, ductility, etc. In this paper, 1.2 mm AA6022 and 2.0mm HDG HSLA340 are joined by SPR and RSW. After the fabrication of these Al/steel joints, cyclic corrosion tests are performed, which lasts 26 cycles and 48 cycles. By comparing the microstructure of the joints with and without corrosion, different corrosion mechanisms in SPR and RSW are revealed, including the corrosion initiation and propagation.
Numerical Investigation of Various Coaxial Nozzle Designs for Direct Laser Deposition
Authors: Gabor Theodore T. , Joe Hang-Eun , Akin Semih , Jun Martin Byung-Guk , Kim Kyung-Han , Park Jong-Kwon
Published: January 2021

Direct Laser Deposition (DLD) is a form of metal-based additive manufacturing. The DLD process involves ejecting powder out of a nozzle by means of an compressed gas and irradiating a laser beam to heat up the powder and the substrate. During the powder spray ejection, tight focusing of the powder stream has the potential to improve the DLD process by reducing powder wastage. Thus, nozzle design and computational fluid dynamics (CFD) analysis of the design parameters become important. This study focuses on the numerical simulation of the gas-solid flow inside a coaxial DLD nozzle and how design features of the nozzle affect powder focusing. The two-phase gas/powder flow was analyzed using a Eulerian-Lagrangian scheme. A total of twelve designs were simulated and analyzed through CFD simulation, with features such as inlet angle, inlet offset, and the presence and shape of flow-straightening grooves considered. It was determined that geometry reducing particle tangential velocity such as flow-straightening grooves produce the best focusing effects, whereas offset inlets without the presence of grooves reduces focusing by maximizing particle swirling. Finally, the simulations show that the distribution of powders within the nozzle is also affected by nozzle inlet angle, with horizontal inlets providing more even distribution over inlets angled towards the nozzle tip.
Fabrication of Nanochannels Using Glancing Angle Deposition With Line Seeds
Authors: Qu Chuang , Ratnayake Dilan , Alphenaar Bruce , McNamara Shamus , Walsh Kevin
Published: January 2021

This paper presents the fabrication of nanochannels using glancing angle deposition (GLAD) with line seeds. GLAD is a bottom-up nanofabrication technique that creates nanometer-level features by the ballistic shadowing effect at oblique incident angles in physical vapor deposition (PVD) processes. GLAD exhibits the unique advantage to create 3D nanofeatures such as nanocolumns, helices, chevrons, and combinations, comparing to top-down nanonamufacturing techniques. Advanced seeding schemes allow GLAD to produce ordered nanostructure arrays. In this paper, we focus on studying the design rules of line seeds for GLAD, and the potential for creating nanochannels using GLAD nanoribbons grown from the line seeds. Unlike traditional one-dimensional (1D) point seeds, the cross-sectional profiles of line seeds have an important impact on the size and morphology of the nanoribbons. We demonstrated that line seeds with circular cross-sections and micrometer widths created from conventional photolithography can be used for creating ribbons with width less than 300 nm. The centimeter-long nanoribbons are used as nanotemplates for nanochannels. The process is compatible with various materials such as parylene C and silicon dioxide as the capping material, and rigid/flexible substrate choices for the nanochannels as well. The nanochannels created by GLAD with line seeds can potentially be used in nanofluidics, biological, and sensing applications.
Simulation and Characterization of Cold Spray Deposition of Metal Powders on Polymer Substrate Electrically Conductive Application
Authors: Tsai Jun-Ting , Bahr David F. , Akin Semih , Zhou Fengfeng , Jun Martin Byung-Guk , Park MinSoo
Published: January 2021

Cold sprayed polymer substrates offer a promising platform for bridging electroless deposition methods and applications. This study’s contribution to the field is the combination of cold sprayed polymer substrate and the electroless-plating process. In simulation, finite element analysis of the as-sprayed polymer substrate using a viscoelastic model that considers large strain time-dependent behavior were conducted. A three-network constitutive model was applied to capture the non-linear and time-dependent response of large strain polymer deformation. In experiment, the process-structure-property relationship was examined from the as-sprayed specimen to the final coated electroless-plated samples. A controlled coating process of Cu powders was first cold sprayed on polyamide 6. The as-sprayed specimen was then electroless deposited. Mechanical testing was performed on as-sprayed specimens and adhesion testing was performed on electroless deposited specimens. Scanning electron microscopy (SEM) was employed to observe the surface and the cross-section of the as-sprayed and electroless deposited specimens. Lastly, the behavior of Cu coated specimens immersed in KOH solution was examined by cyclic voltammetry.
Experimental Investigation of Alginate-Methylcellulose Composition and Printing Direction on Dimensional Accuracy of 3D Printed Constructs
Authors: Thakare Ketan , Wei Xingjian , Jerpseth Laura , Pei Zhijian , Qin Hongmin
Published: January 2021

Bioprinting technology has a great potential in the fields of tissue engineering and regenerative medicine. In tissue engineering, for a bioprinted tissue to be successful in supporting regeneration of new tissue, it should morphologically mimic the native tissue in vivo. Therefore, the bioprinted tissue needs to be dimensionally accurate. In extrusion-based bioprinting, 3D printing process parameters and bioink properties affect dimensional accuracy of printed constructs. Currently, little information is available on effects of bioink composition and printing direction on dimensional accuracy of 3D printed constructs using alginate:methylcelluolose based bioink. In this study, strands were printed using four compositions of alginate:methylcellulose bioink and two printing directions. The four compositions of alginate:methylcellulose bioink were 1:1.5, 1:2, 1:2.5 and 1:3, and the two printing directions were vertical and horizontal. The statistical analysis of strand width measurement data revealed that while bioink composition has significant effect, printing direction does not affect the strand width of 3D printed constructs at the significance level of 0.05.
Novel Sprue Designs to Reduce Casting Defects in Nickel-Aluminum Bronze: A Computational Study
Authors: King Philip , Martinez Daniel , Manogharan Guha P.
Published: January 2021

As 3D Sand-Printing technology becomes more widely available to the casting market, the search for opportunities to take advantage of its freedom of design is critical for its rapid adoption by the casting community. This original research investigates casting design principles towards defect-free alloy Nickel-Aluminum Bronze (NAB). This is an alloy of interest for marine applications due to its corrosion resistance, mechanical strength and good castability. Numerical modeling of flow within a casting is examined, and rigging redesigns are proposed to improve casting quality by controlling flow behavior. It has been demonstrated that turbulence and filling velocity are determining factors that seriously impact casting performance due to the generation of casting defects. Among these are bifilm formations, gas and sand entrapment and cold shut. This work examines the effectiveness of mathematically designed rigging components in controlling mold filling and compares the results to a conventional casting rig. Design solutions are proposed using 3DSP that can be directly applied to casting operations of Nickel-Aluminum Bronze. The results from this study demonstrate the effectiveness of mathematically designed sprues to reduce filling velocity of Nickel-Aluminum Bronze. The procedure followed here can be extended to marine casting production environments. Findings from this study can be seamlessly transferred to castings of any geometry, alloy and pouring conditions.
Machining Behavior and Material Properties in Additive Manufacturing Ti-6Al-4V Parts
Authors: Gong Xi , Manogharan Guha
Published: January 2021

Although Additive Manufacturing (AM) has unique advantages in processing complex part designs using superalloys, metal AM parts currently do not meet the part tolerance and surface finish requirements for most mechanical applications. Hence, there is a growing need for integrated metal hybrid manufacturing through both “in-envelope” and “sequential” additive-subtractive manufacturing. Since AM parts are inherently different from traditionally manufactured parts (e.g., anisotropy, residual stress), there is a critical gap in the literature to correlate as-built AM material properties, material characterization, machining parameters with resulting machining behavior such as cutting force and specific cutting energy. This study reports on the machining behavior of Electron Beam Melting (EBM) and Laser Powder Bed Fusion (L-PBF) processed Ti-6Al-4V parts with highly textured microstructure due to build orientation, and heat treatment across different machining conditions. It was found that specific cutting energy of AM parts changes up to 21.6% based on AM processing, cessed parts, build orientation, and heat treatment conditions. The finding from this study can be used to predict machining behavior based on material characterization. In the future, this study will lead to creating a correlation model on AM parts microstructure and correlated machining behavior, surface finish, and tool wear behavior.
Determination of Modal Parameters Using Finite Element Modeling Considering the Compliance at the Clamping End
Authors: Saraf Aditya , Mittal Rinku K. , Singh Ramesh K.
Published: January 2021

Micromilling process is widely used in biomedical and aerospace industries to produce complex 3D microscale features and components. The benefits of the micromilling process are ability of processing of wide range of materials, high quality surface finish, high material removal rate and submicron accuracy. One of the key limitations of micromachining is the low flexural stiffness of the microtool which can lead to chatter. Chatter in micromilling can be avoided by using the machining parameters within the stability limits. To predict the accurate stability limits, the tool tip dynamics need to be determined precisely. In this paper, a finite element method for determination of modal parameters has been proposed which considers the machine tool compliance at the clamping. The modeling of micro endmill and machine compliance is achieved by introducing elastic foundation interaction at the clamping interface. The model is further validated using experimental modal analysis on micro endmill at various locations and the results obtained were found to be in agreement with simulated results.
Investigation of Porosity and Microstructure-Induced Property Variations in Additive Manufactured Stainless Steel 316L
Authors: Parikh Yash , Carter Julia , Kuttolamadom Mathew
Published: January 2021

The objective of this study is to investigate the porosity and microstructure-induced mechanical property variations in additive manufactured (AM) stainless steel (SS) 316L alloy with a view to create functionally graded (FG) bulk structures in the future. The first step towards fulfilling this objective is to explore the range of mechanical properties of SS 316L (such as hardness, density, Modulus, and stress-strain behavior) achievable by varying Volumetric Energy Density (VED)-related process parameters such as laser power and scanning speed, in a pulsed selective laser melting (SLM) process. In the present work, the mechanical properties of interest are hardness, density, and Young’s modulus. For this, a design of experiments consisting of 28 samples was assembled. The results demonstrate the significant variations achievable in hardness (209–318 HV), relative density (90–99%) and modulus (154–211 GPa) across the samples. In summary, a strong correlation between the process parameters and the resulting mechanical properties were identified which also depends on the underlying porosity and microstructure. Altogether, this study exhibited the feasibility of fabricating tailored spatial mechanical properties, thereby demonstrating the feasibility of SLM to tailor mechanical responses.
Thermal Influence on Printlet Quality in the Selective Laser Sintering of Pharmaceutical Formulations
Authors: Funkhouser Cyrus , Barakh Ali Sogra Fathima , Richardson Laura , Rahman Ziyaur , Khan Mansoor , Kuttolamadom Mathew
Published: January 2021

The objective of this research is to determine the influence of temperature on the mechanical and dissolution performance of pharmaceutical printlets (tablets) fabricated via selective laser sintering (SLS) additive manufacturing. When compared to traditional high-volume pharmaceutical manufacturing, additive manufacturing has the potential to effectively cater to personalized and just-in-time medicine. Among additive manufacturing methods, SLS has the advantage of not needing to reconstitute the drug(s) with other liquids or powders, as well as the ability to tailor certain location-specific properties via process parameter control. One of the critical parameters that affect the printlet quality is the temperature during the printing process. To explore the thermal effects, two separate experiment sets were conducted. First, process parameters including chamber temperature were studied based on a partial-factorial design of experiments, and their effects on parameters such as weight, hardness, structural disintegration and dissolution rates studied. Next, a smaller scale study was conducted to correlate surface temperatures with structural integrity. Results showed the beneficial and detrimental effects of operating at chamber and bed temperature ranges, in relation to the polymer percentage and melting point. A certain minimum energy density needed to be imparted onto the powder mixture combinations (resulting in a certain surface temperature) for proper fusion and performance of the printlets. This work served to investigate and show the potential of using SLS to reliably fabricate pharmaceutical formulations.
Obese Youth Demonstrate Altered Landing Knee Mechanics Unrelated to Lower-Extremity Peak Torque When Compared With Healthy Weight Youth
Authors: Briggs Matthew S. , Spech Claire , King Rachel , McNally Mike , Paponetti Matthew , Bout-Tabaku Sharon , Schmitt Laura
Published: January 2021

Obese (OB) youth demonstrate altered knee mechanics and worse lower-extremity performance compared with healthy weight (HW) youth. Our objectives were to compare sagittal plane knee landing mechanics between OB and HW youth and to examine the associations of knee and hip extension peak torque with landing mechanics in OB youth. Twenty-four OB and 24 age- and sex-matched HW youth participated. Peak torque was measured and normalized to leg lean mass. Peak knee flexion angle and peak internal knee extension moment were measured during a single-leg hop landing. Paired t tests, Pearson correlation coefficients, and Bonferroni corrections were used. OB youth demonstrated worse performance and lower knee extension (OB: 12.76 [1.38], HW: 14.03 [2.08], P = .03) and hip extension (OB: 8.59 [3.13], HW: 11.10 [2.89], P = .005) peak torque. Furthermore, OB youth demonstrated lower peak knee flexion angles (OB: 48.89 [45.41 to 52.37], HW: 56.07 [52.59 to 59.55], P = .02) and knee extension moments (OB: −1.73 [−1.89 to −1.57], HW: −2.21 [−2.37 to −2.05], P = .0001) during landing compared with HW youth. Peak torque measures were not correlated with peak knee flexion angle nor internal knee extension moment during landing in either group (P > .01). OB youth demonstrated altered landing mechanics compared with HW youth. However, no associations among peak torque measurements and knee landing mechanics were present.
Representation of Athletic Girls on Young Adult Sport Fiction Cover Art
Authors: Roper Emily A. , Santiago José A.
Published: January 2021

The purpose of this study was to examine how and how often athletic girls were represented on the cover art of young adult (YA) sport fiction. In this research, 154 YA sport fiction books were analyzed using quantitative content analysis. Using existing sport research and theory focused on women’s representation in sport media, the researchers developed a coding scheme to assess cover art for each of the following categories: (a) presence and racial representation of female character/s on cover; (b) portrayal of female body on cover (whole body, partial body/with head, or partial body/without head); (c) portrayal of female character as active or passive; (d) portrayal of female character in or out of athletic uniform; (e) portrayal of female character in or out of the sport setting; (f) presence of sport equipment; and (g) type of cover. Findings revealed that 81% of the book covers had a female character in which 29% of the covers displayed the whole body, 47% displayed partial body/with head, and 23% displayed partial body/with no head of the female character. Only 0.06% of the book covers had a female character of color. Approximately 31% of the female characters were displayed in active positioning, 58% in athletic attire, and 44% in the sport setting. Of the books reviewed, 55% displayed equipment on the cover. The findings indicate that athletic girls have few images on YA sport fiction cover art that accurately represent their athleticism, and there is a clear absence of diverse representation. It is critical that those responsible for the design and layout of book covers clearly represent active females in action, in uniform, and in the sport context.
Precision Pandemic Preparedness: Improving Diagnostics with Metagenomics
Authors: Govender Kumeren N.
Published: January 2021

The threat posed by novel pandemics in the future remains active. Equipping our routine laboratory with clinical metagenomics to detect unknown threats early on offers a considerable advantage and may be feasible and scalable with the ability to identify complicated infectious diseases in routine care. Though several technical and regulatory challenges still exist, and clinical metagenomics may improve individual patient outcomes and provide earlier warning signs to improve pandemic preparedness.