bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabrication of a Microfluidic Cell Compressor Using a 3D-Printed Mold
Authors: Emeigh Carson , Zhang Haipeng , Ryu Sangjin
Published: September 2022

Microfluidic devices are used to apply mechanical stimuli, such as compressive force and flow shear force, to cells for mechanobiology studies. Previously, we developed a microfluidic cell compressor in which cells embedded in hydrogel scaffolds were compressed by polydimethylsiloxane (PDMS) balloons, which were expanded pneumatically, in proportion to the balloon diameter. The device consisted of two PDMS layers. The bottom layer contained channels connected to circular wells and was fabricated using SU-8 photoresist molds. The top layer was a thin PDMS membrane separately prepared by spin coating PDMS on a plastic film. The two layers were bonded together using plasma bonding to form PDMS balloons and pneumatic channels. Therefore, fabrication of the device involved multiple steps of photolithography and soft lithography.

In this study, we have improved the fabrication method of the microfluidic cell compressor by printing a master mold using a commercial microfluidic 3D printer for more efficient and cost-effective fabrication with higher design flexibility. The new method is more efficient because it does not require separate preparation of PDMS layers, the mold fabrication can be completed quicker, and a photomask is not necessary. We found that proper printing, UV light exposure, cleaning, baking, and temperature control of the mold affected the ability of the 3D printed mold to cure PDMS.

Also, multiple maintenance requirements of the 3D printer were found for curing PDMS on the printed mold. For example, the resin within the 3D printer must be free of debris, the resin in the printer must be stirred before printing to ensure homogeneity, and the light filtering elements of the printer must be clean. With proper methodology and maintenance, the printer can be used to fabricate the microfluidic cell compressor and similar high-quality microfluidic devices capable of performing laboratory experiments efficiently. Further developing a methodology of creating 3D printed microfluidic device molds would expand access to microfluidics.
Detached Eddy Simulation of the 28° Ahmed Body at a Low Reynolds Number
Authors: Siddiqui Naseeb Ahmed , Agelin-Chaab Martin
Published: September 2022

Studies on the Ahmed body with varying slant angles remain an interesting topic, especially analyses of the flow structures and the corresponding changes in aerodynamic drag and lift in the region 25° ≤ α ≤ 30°, which are not fully understood. Physical insights in the aerodynamic performance of a simplified geometry such as the Ahmed body can improve the geometric optimization of road vehicles for fuel economy improvement. Therefore, this paper examines the three-dimensional wake dynamics of a 28° slanted Ahmed body and proposes a flow control method for its drag reduction. This slanted angle is rarely reported in the open literature. The study is conducted by applying the improved delayed detached eddy simulation (IDDES) using the SST k-ω turbulence model to solve the Navier-Stokes equations at a low Reynolds number of 1.4 × 104 based on the model height. The results reveal a flow separation at the slant surface and reattachment at the rear leading to a secondary separation. A small reverse flow develops after the first separation over the slant surface. Similarly, another minor reverse flow region is concentrated in the middle of the vertical base. However, the flow control method modifies the flow structures similar to the low-drag regime Ahmed body. The aspect ratio of the recirculation region is increased, and the reattachment at the rear end vanishes. Consequently, even at the low Reynolds number studied here, the drag is reduced by up 11%. In addition, the study employs both the time-averaged and time-resolved turbulence statistics and vortex identification methods to provide physical insights into flow modifications and drag reduction. Hence, the paper provides additional valuable information on the flow structure at low Reynolds number to the body of knowledge.
Computational Modeling and Hydrodynamic Analysis of Fish Schools in Three-Dimensional Arrangements
Authors: Pan Yu , Zhang Wei , Dong Haibo
Published: September 2022

In this work, numerical simulations are employed to study hydrodynamic interactions in trout-like three-dimensional (3D) fish bodies arranged in vertical and horizontal planes. The fish body is modeled on a juvenile rainbow trout (Oncorhynchus mykiss) and is imposed on a traveling wave to mimic trout swimming. Three typical minimal schools are studied, including the in-line, the side-by-side, and the vertical school. A sharp interface immersed-boundary-based incompressible Navier-Strokes flow solver is then used to quantitively simulate the resulting flow and hydrodynamic performance of the schools. The results show that the hydrodynamic efficiency of the leading fish in the in-line school increases by 5.28%, and the thrust production and efficiency of the side-by-side school are enhanced by 2.28% and 3.86%, respectively. Besides, the thrust production of the vertical school increases by 21.6%. The results suggest great potential in exploiting the hydrodynamic benefits in fish schools arranged in three-dimensional space.
Concentrating Slurries Mesofluidically for Nuclear Waste Processing
Authors: Pease Leonard F. , Bamberger Judith Ann , Burns Carolyn A. , Minette Michael J.
Published: September 2022

High-level radioactive waste stored at the Hanford Site near Richland Washington will be retrieved, transported, treated, and concentrated prior to final vitrification. This waste, stored in million-gallon underground tanks, is to be retrieved and transported via pipeline to the treatment facilities at low solids loading. Concentration is a necessary step to remove transport fluid and supernatant liquid. Several techniques are available to concentrate slurries including settle/decant, filtration, and evaporation that all present unique challenges. Using evaporators to dewater sludge is time consuming and energy intensive; settle-decant is time consuming and requires use of large settling vessels; filtration is prone to clogging and caking. Improvements in slurry concentration capabilities are desirable to help minimize waste treatment costs.

Here we investigate mesofluidic separation to concentrate slurries. This mesofluidic system uses a high void space, low pressure drop grid installed within an existing pipe spoolpiece. The grid spacing is configured to force solids to migrate to one side of the grid and fluid to migrate to the other side of the grid as the slurry flows within the pipe. The fluid component exits the process stream through a branch and can be reused for additional slurry retrieval and transport. The higher concentration slurry component remaining in the “express lane” then flows through a second “grid” to be further concentrated. Several grid inserts in series may be used to obtain the degree of solids separation required to support downstream processes. The concentrated slurry then becomes the process feed for vitrification.

A series of experiments were conducted to evaluate the ability of the mesofluidic grid installed within the spoolpiece to concentrate particles within a size range of interest for radioactive fluid processing. Experiments evaluated the potential to operate units in series in two configurations: further concentrating slurry routed from the express lane and further solids removal of fluid routed from the permeate line. Both configurations yielded enhanced results: additional concentration or additional dilution. Test results are presented and applicability to process enhancements is described.
Sand Erosion Measurements and Simulations Under Churn Flow Conditions in Elbows in Series
Authors: Rajkumar Yeshwanth Raj , Karimi Soroor , Shirazi Siamack A.
Published: September 2022

Pipeline geometries such as elbows, tees, chokes cause a rapid change in the flow direction. Therefore, they are more prone to solid particle erosion when silica particles are entrained with oil and gas production. Consequently, studying the erosion pattern and magnitude for elbows in series in liquid-gas-solid flows is vital. The current work measured erosion data using an ultrasonic transducer (UT) in 76.2 mm inner diameter stainless steel elbows. The second elbow is separated at three diameters from the first elbow. Experiments were conducted with water, air, and 300 μm sand particles at a mixture velocity of 11.4 m/s. Experimental data was collected for two different superficial velocities by keeping the mixture velocity constant. The erosion magnitude and hotspot location change significantly as the gas velocity increases. Moreover, CFD simulations were performed using the Eulerian multiphase model and Reynolds Stress Model (RSM) for liquid-gas-sand flows to predict erosion patterns and magnitude.
On to Quantifying the Effect of Droplet Size Distribution on the Airborne Transmission of the Virus
Authors: Shrestha Rajendra , Delgado Juanpablo , Fontes Douglas , Stiehl Bernhard , Reyes Jonathan , Schroeder Steven , Ahmed Kareem , Kinzel Michael
Published: September 2022

This research will study a novel aspect of the physics of COVID-19 transmission associated with actively altering droplet size distribution. Viruses can be transmitted through droplets and aerosols released during speaking, sneezing, and coughing phenomena. We previously found that these distributions can be altered using food ingredients. The study will be carried out to study the hypothesis of relaxed guidance in social distancing and mask usage is possible with the proposed approach using CFD models of human sneezes. The adult human is positioned inside a ventilated room condition and the droplet/aerosols are to be released to explore the impacts of the various distributions that relate to how the food ingredients vary the function, hence, the size of the droplets will be the function of the use of food ingredients. Results study the concentration of droplet particles at various distances away from the mouth, also called exposure maps and indicate that Corn Starch and Xanthum usage increase the exposure intensity level, while Xanthum reducing the exposure area implies that social distancing can be reduced with its use. In contrast, the use of Lozenge and Zingiber reduces the exposure level, related to the increase in the viscosity and reduction of the mass flow rate of saliva.
Interactions of Aerosol Droplets With Ventilated Airflows in the Context of Airborne Pathogen Transmission
Authors: Schroeder Steven , Stiehl Bernhard , Delgado Juanpablo , Shrestha Rajendra , Kinzel Michael , Ahmed Kareem
Published: September 2022

This multidisciplinary study provides a comprehensive visualization of airborne aerosols and droplets coming into contact with crossflows of moving air utilizing both experimental particle measuring methods and multiphase computational fluids dynamics (CFD). The aim of this research is to provide a Eulerian visualization of how these crossflows alter the position and density of an aerosol cloud, with the goal of applying this information to our understanding of social distancing ranges within outdoor settings and ventilated rooms. The results indicate that even minor perpendicular crossflows across the trajectory of an aerosol cloud can greatly reduce both the linear displacement and density of the cloud, with negligible increases in density along the flow path.
Robust Strain/Rotation-Rate Tensor Reconstruction Based on Least Squares RBF-QR for 3D Lagrangian Particle Tracking
Authors: Li Lanyu , Sakib Nazmus , Pan Zhao
Published: September 2022

Based on the least squares and Radial Basis Function (RBF), we propose to use a robust method to reconstruct the velocity gradient and strain/rotation-rate tensor from Lagrangian Particle Tracking (LPT) data. A stable RBF method, RBF-QR, is employed to provide robust approximation in the flat limit of shape functions without suffering ill-conditioning. Least squares method enables the reconstruction of noisy data and further improves the robustness of the calculation on realistic experimental data. The use of Partition-of-Unity Method (PUM) localizes the calculation and allows handling large data set in 2D and 3D and improves computational efficiency. The accuracy and robustness of the method is validated on both 2D and 3D simulated LPT data with artificial noise based on Direct Numerical Simulation (DNS). The technique is further tested on the 3D LPT data obtained from a synthetic jet experiment.
Numerical Analysis to Study the Effect of Control Temperature Location Inside a Datacenter
Authors: Hashmi Atta Ul Mannan , Tipu Arshan Ahmed , Butt Fahad Rafi , Akhtar Imran , Khalid Muhammad Saif Ullah
Published: September 2022

Modern HVAC control systems lack any sort of a link between the temperature sensors and thermal fields inside closed environments. Whether it is the CRAHBP or a single-unit HVAC system, temperature sensors are coupled with the return air temperature. This connection causes HVAC systems to continue operating until the return air temperature falls below a value defined by an operator. It results in wastage of electricity, because a significant amount of electricity is used to cool down almost the entire closed environment. With rapid advancements in cloud computing services, the expansion of existing and establishment of new datacenters is expected to grow. A major portion of the total electricity consumption in datacenters is consumed by the HVAC equipment. In this work, through high fidelity numerical simulations, we show that a coupling between HVAC sensors and the temperature field in regions of interest inside datacenters can lead to substantial saving of energy. For this study, we consider a tier-2, localized datacenter. It should be noted that the implementation of the proposed flow control method presented in this research work will result in improvement of the overall efficiency of the HVAC system without any major changes to already existing infrastructures of datacenters. Our CFD simulations predict that implementing the proposed control method reduces the power consumption of cooling equipment in the datacenter by 23%.
Are Active Fluids Age-Dependent?
Authors: Samadi Zahra , Mehdizadeh Allaf Malihe , Vourc'h Thomas , DeGroot Christopher T. , Peerhossaini Hassan
Published: September 2022

Active fluids are often is known as the aqueous suspensions of self-propelled elements such as bacteria, algae, or sperm cells, which their properties fundamentally differ from conventional fluids. Active fluids exhibit remarkable physical manifestations over a wide range of scales, from time-dependent microscopic diffusion to the large-scale colonization of aqueous spaces. Properties of active fluids depend on the behavior of microbial suspensions, among which motility plays a crucial role.

In this work, we focus on the effect of microbial growth and aging on microorganism motility. Hence, the motility behavior of cyanobacterium Synechocystis sp. CPCC 534, and its relationship with aging were investigated in a closed microfluidic chip. The growth of Synechocystis cultures was followed from the lag phase, through exponential and linear growth up to the stationary phase. Culture samples were periodically examined; cell populations were measured by spectroscopy technique and cell trajectories were tracked by video-microscopy. Cell trajectory length and average cell motility were extracted from the video recordings and were correlated with the age and growth phase of the bacterium.
Experimental Investigation of Hybrid Propulsion Mechanism for Robotic Fish
Authors: Aly Abdulrahman , Omari Mohamad , Ghommem Mehdi , Romdhane Lotfi
Published: September 2022

In this work, we investigate the performance of a hybrid propulsion mechanism for a robotic fish based on the combined bending and flapping motions of a flexible tail with a bio-inspired caudal fin extension. The tail consists of an Aluminum substrate attached to a pair of macro-fiber composite (MFC) piezoelectric laminates and subject to flapping motion actuated by a servomotor. A testing platform, equipped with a distance laser sensor, is developed to measure the produced tail deformation over a range of actuation frequencies and amplitudes of lateral oscillations. The objective is to verify the biomimicry of the system and identify the optimal actuation that maximizes the thrust generation of the propulsive tail. Optimal actuation entails the vibration of the MFC at resonance and utilizing its dynamic model to synchronize its motion with that of a motor to produce a biomimetic motion. Frequency response curves are generated and verified against a model of underwater beam dynamics. The experimental component of the present work also includes the development of a robotic fish prototype that encompasses a main 3d-printed body designed as a streamlined waterproof enclosure of the electronics including a microcontroller, a Raspberry Pi camera module, and a high-voltage amplifier along with a servomotor actuating the bio-inspired tail. The mass distribution of the electronic components is adjusted to ensure the buoyancy of the robotic fish in water. Free-swimming tests of the robot are successfully conducted to demonstrate the performance of the hybrid propulsion mechanism in terms of forward swimming speed and maneuverability. The performance is then compared against other robotic fish works and found to provide a higher propulsion compared to smart material-based designs while also providing a smaller design compared to the motor-based solutions.
Immersed Boundary Method Implemented in LES for Flow Past a Sphere at Subcritical Reynolds Numbers
Authors: Marefat H. Ali , Alam Jahrul , Pope Kevin
Published: September 2022

Flow within the sub-critical range of Reynolds number around spherical bluff bodies has a complex dynamic behaviour due to transient fluid flow happening in the wake of the sphere. Large-eddy simulation and penalization methods have been used successfully for approximating these flows for the last two decades. In this work, a combination of two approaches is presented for flow past a spherical bluff body at sub-critical Reynolds numbers. Results at Re = 1000 presented in comparison with direct numerical simulation results and experimental data available in the literature. They show a very good agreement with data in the literature despite using a comparably large computational mesh. In addition, the essential characteristics of flow dynamics and the coherent vortical structures in the wake of the sphere are investigated and discussed in detail for Reynolds numbers less than 10,000.
System Dynamics and Tomography-Based Control of a Gas-Liquid Inline Swirl Separator
Authors: Garcia Matheus M. , Portela Luis M.
Published: September 2022

Swirl-based separators are widely used in the separation of two-phase flows with phases of different densities, e.g. in the oil and gas industry. The separation is based on centrifugal forces associated with the swirl motion, that splits the original mixture into a light-phase core and a heavy-phase annulus, captured by two separate outlets equipped with control valves. Due to the complex (unsteady) dynamics of the flow and variations in the mixture that reaches the separator, real-time controllers are required to keep the separation optimal. Traditionally, the control is based on pressure measurements at the boundaries of the separator. However, pressure is only indirectly related to the separation. A more direct (and potentially more effective) control variable is the distribution of phases inside the separator, which can be monitored using soft-field tomography. This idea is explored in this work using an air-water inline-swirl separator facility equipped with an Electrical Resistance Tomography (ERT) sensor, that determines the size of the air core in real-time using a newly developed fast ERT reconstruction algorithm. The dynamics of the system was studied for different valve actions and summarized into a Transfer Function of the process, which is used to design a PI controller. The approach was successful and the control strategy implemented kept the air core near the setpoint in the presence of disturbances in the air flow rate reaching the separator.
Effect of Porosity on Tool Wear During Micromachining of Additive Manufactured Titanium Alloy
Authors: Varghese Vinay , Mujumdar Soham
Published: September 2022

Porosity is a major quality issue in additively manufactured (AM) materials due to improper selection of raw material or process parameters. While porosity is kept to a minimum for structural applications, parts with intentional (engineered) porosity find applications in prosthetics, sound dampeners & mufflers, catalytic converters, electrodes, heat exchangers, filters, etc. During post-processing of additive manufactured components using secondary machining to obtain required dimensional tolerance and/or surface quality, part porosity could lead to fluctuating cutting forces and reduced tool life. The machinability of the porous AM material is poor compared to the homogenous wrought material due to the intermittent cutting and anisotropy of AM materials. The cutting parameters for machining are generally optimized for continuous wrought material and are not applicable for porous AM material. Micromilling experiments were carried out on AM Ti6Al4V alloy with different porosity levels and cutting speed using a 1 mm diameter end mill. The progression of tool wear and associated mechanisms during micro-milling of additive manufactured Ti6Al4V samples with different porosity levels are experimentally investigated. Insights into tool-workpiece interaction during micro-machining are obtained in cases where pore size could be comparable to the cutting tool diameter. This research could lead to efficient hybrid additive-subtractive manufacturing technologies with improved tool life and reduced costs.
Cold Spray Multilayer Metal Build-Up on a Polymeric Substrate
Authors: Tsai Jung-Ting , Jun Martin Byung-Guk , Bahr David F.
Published: September 2022

Copper (Cu) and Tin (Sn) were low-pressure cold sprayed onto polyamide 6 (PA 6) and polypropylene (PP) substrates. The first layer of Sn and Cu was built onto the polymer substrate and continued as an alternative layer of Cu and Sn build-up under controlled process parameters. The chronological order of either first spraying Cu or Sn does not hinder building a coated layer on the PA 6 and PP substrate. The coating thickness can reach as thick as 100 μm of the PA 6 (Cu/Sn/Cu) layer. Results show the potential ability for additive manufacturing using polymeric templates. The cold spray kinetic bonding of the metals avoids any intermediate phase formation. The mechanical performance of the coated material remains the same as the deposition process does not degrade bulk substrates. The contour of the interface and the surface roughness resulting from the cold spray coating process lead to a deformed surface layer of the polymer on the particle size of the powder used for cold spraying. While the metallic coating deforms via plastic deformation and cracking, the through-thickness cracks, which primarily are perpendicular to the loading direction, do not span the width of the coating due to the tortuous nature of the microstructure. The advantage provides electrical conductivity to strains of up to 10% and maintains a low electrical resistance.
Experimental and Numerical Investigation of Short-Term Bio-Degradation Behavior of 3D Printed PLA
Authors: Ilhan Recep , Senaysoy Safa , Lekesiz Huseyin
Published: September 2022

There has been an increasing interest for biodegradable polymers in recent years because they can be formed as scaffolds and safely removed from the body without the need for any surgical operation, and contribute to the healing process. However, the main problem in polymer-based biodegradable materials is the inability to obtain tunable biodegradation behavior to match healing, which limits the clinical feasibility of these biomaterials. In this study, it is aimed to model biodegradation behavior from short term experimental data in an effort to reduce time required for determination of bio-degradation parameters. Thus, the degradation behavior can be determined and controlled at a lower cost. In this context, the biodegradation behavior of poly-lactic acid (PLA) polymer which is widely used in biomedical applications, was investigated experimentally and numerically on different days related to fracture bone healing times (5–12 weeks). First, 4.5 mm × 4.5 mm × 4.5 mm cubes were printed using the fused deposition modelling (FDM). Then, printed samples were exposed to degradation in the incubator by immersion in phosphate buffered saline (PBS) solution at 37 °C at physiological conditions for different time periods (0, 15, 30, 61 and 90 days). Throughout degradation, water absorption, weight loss, mechanical properties and morphological changes were investigated. Water absorption increases up to 13% within 61 days and then decreases to 10% within 90 days. On the other hand, samples gain 1% weight for the first 15 days and following, start losing weight around 0.3% percent at the end of 90 days. This clearly indicates that degradation occurs and water replaces the degraded material. There are fluctuations in the stiffness values that decrease on the 15 and 61 days but they increase on the 30th and 90th days. The increases in stiffness can be attributed to the compressive resistance of the trapped water content. Microscopic investigation clearly verifies the water content that the colors of the samples (opacity increase) changed while no significant change in its size occurred at different degradation days. Experimental results indicate a degradation and mechanical behavior variation throughout the process while dimensional stability during the 90 day degradation period. Numerical model predicts the stiffness values reasonably well within 15 and 30 days of degradation, but differences for 61 and 90 days. This difference possibly stems from the fact that the numerical model does not include any water inclusion disturbance.
An Approach to Extend the Digital Thread From Requirements to Model Geometry
Authors: Zhou Jiwei , D. Camba Jorge , Hartman Nathan , Li Zhongtian
Published: September 2022

As organizations embrace Industry 4.0 and its corresponding digital transformation, new technologies and practices are enabling more resilient, integrated, and sustainable approaches to product development. Researchers have explored the information flows and data relationships between requirements management (RQM) practices and Computer-Aided Design (CAD) to improve New Product Development (NPD) processes. Similarly, Life Cycle Assessment (LCA) tools can be used to assess the environmental impact of a product at the early stages of development. In this paper, we propose a novel approach to integrate RQM, CAD, and LCA in the NPD process in a manner that extends the “digital thread” of information from the definition of design requirements to the geometry of the digital product model. Specifically, we demonstrate the seeding of mechanical design models directly from design requirements as a starting point for parametrization, the linking of data items to facilitate subsequent design changes involving geometry, and the use of data connections between requirements and 3D models for continuous design verification. Our approach is supported by a Product Lifecycle Management (PLM) system and involves a workflow with several stages and various inputs from stakeholders. We validate our approach through the implementation of a case study involving a mechanical assembly and a commercial PLM system.
Thermoplastic Forming Process for Manufacturing Arbitrary Blade Edge Geometries From Bulk Metallic Glass
Authors: Dancholvichit Nattasit , Salapaka Srinivasa , Kapoor Shiv
Published: September 2022

In corneal surgery, several incision instruments including the curvilinear or straight incision blades are required to construct a scleral tunnel to ensure that the wound is self-sealing after the operation. Bulk metallic glass (BMG) is proving to be a good candidate for making surgical blades, where sharp edges can be produced through a thermoplastic molding and a drawing process implemented by designing and controlling the drawing velocity at supercooled temperature. This article presents a mechanistic approach to obtain drawing velocity profile of drawing actuators that accommodates various shapes of the blade edges without having to carry out the entire extensional drawing process, which is extensive and tedious. To manufacture the multi-facet BMG knife blade edges that result in good quality, the velocity profile is developed based on the filament stretching process and the geometry and shape of the mold along with the blade profile to maintain the imposed flow stress during the blade edge formation. Two types of geometrical transformational features including drawing distance and offset angle of the draw direction to the profile, are considered to ensure that the flow stress of the drawing process is in the desirable Newtonian region. To demonstrate the feasibility of the proposed approach, H∞ control design is used to facilitate consistent good quality necking of the blade formation. The velocity profile of 45° and crescent BMG blades are generated and used to manufacture these blades. The 45° blade edge samples are successfully manufactured with the average of X-Z, X-Y straightness, and the edge radius of the blade of 1.4 ± 0.5 μm, 1.4 ± 0.5 μm, and 42.4 ± 2.3 nm, respectively. The crescent blade edge samples are manufactured with roundness deviation, and the edge radius of the blade of 5.4 ± 1.6 μm, and 35.7 ± 4.2 nm, respectively. The effects of BMG sample temperature settings on the quality of the manufactured blades are presented.
Image-Based Fractographic Pattern Recognition With Cluster Analysis
Authors: Guo Shenghan , Paradise Paul , Van Handel Nicole , Bhate Dhruv
Published: September 2022

Scanning Electron Microscopy (SEM) is traditionally leveraged to image fracture surfaces and generate information for analysis. Conventionally, experts identify patterns of interest in SEM images and link them to fracture phenomena based on knowledge and experience. Such practice has substantial limitations. It relies on expert opinions for decision-making, which poses barriers for practitioners without relevant background; manual inspection must be done for individual SEM images, thus time-consuming and inapt for industrial automation. There is a genuine demand for a fast, automatic method for fractographic pattern recognition. Targeting the problem, this study proposes a two-stage data-driven approach based on clustering. In offline analysis (Stage 1), a clustering algorithm identifies the generic fractographic patterns on part. Each pattern corresponds to a cluster. Expert evaluation of the part’s crack status is leveraged to map individual patterns (clusters) to a crack type. In in-situ monitoring (Stage 2), SEM images of new parts are matched to the clusters from stage 1, which reveals the generic patterns on the part and indicates the potential crack status. The proposed approach enables automatic fractographic analysis without experts. It is demonstrated to be effective on real SEM images of additively manufactured Inconel-718 specimens subjected to high cycle fatigue.
Decision Support for Locating Manufacturing Plants in Emerging Economies Using a Reliability Approach
Authors: Gadalla Mohamed , Azab Ahmed
Published: September 2022

In today’s distributed manufacturing reality, investors worldwide are faced with the dilemma of deciding on the optimal geographic spot for their manufacturing plants. On the one hand, emerging economies could be appealing because of their cheap labor as well as possibly their lack of or reduced regulations, litigation, and paperwork in some cases. On the other hand, these very same emerging economies can be quite risky because of the lack of stability of their political systems and hence, the associated economic volatility. Such economies can collapse in a relatively short period of time due to factors such as political instability, corruption, lack of democracy and the rule of law, social and racial injustices, and religious extremism, to name a few. In this paper, we propose a modeling approach where an economy is represented as an engineering system, the lifespan of which is subject to potential conditions, events, and failure modes. Such conditions and factors in the face of these fragile economies are modeled as pushers and deflators contributing to their instability. Hence, all laws of Reliability Engineering can be used to decide on the probability of success of such a system and its lifetime in the face of all uncertainty and given risks in today’s global climate. It is imperative that the health of the economic climate is a critical element solving the facility location and allocation problem; this entails deciding on large manufacturing investments in the form of new manufacturing plants being constructed and the accompanied supply chains. Enablers to allow for packageable manufacturing systems easier to relocate in the wake of this uncertain economic turmoil are also discussed. System Dynamics will be used as future work to account for the forces (deflators and pushers) when quantifying the proposed metrics. AI and Data Analytics techniques are also recommended to quantify the reliability parameters.
A Functionally Gradient NiTi Shape-Memory Alloy Fabricated by Selective Laser Melting
Authors: Li Kun , Zhan Jianbin , Ma Ruijin , Ren Yingzhi , Lin Jinxin
Published: September 2022

The near-equiatomic NiTi alloy has a shape memory function, but the simple forming structure limits its application. Selective laser melting is a promising way to manufacture functionally complex structures due to its layer-wise production advantage, which could broaden the applications of NiTi alloy in the engineering fields. This work explored a novel method of controlling the repetition of laser remelting to manufacture NiTi alloys with multiple phase-transformation temperatures via selective laser melting (SLM). The results demonstrates that the remelting strategy not only increases the ultimate tensile strength and elongation of the SLMed NiTi alloy, but also increases the Ms above room temperature. The increase in laser power increases the temperature at which martensite starts (Ms) to transformation in the range higher room temperature (25°C), thus increasing the critical stress of martensitic detwinning in the final sample. Through the optimized repetitive laser remelting strategy with different laser powers on specific areas of the sample, a functionally gradient NiTi build is successfully obtained. This study suggests SLM embedded with laser remelting is a potential method to realize 4D printing for NiTi alloys.
Directed Energy Deposition Using Non-Spherical Metal Powders?
Authors: Garg Richie , Singh Dhami Harish , Ranjan Panda Priti , Viswanathan Koushik
Published: September 2022

Metal additive manufacturing (AM) enables the production of non-trivial geometries and intricate internal structures. Directed energy deposition (DED) is one such AM process that has the inherent advantage of producing multi-material components on complex pre-existing geometries. Significant recent interest in DED processes has been driven by the need for inexpensive powders and potential material recycling. In this work, we explore the possibility of using non-standard arbitrary shaped metal powders within the DED process. A standard numerical model, comprising a three-dimensional viscous, compressible, turbulent solver with two-way discrete phase coupling is employed to understand the mechanics of gas-driven non-spherical powder flow. Spatial distributions of non-spherical powder on a set of pre-existing geometric features (e.g., corners, curved surfaces) are evaluateds and compared with standard spherical powders. The effect of particle collisions on the substrate is evaluated and corresponding density distributions are quantified. Non-spherical particles are generally found to exhibit higher velocities, and greater deposition track width, compared to spherical particles. Our simulations also reveal the effect of particle shape on their flow properties and final powder density. Using a custom-built DED configuration, we present preliminary experimental results of single-track depositions using both spherical and non-spherical powder particles. Based on our findings, we make a case for the use of non-spherical powders for DED applications.
Vibration Reduction in Robotic Milling Through Spindle Speed Modulation
Authors: Huschke Dominic , Melkote Shreyes N.
Published: September 2022

A simple strategy for the reduction of vibrations during robotic milling is proposed. Here, the vibrations are reduced through a sinusoidal variation of the spindle speed as has been done in machine tools. Experimental results show a significant reduction in the measured forces. Furthermore, an improvement of the generated surfaces through modulation of the spindle speed is observed. Based on the experimental results, a simple empirically-based control strategy for the on-line detection and reduction of vibrations through spindle speed modulation is implemented. On-line detection of vibrations is achieved through comparison of the measured and the expected forces, which are calculated using a mechanistic milling force model.
Ultra-Fine Bubbles (UFB) Inserted Novel Coconut Oil Based Metal Working Fluid (MWF) As a Sustainable Lubricant for Turning of Ti-6Al-4V
Authors: Wickramasinghe K. C. , Sasahara Hiroyuki
Published: September 2022

As for the first time in the advanced manufacturing research and development sector, the nano range bubbles (i.e., UFB) were injected to the coconut oil-based metal working fluid (COCO) to facilitate better cooling and lubrication condition for machining difficult to cut materials. Higher heat transfer characteristics, and better purification properties of the UFB were incorporated to the higher free fatty acid contained COCO to facilitate a favorable machining condition. Moreover, COCO ensures health and environmental friendliness and express higher potential to replace the toxic and hazardous synthetic oil based MWF (SynO) from the machining process. In this study, the cooling and lubrication performance of the UFB inserted novel COCO was clarified and benchmarked with a commercially available high performance SynO for machining Ti-6Al-4V. Eighteen percent cutting force reduction was obtained due to the hybrid effect of UFB and free fatty acid. Additionally, lower work tool interface temperature, surface roughness, and tool wear were obtained at the UFB inserted COCO compared to the SynO. Hence, the excellent tribological and rheological properties of the UFB inserted novel COCO has concluded high performance sustainable machining and provided a promising solution to conquer the challenges (i.e., low machinability index and sustainability) of machining Ti-6Al-4V.
1D and 2D Nanoparticle Assembly Compliant With Tuned 3D-Printed Topology
Authors: Jambhulkar Sayli , Song Kenan
Published: September 2022

Nanoparticle-included polymeric composite coatings with preferential nanoparticle alignment and oriented structures show improved functional and structural properties than randomly oriented structures, suitable for broad applications in microelectronics, automobile, defense, and space missions. Traditionally used techniques, such as drop-casting, chemically modified surfaces, and external fields, have been used for self-assembly but with several disadvantages, such as material limitations. Thus, there is a need to develop a new approach for generating hierarchical nanoparticle structures. Our unique processing is based on advanced additive manufacturing with a colloidal suspension-based deposition approach for layer-by-layer deposition of anisotropic nanoparticles. Leveraging the colloidal deposition technique, these anisotropic nanoparticles were deposited onto the 3D printed substrates with designed patterning. The presence of micropatterns generates selective nanoparticle distribution and assembly along with hydrodynamic forces to initiate the region-specific microscale patterning and nanoscale alignment of 1D and 2D nanoparticles. The polymer and nanoparticle composite film showed different deposition morphologies (e.g., straight or wavy films). In addition, the influence of nanoparticle deposition morphology on functional properties was investigated. This novel technique shows the potential to scale up microelectronics production by 3D printing electronic structures, including interdigitated devices, supercapacitors, fuel cells, and circuits.
Tooling Engineering and its Role in Manipulating Fiber Spinning and Enabled Nanostructures
Authors: Xu Weiheng , Song Kenan
Published: September 2022

One of the challenges to multimaterial multifunctional composite fibers is their scalability during the fabrication process. Additive manufacturing is a cost-effective tooling solution for fast prototyping fiber spinning spinnerets. This work demonstrates a laser powder bed fusion-based tri-axial spinneret that could accommodate three different materials as inner, middle, and outer layers. In the first work, continuous graphene nanoplatelets (GnPs) channel was embedded between core polymer and sheath polymer layers to simultaneously achieve electrical conductivity and high mechanical properties. This multimateiral, multichannel system is too expensive with conventional manufacturing. Our 3D printed spinneret will generate shear stress during the polymer drawing process, resulting in thinning and alignment of the two-dimensional (2D) GnPs. Similarly, in the second research, a multilayered chemiresistor for volatile organic compounds (VOCs) was fabricated in a single step. Each layer played a significant role in the overall sensor functionalities. For instance, (i) the hollow core supported inline gas transportation, (ii) the porous polymer inner layer assisted VOC diffusion, (iii) the middle electrical conductive layer responded to VOCs types and concentrations, and (iv) the outer mechanically stable layer secured sensor’s physical stability.
Digital Twin Platforms: Architectures and Functions
Authors: Huang Huiyue , Ji Tang , Xu Xun
Published: September 2022

In the Industry 4.0 era, many emerging technologies are being embraced by manufacturers, including Digital Twin (DT) technology. DT has been known as a critical enabler for smart manufacturing and has attracted much attention from academia and industry. Meanwhile, the demand for DT platforms is growing as they enable more effective and easy development and deployment for DTs. DT expands to different industrial scenarios, which has led to an increasing variety of DT platforms. However, there are many different understandings and concepts of DT from diverse backgrounds, so it is essential to acquire a good understanding of DT platforms. This paper aims to provide a literature review of DT platforms in manufacturing. Firstly, the current state of DT technology is presented, and a generalized definition of the DT platform is proposed. A comprehensive search for literature related to the DT platform was conducted using the Web of Science database through the definition. Meanwhile, the importance of ISO 23247, an international standard on DT frameworks for manufacturing, has been discussed to give a general view of requirements for building a DT platform. After that, typical DT platforms in both academia and industry were analyzed separately. Finally, a discussion is carried out to summarise the architecture, features, and functions that are important for DT platform development.
Metal Powders via Surface Grinding: Applicability and Performance Evaluation for Laser Sintering
Authors: Singh Dhami Harish , Panda Priti Ranjan , Saikiran Puli , Viswanathan Koushik
Published: September 2022

Commercial metal powders used as feedstock for additive manufacturing (AM) applications are primarily produced via gas or water atomization techniques. These are highly capital-intensive and inflexible, making the resulting powders as much as 3–10 times more expensive than corresponding cast ingots. Recently, we have demonstrated a potential alternative route for making metal powders — using surface grinding. The resulting powders have shown promise for use as stock in metal directed energy deposition (DED) processes. This work explores the applicability of these alternatively produced powders for laser sintering and related applications. Spherical metal powder particles (AISI 52100, SS 304) in the range of 5–100 microns were first produced using surface grinding. These powders were post-processed and segregated into monodisperse and polydisperse batches, representing high quality-low yield and low-quality-high yield stock, respectively. A high-power fiber laser source of 50 microns spot diameter was used to sinter these two stock powders, with nitrogen as a shielding gas, and their performance was evaluated using a range of ex situ analysis techniques. The latter included metallography, SEM/EDS and XRD analysis and was used to evaluate sintering quality in both cases, including melt pool and heat-affected zone characterization. Based on these results, we present recommendations for the use of mono- and polydisperse metallic powders and demonstrate the potential utility of using grinding as an alternative technique for the production of metal powders for laser sintering applications.
Time Domain Simulation of Turning Operations With Flank Textured Tool
Authors: Suzuki Norikazu , Fujinaka Tsubasa , Yokokawa Yuya
Published: September 2022

A flank textured cutting tool has been proposed to improve the chatter stability in cutting. Although excellent stability improvement effects have been reported through experimental studies, a simulation method to estimate the effects has not been established so far. In this study, we propose a time-domain simulation method that can take into account the effect of the flank face textures. In order to consider the effect of arbitrary texture geometry on the flank face, the finite element method (FEM) analysis is applied. The relationship between the chatter vibration and the process damping force is modeled, and the process damping coefficients, which represents the process damping effect quantitatively, is obtained. The process damping coefficients are calculated comprehensively by considering the regions where the amplitude and wavelength of chatter vibration can generate. To verify the validity of the proposed method, the face turning experiment was conducted with the prototyped tools consisting of two straight cutting edges. As a result of the verification experiment, it was confirmed that the chatter stability was improved by using a flank-textured tool. The proposed method could demonstrate roughly this chatter stabilization phenomenon.