bluuebunny/crossref_metadata_2025_split huggingface dataset:
Corrosion Characterization of Resistance Spot Welded Aluminum and Steel Couple
Authors: Maddela Surender , Carlson Blair E. 
Published: November 2019

Abstract
The corrosion resistance of resistance spot welded (RSW) Al-steel couples of varying combinations of 6016-T4 aluminum alloys and steel substrates, including with and without adhesive at the faying interface has been successfully evaluated, and compared to corresponding self-pierce riveted (SPR) couples. The corrosion resistance of resistance spot welded Al-steel couples has performed well in cyclic corrosion testing (GMW 17026) and the results are comparable to or better than that of self-pierce riveted couples. SPR couples are more susceptible to galvanic corrosion than resistance spot-welded couples based upon experimentally measured electrochemical potentials from actual joints. The presence of adhesive acts significantly to reduce galvanic corrosion between aluminum alloy and steel substrates, and moreover tensile lap-shear strength significantly increased with structural adhesive for both RSW and SPR joining systems. However, despite the presence of adhesive the lap-shear strength was reduced by more than 50% after cyclic corrosion testing to strength levels comparable to the lap-shear strength of couples having no adhesive and tested in ambient conditions.
Effect of Time Spacing and Hatch Spacing on Thermal Material Properties and Melt Pool Geometry in Additive Manufacturing of S316L
Authors: Mirkoohi Elham , Sievers Daniel E. , Liang Steven Y. 
Published: November 2019

Abstract
A physics-based analytical solution is proposed in order to investigate the effect of hatch spacing and time spacing (which is the time delay between two consecutive irradiations) on thermal material properties and melt pool geometry in metal additive manufacturing processes. A three-dimensional moving point heat source approach is used in order to predict the thermal behavior of the material in additive manufacturing process. The thermal material properties are considered to be temperature dependent since the existence of the steep temperature gradient has a substantial influence on the magnitude of the thermal conductivity and specific heat, and as a result, it has an influence on the heat transfer mechanisms. Moreover, the melting/solidification phase change is considered using the modified heat capacity since it has an influence on melt pool geometry. The proposed analytical model also considers the multi-layer aspect of metal additive manufacturing since the thermal interaction of the successive layers has an influence on heat transfer mechanisms. Temperature modeling in metal additive manufacturing is one of the most important predictions since the presence of the temperature gradient inside the build part affect the melt pool size and geometry, thermal stress, residual stress, and part distortion. In this paper, the effect of time spacing and hatch spacing on thermal material properties and melt pool geometry is investigated. Both factors are found statistically significant with regard to their influence on thermal material properties and melt pool geometry. The predicted melt pool size is compared to experimental values from independent reports. Good agreement is achieved between the proposed physics-based analytical model and experimental values.
Recycling of Printed Circuit Boards by Direct Molding Technology
Authors: Quadrini F. , Bellisario D. , Tedde G. M. , Santo L. 
Published: November 2019

Abstract
The recovery and reuse of printed circuit boards (PCBs) is becoming crucial in the management of electronic waste that is undergoing an exponential increase. In this study, a simple and eco-friendly process for recycling waste PCBs is discussed. In particular, composite panels were produced by reusing 100% of waste PCBs without the addition of any additive or virgin material. After a two-step grinding process, ground PCB was used to mold panels by direct molding which is pure compression molding without material sorting. Results were very promising in terms of process feasibility and part performances. Molded samples had density about 1.45 g/cm3, flexural modulus and flexural about 3 GPa and 16 MPa, respectively. A smooth surface with low friction coefficient was obtained for the recycled panels. The study shows that despite the presence of metal and other non-metal non-organic fractions, waste PCBs can be re-processed in profitable and environmentally conscious way without the addition of any bonding agent or additive. The recycling technology can be extended to the reuse of the non-metallic fraction only, after separation and recovery of metals.
Sedimentation Study of Bioink Containing Living Cells
Authors: Xu Heqi , Xu Changxue , Zhang Zhengyi 
Published: November 2019

Abstract
3D bioprinting has more and more applications in tissue engineering, in vitro drug testing, and regenerative medicine. The bioink consisting of the biocompatible polymer (as extracellular matrix) and the living cells is the starting material. Because the typical bioprinting process may take several hours, the suspended cells in the bioink sediment with time, which significantly affects the bioink stability as well as the following bioprinting quality and reliability. The cell sedimentation is determined by the integral effects of drag force and buoyancy and gravity. The gravitational force is related to the cells, and the drag force and buoyant force is related to the polymer concentration. This paper is the first paper to quantify the cell sedimentation process of the bioink within 0.5% and 1% (w/v) polymer concentrations respectively. The cell sedimentation phenomenon has been observed using the bioink within 0.5% and 1% (w/v) polymer concentrations. The cell sedimentation velocity has been estimated to be 1.18 μm/s with the polymer concentrations to be 0.5% (w/v) and 0.88 μm/s for the bioink with the polymer concentrations to be 1% (w/v). It is also found that the cell concentration increases significantly at the bottom of the bioink reservoir, resulting in cell aggregates due to cell-cell interaction.
Experimental and Numerical Analyses on the Poly(Lactide-Co-Glycolide) Hollow Fiber Membranes
Authors: Wang Zonghuan , Yin Jun 
Published: November 2019

Abstract
The hollow fiber membranes (HFMs) were widely used as tissue engineering scaffold. The efficacy of the HFMs were affected by the porosity of the HFMs. In this study, the HFMs were prepared with dry-jet wet spinning method. In order to improve the performance of the HFMs, different spinning parameters were applied to systematically investigating the effects of the fabrication conditions on the porosity of the HFMs. A 1-D diffusion model was set to numerically study the volume fraction distribution along the wall thickness. The porosity of the HFMs show a significant decrease in the porosity as the dope concentration increases. The morphology analyses showed that a higher dope concentration leads to a denser porous structure which result in a lower porosity. The results were discussed based on the phase inversion process and the 1-D model was built to numerically analyze the polymer volume fraction distribution in the HFMs cross section. This study can help to better understand the effects of the different fabrication conditions on the morphology of the HFMs.
Modeling and Experimental Study of the Impact on Free Abrasive Machining (FAM) due to Vibration of a Thin Wire Subject to an Oscillating Boundary Condition
Authors: Li Liming , Kao Imin 
Published: November 2019

Abstract
This paper investigates the impact on free abrasive machining (FAM) process using a vibrating wire with an oscillating boundary condition. The experimental results show that the vibration of wire in slurry with abrasive grits can result in material removal due to FAM on brittle material. We present a theoretical model of a wire moving axially at a constant speed, subject to an oscillating boundary condition with damping, and derive an analytical solution of the partial differential equation of motion. Based on the modeling and analysis, the frequency of vibration of wire corresponds to the frequency at the oscillating boundary at steady state. The damping factor suppresses the lateral movement of wire from the fixed boundary to moving boundary when it is increased. The change of axial wire speed or the oscillating frequency at boundary can counteract the suppression on the vibration response induced by increased damping factor. This study also presents an experimental study using an experimental setup of a slurry-fed wire with a periodic excitation to study the FAM process on silicon. The results of experiments show that vibration of wire can impart the silicon carbide abrasive grits in slurry to generate observable grooves and fractures on the surface of silicon in just a few minutes. The grooves and fractures are generated by the indentation of abrasive grits via loading and unloading on the silicon surface. When the vibrating wire is only fed with water without abrasives or under a dry condition, compressive deformation with shallow grooves on silicon is observed; however, the surface is found to be free of surface features of indentation and scratching. Furthermore, evidence of both wire compression and abrasive machining is more pronounced at the edges of silicon specimen, especially at the edge close to the periodic excitation, which is consistent to our modeling.
A High-Fidelity Thermal Model for a Novel Droplet-Based Additive Manufacturing Process for Polymers
Authors: Schroeffer Andreas , Maciuga Thomas , Struebig Konstantin , Lueth Tim C. 
Published: November 2019

Abstract
The claim in additive manufacturing (AM) changes from simply producing prototypes as show objects to the fabrication of final parts and products in small volume batches. Thereby the focus is on freedom of material, dimensional accuracy and mechanical component properties.
A novel extrusion-based AM technology has been developed focusing on these issues. The working principle is to form spheres from a thermoplastic polymer melt and build parts by single droplets. The material preprocessing is similar to the injection molding technology and enables a wide range of different thermoplastic polymers as build materials. With the droplet-based working principle high mechanical component properties and dimensional accuracy can be reached compared to similar processes.
Further improvements to the process need a detailed knowledge of the physical effects during the build process. The temperature distribution during the manufacturing process determines at which temperature material is fused and how solidification takes place and shrinkage can occur or is suppressed. Thus, it has a significant influence on the mechanical properties and warpage effects of produced parts.
In this work a thermal model is presented that describes the heat transfer during the build process. The necessary input data are the material properties and a print job description including the part geometry and building strategy. The basic idea is to simulate each single droplet deposition by applying a dynamic Finite Element Method. All relevant heat transfer effects are analyzed and represented in the model.
The model was validated with measurements using a thermal imaging camera. Several measurements were performed during the build process and compared to the simulation results. A high accuracy could be reached with an average model error of about 4° Celsius and a maximal error of 10° Celsius.
Rotary Ultrasonic Machining of Basalt Rock Using Compressed Air As Coolant: A Study on Edge Chipping and Surface Roughness
Authors: Fernando Palamandadige , Zhang Meng , Pei Zhijian , Owens Adam 
Published: November 2019

Abstract
The aim of this study is to investigate the edge chipping and surface roughness of basalt rock processed by rotary ultrasonic machining (RUM) using compressed air as coolant. Basalt rock is commonly used as a building and construction material for foundations and dams, as well as in architectural designs such as constructing thin veneers and facades. Rotary ultrasonic machining, a hybrid process of grinding and ultrasonic machining, is employed to drill difficult-to-machine materials such as ceramics, composites, titanium alloys, stainless steel, etc. RUM has many advantages over conventional machining processes such as twist drilling. These advantages include lower cutting force, higher surface quality, lower tool wear, etc. This paper is the first in literature to report a study on edge chipping and surface roughness on RUM of basalt rock using cold compressed air as coolant. The effects of three input variables (tool rotation speed, feedrate, and ultrasonic power) on cutting force, torque, edge chipping, and surface roughness were studied. Experimental results obtained from this investigation show that RUM with cold air as the coolant has the capability to machine holes in basalt rock with a surface roughness of less than 3.5 μm without severe edge chipping.
An Analysis of Recent Standards on Composite Product Models to Enable Digital Transformation of Composite Product Manufacturing
Authors: Hedberg Thomas , Feeney Allison Barnard , Srinivasan Vijay , Hunten Keith 
Published: November 2019

Abstract
ASME and ISO are issuing new editions of their standards that deal with definitions and models for composite products. The new edition of ASME Y14.37 deals with standardized product definition for composite parts. The Edition 2 of ISO 10303-242 contains standardized data models for three-dimensional representations of composite products. This paper analyzes several salient features of these two standards with a focus on their potential impact on the digital transformation of composite product manufacturing. It also provides a mathematical and information theoretic exposition of ply table as an important representation for modeling some of the complex composite products and their manufacturing processes.
Ultrasonically-Induced Patterning of Viable Cells in Viscous Bioinks During 3D Biofabrication
Authors: Chansoria Parth , Shirwaiker Rohan 
Published: November 2019

Abstract
In attempts to engineer human tissues in the lab, bio-mimicking the cellular arrangement of natural tissues is critical to achieve the required biological and mechanical form and function. Although biofabrication employing cellular bioinks continues to evolve as a promising solution over polymer scaffold based techniques in creating complex multi-cellular tissues, the ability of most current biofabrication processes to mimic the requisite cellular arrangement is limited. In this study, we propose a novel biofabrication approach that uses forces generated by bulk standing acoustic waves (BSAW) to non-deleteriously align cells within viscous bioinks. We computationally determine the acoustic pressure pattern generated by BSAW and experimentally map the effects of BSAW frequency (0.71, 1, 1.5, 2 MHz) on the linear arrangement of two types of human cells (adipose-derived stem cells and MG63) in alginate. Computational results indicate a non-linear relationship between frequency and acoustic pressure amplitude. Experimental results demonstrate that the spacing between adjacent strands of aligned cells is affected by frequency (p &lt; 0.0001), and this effect is independent of the cell type. Lastly, we demonstrate a synergistic technique of gradual crosslinking in tandem with the BSAW-induced alignment to entrap cells within crosslinked hydrogels. This study represents an advancement in engineered tissue biofabrication aimed at bio-mimicry.
Degradation Assessment of Reciprocating Seal Using Support Vector Regression
Authors: Ramachandran Madhumitha , Keegan Jon , Siddique Zahed 
Published: November 2019

Abstract
Reciprocating seal located directly on the rod/piston of a reciprocating equipment is used for preventing leakage and reducing wear between two parts that are in relative motion. Degradation assessment of reciprocating seal is extremely important in the manufacturing industry to avoid fatal breakdown of reciprocating equipment and machines. In this paper, we have proposed a data-driven prognostics approach using friction force to predict the degradation of reciprocating seal using Support Vector Regression. Statistical time domain features are extracted from friction force signal to reduce the complexity of raw data. Principal Component Analysis is used to fuse the relevant features and remove the redundant features from the process. Based on the selected features, a Support Vector Regression model is then built and trained for the prediction of seal degradation. A Grid search method is used to tune the hyperparameters in the SVR model. Run-to-failure data collected from an experimental test set-up is used to validate the proposed methodology. The study findings indicate that a small set of relevant features which can represent the pattern related to degradation is sufficient to have a high prediction accuracy. The seal tested for this study comes from oil and gas industry, but the proposed method can be implemented in any industry with reciprocating equipment and machines.
Design of Flexible Membrane Fixture for Automobile Door-Trim Infra Stake Welding Machine
Authors: Park Hong-Seok , Namjil Khash-Ochir 
Published: November 2019

Abstract
Flexible membrane fixture is new technology which can adapt to the workpiece shape and size change, such as automobile door-trim parts manufacturing. Due to the use of flexible membrane fixture, significantly reducing manufacturing cost and replacing fixture time. In this paper, the design of the flexible membrane fixture is generated, and the application is showed in a case. Natural rubber sheet used as a flexible membrane. The membrane inflation model generated by ANSYS using Mooney-Rivlin method and its simulation result compared with the experiment result. The door-trim model developed by AUTODESK INVENTOR modelling software. This 3-D geometric model was imported to using ANSYS Workbench 18.2. The Finite element analysis was done after assigning loading and boundary conditions. The applied load considered for this analysis is the pressure applied to the membrane while the door-trim clamped by side clamps. The result shows that Flexible membrane fixture has higher flexibility and fixtured door-trim has smaller deformation value than company requirement. Through comparing the design results, it is found that flexible membrane fixture has higher elastic behaviour.
Numerical Analysis of In-Process Heat Transfer and Material Flow During Dissimilar Friction Stir Welding Process
Authors: Chen Gaoqiang , Liu Xun , Shi Qingyu 
Published: November 2019

Abstract
Friction stir welding (FSW) has been successfully applied to join dissimilar materials in engineering applications. Fundamental understanding on the underlying physical principles of the dissimilar FSW process is generally required to achieve strong and reliable joints. In this study, we aim to develop a theoretical and numerical model based on computational fluid dynamics (CFD) in order to analyze the in-process heat transfer and material flow during the dissimilar FSW of aluminum and steel. The model describes the coupling behavior between the material distribution, thermal-mechanical properties, interfacial friction, heat generation and transfer. To account for the different material behaviors in stirring zone, a VOF-based approach is adopted. In this paper, preliminary numerical simulation is conducted. Simulation results show that the current modeling approach has the capability to capture the material mixing during the dissimilar FSW of aluminum and steel. The predicted temperature field is shown to be asymmetrical, which is attributed to the different properties of aluminum and steel. The predicted thermal history agrees with the experimental measurements in the literature.
Joint Formation and Mechanical Performance of Friction Self-Piercing Riveted Aluminum Alloy AA7075-T6 Joints
Authors: Ma YunWu , Li YongBing , Lin ZhongQin 
Published: November 2019

Abstract
AA7xxx series aluminum alloys have great potentials in mass saving of vehicle bodies due to pretty high specific strength. However, the use of these high strength materials poses significant challenges to traditional self-piercing riveting (SPR) process. To address this issue, friction self-piercing riveting (F-SPR) was applied to join aluminum alloy AA7075-T6 sheets. F-SPR is realized by feeding a high speed rotating steel rivet to aluminum alloy sheets to form a dissimilar material joint. The effects of spindle speed and rivet feed rate on F-SPR joint cross-section geometry evolution, riveting force and energy input were investigated systematically. It was found that the rivet shank deformation, especially the buckling of the shank tip before penetrating through the top sheet has significant influence on geometry and lap-shear failure mode of the final joint. A medium rivet feed rate combined with a high spindle speed was prone to produce a defect free joint with sound mechanical interlocking. F-SPR joints with the failure mode of rivet shear fracture was observed to have superior lap-shear peak load and energy absorption over the joints with mechanical interlock failure. The optimized F-SPR joint in this study exhibited 67.6% and 13.9% greater lap-shear peak load compared to, respectively, SPR and refill friction stir spot welding joints of the same sheets. This research provides a valuable reference for further understanding the F-SPR process.
Cone Electrospinning Polycaprolactone / Collagen Scaffolds With Microstructure Gradient
Authors: Nowlin John , Islam Md Maksudul , Zhou Yingge , Tan George Z. 
Published: November 2019

Abstract
Polycaprolactone (PCL) is a synthetic biomaterial that has been widely used for tissue engineering scaffolds. Collagen, a natural polymer found in various tissues in the human body, can be electrospun in combination with PCL to improve the scaffold’s biological characteristics for cell attachment, growth and differentiation. Recreating the physical structure which mimics the extracellular matrix of musculoskeletal tissues generally requires fibrous patterns, including aligned, random, or a mixture of both to form a gradient structure. This study introduced a novel cone rotation electrospinning technique for nanofiber scaffold with microstructure gradient. The effects of key process parameters on nanofiber attributes were evaluated through a factorial design of experiment. We found that changing the rotation speed, electrospinning distance, and position on the cone had significant effects on the structure gradient of nanofiber mats. This cone rotation technique extends the capability of conventional electrospinning to create tunable anisotropic nanofiber scaffolds as potential biomimetic solutions for tissue regeneration.