bluuebunny/crossref_metadata_2025 huggingface dataset:
The Fabrication of Thin Film NiTi Shape Memory Alloy Micro Actuator for MEMS Application
Authors: Gill John J. , Ho Ken , Carman Gregory P.
Published: December 2021

Thin film SMA (Shape memory alloy) is a useful method for MEMS (Microelectromechanical Systems) actuator. This is because the thin film has an improved frequency response compared to bulk SMA, high work density, and produces large strain. A novel two-way thin film NiTi (Nickel Titanium) shape memory alloy actuator is presented in this paper. Thin film shape memory alloy is sputter-deposited onto a silicon wafer in an ultra high vacuum system. Transformation temperatures of the deposited NiTi film are measured by residual stress measurement at temperatures from 25 ° C to 120 ° C. Test results show that the Mf (Martensite Finish Temperature) is around 60 ° C and Af (Austenite Finish Temperature) is around 110 ° C. A free standing NiTi membrane (10 mm × 10mm and 3 μm thick) is fabricated using MEMS technology. We found that a mixture of HF (Hydro Fluidic Acid), HNO3 (Nitric Acid) and DI (Deionized) water with thick photo resist mask works best for the fabrication process. The membrane is hot-shaped in different shapes such as dome shape, pyramidal shape, and cylindrical shape. Results indicate that when the temperature of the NiTi film exceeds Af, the NiTi membrane transforms into the trained hot-shape. When the temperature cools down to room temperature, the membrane returns to the initial flat shape.
Adaptive Spindle Balancing Using Magnetically Levitated Bearings
Authors: Barney Patrick , Lauffer James , Redmond James , Sullivan William , Petteys Rebecca
Published: December 2021

A technological break through for supporting rotating shafts is the active magnetic bearing (AMB). Active magnetic bearings offer some important advantages over conventional ball, roller or journal bearings such as reduced frictional drag, no physical contact in the bearing, no need for lubricants, compatibility with high vacuum and ultra-clean environments, and ability to control shaft position within the bearing. The disadvantages of the AMB system are the increased cost and complexity, reduced bearing stiffness and the need for a controller. Still, there are certain applications, such as high speed machining, biomedical devices, and gyroscopes, where the additional cost of an AMB system can be justified. The inherent actuator capabilities of the AMB offer the potential for active balancing of spindles and micro-shaping capabilities for machine tools. The work presented in this paper concentrates on an AMB test program that utilizes the actuator capability to dynamically balance a spindle. In this study, an unbalanced AMB spindle system was enhanced with an LMS (Least Mean Squares) algorithm combined with an existing PID (proportional, integral, differential) control. This enhanced controller significantly improved the concentricity of an intentionally unbalanced shaft. The study included dynamic system analysis, test validation, control design and simulation, as well as experimental implementation using a digital LMS controller.
Fuzzy Logic Semi-Active Vibration Control
Authors: Kim Sunghwan , Clark William W.
Published: December 2021

Fuzzy logic control is so-called artificial intelligence because control laws are designed by human decision, not by deterministic numerical calculations. This paper investigates the effectiveness of a fuzzy logic control method in vibration control with a semi-active MR fluid actuator. The system to be controlled is a simply supported beam to which is applied a persistent excitation. Numerical simulation and experimental tests are performed. Three semi-active control laws, one deterministic and two fuzzy-logic, were applied and compared on the basis of vibration control performance and energy consumption. These controllers are compared to the baseline fully-on control where the MR fluids are energized so that the actuator performs as a tuned passive damper. Simulation and experimental data were examined.
Three-Dimensional Microvascular Networks Fractal Structure: Potential for Tissue Characterization?
Authors: Craciunescu Oana , Das Shiva K. , Dewhirst Mark W.
Published: December 2021

It has been shown that the fractal dimension of 2D microvascular networks can discriminate between normal vs. tumor tissue (Gazit et al., 1995, 1997). We have determined the fractal characteristics of five 3D microvascular networks and conclude on the correlation between the computed fractal characteristics and the nature of the tissue of origin. The networks considered in the fractal analysis study were one rat tumor network (RT), one nude mouse tumor (NMT), one hamster skeletal muscle (HSM), one rat cremaster (RC), and one rat cerebral cortex (RCC). The networks were digitized in a 3D lattice starting from the known length, diameter and position of each segment in the network. The digitization process was performed such that the ratio between the initial occupation fraction of the vessels in the network and the occupation fraction after digitization is close to one. The resultant cubic lattices were analyzed using the concept of asymptotic fractals. The fractal dimension df, and the minimum path dimension dmin (that measures the tortuosity of the vessels) were determined for all the networks. Fractal behavior was noticed on length scales from 1–1.3 decades, dependent on the actual network size. The values obtained for the fractal dimension for the RT, NMT, RCC, RC and HSM microvascular networks are respectively, 2.6, 2.2, 2.29, 2.12 and 2.08. For the minimum dimension the values obtained are: 1.2, 1.1, 1.16, 1.1, and 1.1. By analyzing the available data, preliminary conclusions lead us to believe that a correlation between the fractal characteristics and tissue type might exist. Another important aspect is that the 3D RT microvascular network seems to have a percolation-like scaling which can be beneficial in monitoring the growing pattern using invasion percolation growth models. However, for general conclusions to be drawn, more networks have to be analyzed.
Osmotic Stress Initiates Intracellular Calcium Waves in Chondrocytes Through Extracellular Influx and the Inositol Phosphate Pathway
Authors: Erickson Geoffrey R. , Guilak Farshid
Published: December 2021

The biophysical environment of the chondrocytes plays an important role in the health, turnover, and homeostasis of articular cartilage. Under normal physiologic loading, chondrocytes are exposed to a complex and diverse array of biophysical signals, including mechanical and osmotic stresses, fluid flow, and fluid pressures [4]. Due to the charged and hydrated nature of the extracellular matrix, mechanical compression causes exudation of interstitial fluid in cartilage, which alters the osmotic environment of the chondrocytes. Confocal microscopy studies have shown that chondrocytes lose or gain volume in response to tissue compression [4] or changes in extracellular osmolarity [3]. The active process of volume recovery subsequent to osmotic shock has been shown to initiate intracellular signaling cascades [2], which may in turn alter cellular metabolism [6]. Although the mechanisms of intracellular signaling in response to osmotic stress are not fully understood, it has been hypothesized that intracellular transients and oscillations of calcium ion (Ca2+) are involved. The objective of this study was to examine the hypothesis that osmotic stress initiates a transient increase in the concentration of intracellular calcium ion ([Ca2+]i), and to determine the mechanisms of Ca2+ mobilization in isolated chondrocytes exposed to hypo- and hyper-osmotic stress.
Exploration of an Animal Model for Hypertrophic Scar Formation
Authors: Sojka Erik S. , Balis Ulysses , Sheridan Robert , Fowler Alex
Published: December 2021

In this paper we investigate the possibility of creating an animal model for hypertrophic scar formation by grafting healthy split thickness human skin onto the backs of athymic nude mice and then burning the grafts. We were able to show that the human tissue grafts do remain stable over extended periods and prove that the human dermis does not get infiltrated by mouse tissue. By burning the grafts for ten seconds at 70°C we found that we could not reproduce results previously reported; but by changing the burn parameters we were able to produce regions of dermal disorder that may indicate the formation of hypertrophic scar. These results represent the first replication of positive results using this animal model since it was first proposed 10 years ago.
The Question of Thermal Waves in Heterogeneous and Biological Materials
Authors: Tilahun Muluken , Scott Elaine P. , Vick Brian
Published: December 2021

There have been two recent experimental studies that have sparked a renewed interest in thermal wave behavior at the macro-scale level. Both reported thermal relaxation times of 10 seconds or higher. However, no further experimental evidence of this behavior has been reported. Due to the extreme significance of these findings, the objectives of this study were to try to reproduce these earlier studies and offer an explanation for the outcome. These two previous studies were repeated following the experimental protocol provided in the studies as closely as practically possible. First, studies on heterogeneous materials were repeated using sand, an ion exchanger, and NaHC03. A second set of experiments was conducted on bologna. In both cases, the temperature response to a specified boundary condition was recorded. The results from the first set of experiments suggested that the thermal relaxation times presented in the previous study were actually the thermal lag expected from applying Fourier’s Law taking into account the uncertainty of the temperature sensor. In the second set of experiments, unlike the distinct jumps in temperature found previously, no indication of wave behavior was found. Here the explanation for the previous results was more difficult to ascertain. Possible explanations include problems with either the data acquisition system or the temperature sensors used.
A Simplified Model for Encapsulated Phase Change Material
Authors: Hayes Linda J. , Spieker Michael A. , Wissler Eugene H. , Colvin David P.
Published: December 2021

One of the emerging technologies of this decade is macroencapsulated phase change materials (PCM), which is being developed to provide significantly enhanced thermal management for coolants, textile fibers, foams, composites and coatings with applications to avionics, spacesuits, machine coolants, apparel, packaging, and agriculture (Kaska and Chen, 1985, Colvin and Mulligan 1989). The encapsulated PCM is embedded or suspended in a conductive media. The characteristics of the capsules, the phase change material and the conductive media can be designed so as to provide enhanced thermal management in a wide variety of applications. The traditional way to model this system is to take a macroscopic view of the entire system, to use a volume averaged value for the release of latent heat from the PCM and to incorporate this term into the standard heat conduction equation. We propose a simplified model which has its origins in flow in porous media. The system is modeled with two components, the underlying conductive material and the phase change capsules. The amount of latent heat released from the PCM capsules is determined by the local temperature in the capsules, which can differ from the temperature in the conducting media. This model closely represents the physical systems which are being modeled Numerical results using this model are compared to experimental data from a garment layer which is constructed using macroencapsulated PCM capsules.
Melt Spun Fibers Containing Microencapsulated Phase Change Material
Authors: Bryant Yvonne G.
Published: December 2021

MicroPCMs are successfully being incorporated into solution-spun acrylic fibers, significantly increasing their thermal energy storage capability. However, melt-spun fiber production far exceeds that of acrylic fiber. Thus, the commercial potential of melt-spun fibers and resulting fabrics with enhanced thermal energy storage capabilities is enormous for the apparel and industrial insulation markets. However, at melt spinning temperatures, i.e., at temperatures > 200° C, microencapsulated phase change materials (microPCMs) lose their core material, which corrupts the melt spinning process. Before these materials can successfully be incorporated into melt spun fibers, microcapsules < 10 microns in size must be available with a more stable wall structure. This paper will discuss the results of NSF sponsored Phase I and II Small Business Innovation Research (SBIR) grants that investigated PCM microcapsules for high temperature application, and describe their inclusion into melt-spun fibers.
Three-Dimensional Analyses of Single Rivet-Row Lap Joints — Part I: Elastic Response
Authors: Iyer K. , Rubin C. A. , Hahn G. T.
Published: December 2021

Three-dimensional finite element analyses (FEA) of an elastic, single rivet-row, aluminum alloy lap joint are presented. The effects of rivet geometry (countersinking), rivet material and interfacial friction coefficient are examined. Interference and lateral clamping are not treated. Panels loaded in tension with vacant, tapered holes are also examined. Load transfer through the joint, the joint compliance, rivet-tilt, the local slips at rivet-panel and panel-panel interfaces, contact pressures and local stresses are evaluated. Relations between these features and the contact and bending driven stress concentration are clarified. The work shows that the stress concentration factor, rivet-panel slips, peak stresses, contact pressures and rivet deformation are all related, and increase with the severity of the countersink. Panel bending, rivet tilt and countersinking introduce large, out-of-plane stress gradients and shift the peak stresses to the interior surface of the countersunk panel. The results demonstrate the importance of out-of-plane distortions in accounting for the behavior of the riveted lap joints. Three opportunities are identified for improving lap joint performance without increasing the weight.
Two-State Conservation Integrals and Stress Singularities in Generic Wedges
Authors: Im Seyoung , Lee Yongwoo
Published: December 2021

The eigenvalues of Williams’ series expansion for generalized wedge problems, which include cracks, re-entrant corners, free edges, and cracks meeting with material interface, etc. are examined from the viewpoint of conservation laws like J-integral and M-integral. By use of the so-called two-state conservation laws or interaction energy, originally proposed by Eshelby and later treated by Chen and Shield, discussed is that the complementary pairs of eigenvalues exist in the J-integral sense and/or in the M-integral sense when these integrals are conserved. Similar results are shown to hold for the eigenvalues of three dimensional wedges.
Fatigue Behavior of Notched Resin Infusion Molded S2-Glass Twill Woven Composites
Authors: Kelkar Ajit D. , Chaphalkar Pramod
Published: December 2021

The present study provides the performance evaluation of 2 × 2 twill woven composite (S2-Glass and C-50 resin system) material for Integral Armor applications. The laminates were fabricated by using VARIM or RI (Vacuum Assisted Resin Infusion Molding). These components are expected to be under fatigue loading. Fatigue behavior of the unnotched and notched twill woven laminate is presented. Tension-Compression (R = −1) fatigue experiments were performed for both unnotched and notched panels. All the fatigue tests were performed at 1 Hz frequency. S-N diagram and stiffness degradation over the fatigue life of the specimen was obtained.
A Manufacturing Enterprise for Undergraduates, Phase I Report: Implementation
Authors: Carranti Frederick J.
Published: December 2021

An undergraduate course in the fundamentals of manufacturing processes has recently been redesigned to include a significant laboratory experience. Part of the motivation for this redesign was as a response to certain competency gaps in graduating engineers as identified by the Society of Manufacturing Engineers and by the industrial partners of the University. The nature of this laboratory experience prompts the students to participate in and manage an actual manufacturing enterprise. Many facets of a real company are explored including design, manufacturing, operations, accounting, purchasing, and marketing. The students are engaged in the design and production of a line of novelty items sold to the greater university community, and, in addition to product design, are also engaged in the design of all tooling and methods required for production. Due to the holistic nature of the experience, student enthusiasm and involvement are very high, and faculty endorsement has resulted in the course being named a required part of the curriculum for all future students in mechanical engineering. This paper describes the initial implementation of this course.
Mechatronics as a Capstone Design Course
Authors: Murray William R. , Garbini Joseph L.
Published: December 2021

Capstone design courses in engineering, which provide students the opportunity to tackle open-ended, real-world projects, are generally held in high regard as learning experiences. A relatively new and increasingly important component of engineering is the area of mechatronics. In this paper, we review the goals of capstone design courses and examine how well suited mechatronics projects are for use as projects in capstone design courses. Our experiences in using mechatronics projects in the senior-level capstone design course in the Department of Mechanical Engineering at the University of Washington are presented. From these experiences, we demonstrate that mechatronics projects are particulary well suited for use in capstone design.
Failure Analysis of a Shaft Belonging to a Ship Engine Speed Controller
Authors: Figueiredo Miguel V. , Oliveira Fernando M. , de Castro Paulo T. , Fernandes António A.
Published: December 2021

The fracture of a shaft belonging to the speed controller of a ship’s engine is presented. An over-speed situation occurred as a result of the fracture of this shaft, which led to severe damage to the engine.

The failure examination concentrated first on the study of the available evidence, which included the analysis of the shaft’s material and fracture surface.

The shaft’s material was studied as concerns chemical composition, mechanical properties and micrographic structure. The fracture surface was studied using scanning electron microscopy. Several different destructive laboratory tests were conducted on the material, in order to obtain fracture surfaces which could be used for comparison purposes, and thus help to identify the cause of the fracture.

The next step of the failure analysis consisted of a stress analysis of the shaft under service conditions.

A probable scenario for the failure was proposed, which helped the interested parties to reach an agreement concerning responsibilities for the failure. It was found that the shaft material presented low notch toughness. The stress levels at the time of the accident imply that it is unlikely that the fracture was due to fatigue. The probable cause of the failure was sudden blockage of the shaft.
Prediction of Looper Response in the Hot Strip Finishing Mill
Authors: Hsu Yuan-Liang , Cheng Chi-Cheng , Wen San-Lan
Published: December 2021

The looper system, located midway between adjacent stands, is a mechanical levitation device commonly applied on modern hot strip mills. In order to fully understand factors affecting the looper’s behavior and predict its motion during rolling processes, a comprehensively mathematical simulation model of the looper control system for a hot strip tandem mill is developed. The simulator includes three system modules: the looper regulator module, the looper dynamics module, and the mass flow module. Simulation results demonstrate good compatibility with position measurement of real rolling processes. Looper responses under circumstances of different original strip lengths and a varying roller speed are specifically examined. Based on this looper simulator, valuable information can be easily obtained for possible improvements on rolling processes in the future.
Manufacturing Process Optimization With Artificial Neural Networks
Authors: Sihn Wilfried , Schmidt Thomas
Published: December 2021

Today’s manufacturing methods are caught between the growing need for quality, high process safety, minimal manufacturing costs, and short manufacturing times. In order to meet these demands, process setting parameters have to be selected carefully with close attention being paid to quality needs. For such optimization it is necessary to represent the processes in a model. Due to the enormous complexity of many processes and the high number of influencing parameters, however, conventional approaches to modeling and optimization are no longer sufficient. This article shows how the application of neural networks for process modeling can simplify these highly complex interdependences so that both process and quality parameters can be assessed before or during processing. By connecting them with corresponding cost models, it is possible to optimize processes with the help of evolutionary algorithms. Using different manufacturing processes as examples, the authors demonstrate how process modeling can be optimized using neural networks and evolutionary algorithms.
A 3-D Closed-Form Cutting Force Model for End Milling With Application to Sculptured Surface Milling
Authors: Lee T. S. , Farahati R. , Lin Y. J.
Published: December 2021

A comprehensive, 3D mathematical model of desired/optimal cutting force for end milling of free-form surfaces is proposed in this paper. The closed-form predictive model is developed based on a perceptive cutting approach resulting in a cutting force model having a comprehensive set of essential cutting parameters. In particular, the normal rake angle usually missing in most existing models of the same sort is included in the developed model. The model also enables quantitative analyses of the effect of any parameters on the cutting performance of the tool, providing a guideline to improving the tool performance. Since the axial depth of cut varies with time when milling sculptured surface parts, an innovative axial depth of cut estimation scheme is proposed for the generation of 3-D cutting forces. This estimation scheme improves the practicality of most existing predictive cutting force model for milling in which the major attention has been focused on planar milling surface generation. In addition, the proposed model takes the rake surface on the flute of mills as an osculating plane to yield 3-D cutting force expressions with only two steps. This approach greatly reduces the time-consuming mathematical work normally required for obtaining the cutting force expressions. A series of milling simulations for machining free-form parts under scenario cutting conditions have been performed to verify the effectiveness of the proposed cutting force model. The simulation results demonstrate accurate estimating capability of the proposed method for the axial depth of cut estimation. The cutting force responses from the simulation exhibit the same trends as what can be obtained using the empirical mechanic’s model referenced in the literature. Finally, through the simulation results it is also learned that designing a tool with a combination of different helix angles having cutting force signatures similar to that of the single helix angle counterparts is particularly advantageous.
Application of an Internally Consistent Material Model to Determine the Effect of Tool Edge Geometry in Orthogonal Machining
Authors: Schimmel Roy J. , Endres William J. , Stevenson Robin
Published: December 2021

It is well known that the edge geometry of a cutting tool affects the forces measured in metal cutting. Two experimental methods have been suggested in the past to extract the ploughing (non-cutting) component from the (total) measured force; 1) the extrapolation approach and 2) the dwell force technique. This study reports the behavior of zinc during orthogonal machining, using tools of controlled edge radius. It was determined that application of neither the extrapolation nor dwell approaches yielded a material response that is consistent with the known behavior of zinc. Further analysis shows that the edge geometry modifies the shear zone of the material and thereby modifies the forces. When analyzed this way, the measured force data yield the expected material response without requiring recourse to an additional ploughing component.
Generalized Modeling of Milling Mechanics and Dynamics: Part II — Inserted Cutters
Authors: Engin Serafettin , Altintas Yusuf
Published: December 2021

Inserted cutters are widely used in roughing and finishing of parts. The insert geometry and distribution of inserts on the cutter body vary significantly in industry depending on the application. This paper presents a generalized mathematical model of inserted cutters for the purpose of predicting cutting forces, vibrations, dimensional surface finish and stability lobes in milling. In this paper, the edge geometry is defined in the local coordinate system of each insert, and placed and oriented on the cutter body using cutter’s global coordinate system. The cutting edge locations are defined mathematically, and used in predicting the chip thickness distribution along the cutting zone. Each insert may have a different geometry, such as rectangular, convex triangular or a mathematically definable edge. Each insert can be placed on the cutter body mathematically by providing the coordinates of insert center with respect to the cutter body center. The inserts can be oriented by rotating them around the cutter body, thus each insert may be assigned to have different lead and axial rake angles. By solving the mechanics and dynamics of cutting at each edge point, and integrating them over the contact zone, it is shown that the milling process can be predicted for any inserted cutter. A sample of inserted cutter modeling and analysis examples are provided with experimental verifications.
Improved Generalized Intelligent Grinding Advisory System
Authors: Lee Cheol W. , Shin Yung C.
Published: December 2021

The intelligent grinding advisory system (Shin et al., 1992), which was further expanded to the generalized intelligent grinding advisory system (GIGAS) by Vishnupad and Shin (1998), provides a novel way of incorporating heuristic knowledge, analytical equations, experimental data into optimization of grinding processes. The improvement of GIGAS, especially in the solution’s accuracy and convergence property for complex multi-modal processes, is sought in this study. A method of combining fuzzy rules is proposed with other modifications. Simulation studies with numerical examples and a cylindrical grinding process show that the improved fuzzy optimization algorithm can achieve numerical accuracy comparable to that of conventional optimization methods while it retains the benefits of the original GIGAS algorithm in computational efficiency, robustness and the ability to incorporate heuristic knowledge. Finally, the improved GIGAS, constructed by combining the improved optimization algorithm with the generalized grinding models, is presented.
A Strategy for the Sensor Placement Optimization for Machine Thermal Error Compensation
Authors: Ma Youji , Yuan Jingxia , Ni Jun
Published: December 2021

This paper proposes a strategy of optimizing temperature sensor placement for thermal error compensation based on dynamic characteristics of temperature field and thermal deformation of a machine tool structure. A simple example of one-dimensional thermal expansion is given to signify the importance of sensor placement to the accuracy and robustness of thermal error modeling. Time and frequency domain analyses of optimal sensor placement are carried out for the simple one-dimensional thermal expansion and then extended to more complex two and three-dimensional thermal expansions. To apply the strategy to a machine tool, a new method of analyzing machine tool thermal errors called thermal deformation chain analysis is proposed to predetermine the sensor locations on a machine tool structure. The method is very effective in identifying thermal error contributors and their significance, and has been proven to be efficient in choosing sensor locations on a turning center.
System Modeling to Support Variation Reduction in a Sheet Stretch Forming Manufacturing System
Authors: Suri Rajiv , Otto Kevin
Published: December 2021

Quality is a major issue in the production of sheet stretch-formed aircraft skins. A typical stretch-forming system is composed of a series of operations, including heat treatment, stretch forming, chemical milling, and trimming. Each of these operations is subject to significant input and process variation, leading to variation on the work-in-process. This variation then results in fit-up problems at the assembly stage and high scrap or rework cost. In this paper we use a mathematical model of a stretch-forming manufacturing system to aid in reducing end-of-line variation. For the paper we reduce the system to two key operations: heat treatment and stretch forming. Physics-based mathematical models of each are used to derive a variational model of the system, which maps output quality characteristic variations to input variations. This variational model is used to identify the major sources of variation in the system: aging time and forming force. To reduce the effects of these variables, a feed-forward control strategy is proposed, in which aging time is measured after heat treatment and used to determine force during stretch forming. Feedback control is not effective. Analytical expressions are developed to predict the effects of the system control strategy on end-of-line variation. Finally, the results of a shop floor implementation of this strategy are presented, showing a 30% reduction in strain variation on production parts.
Detection of Roller Bearing Conditions Using Mechatronics Approach
Authors: Liu T. I. , Ordukhani F.
Published: December 2021

An on-line monitoring and diagnostic system is needed to detect faulty bearings. In this work, by applying the feature selection technique to the data obtained from vibration signals, six indices were selected. Artificial neural networks were used for nonlinear pattern recognition. An attempt was made to distinguish between normal and defective bearings.

Counterpropagation neural networks with various network sizes were trained for these tasks. The counterpropagation neural networks were able to recognize a normal from a defective bearing with the success rate between 88.3% to 100%. The best results were obtained when all the six indices were used for the on-line classification of roller bearings.
Effect of Cutting-Edge Geometry and Workpiece Hardness on Surface Residual Stresses in Finish Hard Turning of AISI 52100 Steel
Authors: Thiele Jeffrey D. , Melkote Shreyes N. , Peascoe Roberta A. , Watkins Thomas R.
Published: December 2021

An experimental investigation was conducted to determine the effects of tool cutting-edge geometry and workpiece hardness on surface residual stresses for finish hard turning of through-hardened AISI 52100 steel. Polycrystalline cubic boron nitride (PCBN) inserts with representative types of edge geometry including “up-sharp” edges, edge hones, and chamfers, were used as the cutting tools in this study. This study shows that tool edge geometry is highly influential with respect to surface residual stresses, which were measured using x-ray diffraction. In general, compressive surface residual stresses in the axial and circumferential directions were generated by large edge hone tools, for longitudinal turning operations. Residual stresses in the axial and circumferential directions generated by small edge hone tools are typically more tensile than stresses produced by large edge hone tools. Microstructural analysis shows that thermal effects are significant at high feed rates, based on the presence of phase changes on the workpiece surface. At high feed rates, compressive stresses correlate with continuous white layers and tensile stresses correlate with over-tempered regions on the surface of the workpiece. Mechanical effects play a larger role at low feed rates, where phase changes are not observed to a significant degree. For these cases, large edge hone tools generally produce more compressive values of residual stress than small edge hone tools.
Machine-Tool Chatter Suppression by Multi-Level Random Spindle Speed Variation
Authors: Yilmaz Alpay , AL-Regib Emad , Ni Jun
Published: December 2021

This paper presents a new method for varying the spindle speed to suppress chatter in machining. The spindle speed is varied in pseudo-random fashion within the bandwidth of the spindle system. Both implementation issues and spindle system responses to such signals are investigated. A new method to analyze the stability of machining systems with varying spindle speed is also introduced. The effectiveness and advantages of the random spindle speed variation in chatter suppression is verified using numerical simulations and experiments.
On Simulation of Bend/Reverse Bend of Sheet Metals
Authors: Zhao K. M. , Lee J. K.
Published: December 2021

Bend/reverse bend tests are performed with a three-point bend test apparatus on two types of sheet metals, mild steel and high strength steel. The bend/reverse bend process tends to a steady cycle upon applying repeated cycles of displacements. Strain hardening and Bauschinger effects for both materials are detected. Three different hardening laws are used to simulate the bend process numerically. Isotropic hardening law overestimates the hardening component and by missing the Bauschinger effect and the plastic shakedown. Kinematic hardening rule underestimates the hardening component and exaggerates the Bauschinger effect. The combination of isotropic and nonlinear kinematic hardening predicts accurately both the Bauschinger effect and the plastic shakedown. The hardening parameters in the combined model are identified inversely by using micro genetic algorithm.
Design and Control of a Spherical Air Bearing System for Multi-DOF Ball-Joint-Like Actuators
Authors: Lee Kok-Meng , Ezenekwe Dan E. , He Tian
Published: December 2021

This paper presents an analytical investigation on the design method and modeling of an air bearing system for ball-joint-like actuators. It addresses the method of regulating the three DOF translations of the rotor introduced by the air bearing system and thereby improving the dynamic performance of the orientation motion manipulation. The kinematics, which relates the rotor displacement and the air gaps, are essential for design optimization, dynamic simulation and motion control, are derived in closed-form. With a detailed modeling of the pressure-flow relationship as a function of the rotor position, the forces and dynamics of the system are formulated, and design methods of regulating the rotor displacement have been explored analytically. Simulation results suggest that the fluid forces could be generated to passively stabilize the otherwise open loop unstable electromagnetic system. It is expected that this research will be a basis for designing and evaluating an improved VR spherical motor with enhanced torque capability by eliminating mechanical friction.
Transport Phenomena in Heterogeneous Media: Experimental Data Reduction and Analysis
Authors: Travkin V. S. , Catton I. , Hu K. , Ponomarenko A. T. , Shevchenko V. G.
Published: December 2021

Volume averaging theory (VAT) is used to bring a consistent basis to experimental data reduction and analysis by examples in several areas of transport phenomena. Many common correlations, and their weaknesses, are examined using a unified scaling procedure that allows them to be compared to one another. Momentum resistance and internal heat transfer dependencies are analyzed and compared. VAT based analysis is shown to reveal the influence of morphological characteristics of the media, to suggest scaling parameters that allow a wide variety of different porous media morphologies to be normalized, often eliminating the need for further experimental efforts, and to clarify the relationships between differing experimental configurations. The origin, and insufficiency, of electrical conductivity and momentum transport “cross-correlation” approaches in efforts to find analogies by mathematical comparison without examining the physical foundations of phenomena are described and explained.
Mesoscale Combustor/Evaporator Development
Authors: Brooks Kriston P. , Martin Peter M. , Drost M. Kevin , Call Charles J.
Published: December 2021

Battelle has developed a mesoscale combustor/evaporator that provides a lightweight and compact source of heating, cooling, or energy generation for both man-portable and stationary applications. The device uses microscale flow channels that increase the available surface area for heat transfer and reduce the fluid boundary layer. These characteristics in turn result in heat fluxes for hydrocarbon/air combustion in excess of 25 W/cm2 and thermal efficiencies of 80 to 90%. Furthermore, high heat transfer rates allow for short channels and reduced pressure drops.

Recent development efforts have focused on obtaining low emissions and improving the combustor/evaporator fabrication process. By using spatially varying stoichiometry inside the combustor, catalyst coated microchannels, and increased coolant temperature, the combustor’s CO and NOx emissions were reduced to below California standards for hot water heaters and boilers. The fabrication process photochemically machines thin metal laminates and then uses diffusion bonding to form a monolithic component. This approach is capable of high fin aspect ratios and can be scaled up for mass production.
Thermo-Electro-Mechanical Refrigeration Based on Transient Thermoelectric Effects
Authors: Miner Andrew , Majumdar Arun , Ghoshal Uttam
Published: December 2021

This paper introduces the concept of a thermo-electro-mechanical cooler (TEMC), which modifies a traditional thermoelectric cooler (TEC) by using intermittent contact of a mechanical element synchronized with an applied pulsed current. Using Bi2Te3 as the thermoelectric material, it is predicted that the maximum temperature drop across a TEMC may be as much as 35 percent higher than that of a TEC in low heat flux applications. This effectively increases the figure of merit by a factor of 1.8.
Heat Recovery Enhancement and Operational Issues of a 200 kWe Fuel Cell Cogeneration Plant
Authors: Söderlund Erika , Martin Andrew R. , Alvfors Per , Forsman Jonas , Sarközi Laszlo
Published: December 2021

This study presents some of the experiences gained during a two year operational period of a decentralized fuel cell cogeneration plant installed in southern Sweden. Various modifications to the system are described, most notably a plume eliminator for the reduction of an undesirable vapor cloud emitted by the original system. Aside from vapor cloud elimination, the plume eliminator allows for more efficient plant operation, as a larger fraction of the system cooling requirements can be shifted to the district heating system. In-field measurements show a 17 to 26% increase in district heat production with use of the plume eliminator, depending upon the season of operation (winter or summer). The study also presents two options for added heat recovery, which are employed in conjunction with the plume eliminator: an air preheater module; and an air preheater/humidifier module. Calculations show that air preheating has a small but measurable impact on heat recovery (an additional 8% gain), while combined air preheating and humidification allows for nearly a 50% increase in district heat production.
Predicting the Effect of Gas-Flow Channel Spacing on Current Density in PEM Fuel Cells
Authors: Naseri-Neshat Hamid , Shimpalee Sirivatch , Dutta Sandip , Lee Woo-kum , Van Zee J. W.
Published: December 2021

The effects of change in diffusion layer width for constant diffusion layer thickness and constant gas-flow channel width are investigated with a straight channel model of a Proton Exchange Membrane (PEM) fuel cell. A three-dimensional 10-cm long straight channel model of the PEM fuel cell is presented. The geometrical model includes diffusion layers on both the anode and cathode sides and the numerical model couples three-dimensional Navier-Stokes flow with electro-chemical reactions occurring in the fuel cell. Contours of the current density, anode water vapor concentration, anode water activity, water molecules per proton flux, and secondary flow velocity vectors at different cross sections are presented for the two diffusion layer widths. For the particular conditions and properties used for this study, the results show a marked difference between the base case (0.16-cm) and the wide (0.72-cm) diffusion layer. The current density is quite uniform at different axial cross sections and cross-flow sections for the 0.16-cm wide diffusion layer. However, for the 0.72-cm wide diffusion layer, the current density decreases more significantly in the axial direction near the edges of the diffusion layer. Numerical predictions of the water transport between cathode and anode across the width of the MEA show the delicate balance of diffusion and electro-osmosis and their effect on the current distribution along channel.
Evaluation of Insulated Pressure Vessels for Cryogenic Hydrogen Storage
Authors: Aceves Salvador M. , Martinez-Frias J. , Garcia-Villazana O.
Published: December 2021

This paper presents an analytical and experimental evaluation of the applicability of insulated pressure vessels for hydrogen-fueled light-duty vehicles. Insulated pressure vessels are cryogenic-capable pressure vessels that can be fueled with liquid hydrogen (LH2) or ambient-temperature compressed hydrogen (CH2). Insulated pressure vessels offer the advantages of liquid hydrogen tanks (low weight and volume), with reduced disadvantages (lower energy requirement for hydrogen liquefaction and reduced evaporative losses).

The purpose of this work is to verify that commercially available aluminum-lined, fiber-wrapped vessels can be used for cryogenic hydrogen storage. The paper reports on previous and ongoing tests and analyses that have the purpose of improving the system design and assure its safety.

The analytical and experimental results carried out until now indicate that it may be possible to use fiber-wrapped aluminum-lined vessels for operation at LH2 temperature and high pressure. Required future tests are described that will assure vessel safety under daily operating conditions.
Operating Characteristics of Natural Gas Fueled Homogeneous Charge Compression Ignition Engine
Authors: Kawabata Y. , Nakagawa K. , Shoji F.
Published: December 2021

Recently, a new design of engine combustion that achieves higher efficiency and less NOx emission has been proposed. Some researchers have started studying the concept, which is called Homogeneous Charge Compression Ignition (HCCI), but there have been few reports on investigations using a future prospective alternative fuel, natural gas.

In this study, natural gas fueled operation of HCCI using a single cylinder gas engine was conducted. Operating and exhaust characteristics were obtained. Experimental data confirmed the potential of higher efficiency and less NOx emission, though THC and CO were higher. Based on these data, the feasibility of this concept for gas engines is also examined.
Thermodynamic and Hydraulic Testing of Cryogenic Turbines
Authors: LeGoy Philip R. , Cengel Yunus A.
Published: December 2021

Thermodynamic and hydraulic testing of the newly developed Cryogenic Hydraulic Radial Turbine-Generator assembly was successfully performed. It is an alternative to the conventional Joule-Thompson valve used in Cryogenic Liquefaction plants.

Included in this process was the complete design and manufacture of the first turbine of this kind from concept to the prototype turbine, the creation of a test bed and the development of algorithms for the analysis.

Significant power recovery and refrigeration were demonstrated by testing. This is an advantage over the Joule-Thompson valve, which wastes power potential and adds to the refrigeration load. Up to 78% isentropic efficiency for the Turbine-Generator assembly and up to 0.84°C temperature drop across the turbine are calculated from test data.

A “rule of thumb” is presented to identify conditions under which the use of a turboexpander is justified.
The Application of Multi-Zone Thermal Radiation Models to Investigate the Energy Efficiency of a Metal Reheating Furnace Under Start Up Conditions
Authors: Ward John , Correia Sara A. C. , Sousa João L. V. A.
Published: December 2021

The zone method of radiation analysis has been widely used in mathematical models of a range of industrial heating processes. This paper is thus concerned with the use of a two-dimensional, multi-zone model to predict fuel consumptions, heating rates and load temperatures following the “cold start up” of a gas-fired furnace heating steel bars to a nominal discharge temperature of 1250°C. The model takes into account variations in the flows of the combustion products and in particular examines the influence of the re-circulation of these hot gases within the furnace chamber. The predictions of this complex two-dimensional model are compared with those of a one-dimensional so-called “long furnace model” to illustrate the differences resulting from the use of a more sophisticated multi-zone model.
Analysis of Nonlinear Flexural Behavior of Thick Composites With Fiber Waviness
Authors: Chun H.-J. , Lee S. W. , Daniel I. M.
Published: December 2021

A finite element analysis model was developed to predict flexural behavior of thick composites with uniform, graded and localized fiber waviness. In the analyses, material and geometrical nonlinearties due to fiber waviness were incorporated into the model utilizing energy density and an incremental method. In the model, two kinds of geometrical nonlinearity were considered, one due to reorientation of fibers and the other due to difference of curvatures from one finite element to another during deformation. The finite element analyses utilize the iterative mapping method to incorporate these geometrical nonlinear factors. The model was used to predict not only the flexural behavior of a flat thick composite plate but also of a thick composite plate with initial curvature. Flat composite specimens with various degrees of fiber waviness were fabricated and four-point flexural tests were conducted. The predicted nonlinear behavior by the current model was compared with results from the thin slice model [7] and experiments. Good agreement was observed among them.
Dynamic Behavior of Fiber Reinforced Composites Under Multiaxial Compression
Authors: Oguni Kenji , Ravichandran G.
Published: December 2021

Results from an experimental investigation on the mechanical behavior of a unidirectional reinforced polymer composite with 50% volume fraction E-glass/vinylester under uniaxial and proportional multiaxial compression are presented. Specimens are loaded in the fiber direction using a servo-hydraulic material testing system for low strain rates and a Kolsky (split Hopkinson) pressure bar for high strain rates, up to 3000 s−1. The results indicate that the compressive strength of the composite increases with increasing levels of confinement and increasing strain rates. Post-test optical and scanning electron microscopy is used to identify the failure modes. The failure mode that is observed in unconfined specimen is axial splitting followed by fiber kink band formation. At high levels of confinement, the failure mode transitions from axial splitting to kink band formation and fiber failure. Also, a new energy based analytic model for studying axial splitting phenomenon in unidirectional fiber-reinforced composites is presented.