bluuebunny/crossref_metadata_2025_split huggingface dataset:
Three-Dimensional Transient Heat Conduction Equation Solution for Accurate Quantification of Heat Transfer Coefficient in Transient Liquid Crystal Experiments
Authors: Ahmed Shoaib , Singh Prashant , Ekkad Srinath V. 
Published: January 2020

Abstract
Liquid crystal thermography and infrared thermography techniques are typically employed to measure detailed surface temperatures, where local heat transfer coefficient (HTC) values are calculated by employing suitable conduction models. One such practice, which is very popular and easy to use, is the transient liquid crystal thermography using one-dimensional semi-infinite conduction model. In these experiments, a test surface with low thermal conductivity and low thermal diffusivity (e.g. acrylic) is used where a step-change in coolant air temperature is induced and surface temperature response is recorded. An error minimization routine is then employed to guess heat transfer coefficients of each pixel, where wall temperature evolution is known through an analytical expression. The assumption that heat flow in the solid is essentially in one-dimension, often leads to errors in HTC determination and this error depends on true HTC, wall temperature evolution and HTC gradient. A representative case of array jet impingement under maximum crossflow condition has been considered here. This heat transfer enhancement concept is widely used in gas turbine leading edge and electronics cooling. Jet impingement is a popular cooling technique which results in high convective heat rates and has steep gradients in heat transfer coefficient distribution. In this paper, we have presented a procedure for solution of three-dimensional transient conduction equation using alternating direction implicit method and an error minimization routine to find accurate heat transfer coefficients at relatively lower computational cost. The HTC results obtained using 1D semi-infinite conduction model and 3D conduction model were compared and it was found that the heat transfer coefficient obtained using the 3D model was consistently higher than the conventional 1D model by 3–16%. Significant deviations, as high as 8–20% in local heat transfer at the stagnation points of the jets were observed between h1D and h3D.
Period-1 Motions in a Periodically Forced, Nonlinear, Machine-Tool System
Authors: Xing Siyuan , Luo Albert C. J. 
Published: January 2020

Abstract
In this paper, period-1 motions in a two-degree-of-freedom, nonlinear, machine-tool system are investigated by a semi-analytical method. The stability and bifurcations of the period-1 motions are discussed from the eigenvalue analysis. A condition is presented for the tool-and-workpiece separation in period-1 motions. Machine-tool vibrations varying with displacement disturbance from a workpiece are discussed. Numerical simulations of period-1 motions are completed from analytical predictions.
Control Simulations for a Stewart Platform Compensator Mounted on Moving Base
Authors: Ono Takeyuki , Eto Ryosuke , Yamakawa Junya , Murakami Hidenori 
Published: January 2020

Abstract
In this paper, utilizing the analytical equations of motion for a base-moving Stewart platform, we design an active wave compensation system for a surgery table installed on the top plate of a Stewart platform in a ship. In our medical application, the base plate of a Stewart platform moves with the motion of the ship. For a base-moving Stewart platform, we presented analytical equations of motion in matrix form in the paper: IMECE2018-87253. The objective of the platform is to compensate the pitching, rolling, and heaving motions of the ship (with respect to an inertial coordinate system).
As control methods for the nonlinear system, we employ a hybrid controller combining resolved acceleration control with H∞ control, and integral sliding mode control (ISMC). The ISMC with input time delay is also designed with a state predictor, which includes a ship motion predictor utilizing an autoregressive model.
Finally, to assess the control performance and robustness for the system with uncertainties, numerical simulations are presented. In addition, the simulation results of the predictor based ISMC for the system with input time delay are illustrated showing the effectiveness of the controller.
Design and Analysis of an Innovative Portable Water-Cooled Thermoelectric Generator Apparatus
Authors: Coday Eric , Parker Jordan , Johnson Randall , Duan Shawn 
Published: January 2020

Abstract
Thermoelectric generator technology can be utilized as a renewable energy source and has untapped potential. Thermoelectric generators (TEGs) have been used by industry experts to make some thermodynamic processes slightly more efficient. However, TEGs can be operated in a manner that allows for greater energy production at a higher efficiency and in a stand-alone setting. This paper presents design and analysis of an innovative portable water-cooled thermoelectric generator apparatus. The apparatus can create clean energy using optimal heat transfer through the device. To reduce the amount of power lost to internal heat resistance, the device is cooled by a large body of water. Solar irradiation is the primary heat source for the TEGs and is absorbed using copper foil and high emissive paint. The temperature differential predicted during device operation was modeled using ANSYS. The ANSYS heat transfer model revealed that heat absorption and subsequent transfer to a body of water was possible without exceeding the operating parameters of the TEGs. Experimental results revealed that a 120°C temperature difference across the TEGs produced 12.5 V of electricity. Analysis of the water-cooled TEG prototype performance revealed that power production is possible, and the design has numerous applications.
Contact Properties Research for Linear Sliding Guide Rail With the Fractal Theory
Authors: Li Xinxin , Li Zhimin , Jin Sun , Zhang Jichang , Niu Zhihua , Liu Jinyu 
Published: January 2020

Abstract
High quality products are primarily dependent on the accurate translation motion of each linear sliding guide rail (LSGR) of CNC machine tools in the advanced manufacturing industry. The existing researches about LSGR precision pay much more attentions on the components dimensional variation and deformations, while micro-geometric form errors (such as surface roughness) have been ignored in most previous studies. Therefore, the true contact interface property is so crucial that it will affect macro-mechanical performance, such as friction, wear, assembly relation, tightness, fatigue strength, etc. In order to obtain the contact behaviors of LSGR accurately, a novel finite element model contact analysis is proposed in this paper. Instead of adopting the conventional statistic characterization method, such as Greenwood-Williamson (GW) model, the rough slider surface generated by the fractal function get closer to the real surface topography. In this study, the true contact area, contact pressure, contact stress and deformation are all investigated. Furthermore, the contact properties results of the present model are in a good agreement with other analytical solutions. In conclusion, the proposed finite element model combining with the fractal theory may provide an accurate contact analysis for LSGR. It is also great of guiding significance for the prediction of assembly quality and operation performance in high-precision measurement region as well as other precise engineering applications.
The Relationship Between the Arterial Geometry and Wall Shear Stress in the Vertebrobasilar System
Authors: Pan Fangjia , Anzai Hitomi , Mugikura Shunji , Kitamura Ko , Ohta Makoto 
Published: January 2020

Abstract
Vertebrobasilar atherosclerosis is an arterial disease; without successful treatment, it has a mortality rate approximately 80%–95%. Thus, predicting risk factors of vertebrobasilar atherosclerosis is of utmost importance. Previous studies have demonstrated that wall shear stress (WSS) contributes to atherosclerosis. In addition, geometry and WSS are correlated. The present study focuses on the description of equation using detailed relationship between arterial geometry and WSS in the vertebrobasilar system (VBS); magnetic resonance (MR) imaging with computational fluid dynamics (CFD) was used for the analysis. Using constructed patient-specific models, WSS of basilar arteries (BAs) was calculated and then analyzed with morphological parameters. According to the statistical results, both the area and curvature of BAs are associated with WSS. Based on the relations, a liner fitted equation can be proposed. As this study is underway, more precise evaluation of the correlation between morphology and fluid shear stress could help predict risk factors and select treatment methods for this arterial disease.
Numerical Investigation of Nonlinear Lamb Wave Time Reversing for Fatigue Crack Detection
Authors: Wang Junzhen , Shen Yanfeng 
Published: January 2020

Abstract
This paper presents a numerical study on nonlinear Lamb wave time reversing for fatigue crack detection. An analytical framework is initially presented, modeling Lamb wave generation, propagation, wave crack linear and nonlinear interaction, and reception. Subsequently, a 3D transient dynamic coupled-field finite element model is constructed to simulate the pitch-catch procedure in an aluminum plate using the commercial finite element software (ANSYS). The excitation frequency is carefully selected, where only single Lamb wave mode will be generated by the Piezoelectric Wafer Active Sensor (PWAS). The fatigue cracks are modelled nucleating from both sides of a rivet hole. In addition, contact dynamics are considered to capture the nonlinear interactions between guided waves and the fatigue cracks, which would induce Contact Acoustic Nonlinearity (CAN) into the guided waves. Then the conventional and virtual time reversal methods are realized by finite element simulation. Advanced signal processing techniques are used to extract the distinctive nonlinear features. Via the Fast Fourier Transform (FFT) and time-frequency spectral analysis, nonlinear superharmonic components are observed. The reconstructed signals attained from the conventional and virtual time reversal methods are compared and analyzed. Finally, various Damage Indices (DIs), based on the difference between the reconstructed signal and the excitation waveform as well as the amplitude ratio between the superharmonic and the fundamental frequency components are adopted to evaluate the fatigue crack severity. The DIs could provide quantitative diagnostic information for fatigue crack detection. This paper finishes with summary, concluding remarks, and suggestions for future work.
Digital Tools to Capture Manufacturing Tacit Knowledge to Support Next Generation Automation Systems
Authors: Guerra-Zubiaga David A. , Schwaig Kathy S. , Nasir Sabih , Bondar Alex 
Published: January 2020

Abstract
In today’s complex environment, it is not only important to handle/control digital manufacturing tools, but also essential to capture tacit knowledge from people. Creating a digital twin, it is an extensive effort including different fields and subjects. For example, creating a physical prototype and connecting it with a virtual prototype. From this, two questions arise. What will be the framework used to create the digital twin and what method will be used to capture the experiences to develop Next Generation Automation System (NGAS). This research explores a new method capturing tacit knowledge creating a digital twin for a NGAS, worked at station level connecting machines and humans implementing knowledge modelling and providing guidance in design for manufacturability at NGAS. The motivation of this research is that capturing tacit knowledge is an important aspect in Industry 4.0.
According to literature review, different researchers have been exploring digital twins using digital tools. This research proposal explores the effects of automation in the workplace using Digital Manufacturing Tools (DMT). The proposed approach demonstrates how to capture valuable experiences we can transfer or communicate between the digital twins, increasing productivity to fulfill the need to adopt new and emerging technologies in the workplace. The research will talk about capturing Tacit Knowledge in different forms like experiences, analysis, and intuitions etc and how this type of knowledge is processed by DMT and communicated to the other digital twin. Tacit knowledge modeling and sharing is used by implementing the Internet of Things (IoT) to understand the interaction among humans, instruments, controls, and robots. Understanding tacit manufacturing knowledge types is required to create better digital twins.
Thermo-Mechanical Modeling of 3D Woven Fabric Composites Using Two-Step Homogenization Approach
Authors: Siddgonde Nagappa , Ghosh Anup 
Published: January 2020

Abstract
A 3D finite element based Representative Volume Element (RVE) model has been developed to predict the thermo-mechanical properties of 3D orthogonal interlock woven fabric composites (OIWFC) and angle interlock woven fabric composite (AIWFC) using a two-step homogenization approach. The first step homogenization, micro-homogenization, deals with resin infiltration effect of yarn as a unidirectional continuous fiber with an assumption of 80 percent of fiber volume fraction based on initial fiber and matrix properties. The second step, meso-homogenization, predicts effective thermo-mechanical properties of 3D woven fabric composites based on effective yarn and matrix properties. The RVE analysis has been performed using 3D FEA method with periodic boundary conditions (PBCs). Further, a void study has been performed considering the influences of void on thermo-mechanical properties of the 3D woven fabric composite. It is noted that the influence of void contents plays a significant role in predicting the thermo-mechanical properties of the 3D WFC. The thermo-mechanical properties gradually decrease with an increase of void contents. Studies have been carried out considering the same fiber volume fractions in both 3D WFC models. An AIWFC model predicts higher values of thermo-mechanical constants than OIWFC model.
Machining of High Aspect Ratio Micro-Holes on Titanium Alloy Using Silver Nano Powder Mixed Micro EDM Drilling
Authors: Liu Chong , Rashid Asif , Jahan Muhammad P. , Ma Jianfeng 
Published: January 2020

Abstract
Titanium alloy Ti-6Al-4V is used extensively in aerospace engines because of its high strength-to-weight ratio and corrosion resistance. Machining of cooling holes in turbine blades for aerospace engines is one of the major challenges faced in aerospace industries. Ti-6Al-4V is known as a difficult to be machined material by conventional machining processes, and machining of micro-through-holes with diameter less than 100 microns is even more challenging. Therefore, the objective of this study is to investigate the feasibility of machining high aspect ratio micro-through holes in Ti-6Al-4V using micro electrical discharge machining (micro-EDM) with the silver (Ag) nanopowder mixed dielectric. The machining time, overcut, recast layer, crater size, aspect ratio and surface finish of the micro-holes were evaluated. In order to minimize the positional inaccuracy and spindle runout, the microelectrodes were fabricated in-situ using block micro-EDM process. In this study, as received electrode of 300 microns diameter tungsten wire was reduced to about 50 microns diameter rod by micro block EDM using a tungsten carbide block. The effect of powder concentration, gap voltage, capacitance and electrode rotational speed was studied. It is found that high quality micro-holes of about 50 microns diameter can be achieved successfully and repeatedly using powder mixed micro-EDM (PM-μEDM). The micro-holes generated by PM-μEDM provides comparatively smoother surface finish and minimal recast layer around the rim of the micro-holes. In addition, PM-μEDM process improves machining stability, thus allowing to minimize the hole size and quality, thus enhancing the aspect ratio of micro-holes.
Development of Trends and Methodologies for Shaping Ceramics by Electrical Discharge Machining: A Review
Authors: Rashid Asif , Jahan Muhammad P. , Perveen Asma , Ma Jianfeng 
Published: January 2020

Abstract
Ceramic materials possess excellent properties like high hardness, superior corrosion resistance and great resistance to wear. These materials are low in density and demonstrate high strength to wear ratio. There is an increasing need to machine these hard and brittle materials as they have various engineering applications. The distinguishing properties of ceramics do not allow them to be machined by conventional processes. Electrical discharge machining (EDM) is a non-conventional process and a viable option to machine and generate complex shapes in hard materials. EDM can be used on materials irrespective of its hardness and wear resistance as it is a non-contact machining process and no active force is applied between the workpiece and electrode during machining. As EDM requires the workpiece to be electrically conductive, machining ceramics by this process is a challenge. Alterations need to be carried out in order for insulating ceramics to be machined by this process. This paper discusses the basics of EDM process and its control parameters. A classification of ceramic materials based on their electrical conductivity is established and their relevance to the respective material removal mechanisms have been identified. Different approaches to successfully machine ceramics by EDM have been reviewed. The challenges and modifications of each method have been discussed. An outline and expectations for machining a particular ceramic material and its composites have been generated. Finally, the prospects of future research in this area have been identified.
Comparative Study of the Dynamic Behavior of AA2519 Aluminum Alloy in T6 and T8 Temper Conditions
Authors: Olasumboye Adewale , Owolabi Gbadebo , Koya Olufemi , Whitworth Horace , Yilmaz Nadir 
Published: January 2020

Abstract
This study investigates the dynamic response of AA2519 aluminum alloy in T6 temper condition during plastic deformation at high strain rates. The aim was to determine how the T6 temper condition affects the flow stress response, strength properties and microstructural morphologies of the alloy when impacted under compression at high strain rates. The specimens (with aspect ratio, L/D = 0.8) of the as-cast alloy used were received in the T8 temper condition and further heat-treated to the T6 temper condition based on the standard ASTM temper designation procedures. Split-Hopkinson pressure bar experiment was used to generate true stress-strain data for the alloy in the range of 1000–3500 /s strain rates while high-speed cameras were used to monitor the test compliance with strain-rate constancy measures. The microstructures of the as received and deformed specimens were assessed and compared for possible disparities in their initial microstructures and post-deformation changes, respectively, using optical microscopy. Results showed no clear evidence of strain-rate dependency in the dynamic yield strength behavior of T6-temper designated alloy while exhibiting a negative trend in its flow stress response. On the contrary, AA2519-T8 showed marginal but positive response in both yield strength and flow behavior for the range of strain rates tested. Post-deformation photomicrographs show clear disparities in the alloys’ initial microstructures in terms of the second-phase particle size differences, population density and, distribution; and in the morphological changes which occurred in the microstructures of the different materials during large plastic deformation. AA2519-T6 showed a higher susceptibility to adiabatic shear localization than AA2519-T8, with deformed and bifurcating transformed band occurring at 3000 /s followed by failure at 3500 /s.
Predictive Modeling of Polymer Saturation in Porous 3D Printed Matrix
Authors: Mihalko Adam , Michael Robert , Piovesan Davide 
Published: January 2020

Abstract
Due to the accuracy, speed, and ability to produce controllable complex geometries, additive manufacturing has gained traction in the medical industry. Additive manufacturing based on powder binder-jetting allows fabricating composite ceramic artifacts to mimic the physical properties of cortical bone. Given the porous nature of the artifacts their physical properties can be manipulated based on the percentage of solid matrix and adhesive binder. It has been demonstrated that a reduction of porosity via infiltration greatly increases the mechanical properties of the artifact. In this paper experiments are presented investigating the post processing of porous materials using different adhesives to infiltrate the artifact. The resulting saturation and porosity profiles of the produced composite are analyzed.
Experimental Study on Geometric Precision of Microholes Drilling by Picosecond Laser
Authors: Zhang Zhanfei , Wang Wenhu , Jiang Ruisong , Jin Chengcheng , Zhu Xiaoxiang , Liu Xiaofen 
Published: January 2020

Abstract
The geometric precision of the film cooling hole has a great influence on the cooling efficiency and fatigue life of the turbine blade. In the paper, the processing of film cooling holes on DD6 single crystal superalloy by picosecond laser is investigated. The pulse laser at pulse duration of 2.1ps, the wavelength of 1030 nm and the repetition frequency of 75 kHz are selected to study the pulse energy, scanning speed, defocus and scanning width on the geometric precision of the film cooling hole. After drilling, the three-dimensional coordinates of the entrance and exit plane of the film cooling holes are obtained by using the three-dimensional surface measuring instrument. The diameter, roundness and taper of the film cooling holes are calculated by extracting and processing the coordinate points of the contour around the microholes. The experimental results show that defocusing has the greatest influence on the taper and roundness of film cooling holes. Negative defocusing can produce severe plasma shielding, which makes the exit roundness and taper larger. With larger pulses, positive defocusing and larger scanning width, smaller roundness and taper can be produced.