bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gas Fuel Variability Using Buffer Volume in Aeroderivative Gas Turbines
Authors: Yerram Ravinder , Ponnuraj Balakrishnan 
Published: January 2020

Abstract
General Electric (GE) DLE gas turbines typically use a Gas Chromatograph (GC) and/or a Wobbe Index Meter (WIM) to monitor changing fuel properties during operation. These conventional fuel sensors experience a significant time lag during operation, so a patented buffer volume device and a software algorithm is used to compensate for this lag and to ensure that the control system including metering valves can react to rapid fuel changes. Computational Fluid Dynamics (CFD) was used to design and analyze the buffer volume device that increases the time and distance taken by the gas to the metering valve. This delay provides the control system time to adjust the metering valves when the fuel transitions at the combustor to maintain gas turbine combustor stability and operation during rapid gas property changes that could otherwise result in a trip or flame-out condition. In GE’s Aeroderivative Gas Turbine Gas Fuel transfer system, the innovative buffer volume was the critical component, and this paper describes its performance in detail.
Analysis of Symmetric Angle-Ply Laminated Composite Skew Plates Using Hybrid Trefftz Finite Element
Authors: Dwibedi Subhasankar 
Published: January 2020

Abstract
Analysis of symmetric angle-ply skew laminated composite plates has been presented in the study using a newly developed hybrid Trefftz finite element (hTFE). Mindlin’s plate theory has been used to develop the present hTFE. The forms of displacement are assumed such that governing partial differential equations are satisfied a priori inside the element domain. Particular solutions of the governing equations have been ignored and Trefftz functions are derived using the homogenous solutions only. Inter-element continuity has been established by employing another displacement field along the edges of the hTFEs. The transverse shear stresses have been ignored at the top and bottom surfaces of the laminate. The angle of inclination of the width of the plate with the y-axis has been taken as the skew angle and different forms of skew plates are obtained by varying the skew angle. Sinusoidally distributed load (SDL), uniformly distributed load (UDL), and point load (PL) have been subjected to the top surface of the laminate and the non-dimensionalized center point deflection have been evaluated to assess the performance of the present hTFE. The observation from the present study further reinforce the versatility of the hTFE method for analysis of composite structures with complex shapes or geometries.
First Principle Analysis of the Effect of Strain on Electronic Transport Properties of Dumbbell-Shape Graphene Nanoribbons
Authors: Kudo Takuya , Zhang Qinqiang , Suzuki Ken , Miura Hideo 
Published: January 2020

Abstract
Graphene nanoribbons (GNRs), nano scale strips of graphene which consists of carbon hexagonal unit cell, are expected as next generation materials for high performance devices because of its unique super-conductive properties. When the strip width of graphene is cut into nano-scale, thinner than 70 nm, however, band gap starts to appear in the thin GNRs at room temperature, and thus, they show semiconductive properties. Previous studies have shown that the bad gap of GNR is highly sensitive to strain, which indicates that GNRs are candidates for a detective element of highly sensitive strain sensors. In practical applications, ohmic contact between a metallic electrode and a semiconductive detective element is indispensable for these sensors. By considering the effect of the width of GNRs on their electronic properties, dumbbell-shape GNRs (DS-GNRs) structures have been proposed for the basic structure of the GNR-base strain sensors, which consisted of GNRs with two different widths. Center portion of the DS-GNR is narrower than 70 nm and GNRs wider than 70 nm are attached at the both ends of the center GNR as electrode. Both semiconductive and metallic portions of a strain sensor consist of only carbon atoms using this DS-GNR structure. Even though this structure consists of one material, the effect of the interaction between two metallic and semiconductive GNRs must be clarified to realize the strain sensor with high performance. In this study, first principle calculations were applied to the analysis of the electronic band structure of the DS-GNR based on density functional theory (DFT). It was found that the local distribution of energy states of electrons and charges varied drastically as strong functions of the length of GNRs and the magnitude of the applied strain. The current through the DS-GNR structure was converged as the length of the semiconductive portion increased. In the models with enough length, transport property of the DS-GNR showed high sensitivity to strain. Thus, the effective resistivity of the structure varied from metallic to semiconductive, and therefore, this structure is appropriate for the next-generation highly sensitive and deformable strain sensors.
Dynamic Modelling of an Elephant Trunk Like Flexible Bionic Manipulator
Authors: Mishra Mrunal Kanti , Samantaray Arun Kumar , Chakraborty Goutam , Jain Aditya , Pathak Pushparaj Mani , Merzouki Rochdi 
Published: January 2020

Abstract
In this paper, an attempt is made to model and study the planar and spatial dynamics of flexible elephant trunk-like manipulator by using multi-body dynamics software MSC-ADAMS. The flexible manipulator is modelled for bending with variable curvature. The entire manipulator length is divided into two sub-sections with associated lumped mass, damping and stiffness for the dynamic analysis. In this model, each section has three pressure actuated bellow tubes, which are modelled as simple spring-damper with the net mass distributed at the ends. Besides, a torsional spring-damper system is also incorporated in each section model to resist the bending about the transverse axes when the pressures in the bellow tubes are unequal. The manipulator is so designed that due to different actuation forces (corresponding to different bellows), the resultant action is finally a bending moment at the tip of each section. The effect of the gravitational force is also included. The change in behaviour of the end-effector position and orientation with respect to time is studied along with the elongation of bellow tubes. The nature of the velocity profile of the end-effector is also determined to study the behaviour of the manipulator.
Ride Index for Metro Coaches: Experimental Evaluation and Vehicle Dynamics Results
Authors: Singh Sudhir Kumar , Danawe Hrishikesh Gajanan , Racherla Vikranth , Singh Sanjay R. , Prasad Arun 
Published: January 2020

Abstract
Instrumented field studies during oscillation trials for a new metro line and metro coaches were used to obtain Sperling’s ride index for the same. Ride index was also evaluated using a SIMPACK model. Actual coach, track, and speed information were used in the SIMPACK model. Ride index was seen to be influenced by track, velocity, and acceleration profiles. Ride indices were seen to be different in different directions (vertical, lateral and longitudinal). In the absence of track irregularities in SIMPACK, match between oscillation trail and SIMPACK results is best for longitudinal and worst for vertical ride indices.
Load Capacity of Support Structures for Direct Machining of Selective Laser Melted Parts
Authors: Höller Christian , Zopf Philipp , Schwemberger Philipp , Pichler Rudolf , Haas Franz 
Published: January 2020

Abstract
Selective Laser Melting (SLM), as a fast-growing metal-based Additive Manufacturing technology, allows to produce high strength parts with complex geometries. However, limited part properties in the as-built condition require effortful post-processing tasks (e.g. milling, drilling, polishing) to meet technical specifications and tolerances. This significantly increases the manufacturing costs of SLM parts. To address this problem, the concept of Direct Machining is presented. Direct Machining is defined as the post-processing of SLM parts via machining without prior removal of the parts from the build platform to achieve economic benefits. For this, the support structures have to withstand the occurring cutting forces during machining — a task for which they were not initially designed.
The aim of this study is to investigate the load capacity of 316L SLM support structures. For this, machining experiments on a five-axis milling machine were conducted. Cutting parameters, support geometries and support volume were varied and the cutting forces were measured to investigate their influence on the stability of the support structures. Results show, that deliberate SLM support structures allow precise machining directly on the build platform. Furthermore, a theoretical load model of Direct Machining is developed. Based on this, further optimization of the support structures regarding cutting force absorption and material volume are presented.
Investigation on the Condition Evaluation Method Based on NSET Model of the Propulsion System in Large Scale Ship
Authors: Zhao Jinxin , Zhou Jian , Shang Peng , Zhang Yinxun 
Published: January 2020

Abstract
The condition of the propulsion system in large scale ship directly affects the quality and safety of the ship’s operation, so it is important to evaluate the condition of the propulsion system. The Nonlinear State Estimation Technology (NSET) method is a nonparametric modeling method, which is mostly used in nuclear power plant sensor calibration, equipment monitoring, and electronic product life prediction. In this paper, the nonlinear state estimation technology (NSET) method is applied to the condition evaluation of the propulsion system. According to the operating characteristics and state parameters of the propulsion system, this paper first performs data preprocessing, and then uses the prepossessed data to perform condition evaluation by the NSET method. The model method can be connected with the database system. It has the advantages of faster evaluation speed and higher precision, and can detect possible failures of equipment system in time. This method has a wide range of adaptability.
The Effect of Creep-Fatigue Interactions on Thermo-Mechanical Fatigue Life and Reliability Estimates for a Typical Gas Turbine Engine Component
Authors: Muthu Shanmugam Esakki , Prakash Raghu V. 
Published: January 2020

Abstract
The low cycle fatigue-creep damage is the main parameter for the failures of gas turbine components under high temperature and cyclic loading. In this work, different combinations of Creep-Fatigue damage are introduced and checked for its impact on the Turbine life and its reliability. Linear and Non-Linear Creep-Fatigue combinations were considered as part of this work. The Turbine rotor under present study is made out of Nimonic-90 nickel base alloy forging. Weibull distribution method was used to study the reliability. It was found that, the reliability reduces from 99% to 25% when creep damage component is increased from 20% to 40% for a fixed Turbine life. The damage factor was found more in above linear Creep-Fatigue curve and less in below linear Creep-Fatigue curve.
Grain Boundary Cracking of Nickel-Based Alloy 625 Under Creep Loadings at Elevated Temperatures
Authors: Liang Yan , Luo Yifan , Suzuki Ken , Miura Hideo 
Published: January 2020

Abstract
Since the operating condition of thermal power plants has become harsher for minimizing the emission of CO2, Ni-based superalloys, such as Alloy 617 and 625, have been used in the plants to replace the conventional ferritic materials. Unfortunately, the increase of coefficient of thermal expansion compared with conventional steels is a concern. In addition, Ni-based superalloys have to suffer creep-fatigue random loading because thermal power plants have to compensate the random output of various renewable energies. It was found that the lifetime of Ni-based superalloys under creep-fatigue loading was much shorter than that under simple fatigue or creep loading. Thus, it has become very important to clarify the crack mechanism and establish the quantitative theory for estimating their lifetime under various loading conditions at elevated temperatures.
Thus, the elucidation of the initial damage mechanism of Alloy 625 under various loading is indispensable. Hence, the initial cracking mechanism of Alloy 625 at grain boundaries under creep loading was investigated experimentally. The creep test was applied to small specimens in Argon atmosphere. The change of the micro texture during the creep test was observed by using SEM. It was confirmed that all the initial cracks appeared at certain grain boundaries. The change of the crystallinity was observed by EBSD (Electron Back-Scatter Diffraction) analysis quantitatively. It was found that the local accumulation of dislocations at the cracked grain boundaries caused the initial cracks at those grain boundaries. The initiation of cracks appeared clearly between two grains which had difference of KAM (Kernel Average Misorientation) values larger than 0.2. Therefore, dislocations were accumulated at one side of the grain boundary. By measuring the KAM values near grain boundaries, the appearance of initial cracks can be predicted approximately.
Noncoaxial Vibration of Electrostatically Actuated DWCNT: Frequency Response of Primary Resonance
Authors: Caruntu Dumitru I. , Juarez Ezequiel 
Published: January 2020

Abstract
In this paper, the Method of Multiple Scales (MMS) is used to investigate the influences of the nonlinear intertube van der Waals coefficient, dimensionless damping, and voltage on the amplitude-frequency response of an electrostatically actuated double-walled carbon nanotube (DWCNT). The forces responsible for the nonlinearities in the vibrational behavior are intertube van der Waals and electrostatic forces. For perturbation, a small viscous damping and soft AC actuation are assumed for numerical simulation. For the first time in literature, forced vibration of the noncoaxial (out-of-phase) case is investigated. In this mode of vibration, the outer and inner carbon nanotubes move at ultra-high frequency in opposite direction, i.e., negative amplitude ratio. The DWCNT structure is modelled as a cantilever beam with Euler-Bernoulli beam assumptions since the DWCNT is assumed to have a high length-diameter ratio. The results shown assume steady-state solutions in the second-order MMS solution. The importance of the results in this paper are the effect of the strong nonlinearity of the van der Waals coefficient, damping, and voltage on the the DWCNT vibration.
Data-Driven Feedforward Tuning Approach for LPV Motion Systems
Authors: Huang Weicai , Yang Kaiming , Zhu Yu , Lu Sen 
Published: January 2020

Abstract
This paper aims to develop a new data-driven feedforward tuning approach to achieve high performance for linear parameter varying (LPV) motion systems. In the proposed approach, the feedforward controller is linearly parameterized with polynomial basis functions and parameter varying coefficients. Gauss-Newton Method is exploited to solve the corresponding parameter optimization problem. Parameter perturbing experiments are employed to estimate the gradient. The truncated singular value decomposition (SVD) method is adopted to deal with the ill-conditioned matrix inversion problem. No parametric model is required throughout the tuning process. Simulations are conducted to test the performance of the proposed approach. And the results indicate that the parameter varying dynamics of the plant are well compensated by the proposed approach.
Improving Packing Efficiency and Component Handling Reliability in Logistics With a Novel CAD Approach
Authors: Chekurov Sergei , Mäkelä Ismo 
Published: January 2020

Abstract
This paper presents a novel method of designing logistic separators based on existing 3D models of components. The proposed method is used to create horizontal sheet separators with cavities that conform to the geometry of the component. Because the method allows the components to be packed closer to one another, and because they can be made to overlap in the vertical direction, it increases the number of components that can be transported per logistic box. Additionally, because the components are constrained by cavities based on their geometry, a predefined grasping orientation for robotic arms can be guaranteed. The paper presents two methods to create separators that allow packing in three dimensions: manual and automatic.
The automatic method presented in the paper generates sheets without manual input after setting the components in a three-dimensional space. As there are several technical solutions to performing the method, the paper describes the approach on a general level, while pointing out significant hurdles that can be encountered in development.
The paper describes each step of the workflow of creating the separators in detail by using an example component. The presented method works with practically any component that has a 3D model. However, the extent of the improvement in packing efficiency is highly dependent on their complexity. The paper discusses the factors that contribute to the complexity and gives recommendations on what type of components benefit most from the concept.
Change of the Effective Strength of Grain Boundaries in Alloy 617 Under Creep-Fatigue Loadings at 800°C
Authors: Suzuki Wataru , Ishihara Kenta , Kikuchi Ryo , Suzuki Ken , Miura Hideo 
Published: January 2020

Abstract
In this study, both EBSD (Electron Back-Scatter Diffraction) analysis and a micro tensile test system with FIB (Focused Ion Beam) equipment were applied to bicrystal specimens of Alloy 617 in order to establish a quantitative theory of the lifetime evaluation method under creep-fatigue loadings. The IQ (Image Quality) value which is obtained from the diffraction pattern (Kikuchi pattern) indicates the total density of defects such as vacancies, dislocations, and local strain was used for quantitatively evaluating the crystallinity of the alloy. KAM (Kernel Average Misorientation) value was also used for density analysis of GN (Generally Necessary) dislocations. Continuous changes of microtexture of grains and grain boundaries were observed by applying an intermittent creep fatigue test. As a result, it was confirmed that the IQ value around specific grain boundaries in damaged specimen was drastically degraded compared to that of the initial specimen. Intergranular cracks always occurred when the IQ value decreased to a certain value. Therefore, there is a correlation between the IQ value and the strength of a grain boundary in this alloy. The decrease of the IQ value was attributed to the accumulation of both dislocations and vacancies around the specific grain boundaries under creep loading. The accumulation rate under the creep-fatigue loading was clearly higher than that under simple fatigue and creep loadings. Finally, it was clarified that the degradation of the crystallinity in the vicinity of a grain boundary was a criterion of an intergranular crack under creep-fatigue loadings.
Edge States in Nonlinear Model of Valve Spring
Authors: Gzal Majdi , Gendelman Oleg V. 
Published: January 2020

Abstract
We address the dynamics of helical compression valve springs of an internal combustion engine. To this end, the spring is mathematically modeled as a finite non-homogenous one-dimensional mass-spring-damper discrete chain. Regarding the boundary conditions, the upper end of the chain is forced with periodic displacement, which mimics the actual camshaft profile, while the other end is fixed. In order to model the interaction between the valve and valve seat, the displacement of the upper mass is constrained to be nonnegative by adding an obstacle such that when it approaches the obstacle, it experiences an impact that satisfies the Newton impact law with restitution coefficient less than unity. Another source of damping in this model arising from the internal damping of the spring material. The nonlinearity of the model originates from the periodic impact interactions.
This interplay between nonlinearity and discreteness supports time-periodic and spatially localized solutions characterized by a strong localization at the edge of the chain (i.e. edge states) such that the periodicity of the impact allows derivation of exact analytical solutions for the forced-damped edge state. Then, the governing equations are solved numerically in order to illustrate the exact solution. The results are compared to experimental findings from analysis of actual automotive valve spring.
Experimental Investigation of a Backing Sheet Stiffener in Incremental Forming of Polycarbonate
Authors: Grimm Tyler J. , Kulkarni Shubhamkar , Mears Laine , Mocko Gregory 
Published: January 2020

Abstract
Single point incremental forming (SPIF) is a dieless forming process for sheet materials. This process forms materials with a hemispherical forming tool which locally deforms the sheet at incremental depths. The freeform nature of this process promises significant efficiency improvements within small and medium volume industries where stamping is traditionally used. However, several drawbacks currently inhibit its widespread use. One of these drawbacks is springback or elastic recovery resulting in reduced geometrical accuracy. An existing approach to counter this involves using a dedicated backing die, increasing the cost of the forming apparatus and the overall energy input per part. Other springback reduction methods involve the direct addition of energy to the workpiece through electrical or heat input.
This study investigates the use of sacrificial steel blanks as backing dies for incremental forming of polycarbonate sheets, to overcome the loss in geometrical accuracy affiliated with forming geometries with a relatively large distance between the geometry periphery and the clamped edge. The blanks were not bound to each other, but rather clamped along their edges. In this study, polycarbonate blanks were tested using a three-factorial design of experiments, with relative plate thicknesses of 0.4, 0.5, and 0.6, and wall angles of 15°, 30°, 45°, and 60° as independent factors. The test geometry used was a straight walled pyramid with a square base. Using the backing sheet, a reduction in the springback was observed, demonstrating the effectiveness of sacrificial backing blanks. Particularly, the ‘pillow effect’ at the base of the geometry was reduced. This is attributed to the higher stiffness of the steel plates, increasing the plastic strain on the polycarbonate. However, the formability is found to decrease for higher values of the backing plate thickness due to premature steel failure. In future studies, this work will be expanded to include additional thickness ratios, geometries, toolpath types, step sizes and materials to form a more complete trend.
Computationally Efficient Thermo-Mechanical Analysis for Predicting Process-Induced Deformations of Composite Structures
Authors: Zappino Enrico , Zobeiry Navid , Petrolo Marco , Vaziri Reza , Carrera Erasmo , Poursartip Anoush 
Published: January 2020

Abstract
This paper presents an innovative numerical model for the calculation of process-induced deformations of composite structures. The capabilities of a refined one-dimensional model, based on the Carrera Unified Formulation, have been exploited to describe the complex displacement field that originates during the curing process of a composite component. The refined kinematic models adopted are able to describe a three-dimensional solution and make it possible to predict the through-thickness deformation that is one of the causes of the origins of the process-induced deformations. The evolution of the material properties during the curing process is evaluated using the software RAVEN and the manufacturing process is simulated using an ‘incrementally elastic’ constitutive model. The results demonstrate the capabilities of the present approach to predict the process-induced deformations including the complex stress field due to thermal and mechanical loads.