bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling and Control of Pantograph and Contact Wire for High Speed Train
Authors: Muenchhof Marco , Hindle Timothy , Singh Tarunraj
Published: November 2021

The paper focuses on the modeling and control of a catenary-pantograph system. For the catenary system, only the contact wire is considered. Initially, the case of a constant force traveling at a constant velocity along the wire is investigated and closed form solutions are derived. Next, the pantograph dynamics are considered using a simple spring-mass-damper model, where the force is no longer assumed to be constant. The need for control in this case is apparent and motivates two different control strategies. The first control strategy utilizes a feed-forward Fourier series control profile. For the second control strategy, a proportional force feed-back control is added. All control parameters are obtained using constrained optimization techniques. Stability and sensitivity issues are addressed.
Process-Oriented Tolerance Synthesis for Multistage Manufacturing Systems
Authors: Ding Yu , Jin Jionghua , Ceglarek Dariusz , Shi Jianjun
Published: November 2021

In multistage manufacturing systems, quality of final products is strongly affected not only by product design characteristics but also by key process design characteristics. However, historically, tolerance research has primarily focused on allocating tolerances based on product design characteristics for each component. Currently, there is no analytical approach for multistage manufacturing processes to optimally allocate tolerances to integrate product and process characteristics at minimum cost. One of the major obstacles is that the relationship between tolerances of process and product characteristics is not well understood and modeled. Under this motivation, this paper aims at presenting a framework addressing the process-oriented (rather than product-oriented) tolerancing technique for multistage manufacturing processes. Based on a developed state space model, tolerances of process design characteristics at each fabrication stage are related to the quality of final product. All key elements in the framework are described and then derived for a multistage assembly process. An industrial case study is used to illustrate the proposed approach.
Effect of Mechanical Alignment System on Assembly Accuracy
Authors: Lee Neville K. S. , Yu Grace H. , Zou Y. , Chen J. Y. , Joneja Ajay
Published: November 2021

Mechanical means of positioning are frequently used in mechanical assembly processes. However, very little attention has been paid to the selection of mechanical alignment systems (MAS) for assembly processes. Our analysis shows that if the MAS are not properly selected, the form errors as well surface waviness and roughness of the workpieces to be assembled can badly limit the level of accuracy achievable. A simulation-based methodology is described to study the alignment accuracy for multi-stage processes. Such cases are common, where fabrication operations are done on parts before they are assembled. The study shows that if the workpieces are aligned in the same orientation, using similar or identical MAS for the fabrication processes and assembly processes, then the effect of the form errors as well as surface waviness and roughness of the workpieces can be greatly suppressed.
Stream of Variation Modeling and Diagnosis of Multi-Station Machining Processes
Authors: Huang Qiang , Zhou Nairong , Shi Jianjun
Published: November 2021

Product dimensional quality is one of the most important topics in machining processes. However, limited research has been done on the dimensional control and root cause identification methodologies in multi-station machining processes. This paper will study the stream of variation (SOV) problem by developing a new type of model — State Space Model — to describe the dimensional deviation of the multistation machining processes. A process level diagnostic methodology is also developed. A case study is presented to illustrate the developed modeling and diagnostics methodology.
Feature Selection for Tool Wear Diagnosis Using Soft Computing Techniques
Authors: Goebel Kai , Yan Weizhong
Published: November 2021

This paper examines feature selection methods in the context of milling machine tool wear diagnosis. Given raw sensor signals acquired during experiments, a pool of features was created through calculation by several feature extraction methods. Five techniques for selecting the most discriminating features were employed. These techniques included decision trees, neural-fuzzy methods, scatter matrix, and a cross-correlation method. We used a diagnostic neural network to evaluate the five different feature selection schemes by comparing their classification rate and test errors.
Effects of Thermal Expansion on Surface Error in Metal Cutting
Authors: Wu Chung_sheng , Kuo Chuan-Hsien , Yang Wen-Jei
Published: November 2021

An experimental study is performed to measure thermal expansion and surface roughness of 6061 aluminum workpiece subjected to a cutting process in turning on a lathe. Four capacitance probes are used to detect changes in the air gap between the probes and the surface of the workpiece during the machining process, and after the workpiece is cooled down to the initial temperature. The signal output from the probes is filtered before being fed into a data acquisition system. Operational conditions are varied. The thermal expansion-time history of the workpiece is obtained at different locations behind the cutting point, together with the filtered surface profile of the workpiece. The effects of cutting speed, flank wear length, and workpiece diameter on thermal expansion and average surface roughness are determined. A novel approach is developed to correlate thermal expansion against surface roughness, both in dimensionless form. It is disclosed that these two quantities are linearly related on a semi-logarithmic plot, with all test data falling within upper and lower limits. A quantity analogous to the elastic modulus is defined to characterize the surface roughness of materials resulting from the cutting process in turning. This approach will suggest new directions for the study of surface roughness in machining.
An Improved Cutting Force Model Considering the Size Effect in End Milling
Authors: Yun Won-Soo , Cho Dong-Woo
Published: November 2021

In this paper, a mechanistic model is first constructed to predict three-dimensional cutting forces, and the uncut chip thickness is calculated by following the movements of the position of the center of a cutter, which varies with the nominal feed, cutter deflection and runout. For general implementation to a real machining, this paper presents the method that determines constant cutting force coefficients, irrespective of the cutting conditions or cutter rotation angles. In addition, this study presents the approach which estimates runout-related parameters, the runout offset and its location angle, using only one measurement of cutting forces.

For more accurate cutting force predictions, the size effect has to be considered in the cutting force model. In this paper, two approximate methods are suggested since the strict approach is practically impossible due to a measurement problem. The size effect is individually considered for narrow and wide cuts.
A Predictive Model for Helical End Milling Forces
Authors: Li Huaizhong , Zhang Wenbin , Li Xiaoping
Published: November 2021

A predictive model for helical end milling forces is developed using a predictive machining theory, which predicts cutting forces from input data of workpiece material properties, tool geometry and cutting conditions. In the model, each tooth of a helical end milling cutter is discretizised into a number of slices along the cutter axis to account for the helix angle effect on the cutting forces. The cutting action of each of the slices is modeled as an oblique cutting process. For the first slice of each tooth, it is modeled as oblique cutting with end cutting edge effect and tool nose radius effect, whereas the cutting actions of other slices are modeled as oblique cutting without end cutting edge effect and tool nose radius effect. The total cutting forces acting on the cutter is obtained as the sum of the forces at all the cutting slices of all the teeth. Experimental milling tests have been conducted to verify the model which showed good agreements.
Advanced Deposition Techniques for Freeform Fabrication of Metal and Ceramic Parts
Authors: Tseng Ampere A. , Tanaka Masahito
Published: November 2021

Two newly invented deposition techniques for the freeform fabrication of metal and ceramic parts are presented. The first deposition technique studied is one that can deposit variable sizes of filaments in a controlled manner. The second technique consists of layer deposition using an adjustable planar nozzle to generate layers directly. Laboratory scale apparatus has been built to study the behavior of filament and layer formation of these two techniques. Experiments are conducted in typical operation ranges. Analytical solutions are also developed to parametrically study the effects of changing major operational parameters as well as to provide necessary information for designing the apparatus. All results indicate that the analytical predictions agree very well with the experimental observation. Finally, recommendations on the future development of these two techniques are given.
Solid Freeform Fabrication of Metal Parts by 3D Laser Cladding
Authors: Hu Dongming , Kovacevic Radovan , Valant Mike
Published: November 2021

This paper presents the development of a method of three-dimensional laser cladding for Solid Freeform Fabrication (SFF). A SFF system developed at SMU (SMU-SFF) is introduced which can build 3D metal parts by cladding metal powder delivered by a nozzle mounted coaxially to a Nd: YAG laser focusing head. An on-line slicing process that uses machine vision to measure the height of the part being built is also introduced as an effective means of optimizing the cladding process. Further, to explore the effects of the laser cladding parameters on the SFF results, machine vision with a high-speed shutter camera is utilized to observe the laser cladding process. The relationships between processing parameters (laser power, scan velocity) and cladding results are then discussed.
Ultrasonic Rapid Manufacturing of Layered Objects
Authors: Doumanidis Charalabos , Gao Yuan , Johnson Norbert , Greif Robert
Published: November 2021

The Ultrasonic Rapid Manufacturing process is a new non-thermal rapid prototyping technique for layered fabrication of metallic or multiple-material products. The process introduced in this paper employs ultrasonic welding and contour cutting of thin material foils. Its laboratory implementation, automation and integration, and parameter optimization are described first. Next, a numerical FEA simulation of the static and dynamic stress/strain field, based on experimental calibration of the friction coefficient between the welded surfaces, is established and found in agreement with laboratory strain data. Last, the technical advantages of the process, including fabrication of dense, full-strength functional solid metal parts, multiple-material composites, and active parts with embedded intelligent components and electronic, mechatronic, optic and fluidic structures, are examined in the manufacturing industry.
Design and Analysis of Piezoelectric Actuators Produced by Solid Freeform Fabrication
Authors: Cheeseman Bryan A. , Chen Baoxing , Safari Ahmad , Danforth Stephen C. , Chou Tsu-Wei
Published: November 2021

Solid Freeform Fabrication (SFF) techniques permit the ready manufacture of ceramic actuators possessing unusual and complex shapes. These actuator designs allow for the optimization of material orientation, poling direction and applied potential direction, which can result in increased displacement. Examples of such designs are detailed in this paper and include a dome shaped actuator possessing tangentially alternating poling and a spiral shaped actuator.
A Gradient Based Optimization Framework for the Design of Single and Multi-Stage Metal Forming Processes
Authors: Srikanth Akkaram , Zabaras Nicholas
Published: November 2021

A gradient based optimization methodology is developed for the design of metal forming processes. A novel, efficient and mathematically rigorous scheme is proposed for a continuum based sensitivity analysis of metal forming processes that can be used to accurately evaluate gradients of the objective function and design constraints. In particular, a sensitivity analysis is being developed for the Lagrangian analysis of finite inelastic deformations of hyperelastic-viscoplastic materials involving frictional contact. A framework for shape as well as parameter optimization for single-stage metal forming processes was introduced in [1–4]. Weak sensitivity equilibrium equations were derived for the large deformation of the workpiece in a typical forming operation. This sensitivity kinematic problem was linearly coupled with the appropriate sensitivity constitutive and contact sub-problems. Thus a linear sensitivity problem with appropriate driving forces was identified and the analysis carried out in an infinite dimensional framework. This work on the design of single-stage forming processes is currently expanded to include the design of multi-stage forming processes which necessarily involve the computation of both shape as well as non-shape (parameter) sensitivities. The direct deformation and sensitivity deformation problems are implemented using the finite element method. The effectiveness of the proposed methodology is tested here with the solution of two practical design problems in single and two-stage forming processing.
A Study on Fundamental Mechanisms of Warp and Recoil in Hemming
Authors: Zhang Ellen , Wu Xin , Hu S. Jack
Published: November 2021

In this paper, the occurrence of recoil and surface warp during flat surface-straight edge hemming process is investigated. A general-purpose finite element code ABAQUS/Standard is used to simulate the hemming operations. Reverse bending, localized buckling and springback are the fundamental mechanisms that cause surface warp and recoil. Recoil and warp are not independent. One parameter called final equivalent residual warp is obtained to represent both. Feasible pre-hem ending zone is proposed based on final equivalent residual warp. The influence of the geometrical and process parameters on recoil and warp are also investigated.
Non-Linear Kinematic Hardening Identification for Anisotropic Sheet-Metals With Bending-Unbending Tests
Authors: Brunet M. , Morestin F. , Godereaux S.
Published: November 2021

An inverse identification technique is proposed based on bending-unbending experiments on anisotropic sheet-metal strips. The initial anisotropy theory of plasticity is extended to include the concept of combined isotropic and non-linear kinematic hardening. This theory is adopted to characterise the anisotropic hardening due to loading-unloading which occurs in sheet-metals forming processes. To this end, a specific bending-unbending apparatus has been built to provide experimental moment-curvature curves. The constant bending moment applied over the length of the specimen allows to determined numerically the strain-stress behaviour but without Finite Element Analysis Four constitutive parameters have to be identified by an inverse approach. Our identification results show that bending-unbending tests are suitable to model quite accurately the constitutive behaviour of sheet metals under complex loading paths.
Methodology to Expedite Mechanical Component Design and Analysis in Gas Turbine Engines
Authors: Nguyen Ly D. , Ku Taison
Published: November 2021

Advances in computer technology have enabled the utilization of sophisticated computer software to assist in mechanical design and analysis in various fields. CAD/CAM/CAE software, such as CATIA, UG (Unigraphic), CV (Computervision), ANSYS, NASTRAN, ABAQUS, Hypermesh and Tgrid, have proven to be effective tools for aiding designers and analysts. The challenges offered by these software improvements, are an efficient engineering design and analysis process, and the need for broader training of the designers and analysts conducting these processes. In the past these processes were often done sequentially and proved to be very time consuming.

At Honeywell International Inc., a methodology has been established to synchronize CATIA®, CAD-fix®, ANSYS®, Hypermesh® and Tgrid® in the design and analysis of gas turbine engine components to speed the design analysis process. This paper describes the techniques used on such complex parts as the combustor case, the front frame support and the turbine nozzle to reduce cycle time in the design and analysis process. Modeling process techniques described in this paper include the implementation of cyclic symmetric boundary conditions, data transfer between CATIA and ANSYS using CAD-fix, and mesh control and sizing through the used of Hypermesh and Tgrid.
A High-Order Solution for the Added Stability Lobes in Intermittent Machining
Authors: Corpus William T. , Endres William J.
Published: November 2021

An earlier work by the authors presented a solution for the added ultrahigh-speed stability lobe that has been shown to exist for intermittent and other periodically time varying machining processes. That earlier first-order solution was not clearly extendible to a higher order. A more general analytical technique presented here does permit higher-order results. The solution is developed first for the case of zero damping for which a final closed-form symbolic result can be realized up to second order. More important than improved accuracy, the higher-order nature of the result confirms that there exist multiple added lobes and permits a mathematical description of their locations along the spindle-speed axis. A solution is then derived for the structurally damped case, where the first-order case permits a final closed-form symbolic result while the second-order case requires computational evaluation. The first-order result matches perfectly the previously published one, as expected. The second-order result improves accuracy, measured relative to numerical simulation results, and, more important, permits a second added lobe to be predicted. The second added lobe tends to cut into the region of the high-speed stability peak that is predicted under traditional zero-frequency (time-averaged) analyses. The damped solutions also indicate that structural damping of the dominant mode becomes virtually unimportant at ultrahigh speeds.
Biomechanical Models of the Developing Cardiovascular System
Authors: Taber Larry A.
Published: November 2021

It long has been known that mechanical forces influence the development of the cardiovascular system, but how these forces interact with genes to shape the heart and blood vessels is poorly understood. Recently, biomechanical models have been used to aid researchers studying the developmental processes of growth, remodeling, and morphogenesis. This paper reviews the biology and models for each of these processes.
ER Effect in Liquid Crystal
Authors: Tsukiji Tetsuhiro , Tanabe Shinsuke
Published: November 2021

Liquid crystal is one of homogeneous ER (Electro-rheological) fluids in some range of temperature. In the present study the effect of electric fields on shear stress in liquid crystal is investigated using rotational viscometer. The shear stresses are measured by changing a shear rate, amplitude and frequency of electric fields. Dependence of the shear stress on electrical excitation frequency is mainly investigated. Furthermore flow visualization is conducted and relation between flow rate and pressure drop is measured when liquid crystal flows between two parallel-plate electrodes under application of electric fields. The experimental results are compared with previous ones for ER suspensions.
Dynamic Compressive Failure of Unidirectional E-Glass/Vinylester Composites
Authors: Oguni Kenji , Ravichandran Guruswami
Published: November 2021

Results for unidirectional fiber reinforced polymer composites (E-glass/vinylester) with 30%, 50% fiber volume fractions under dynamic uniaxial 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. The results indicate that the compressive strength of the composite increases with increasing strain rate. Post-test scanning electron microscopy is used to identify the failure modes. In uniaxial compression the specimens are split axially (followed by fiber kink band formation). Based on the experimental results and observations, an energy-based analytic model for studying axial splitting phenomenon in unidirectional fiber reinforced composites is extended to predict the compressive strength of these composites under dynamic uniaxial loading condition.
Robust Control of Electrohydraulically Actuated Friction Damper
Authors: Guglielmino Emanuele , Edge Kevin A.
Published: November 2021

This paper focusses on the Sliding Mode Control (SMC) of a servo-driven dry-friction damper employed in a force control loop for the purpose of vibration reduction. An application to a car suspension is investigated using a quarter car model.

The friction damper is a semi-active device: it can only oppose to the motion but not assist it. This inherent limitation requires particular attention in the design of the sliding surfaces. The performance of various types of sliding surface are compared, by means of computer simulation.
Analytical Method for Defining Pressure Compensator Dynamics
Authors: Käppi Timo J. , Ellman Asko U.
Published: November 2021

Computer simulation is a powerful and generally accepted practice to carry out research in the area of fluid power. However, accurate parameterization of the component models is required to achieve correct simulation results. The parameters describing the stationary behavior of hydraulic valves are easily available from valve manufacturers’ catalogues. The dynamics are presented typically for the servo valves only. The dynamics of pressure valves are usually more or less unknown even for the manufacturers. Numerical values for simulation purposes are very rarely available.

The lack of information concerning valve dynamics makes the component measurements unavoidable. This is time consuming and costly and the benefits of simulation concept in general are reduced. In this paper a method for defining first order dynamics for the pressure compensator is presented. This method can be used in time-domain simulation of fluid power components and systems. The method is based on the analytical dimensions of valve such as diameter of damping orifice, spring constant and mass.

Pressure compensated mobile valve is measured for method verification. The presented method can be applied to any type of commercially available well damped single-stage pressure valves. It makes the fluid power component parameterization considerably easier and thereby the advantages reached by simulation are increased.
Comparison of Different Viscoelastic Models for Nonlinear Free Vibrations of Moving Belts
Authors: Zu Jean W. , Hou Zhichao
Published: November 2021

Four classical viscoelastic models are adopted to analyze the nonlinear free vibrations of moving belts. The models include Kelvin solid, Maxwell fluid, standard linear solid and Maxwell-Kelvin fluid. Two model-dependent parameters are given for each model. In terms of these parameters, general solutions of the free oscillation responses are given in closed forms for all these models. For the resulting amplitudes and frequencies, numerical simulations are performed to compare these viscoelastic models.
Stability of a Gyroelastic Plate
Authors: Yamanaka K. , Heppler G. R.
Published: November 2021

An model of a gyroelastic thin plate is presented. The equations of motion and boundary conditions are derived when the system is subject to in-plane external loads. It is shown that these systems can display both static instabilities (divergence) and dynamic instabilities (flutter), that the structure of the stability regions depends on the aspect ratio of the plate and that gyroscopic stabilization is sometimes possible.
Analysis and Optimization of Foam Core Mid-Plane Asymmetric Sandwich Beams Under Lateral Loads
Authors: Vinson Jack R. , Satapathy Nihar R.
Published: November 2021

The equations with which to analyze, design and optimize honeycomb sandwich beams subjected to laterally distributed loads are presented. They apply to beams using composite materials and for isotropic materials. Specifically they account for mid-plane asymmetry in order to maximize the structural efficiency, thus providing for differing face materials, ply sequencing and/or thicknesses. Explicit solutions are given for the beam subjected to a uniform lateral load for several boundary conditions. To attain minimum weight, the means to select each face thickness, the core depth and the honeycomb core wall thickness and cell size are given. Localized face dimpling and face wrinkling, using and comparing the results of Heath equation and the Hoff-Mautner equation are included. The effects of transverse shear deformation are also shown. In order to choose the face material and core materials to achieve a minimum weight structure, Factors of Merit are defined for the faces and the core. Various face materials are then compared.
A New Modeling Approach to Reacting Dispersed Flow in Smelting Cyclones
Authors: Modigell M. , Weng M.
Published: November 2021

The present paper proposes a new approach to analyse the conversion of complexly composed particles that are dispersed in a cyclone gas flow at high temperatures. The numeric simulation of flow field and particle trajectories is coupled with a thermodynamic equilibrium calculation which describes the particle reaction progress. First simulation results and the comparison with experimental data are shown in this paper.
Finite Element Simulations of Gas-Liquid Flows With Surface Tension
Authors: Wang Gang
Published: November 2021

The finite-element program, ANSYS/FLOTRAN, has been enhanced at Release 5.7 to predict gas-liquid flows with surface tension. The two-dimensional incompressible Navier-Stokes and energy equations are solved in both Cartesian and axisymmetric geometry. The location of the interface is computed and tracked with the CLEAR-VOF algorithm. Normal and tangential boundary conditions at the interface are enforced through a continuum surface force (CSF) model. This new algorithm is first validated with two model problems: a droplet in equilibrium and an oscillating droplet. For the first problem, the computed pressure value is compared with the theoretical value, whereas for the second problem, the oscillation frequency is compared with both the analytical solution and the experimental data. The computer program is then applied to a number of interesting free surface problems: droplet impacting on a rigid wall, binary droplet collision, flow induced by wall adhesion, and marangoni convection in a rectangular cavity.
Scaled Experiments and CFD Simulations Supporting the Design of the Spallation Neutron Source Mercury Target
Authors: Pointer W. David , Wendel Mark W. , Crye Jason M. , Ruggles Arthur E. , Felde David K. , Jalouk Philip A. , Yoder Graydon L. , Haines John R.
Published: November 2021

A combination of experimental and computational methods is necessary to adequately characterize the flow patterns in the liquid mercury target of the Spallation Neutron Source (SNS). Since liquid mercury is completely opaque and corrosive to many materials, the use of liquid mercury as the working fluid makes complete characterization of the flow field by experiment difficult. Furthermore, flow asymmetries and quasi-periodic instabilities that are observed in early target flow experiments are difficult to capture in computational fluid dynamics (CFD) simulations of the system. Therefore, an experimental program using several scaled experiments is combined with CFD simulation for the design and development of the SNS mercury target.
A Design of Experiment Using Computation Fluid Dynamics for Spool-Type Hydraulic Valves
Authors: Miller Ronald H. , Strumolo Gary S. , Leon Carlos
Published: November 2021

In order to compete successfully in the global market place, manufactures must have the ability to produce high-quality, low-cost products that fully satisfy the customer’s needs. Many analytical techniques have been adopted by these manufactures aimed at improving customer and engineering quality. Nonlinear multivariate systems, however, complicate this process making the determination of controlling factors difficult. Often times, improvements in one area of the process or product compromises the performance in other areas. The Design of Experiments (DOE), pioneered by Taguchi, represents a powerful statistical method to help better understand nonlinear systems with the aim to improve quality and performance in engineering. A DOE using Computational Fluid Dynamics (CFD) is developed to better understand the influences of flow forces on valve design and performance. Geometric control factors for the spool valve are determined, enabling optimization and performance improvements.
Development of an Anti-Interference Swirl Meter Based on Numerical Simulation of Hydrodynamic Vibration
Authors: Fu Xin , Yang Huayong
Published: November 2021

Having the advantages of no motion elements, high reliability, undemanding maintenance and good medium flexibility, the swirl meter has been widely used to measure the gas, liquid and steam in chemical, petroleum as well as processing industries. For the current one-piezoelectric-pressure-sensor swirl meter, however, the measuring error caused by the interference pressure oscillation limits its application in the system where pressure is unsteady, or a noisemaker is nearby. In this paper, the fluid dynamic features inside the channel of the swirl meter are studied numerically and by experiment. The time dependent vortex motions as well as the hydrodynamic vibrations within the channel of the swirl meter are simulated using the CFD approaches of the RNG k-ε model. The computed flow fields indicate that the eccentric motion of vortexes initiates an axisymmetric pressure oscillation within the vortex precession area of the swirl meter. The frequency of the oscillation shifts linearly with volume flow rates. Both the calculated and the measured results prove that the hydrodynamic vibrations on the arbitrary axisymmetric points are equal in amplitude and frequency but with a 180 degree phase difference. By installing differential pressure transducers on such the axisymmetric points, the signals of the vortex pressure oscillations are enhanced, while the interferential signals are suppressed, enabling the anti-interference performance and low-flowrate sensibility of the swirmeter to be effectively improved.
Turbulent Flow Forces on Hydraulic Valves: A Parallel Vortex Simulation Method
Authors: Dimas Athanassios A. , Lottati Isaac , Miller Ronald H. , Strumolo Gary S. , Bernard Peter S.
Published: November 2021

The unique software VORCAT (VORtex Computational Algorithm for Turbulence), which is based on a fast parallel vortex method, is employed to perform a time-accurate simulation of the flow in the spool valve of a pressure regulator from an automotive automatic transmission. The spool valve experiences flow forces which affect its axial motion and radial clearance. The vortex method is based on a parallel implementation of the Fast Multipole Method, and includes a hybrid vortex filament/sheet representation of the flow field, a vortex filament creation model that imitates the physical vortex self-replication process, and a hairpin removal and reconnection mechanism to limit the number and scale of vortical structures to those that are dynamically essential. In this paper, velocity and vorticity distribution results are presented for spool valve openings of 1mm and 0.25mm. The predicted velocity results agree well with corresponding experimental measurements, while the predicted vorticity results correlate well with experimental pressure measurements.
Parallel Optimization Algorithms for Multi-Body Systems in High Performance Computing and Networking
Authors: Hamma Beidi S. , Jiménez José M. , Chehayeb Nassouh A. , Giraud Luc
Published: November 2021

In this paper we present some parallel optimization experiments achieved in ODESIM project, a High Performance Computing and Networking (HPCN) project funded by the European Commission within ESPRIT programme. The project acronym stands for Optimum DESIgn of Multi-Body systems. The project main objective has been the development of a set of software tools for finding optimal designs of MBS for kinematic and dynamic simulation. One part of the work in this project was the definition of parallel optimization algorithms suitable for MBS (Multi-Body Systems) and their implementation in a HPCN framework. In this paper we will present local optimization algorithms as well as some simple global optimization algorithm for MBS simulation.
Simulation of Reynolds’ Color-Dye Experiments on Instability of Circular Pipe Flows: Part 1—Discussion of the Problem
Authors: Kanda Hidesada
Published: November 2021

In previous studies, a conceptual model was constructed for the problem of determining in circular pipes the conditions under which the transition from laminar to turbulent flow occurs. The model is based on the assumption that the shape of the pipe entrance (geometry) governs the critical Reynolds number Rc, such that the minimum value of 2040 was obtained in the case of a straight circular pipe. This implies that the minimum value is obtained when there is no bellmouth attached to the inlet of the pipe. In reality, the normal wall strength, which is generated on the wall, determines a critical Reynolds number. Accordingly, the author assumes that the shape of the bellmouth will lead to the critical Reynolds number of approximately 12,600 observed by Reynolds in his color-dye experiments.

To begin the numerical simulation of Reynolds’ color-dye experiments, it is desirable to validate the model based on the common understanding gained from previous conclusions. As a result, the verification showed the consistency of the model with well-known experimental results, and it was proven why initially disturbed flow becomes laminar flow downstream at Reynolds numbers below the minimum critical value of approximately 2000.
Simulation of Reynolds’ Color-Dye Experiments on Instability of Circular Pipe Flows: Part 2—Definition of the Problem
Authors: Kanda Hidesada
Published: November 2021

Reynolds experimentally studied the flow in circular pipes and then derived the similarity law which is represented by the Reynolds number. The present situation, however, of the study of the transition from laminar to turbulent pipe flows is not obvious. Accordingly, it is desirable to first focus on Reynolds’ color-dye experiments and then to define what the simulation should be. Without the correct definition of the simulation, the study will go astray. By taking the author’s model (described in Part 1) to be valid, a simple definition for the simulation of Reynolds’ color-dye experiments is obtained, which will satisfy the experimental results of Reynolds.
Coupling Between Internal Vortex Shedding and the Axial Acoustic Modes in a Choked Duct Flow: New Experiments
Authors: Petersen Eric L. , Murdock John W.
Published: November 2021

Experiments on vortex shedding within a choked duct and its coupling with the duct’s longitudinal acoustic modes are reported. The vortex shedding and impingement mechanism was produced by a pair of concentric orifice plates placed within the duct. The results of the experiments demonstrate that the frequencies and strengths of the measured acoustic tones depend on the flow velocity, Reynolds number, orifice size, and orifice spacing. A standing wave was produced when the orifice-pair tone was near a longitudinal acoustic mode of the chamber. The oscillation frequency increased slightly with increasing Reynolds number but usually remained within 2-3% of a chamber longitudinal mode. Dual tones and abrupt frequency shifts in singular tones were observed for changes in Reynolds number and/or plate-to-plate spacing. The results of these experiments are part of an ongoing study to better understand the fundamental mechanisms of vortex-induced pressure oscillations within a flow chamber.
Effect of Liquid on a Reciprocating Compressor
Authors: Shiva Prasad B. G.
Published: November 2021

Compressors are intolerant to liquids. Liquids can form inside compressor cylinders by condensation as in refrigerant compressors, or find its place inside cylinders by a gradual or sudden ingestion through the inlet piping in the form of slugs. In reciprocating compressors with inherently large volumetric displacement rates, all modes of ingestion pose a serious problem and can even result in catastrophic failures. This paper describes a simple method of estimating the cylinder pressure and “rod load” (force on the crosshead pin, in compressor terminology) in a double-acting reciprocating compressor. The results indicated that even with moderate volume of liquid present inside the cylinder, the pressure could reach values as high as 4 to 5 times its normal value with a correspondingly higher rod load.
Unsteady Fluid Flow and Force on an Obstruction in a Pipe
Authors: Choe Hwang
Published: November 2021

An unsteady fluid flow in a pipe with an orifice or an obstruction is studied. The velocity in the pipe and the force on the obstruction are calculated numerically. Several different forcing functions are considered for this unsteady flow system: a sinusoidal forcing function, a step forcing function, and a ramp forcing function. The response to the sinusoidal forcing function as a function of frequency for the fluid flow system is the main focus of this paper. The results for this non-linear system are found to be significantly different from those of a linear system. The results and the method of this study may be applied to the calculations of unsteady forces acting on objects such as check valves or probes in a pipe with unsteady turbulent flow.
Validation of the RFG Method for Generating Time-Dependent Inflow Boundary Conditions
Authors: Shi Shaoping , Smirnov Andrei , Celik Ismail
Published: November 2021

A new Random Flow Generation (RFG) (Smirnov et al., 2000b) approach is proposed which can provide turbulent initial or inflow conditions for unsteady flow calculations. This methodology is briefly described. Boundary layer flow with the the Reynolds stresses known from experiments is used to validate the method. The issues of anisotropy and continuity of the fluctuating field are discussed. This approach has been applied for the wake behind a flat plate using large eddy simulation (LES) technique. Good results are obtained as compared to experiments.
Damage Tolerance Analysis of Railroad Tank Cars
Authors: Zhao Wei , Sutton Michael A. , Penã Jose , Hattery Brenda K. , Wang Duan Q. , Hubbard Camden R.
Published: November 2021

The paper summarizes an effort in improving structural integrity of the railroad tank cars. Damage tolerance analysis is performed on a DOT 111A100W1 general purpose tank car. Stress distributions and potential fatigue critical locations are determined using global and local finite element models. Welding residual stresses in an unconstrained TC128-B butt weld are obtained using neutron diffraction technique. Fatigue crack growth analysis under a tank car service load spectrum is carried out and inspection intervals are determined for various postulated initial flaws. Two materials are considered, a generic steel (presumably representing A516-70), and A515 for older tank cars.
Rail Passenger Equipment Collision Tests: Analysis of Structural Measurements
Authors: Severson Kristine J. , Tyrell David C. , Perlman A. Benjamin
Published: November 2021

A two-car full-scale collision test was conducted on April 4, 2000. Two coupled rail passenger cars impacted a rigid wall at 26 mph. The cars were instrumented with strain gauges, accelerometers, and string potentiometers, to measure the deformation of critical structural elements, the longitudinal, vertical, and lateral car body accelerations, and the displacements of the truck suspensions. Instrumented crash test dummies were also tested in several seat configurations, with and without lap and shoulder belts.

The objectives of the two-car test were to measure the gross motions of the car, to measure the force/crush characteristic, to observe the car-to-car interaction, to observe failure modes of the major structural components, and to evaluate selected occupant protection strategies. The measurements taken during the test were used to refine and validate existing computer models of conventional passenger rail vehicles. This test was the second in a series of collision tests designed to characterize the collision behavior of rail vehicles.

The two-car test resulted in approximately 6 feet of deformation at the impacting end of the lead vehicle, and a few inches of deformation at the coupler. The cars remained coupled, but buckled in a saw-tooth mode, with a 15-inch lateral displacement between the cars after the test.

The test data from the two-car test compared favorably with data from the single-car test, and with analysis results developed with a lumped-mass computer model. The model is described in detail. The methods of filtering and interpreting the test data are also included.
Rail Passenger Equipment Collision Tests: Analysis of Occupant Protection Measurements
Authors: Tyrell David , Zolock John , VanIngen-Dunn Caroline
Published: November 2021

The Federal Railroad Administration has been conducting research on occupant protection in train collisions. As part of this research, computer simulations have been performed, passenger seats have been sled tested, and two full-scale collision tests of rail passenger cars have been conducted. The passenger equipment collisions tests that have been performed to date are:

1. Single car impact into a fixed barrier at 35 mph.

2. Two coupled car impact into a fixed barrier at 26 mph.

As part of these tests, the cars were instrumented to measure the deformations of critical structural elements; the vertical, lateral, and longitudinal deceleration of the carbody and trucks; and the suspension displacements. The cars were also equipped with instrumented anthropomorphic test devices (test dummies) in three interior arrangements:

1. Forward-facing unrestrained occupants seated in rows, compartmentalized by the forward seat in order to limit the motions of the occupants.

2. Forward-facing restrained occupants with lap and shoulder belts.

3. Rear-facing unrestrained occupants.

This paper describes the vertical and lateral motions of the cars during the two-car impact test, and discusses their influence on the responses of the instrumented dummies. The lateral motions of the cars appear to have had little influence on the response of the test dummies. The vertical motions of the cars may have had an influence on the forward facing unrestrained test dummies seated in rows. Such experiments were conducted in both the leading and trailing cars, and in both these experiments, the heads of the test dummies rose above the seatback ahead, allowing high neck loads.
Alternative Analyses of Locomotive Structural Designs for Crashworthiness
Authors: Martinez Eloy , Tyrell David
Published: November 2021

Enhanced crashworthiness performance of North American locomotives is proposed by both increasing the design loads on specific structural components or by describing the crashworthiness performance under specific impact conditions. The design loads for a conventional North American locomotive and the description of performance are intended to provide the same level of crashworthiness protection. A generic design was developed to illustrate the types of calculations that can be used to show that the design loads can be supported and the desired level of performance can be met. The performance of the generic locomotive subjected to a collision with a grade crossing object is measured by its ability to prevent penetration of the object into the occupied volume where the crew rides out the collision. The closed form hand calculations apply established structural analysis limit load theory and show the design loads can be supported. The finite element analysis results capture large deformation non-linear behavior and show the desired level of performance is achieved.
Recent Advances in 3D Weaving for Textile Preforming
Authors: Dickinson Larry , Mohamed Mansour
Published: November 2021

There have been many publications on “3D Weaving”, and there are numerous patents on a variety of devices that may be used to make a “3D Woven” structure. The majority of the 3D woven products that are currently commercially available are formed by a 2D weaving process that is used to build up a preform with fibers oriented in three dimensions. Recent advances have lead to multiple insertion 3D weaving, i.e. 3D fabric formation with each process cycle, or multi-layers at one time. The 3Weaving™ process is a multiple insertion 3D weaving technology that is different from traditional weaving. These distinctions about the different processes will be detailed in this paper. Additionally, the economics, manufacturing and performance of 3D woven textile preforms for composites will be discussed. Problems and solutions in each of these areas that prevent the large scale production of advanced composites will be presented. The advantage of 3D textile preforming is the ability to take complexity and labor out of manually intensive and expensive composites fabrication processes, and put it in the relatively inexpensive automated preforming process.
Silent Chain Noise of Cab Motorcycles
Authors: Pan M. , Shieh Eddy T.
Published: November 2021

In the design of driving systems, silent chains have extensively replaced roller chains thanks to annoying noise problems. But, for some types of cab-motorcycles, especially sheet-frame cabs, the annoying noise originated from silent chains can still not been accepted. In this study, silent chain noise of cab motorcycles has been well investigated by firstly the order analysis and time-frequency analysis of measured noise, and secondly the analysis of noise-origination, transmission and amplification via frame. Thus the noise mechanism can be precisely uncovered and understood. Some experiments were conducted to discover three primary issues of a noise problem, i.e., noise source, transmission path, and response. In addition, an odd mode shape, i.e. mode (1,3), was constructed based on the running mode principle. Then, a dominant noise component resulting from structure resonance can be interpreted. In the study, different engineering modifications have been validated to reduce this transmission-part noise.
Modeling of an Elastic Fin Micromotor
Authors: Lu P. , Lee K. H. , Lim S. P. , Dong S. , Lin W. Z.
Published: November 2021

In the present work, a simplified mathematical model of ultrasonic elastic fin micromotors has been developed. According to the operating principle of this type of motors, motions of rotor in each cycle of stator vibration are divided into several stages based on whether the fin tip and the stator is in contact with slip, contact without slip or separation, respectively. The motion equations of the rotor in each stage are established and derived. The validity range of the model has been discussed through numerical examples. This work provides an initial effort to construct a model for the elastic fin motor by considering dynamical deformation of the rotor as well as intermittent contacts.