bluuebunny/crossref_metadata_2025_split huggingface dataset:
Feature-Based Design in an Integrated CAD/CAM System for Design for Manufacturability of Machining Prismatic Parts
Authors: Lu Wen F. , Modi Ronak 
Published: March 2022

Abstract
In this paper, we put forth an approach of incorporating manufacturing knowledge in the design cycle for an integrated CAD/CAM system for design for manufacturability based on feature-based design. This system is intended to assist the designer to evaluate the design from the manufacturing point of view from the start of the product design cycle. The proposed system is composed of three major modules: design module, interface module, and design for manufacturability module. The design module includes a 3D geometric modeler and a feature library with features that are created by a hybrid CSG, B-rep and sweep approach. The design is communicated to the design for manufacturability module by an interface module. The interface module maps design features into manufacturing features. This mapping involves certain geometric reasoning, and thus, the mapping module interacts considerably with the geometric modeler. The mapping results are then used by the design for manufacturability module to evaluate the manufacturability of the designed part. This paper focuses on how the CAD data from design module are transformed into information that can be used by the design for manufacturability. Only machining of prismatic parts are considered in this paper. An example is given to illustrate the use of the proposed system.
Conceptual Design Tool for the Systematic Design Method
Authors: Sieger David B. , Salmi Reino E. 
Published: March 2022

Abstract
The significance of activities performed during the initial design process stages suggests the need for supporting computer applications. Currently, such support is not available until the detailed design stage is reached. Although several models addressing activities occurring prior to this stage appear in the literature, these models are limited in their ability to be scaled up to real-world problems, integrated with existing tools, and/or provide guidance to participants. A window-based application for the conceptual design stage that effectively addresses these limitations is presented in this paper. Our approach is unique in that it combines existing methodologies for function and system decomposition in a way not previously considered, as well as facilitating the use of a design guidance mechanism. An example demonstrating the use of the resulting tool to a conceptual design problem is provided.
A Software Tool for Economic Input-Output Life-Cycle Assessment
Authors: Espinosa Octavio Juarez , Garrett James , Hendrickson Chris 
Published: March 2022

Abstract
Software tools can be used to apply green design guidelines during product and process design. However, most current design systems do not consider the environmental impacts over the life-cycle of a product. This paper describes a software tool to calculate indirect and direct estimates of toxic releases and other environmental impacts during a product life-cycle. This software implements the EIO-LCA method, provides a Graphical User Interface (GUI) and includes some new features to facilitate the application of this method EIO-LCA is a life-cycle assessment method based upon economic input-output matrix models of the entire economy and, depending upon user needs, specific products or processes. The system architecture is presented and a session with the system is described. Future research directions and a discussion of the advantages and disadvantages are also included.
Nuclear Power Hazard and Economic Risk Assessment
Authors: Margulies T. 
Published: March 2022

Abstract
This paper addresses a complex debate of national importance related to the safety of existing light water reactors and preventing, mitigating, or improving emergency preparedness for response to severe reactor accident releases of radioactivity for operating reactors. The costs and benefits of several key alternatives are assessed for the NUREG-1150 reference plants, as well as, a representative medium population density site. Annual levelized cost calculations using a 105 annual release rate were made using ICRP annuity factors for potential safety improvements resulting in cost-beneficial justifications for engineering safety improvements such as supplemental filtering and scrubbing to the present containments, and for instrumentation and monitoring to minimize a bypass scenario. Probabilistic risk financing formulas for expected continuous discounting are presented. Improvements to emergency preparedness measures such as stockpiling potassium iodide for the population would not have the additional protection benefits of reducing substantially non-inhalation pathway contributions to offsite health effects, as well as, protecting land from contamination.
An Experimental Study on Galloping of a Square Prism With a Splitter Plate Through Indicial Lift Response
Authors: Hirata Katsuya , Nakamura Yasuharu , Iwasaki Tohru 
Published: March 2022

Abstract
To elucidate the aerodynamic mechanism of galloping, the authors attempt another approach in the time domain relative to this oscillatory instability. As a test body, the present study takes up a square-section prism with a stationary long splitter plate in its wake. A black-box theory of galloping is presented. Wind-tunnel experiments are reported on the indicial pressure responses together with flow visualizations. The corresponding Reynolds numbers were approximately 1.9 × 104 and 8.9 × 103, respectively. In addition to the measurement of the indicial pressure responses, the sinusoidal pressure responses are also measured by forcedly oscillating the same model. As a result, the indicial body motion produces the separation-induced vortices on two sides parallel to the uniform flow, and these vortices are responsible for the lift force related to the onset of galloping. The quantitative agreement between theory and experiment is reasonable for slowly oscillating galloping.
Experimental Study of Vibration and Acoustic Radiation of a Pipe Induced by Fully-Developed Turbulent Air Flow
Authors: Durant C. , Robert G. 
Published: March 2022

Abstract
Experimental results are presented concerning the vibro-acoustic response of a pipe excited by an internal fully-developed turbulent air flow. The internal wall pressure field generated by the flow, the vibration response and the external acoustic field were measured for Reynolds numbers Re = UoD/v ranging from 5.3 × 105 to 12.5 × 105.
The measured statistical properties of the wall pressure field include power spectral densities and cross-spectra. Power spectral density is analyzed after cancellation of a contaminating acoustic component of the wall pressure fluctuations. Convection velocity and correlation lengths are calculated from measured cross-spectra to complete a Corcos model for the cross-spectrum of the turbulent wall pressure fluctuations. The ratio of convection velocity to centerline velocity ranges from 0.7 to 0.8. The coefficient α1 of the standard Corcos model is calculated from the longitudinal correlation length and is found to be around 0.18. To have further information about the convection velocity and correlation lengths in a lower frequency range than presented here, the measured cross-spectral data need to be decontaminated from the acoustic component of the wall pressure.
The acceleration response of the pipe wall shows the influence of the structural modes of the test section. Only some of them have a significant influence on the external acoustic field.
Computation of Jet Noise Using Large-Eddy Simulation and Lighthill’s Analogy
Authors: Schein David B. , Meecham William C. 
Published: March 2022

Abstract
Computational aeroacoustics involves numerical study of the acoustic field generated by unsteady fluid motion. An area of significant interest is unsteady turbulent flow in free jets and resultant far field acoustic pressure fluctuations. Since Lighthill’s mathematical formulation for jet noise generation in the early 1960’s, a search has continued for a physical interpretation of his formal results and, in particular, the noise source term. Far field measurements have not provided a clear picture concerning the nature of the acoustic source. Therefore, industry standard procedures for prediction of far field noise from exhaust jets rely on semi-empirical methods to calculate mean sound pressure levels and directivity. Our objective is to contribute to a more thorough understanding of the acoustic source from a shear flow using Large-Eddy Simulation (LES) turbulence modeling.
Published work for direct numerical simulation of these flows has been confined to low Reynolds number (&lt; 3000) with Mach numbers up to 2.0, to study the physics of sound generation and test aeroacoustic prediction methods (Mitchell, et al, 1995). While furthering understanding of jet noise generation, these cases limit exhaust dimensions to millimeters and make it difficult to compare results to measured data. Here we address large Reynolds numbers and high subsonic Mach number (compressible) flow combined with realistic geometries more representative of aircraft engine exhausts.
Standard turbulence models compute the average flow field, which cannot be used to calculate the aeroacoustic field. Temporal fluctuations are required and can be obtained using LES, with a spatial filtering operation applied to the equations of motion. The technique is based on computing only large scale motions directly subject to the problem’s boundary conditions, while small scale motions are assumed to be more universal and their statistics and effect upon large scales are predicted using a “subgrid-scale” model. The motivation for this approach is that experimental observations of turbulent flows show that large scale turbulent structures vary markedly from one flow situation to another, while small scales show less variation from case to case.
The acoustic radiation calculation consists of three steps; 1) an approximate result for the mean flow field using a compressible flow code employing a k-ϵ turbulence model, 2) unsteady turbulent fluid field simulation using the CFD code appended with a LES turbulence model (the k-ϵ prediction serving as an initial guess) and 3) far field acoustics obtained using Lighthill’s analogy. Extensive far field noise data from ground static measurements of a WR19-4 mini-turbofan engine are being drawn from for comparisons between computed results and measurements.
Dynamics of Axially Moving Beams
Authors: Behdinan K. , Tabarrok B. 
Published: March 2022

Abstract
In this investigation we consider the lateral motion of axially rigid sliding beams protruding from a stationary rigid wall. The main objective is to consider the large rotations and small strains and to examine the nature of the motion of sliding beams and point out the salient features of the motion.
Once we obtain the equation of motion for geometrically nonlinear sliding beams, we compare them with those for pipes conveying fluids and we show similarities in these equations for the two physically different systems. Next we use the Galerkin method and obtain the transient response of the problem. To verify the formulation and its computational implementation we analyse several examples and compare our findings with those reported in the literature.
Free Surface Effects on the Dynamics of Cylindrical Shells Partially Filled With Liquid
Authors: Lakis A. A. , Neagu S. 
Published: March 2022

Abstract
This paper presents an analytical model for the dynamic analysis of thin cylindrical shells partially filled with liquid. The method used is a combination of finite element analysis and classical shell theory, and the objective is to determine the specific displacement functions which best represent the real deformations.
The effect of oscillations of the free surface of the liquid on fluid-shell vibration is studied, and consideration is given to the influence of such parameters as: the circumferential mode, the axial mode, the structural damping, the length of the shell and the forces induced by the liquid.
The shell is divided into cylindrical finite elements and the displacement functions are derived using Sanders’ thin shell theory. The stiffness and mass matrices of the shell are derived analytically.
For the liquid contained in the shell, boundary conditions are prescribed and the behaviour of the liquid is expressed by a potential function. The kinetic and potential energies of the liquid are evaluated in order to establish the influence of surface oscillation on fluid-shell vibration.
Vibration Analysis of Single-Anchor Inflatable Dams
Authors: Mysore Guruprasad V. , Liapis Stergios I. , Plaut Raymond H. 
Published: March 2022

Abstract
Inflatable dams are flexible, cylindrical structures anchored to a foundation. They are used for various purposes, e.g., diverting water for irrigation or groundwater recharging, impounding water for recreational purposes, and raising the height of existing dams or spillways. Early inflatable dams were anchored along two of their generators, but recently-constructed dams are anchored along a single line. They also have a fin near the top which is useful in overflow conditions. The vibrations of such dams in the presence of external water are considered in this paper.
The dam is modeled as an elastic shell inflated with air and resting on a rigid foundation. First the equilibrium shape of the inflated dam is determined. Next, the dam is clamped with this cross-sectional shape at its two ends, and then water is applied on the anchored side with a height less than the “dry” equilibrium height. The new equilibrium configuration is obtained and small vibrations of the dam about this equilibrium shape are analyzed. The water is assumed to be inviscid and incompressible, and potential theory is used. The infinite-frequency limit is assumed on the free surface. A boundary element technique is utilized to determine the behavior of the water, and the finite element method is applied to model the structure using ABAQUS with a shell element (ABAQUS, 1994). Three-dimensional vibration frequencies and mode shapes are computed. The effect of the internal pressure of the dam is investigated, and the results are compared to those for the dam in the absence of external water.
Random Excitation by Fluid Forces Acting on a Single Flexible Tube in Bundles Subjected to Cross-Flow
Authors: Romberg Oliver , Popp Karl 
Published: March 2022

Abstract
This paper reports on investigations using a new pressure test tube, that provides the non-stationary pressure distribution simultaneously at 30 points on the circumference and at 15 points across the tube. The tube motions due to fluidelastic instability as well as to turbulent buffeting can be measured together with the acting fluid forces. The investigations has been carried out for normal and rotated square arrays as well as normal and rotated triangular arrays. In the last case the investigation has been carried out for two different pitch to diameter ratios. The tests show clearly, that the correlation length of the non-stationary lift and drag forces, which has been determined at the whole circumference of the tube, decreases within the first three to four tube rows depending on the tube bundle configuration. The results show further that in case of instability due to galloping the correlation length increases suddenly to large values. For certain configurations the fluid forces are correlated well for the whole tube when galloping is dominant. Moreover, it can be shown that very thin tripwires put on the surfaces of the tubes destroy the correlation. This could be a possible explanation for the significant stabilization effect by tripwires for certain tube bundle configurations. Reflecting on turbulent buffeting the amplitudes are calculated as a function of the reduced gap velocity using the covariance method. Therefore, an excitation model deduced from the power spectral density of the measured fluid forces has been developed. Finally, a comparison of calculated and measured amplitudes for some examples is given.
Probabilistic Methods for the Prediction of Damage in Process Equipment Tubes Under Nonlinear Flow Induced Vibration
Authors: Sauvé R. G. , Morandin G. , Savoia D. 
Published: March 2022

Abstract
The use of deterministic methods in the assessment of process equipment tube integrity due to flow-induced vibration has become general practice. In cases were susceptibility of the tubes to fretting wear is addressed, nonlinear structural dynamic simulations are often required in order to quantify the work rate. In operating process components such as nuclear heat exchangers and steam generators the range of values for the key parameters such as flow regime, support clearances, manufacturing tolerances, tube/support material, etc. can vary to quite an extent. As a result, probabilistic techniques are proposed to account for the lack of well-posed input parameters needed for the nonlinear flow-induced vibration predictions. In this paper, a Monte Carlo simulation that incorporates an existing nonlinear time domain solution for tube response is described. An application of the technique to a nuclear steam generator is presented. The effect of variability of a number of key parameters on work rate is discussed along with the attendant implications.
Eliminating Air Flow-Induced Acoustic Vibration in Coal Pulverizers
Authors: Eisinger Frantisek L. 
Published: March 2022

Abstract
A novel method is presented here for eliminating acoustic vibration within coal pulverizers. The method emerged from the study of an acoustic vibration which developed within the casing of a coal pulverizer at low to medium loads. The vibration was characterized by an acoustic quarterwave driven by swirling air flow of parallel high velocity air jets issuing from a rotating multi-air port arrangement. By converting the single frequency excitation energy of the air jets into turbulent energy utilizing a new air port design with strongly interacting (colliding) air jets, the vibration was eliminated. The theoretical background and results of the pre- and post-modification operational tests are presented.
Dynamics of an Inline Tube Array in HCFC-123 Two Phase Flow: Comparison With Steam-Water Two Phase Flow
Authors: Hirota K. , Nakamura T. , Mureithi N. , Ueno T. , Tomomatsu K. 
Published: March 2022

Abstract
Comprehensive flow induced vibration tests have been conducted on an inline array. HCFC-123 is used as the test fluid. HCFC-123 stands for Hydrochlorofluorocarbon, whose chemical formula is CHCl2CF3. The critical flow velocities and two phase flow induced damping were compared with the steam-water two-phase flow test results. For that purpose, the same test equipment as steam water two-phase flow test one were used. The responses of three essentially isolated flexible cylinders at different depths within the array were simultaneously measured. Unsteady fluid forces were also measured. Tests were conducted corresponding to some thermal hydraulic conditions. First, two-phase flow test at high pressure (0.76Mpa, 98°C), homogeneous void fraction β = 0.90, was conducted. This condition can simulate the flow pattern of the steam water two phase flow (5.8MPa, 273°C) because the density ratio between gas and liquid is equal for both fluids. Second, a single-phase liquid flow test at atmospheric conditions was conducted. Finally, a single-phase flow test at high pressure (0.76Mpa) in HCFC-123 vapor was conducted. The characteristics of fluidelastic vibration were very close between HCFC-123 and steam-water two phase flow.
Nonlinear Models for Long Cylindrical Squeeze Films Incorporating Elliptical Velocity Profiles
Authors: Han Yingke , Rogers Robert J. 
Published: March 2022

Abstract
In this paper, nonlinear models for infinitely long, cylindrical squeeze films with arbitrary inner cylinder motion have been derived using three approximation methods. Two kinds of fluid velocity profiles are employed in the derivation with the aim to see the differences caused by using the two profiles, parabolic and elliptical. Each term in the squeeze film force equations is a nonlinear function of cylinder position (or eccentricity). The only differences in the final squeeze film force equations, due to the three approximation methods and the two different velocity profiles, are in the four constant coefficients. Comparing the present nonlinear expressions with existing models shows that: (1) the viscous, unsteady inertia and convective inertia terms, acting in the normal direction, are essentially the same as in other studies; (2) the normal-direction centripetal inertia term shows similar variations with position as one published study, but very different from another study; and (3) the three tangential-direction force terms show variations with position which are very different from a previous published study.
Elimination of Pulsations in a Chemical Plant: A Combination of Measurements, Calculations and Scale Model Experiments
Authors: van Bokhorst E. , Goos F. , Korst H. J. , Bruggeman J. C. 
Published: March 2022

Abstract
The aim of the work described in this paper was to trace and eliminate vibration sources in a low pressure system with high flow velocities.
Considerable vibration on the pipe system between a flashing vessel (6.5 m diameter) and heat-exchangers resulted in leakages and subsequent shut downs of a chemical production plant.
As compressors or pumps were not directly involved in the process, we considered aero-acoustic pulsations as the main cause of the high vibration levels. Analysis of the flow in the pipe system showed that mean flow velocities could rise up to 50 m/s, which is rather high considering the speed of sound in the gas of 195 m/s. Furthermore separation of the flow from the pipewall occurs at the outlets of a flashing vessel, which resulted in estimated flow velocities of over 100 m/s in the vena contracta.
This paper provides an overview of the analysis done by a one-dimensional acoustical and a mechanical finite element model.
The recommended modification consists of a perforated pipe-section between the outlets of the vessel and has been tested in a scale model. Tests have been performed with airflow at identical Mach numbers for different configurations with perforation ratios from 70 to 36%.
The modification with a perforation ratio of 50% shows a reduction of a factor 5 of the pressure pulsation and vibration levels over the entire frequency range.
The net pressure loss for this configuration is similar to that in the original lay-out without the perforated tube.
This modification was implemented during a plant shutdown in October 1996 and proved to be very effective. The results are well in line with the predicted levels and on the basis of this success a similar design has been planned for two new installations.
Simulation of Housing Separation in a Rotatable Mechanical Prosthetic Heart Valve
Authors: Ryder Kenneth 
Published: March 2022

Abstract
Today the mechanical heart valve prosthesis offers a number of advanced features which enhance the performance relative to the early valve designs. Most notable is the ability to rotate the valve housing in situ, that is after the valve is sewn in place [1]. In some cases, anatomical obstructions may exist which would preclude optimum valve function without proper valve orientation. Additionally, the position of the pivot mechanism relative to the coronary ostia is a placement constraint for some surgeons. Rotatability in situ offers the surgeon the ability to make decisions about final valve placement after the valve is in the anatomy as opposed to outside the chest during the suturing process. However, this advantage does not come without additional reliability requirements. The rotation feature requires the housing have mechanical clearance from the sewing cuff. Some designs feature sewing cuffs with stiffening elements and others do not. The structural reliability must be proven against a new set of potential failure modes.