bluuebunny/crossref_metadata_2025_split huggingface dataset:
Die Stress Measurements Using High Temperature Die-Attachment Materials
Authors: Zou Yida , Suhling Jeffrey C. , Jaeger Richard C. , Lin Shun-Tien , Benoit Jeffrey T. , Grzybowski Richard R. 
Published: January 2022

Abstract
In this work, special (111) silicon stress test chips containing an array of piezoresistive sensor rosettes have been applied within 281-pin ceramic Pin Grid Array (PGA) packages. The test chips contained optimized eight element dual polarity rosettes, which are uniquely capable of evaluating the complete stress state at points on the surface of the die. Calibrated and characterized test chips were attached to the PGA packages using five high temperature die attachment adhesives designed for avionic applications. The adhesive systems included silver filled glasses, polyimide pastes, and thermoplastic films. The resistances of the sensors were recorded at room temperature before and after die attachment. The induced thermal stresses at sites on the die surface have been calculated using the measured resistance changes and piezoresistive theory. A comparison of the room temperature die stresses caused by the different die-attachment materials has been made. The stresses on the die surface after packaging were also characterized as a function of temperature. In addition, thermal aging and thermal cycling tests were conducted on the packages. The various die attachment materials were further evaluated by observing the changes in stress that occurred during these reliability tests. Finally, three-dimensional finite element simulations of the PGA packages were performed, and the stress predictions were correlated with the experimental test chip data.
A Heuristic Model for the Shear and Bulk Viscosity of Concentrated Quiescent Suspensions
Authors: Buyevich Yuri A. 
Published: January 2022

Abstract
A simple model is presented to describe both first (shear) and second (bulk) viscosity coefficients for quiescent suspensions of fine spherical particles flow-induced fluctuations of which may be ignored. Components of the shear viscosity coefficient are distinguished that must be associated with mean flow of the continuous and dispersed phase. In dilute, and also moderately concentrated suspensions, the shear viscosity component attributed to the continuous phase is by far larger than that related to the dispersed phase. In dense suspensions whose concentration approaches that for the state of close packing, it is the shear viscosity of the dispersed phase that plays a dominant role. This viscosity characterizes shear stresses that are transmitted through a transient fluctuating network of occasional interparticle contacts. It is essentially dependent on the particle Peclet number, that is, on relative intensity of Brownian motion of the suspended particles. This dependence is ultimately responsible for the shear-thinning of suspensions, and it is can be described with the help of a reasonable semi-empirical approach. In accordance with the developed model, the bulk suspension viscosity must be wholly attributed to the dispersed phase, and it should not depend on the Peclet number.
Elastic Property of the So Called Newtonian Fluids
Authors: Hasegawa Tomiichi 
Published: January 2022

Abstract
It has been believed that water and silicon oil are Newtonian fluids. But recently it was found that both the fluids do not always fit the result of numerical calculation obtained using Navier-Stokes equation for the pressure drop in the flow through very small orifices. In the present study, the author measures the reaction force and the diameter of jets of water and silicon oil issuing from small orifices and examines the possibility of elasticity in these fluids. The measured values are compared with the numerical values calculated using N-S equation. The result shows that silicon oil of 30 centistokes of kinematic viscosity gives the data consistent with the numerically obtained data but water gives the characteristic of viscoelastic fluids; the reaction force is smaller than the numerically calculated value and the measured diameter of jet is larger than the value predicted with N-S equation. Then water is regarded as viscoelastic fluids and the elastic stress is estimated.
Electrorheological Fluids Applied to Impulsive Loads
Authors: El Wahed Ali K. , Sproston John L. , Schleyer Graham K. 
Published: January 2022

Abstract
This paper is concerned with an experimental determination of the dynamic performance of a prototype device employing an Electrorheological fluid for the rapid modification of the structural characteristics of fixing elements for use in offshore members subject to sudden explosive forces.
The squeeze device has been built to incorporate an ER fluid sandwiched between two electrodes and which, upon sudden impact, is capable of absorbing the impulsive forces.
The transient characteristics of the device were assessed under various mechanical force levels for DC excitation of the fluid in conjunction with a digital controller to provide a constant applied electrical field.
Input and output force levels were monitored using a dedicated data acquisition system in conjunction with a PC enabling the dynamic response of the device to be determined using a combination of displacement, force, velocity and acceleration measurements.
Granular Modeling for Powder-Binder Compound Characterization in Powder Injection Molding
Authors: Aizawa Tatsuhiko , Iwai Takashi 
Published: January 2022

Abstract
New granular modeling is proposed to deal with the powder morphology. The simple shear viscosity testing is utilized to computationally measure the variation of relative viscosity with increasing shear strain or solid loading ratio of particles. Abrupt increase of non-newtonian viscosity with increasing the loading ratio has close relationship with the forced orientation of irregularly-shaped particles. This interparticle interaction reveals on the effect of powder morphology on the actual viscous behavior of the powder-binder compound in the powder injection molding.
Comprehensive Compensation for the Disturbance Torque of Electro-Hydraulic Load Simulator
Authors: Donghai Su , Qinghe Liu , Shenglin Wu 
Published: January 2022

Abstract
Electro-hydraulic load simulator is testing equipment used to simulate the actual torque exerted by air on the steering axle of flying object flying over through air. It belongs to the typical passive loading system, in which, in dynamic loading process, the disturbance torque generated by the rotation of steering axle will decrease loading accuracy and influence control performances of loading system. Because the highest rotation frequency of the steering axle may reach 20Hz, the loading system can not work normally with simple compensation. According to the characteristics of electro-hydraulic simulator, this paper presents a comprehensive compensation method to eliminate the disturbance torque and improve the control performances. Based on the synchro-compensation, this comprehensive compensation feeds the velocity difference between loading motor and synchronous motor forwards to realize the second discharge of disturbance torque coupling to the loading system. After founding mathematics model, the performances of the compensated system is analyzed through computer simulation. The correctness and effectiveness of the comprehensive compensation for eliminating disturbance torque are proved by experimental results.
Numerical Analysis of the Lateral Forces Acting on Spools of Hydraulic Components
Authors: Borghi M. , Cantore G. , Milani M. , Paoluzzi R. 
Published: January 2022

Abstract
This paper deals with the analysis of pressure distribution within the fluid film in the clearance between spool and sleeve of hydraulic components, in order to predict the value of the locking force induced by unbalanced pressure acting on tapered geometries.
Particular care is devoted to the investigation of the lateral force dependency on clearance and eccentricity of the spool.
Some theoretical results are presented, obtained solving (by the finite difference method) the two dimensional Reynolds equation for the fluid film. These results are then compared to those deriving from a generally adopted predictive formula. Results show remarkable differences, up to 70%, in presence of high values of eccentricity.
Moreover, an analogous Reynolds’ based solution is performed for a tapered geometry of the spool with one balancing groove, with particular attention to the influence of its length and position on resulting locking force and leakage flow.
Also the locking force reducing effect of a balancing groove is characterized, and a saturated behavior when the groove is placed very close to the high pressure spool side has been found.
The Generalized Pulse Code Modulation Pneumatic Servo System and its Control
Authors: Wang Xuanyin , Tao Guoliang , Ding Fang 
Published: January 2022

Abstract
Being aimed at the asymmetric pneumatic cylinder, a new type of pneumatic drive circuit is designed. The generalized pulse code modulation (GPCM) pneumatic control system is used for improving performances of the system. In addition, in stead of establishing a nonlinear mathematical model of pneumatic GPCM servo system, system identification by the recursive least square method is applied to find its mathematical model, then a self-tuning controller with the pole-placement approach is designed. In the end, experiments are run in detail. The results show that the GPCM pneumatic servo system is better than the PCM, the self-tuning controller is better than the conventional PID and they are effective in achieving a desired positioning and following accuracy.
Broadband Stator Noise From Distorting Turbulence
Authors: Martinez R. , Rudzinsky J. , Milewski W. M. 
Published: January 2022

Abstract
This paper describes new calculations of broadband stator noise from the ingestion of rapidly distorting turbulence. The stator blades may be thick, cambered, and at an arbitrary angle of attack relative to upstream infinity. The new numerical tool applies Notre Dame’s Euler code “CASGUST” to compute the basic influence function for gust ingestion by a cascade in freefield. i.e., in the absence of a finite-length diffraction duct, or cowl. The theory accounts fror spanwise variations in the building-block input gusts, on the resulting blade loading patterns, and so also on the computed nearfield and farfield pressures, the predictions of broadband radiated stator noise address observer positions both in the aircraft and ground reference frames. They are in the form of frequency spectra for any prescribed ray direction, and of directivity patterns for any chosen frequency.
Flow-Induced Lift Forces on a Towed Sphere
Authors: Lauchle Gerald C. , Jones Andrew R. , Dreyer James J. , Wang Jack 
Published: January 2022

Abstract
An experimental and computational effort to characterize the broadband flow-induced forces on a spherical body that is towed underwater is described. The body itself is the transducer which is comprised of a small geophone encased in a near-neutrally-buoyant sphere, 7.62 cm in diameter. The research described in this paper quantifies the flow-induced unsteady lift force signal as a function of the sphere diameter Reynolds number (215 &lt; Re &lt; 34,290) and the Strouhal number (1.5 &lt; St &lt; 30). It is found that the broadband flow-induced force spectral levels may be separated into two regimes characterized by: 1) unsteady laminar flow in which the forces are proportional to the product of viscosity, mean shear, and area; and 2) turbulent flow in which the unsteady lift forces are proportional to the product of an area and the dynamic pressure of the flow. The low-Reynolds number data were acquired by towing the sphere in various mixtures of glycerine and water. The high Reynolds number lift force spectra, obtained in pure water, are compared to similar data measured previously on a finite-length, right-circular cylinder in cross flow. This comparison indicates that the cylindrical body creates more unsteady side force than does the spherical one, particularly at the lower end of the Strouhal number range. This is also the range of Reynolds number (Re &lt; 3,000) where a simulation of the unsteady laminar flow-induced forces, based on a numerical solution of the Reynolds-averaged Navier-Stokes equations, could be performed. The sphere was held fixed in these simulations, and the resulting forces are thus due to the unsteady flow of fluid around the body itself, with no influence due to free-stream turbulence or tow cable. The computational spectra are found to agree remarkably well with those measured.
Loudspeaker Vibro-Acoustic Computational Analysis Methods and Experimental Validation
Authors: Miccoli Giuseppe , Nizzoli Tommaso , Bie David 
Published: January 2022

Abstract
In this paper the results are reported of a computational analysis aimed at evaluating the sound field emitted by a loudspeaker as a production line commercial product and optimizing its working as a prototype. The elasto-aeoustic characteristics of the loudspeaker have been simulated by means of a commercial computational code. The system fluid/structural model as input to the acoustic analysis has been developed by the finite element code. The results on the emitted sound field have been computed as frequency response functions at the loudspeaker horn groove and acoustic pressure distributions on different planes. Such results achieved by means of 2D/3D finite element (FEM) and boundary element (BEM) coupled analysis methods have been compared and validated by experimental measurement procedures.
Prediction of Engine Cooling Fan Noise Radiation
Authors: Wu Sean F. , Su Shigong , Shah Hemant 
Published: January 2022

Abstract
A semi-empirical formulation is developed for predicting noise radiation from an engine cooling fan. This formulation is based on the mathematical model previously derived by the authors (Wu et al., 1997) for predicting noise spectra of axial flow fans running in a free field. The effects of shroud, radiator/condenser, and engine block on the ingested and discharged flow fields around the fan blades are taken into account by using certain shape functions. The computer model thus developed is used to predict the noise spectra from different fan assemblies under various working conditions, and the results thus obtained are compared with the measured data. Also, this model is used to calculate the overall sound pressure levels from dimensionally similar fans running under different working conditions, and the results are compared with those predicted by the fan laws currently used by engineers in the automotive industry.
Locating Damage in Beams Using Experimental Broadband Vibration Data
Authors: Ratcliffe Colin P. 
Published: January 2022

Abstract
This paper develops a method for locating structural damage using experimental broadband data. The method uses measured frequency response functions to obtain displacement as a function of frequency. The displacement functions are processed to yield a damage index, displayed on a plot of position versus frequency. The method can be applied when there is no a priori knowledge about the undamaged structure. The method can be automated. This paper details the theory of the broadband method, and the results of an experimental demonstration in which a steel beam was damaged with a narrow slot. It is shown that this method is highly sensitive, and can locate a very small amount of damage. For example, the slot was correctly located when there was only a 0.8% reduction in thickness. Traditionally, damage causes a change in natural frequencies, but at this small level of damage the frequency changes were within experimental error.
Improved Accurate Identification of the Modal Damping of Composite Structures Using Multi-Degree-of-Freedom Singular Value Decomposition in the Time Domain
Authors: Gibson Ronald F. , Liu Zhengyu 
Published: January 2022

Abstract
An improved approach for determination of modal vibration parameters of composite structures has been developed on the basis of the Least Squares Complex Exponential (LSCE) method and Singular Value Decomposition (SVD). When the SVD is applied to the Impulse Response Function (IRF) matrix of the system, the order of the system can be easily determined according to the rank of the system matrix. Furthermore, recalculation of the IRF matrix filters the IRF matrix of the system. The signal-to-noise ratio of the IRF is enhanced and, hence, more accurate damping parameters can be identified. MDOF SVD results from both simulations and experiments with E-glass fiber-reinforced composite beams and automotive composite components are presented and compared with results from the SDOF half-power bandwidth method.
Damping of Cantilever Beams With Constrained Viscoelastic Layers Using a Prony Series Representation
Authors: Slanik Marta L. , Nemes James A. , Potvin Marie-Josée , Piedboeuf Jean-Claude 
Published: January 2022

Abstract
The response of cantilevered steel beams treated with various configurations of constrained viscoelastic layers is considered experimentally and analytically. Modal analyses and spike input tests are performed. Analysis of the response of the beams to spike input loading is performed in the time domain using a Prony series representation of viscoelastic behavior. The number of terms required in the series to adequately simulate damping is addressed. Comparison of both natural frequencies and damping factors show good agreement.
Prediction of the Dynamic Response of Compliant Layers on Elastic Plates
Authors: Keltie Richard F. 
Published: January 2022

Abstract
An analytical model of an elastic coating attached to a submerged thin plate has been developed. A plane acoustic wave is incident from the water on to the elastic coating. The normal and tangential velocity components induced in the coating by the acoustic wave are calculated. The effects of incidence angle, frequency, location throughout the coating, and coating properties on the response velocity components are evaluated and examined. Many details of the dynamic response are explained based on simple uncoupled waveguide characteristics of the elastic coating. Typically, the normal velocity components in the coating are several tens of decibels higher in amplitude than the tangential velocity components. Results showed, however, that the tangential velocity component could be increased by an average amount of about 20 dB, without serious degradation of the normal component, by altering the coating elastic properties. In particular, combinations of high longitudinal wavespeed and low shear wavespeed were found to be advantageous. The effects of an outer plate on the compliant coating velocity response components are also presented.
Investigation of Centrifugal Blower Noise
Authors: Banks Christopher L. , Wu Sean F. 
Published: January 2022

Abstract
This paper presents the results of an investigation of centrifugal blower noise. Experiments on three different types of blowers were conducted to determine the major noise generation mechanisms. The information thus gained has led to an innovative noise reduction method utilizing a stationary, non-contacting transition mesh. Experiments showed that an overall noise reduction of up to 4 dB(A) was achieved for the blowers running at impeller tip speeds of 10 to 30 (m/s). In addition, a semi-analytical model was developed to predict the noise spectra from dimensionally similar blowers. This model yielded an acoustic power proportional to the fourth power of the blower speeds. Comparisons of the calculated and measured noise spectra from different blowers running under various speeds were demonstrated. Good agreements were obtained in all cases.
Estimating the Probability Distribution of von Mises Stress for Structures Undergoing Random Excitation: Part 1 — Derivation
Authors: Segalman Dan , Reese Garth 
Published: January 2022

Abstract
The von Mises stress is often used as the metric for evaluating design margins, particularly for structures made of ductile materials. For deterministic loads, both static and dynamic, the calculation of von Mises stress is straightforward, as is the resulting calculation of reliability. For loads modeled as random processes, the task is different; the response to such loads is itself a random process and its properties must be determined in terms of those of both the loads and the system. This has been done in the past by Monte Carlo sampling of numerical realizations that reproduce the second order statistics of the problem. Here, we present a method that provides analytic expressions for the probability distributions of von Mises stress which can be evaluated efficiently and with good precision numerically. Further, this new approach has the important advantage of providing the asymptotic properties of the probability distribution.
A Time-Domain Study of the Use of Moving Weights to Reduce Roll Motions
Authors: Treakle Thomas W. , Mook Dean T. , Liapis Stergios I. , Nayfeh Ali H. 
Published: January 2022

Abstract
The use of actively controlled moving weights on board ships to reduce roll motion is investigated. The weights simulate in principle anti-roll-tank systems and can also be considered a possible anti-roll device in their own right. The investigation is based on time-domain simulations. The full seven-degree-of-freedom set of governing equations for the complete system is derived. And a two-degree-of-freedom non-linear approximation for the roll motion only is derived from these seven equations. The reduced set of equations is used to determine the influence of various parameters and to evaluate control strategies. A PID controller is developed to command the position of the weight and a servomechanism model is used to predict its actual position. Then, the moving-weight system is incorporated into LAMP (Large-Amplitude-Motion Program), a computer code developed by SAIC that integrates the governing equations of the sea and the equations of motion of the ship interactively and predicts the motion of the ship in the time domain. Comparison of the results from the two simulations shows that there is fairly good correlation between the simple and complex models, but the simple model is a little optimistic in predicting the effectiveness of the moving-weight system. The results predict that the moving-weight system can be an excellent roll-suppressing device when (1) the moving weight is as small as 1% of the displacement of the ship, (2) the weight is located below the center of gravity, and (3) the maximum distance the weight moves is as small as 15% of the half-beam.
Simulation and Optimization of a Piezoelectric Micropump
Authors: Mu Y. H. , Hung N. P. , Ngoi B. K. A. 
Published: January 2022

Abstract
A new aluminum based valveless fluid micropump is designed by micromachining method. The pump consists of two fluid diffuser/nozzle elements on each side of a chamber with an oscillating diaphragm which is actuated with a piezoelectric disc. The two simultaneously vibrating diaphragms produce a large oscillating chamber volume. To obtain the optimal structural parameters at the design stage of the pump, the ANSYS finite element software is used for the simulation. The pump prototype with two aluminum diaphragms of ϕ10mm × 0.1mm has been simulated. The chamber oscillating volume can reach as high as 800μl for water pumping.