bluuebunny/crossref_metadata_2025 huggingface dataset:
A Methodology to Assess the Suitability of Typical Meteorological Year Weather Data for Simulating the Performance of Buildings Conditioned Entirely by Ambient Energy
Authors: Sharp M. Keith
Published: July 2023

This study evaluates for the first time the suitability of typical meteorological year (TMY) weather data for simulating the performance of buildings that are entirely conditioned by ambient energy. A home in Durango, CO, was simulated with TMY data, with real data for 1998–2020 and with extreme meteorological year (XMY) data. For this climate, the indoor temperature in the house designed with TMY data drops below the range of comfortable indoor temperature (20–25 °C) for 16 of 23 years, including as low as 13 °C during 2008. With the thermal time constant of the house adjusted for each data set to maintain comfort, the required time constants for the real data ranged from 1.178 to 7.56 days with a mean of 3.14 and a median of 2.38, while the TMY value was 1.862 for a percentile rank of 0.318. XMY data did not produce significantly better results. The correlation of the time constant to weather parameters showed that the maximum interval during which the 24-h average solar load ratio remains below 1 is a promising index for identifying the most challenging year. Until more representative TMY and XMY weightings are developed for ambient-conditioned buildings across other climates, it is advisable that current TMY data are used only for preliminary design and that multi-year simulations are conducted for final design.
Signal and Model Based Analysis of Systems With Friction and Impacts
Authors: Oestreich Markus , Hinrichs Nikolaus , Popp Karl
Published: July 2023

Nonsmooth dynamical systems become increasingly important in engineering and other applied sciences since nonsmooth effects are taken into account and are no longer smoothed out. Due to the lack of smoothness, classical mathematical methods are not or only limited applicable and require often extensions in order to apply analytical and numerical methods. In mechanical systems the consideration of e.g. friction and impacts leads to discontinuities in the corresponding mathematical models.

In the proposed paper different methods will be applied, based either on models or on measured or simulated time signals. The investigation comprises a friction oscillator with self- and external excitation and a simple impact oscillator.

The methods under consideration are one-dimensional maps, bifurcation and stability analysis, the determination of Lyapunov exponents, and the phase-space reconstruction by the help of general mutual information and false nearest neighbours.
Thermal Contact Conductance of Non-Flat, Rough, Metallic Coated Metals
Authors: Lambert M. A. , Fletcher L. S.
Published: July 2023

Thermal contact conductance is an important consideration in such applications as thermally induced stress in supersonic and hypersonic flight vehicles, nuclear reactor cooling, electronics packaging, spacecraft thermal control, and gas turbine and internal combustion engine cooling. In many instances, the highest possible thermal contact conductance is desired. For this reason, soft, high conductivity, metallic coatings are sometimes applied to contacting surfaces (often metallic) to increase thermal contact conductance. Two previously developed theoretical models for thermal contact conductance of metallic coated metals have been proven accurate for flat, rough surfaces. However, these two theories often substantially over-predict the conductance of non-flat, rough, metallic coated metals. In this investigation, a previously developed semi-empirical conductance model for flat and non-flat, rough, uncoated metals is employed in predicting the conductance of flat and non-flat, rough, metallic coated metals. The more commonly cited of the previous theoretical models for flat surfaces and the semi-empirical model are compared to experimental thermal contact conductance results from a number of investigations in the literature. Results for a number of metallic coating/substrate combinations on surfaces with widely varying flatness and roughness were analyzed. Both models agree well with experimental results for flat, rough, metallic coated metals. However, the semi-empirical model is substantially more accurate and more conservative than the theoretical model compared to the majority of experimental results for non-flat, rough, metallic coated metals.
Flow Field Measurements in Confined and Submerged Jet Impingement
Authors: Fitzgerald Janice A. , Garimella Suresh V.
Published: July 2023

The flow field of an axisymmetric, confined and submerged turbulent jet impinging normally on a flat plate was studied experimentally using laser-Doppler velocimetry. Single jets of a perfluorinated dielectric liquid (FC-77) were used in the experiments, with nozzle diameters of 3.18 and 6.35 mm, and nozzle-to-target plate spacings of up to 4 jet diameters. The experiments were conducted for turbulent jet Reynolds numbers in the range of 8500 to 23000. Velocity measurements just downstream of the nozzle exit show an increase in volume flow rate of 10–26% relative to the volume flow rate at the exit due to entrainment of the surrounding fluid. Very near the target plate, a maximum in the radial velocity is observed to occur at a radial distance from the stagnation point of 1 nozzle diameter. The location where transition to turbulence is observed in the wall jet is shown to move radially outward for increasing nozzle-to-target plate spacing, and lies between 2d and 2.5d for all cases. The flow field characteristics of the confined and submerged jets in the present study are contrasted to those reported in the literature for free-surface jets and submerged but unconfined jets.
Detailed Heat Transfer Coefficient Distributions Under an Array of Impinging Jets With Coolant Extraction
Authors: Huang Yizhe , Ekkad Srinath V. , Han Je-Chin
Published: July 2023

Jet impingement cooling is a high performance technique for heat transfer enhancement. Local heat transfer distributions are presented for an array of jets impinging on a target plate with a series of coolant extraction holes. The flow enters the pressure channel, impinges on the target plate and exits toward the sides and through the coolant extraction holes. The impingement plate has four rows of 12 jet holes and the target plate has three rows of 11 coolant extraction holes. The jet holes and the coolant extraction holes have the same diameters and are staggered such that the air impinging from the jet hole does not exit directly through the extraction hole. The detailed heat transfer coefficient distributions are measured using a transient technique and liquid crystal coating. Results are presented for a range of jet Reynolds numbers between 4000 and 20000. The effect of crossflow is also studied by changing the exit opening of the impingement channel to provide three different spent air exit directions. Heat transfer results for the target plate with coolant extraction are compared with those without coolant extraction at the same flow conditions.
Heat Transfer From a Liquid Bath due to an Impinging Gas Jet: Effect of Liquid Prandtl Number
Authors: Qian F. , Farouk B. , Mutharasan R. , Macken N.
Published: July 2023

There have been extensive heat transfer studies of impinging gas jets on solid surfaces, but few investigations of gas jet/liquid bath interaction. Here we report on the effects of liquid Prandtl number on air-jet induced transport in a bath. Two different liquids having widely different Prandtl numbers (silicone oil and a molten metal alloy, Amalloy-203®) were used. Both numerical calculations and experiments were carried out to characterize the jet induced flow and heat transfer in the liquid. The mixing and thermal behavior of the heated bath were determined as functions of the air jet characteristics (inlet temperature, Reynolds number, diameter and nozzle distance from the bath surface) and bath properties (depth, diameter, and liquid Prandtl number).
Forced Convective Liquid Cooling of Arrays of Protruding Heated Elements Mounted in a Rectangular Duct
Authors: Gupta Anurag , Jaluria Yogesh
Published: July 2023

Experiments are performed to study single-phase forced convection water cooling of arrays of protruding heat sources. Each array has four rows, with three elements in each row. Two arrays are mounted, one at the top and the other at the bottom of a rectangular channel. The Reynolds number based on channel height is varied from 2500 to 9000. Flow visualization revealed that the flow was fully turbulent even at the smallest Reynolds number. Different channel heights, ranging from 3 to 4 times the height of the elements, different heat inputs to the modules and different streamwise spacing between the elements are employed. The spanwise spacing between the elements is kept constant. It is found that the Nusselt number is higher for smaller channel heights and streamwise spacing, at constant Reynolds number. Buoyancy effects are found to be negligible over the parametric ranges considered here. A small variation in the heat transfer coefficient is found in the spanwise direction. The observed trends are considered in terms of the underlying transport processes. The heat transfer data are also correlated in terms of algebraic equations. High correlation coefficients attest to the consistency of results. The data are compared with previous air and water cooling studies, wherever possible, and a good agreement is obtained.
Application of Isokinetic Sampling Technique in Stratified Multiphase Flows
Authors: Khor Siew H. , Mendes-Tatsis Maria-Alcina , Hewitt Geoffrey F.
Published: July 2023

This paper describes the development of an isokinetic sampling probe ultimately intended for application in three-phase gas-liquid-liquid stratified flows in horizontal pipes. The probe is designed with an aim to give information on local fluid flow rates and the fractions of the respective liquids (oil and water) within the flow. The paper also presents the validation of the developed isokinetic sampling probe against single phase flow measurements and preliminary tests with the probe in air-water and air-oil-water stratified flows in a horizontal pipe. The results obtained (believed to be the first application of such a probe in stratified flows) are encouraging and consistent with previous findings.
A Comparison of Correlations for Forced Convection Heat Transfer From a Submerged Melting Ice Sphere to Flowing Water
Authors: Aziz Syed Amer , Janna William S. , Jakubowski Gerald S.
Published: July 2023

The objective of this study is to develop an empirically based expression for forced convection heat transfer from a melting ice sphere to a flowing liquid. A series of experiments were conducted to measure the forced convection heat transfer rate from a submerged ice sphere to water. The range of Reynolds numbers, based on characteristic length of the sphere, was between 2 500 and 25 000. The characteristic length for the melting sphere was defined in terms of the initial and final conditions of the specimen. Results of this study correlate well with previous studies related to forced convection. The data of this study can be described with an equation for the Nusselt number in terms of Reynolds and Prandtl numbers.
Finite Element Analysis of a Dissimilar Mixed Mode Bimaterial Interfacial Fracture Specimen
Authors: Zhang Jinmiao , Lu Gui-Ying , Kenner Vernal H. , Soboyejo Wolé
Published: July 2023

A finite element model of a dissimilar mixed mode bimaterial interfacial was generated using the commercial FEMAP software and analyzed using ABAQUS. Finite element techniques were used to estimate the strain energy release rates of interfacial cracks in a copper/moulding compound system. The finite element results are shown to be in good agreement with theoretical predictions of the strain energy release rate obtained from an analytical linear elastic fracture mechanics model. The finite element techniques were also used to estimate the loading conditions that are required to avoid contact between the crack surfaces under monotonic loading.
Damage Initiation and Propagation in Metal Laminates
Authors: Riddle Robert A. , Lesuer Donald R. , Syn Chol K.
Published: July 2023

The metal laminates proposed here for use in aircraft structures consist of aluminum alloy interlayers between aluminum alloy based metal matrix composite (MMC) plates reinforced with silicon carbide particles. The properties of the laminates are to be tailored for applications in jet engine fan containment and in various wing and auxiliary support structures. One important mechanical property of the metal laminate is fracture toughness.

This composite metal structure is designed to have enhanced ductile fracture properties as a result of the plastic formability of the aluminum layers and increased strength and stiffness due to the layers of the metal matrix composite.

The enhanced fracture properties of the metal laminates are measured by fracture toughness specimens of several designs. Of particular interest is the optimum thickness of the ductile interlayer to optimize the fracture properties, but have the least effect on the strength and the stiffness. Specimen designs have been chosen which should allow measured properties of the specimen deformation and failure to be translated into predictions of component strength in actual aerospace applications.

One mode of crack growth which increases fracture toughness and damage resistance in applications of interest is extensive delamination between the ductile interlayer and the MMC plates.

The total area of delamination is increased by the tendency of metal laminates to have damage initiate at the lobes of contours of effective plastic strain which are significantly off-axis from the plane of Mode I or tensile mode opening crack growth. This off-axis damage increases the delaminated area and is a factor in forcing the crack to reinitiate at a new location in the next MMC plate.

Experimental evidence for this phenomena is presented, along with finite element calculations which quantify and explain enhanced fracture values. The progressive damage is modeled using tie-break slidelines with critical strains to failure chosen with the help of elastic-plastic fracture mechanics calculations.
Evaluation of Multi-Phase Heat Transfer and Droplet Evaporation in Petroleum Cracking Flows
Authors: Chang S. L. , Lottes S. A. , Zhou C. Q. , Petrick M.
Published: July 2023

A computer code ICRKFLO was used to simulate the multi-phase reacting flow of fluidized catalytic cracking (FCC) riser reactors. The simulation provided a fundamental understanding of the hydrodynamics and heat transfer processes in an FCC riser reactor, critical to the development of a new high performance unit. The code was able to make predictions that are in good agreement with available pilot-scale test data. Computational results indicate that the heat transfer and droplet evaporation processes have a significant impact on the performance of a pilot-scale FCC unit. The impact could become even greater on scale-up units.
Experimental Observations of Swirling Fires
Authors: Satoh Kohyu , Yang Kwang-Tzu
Published: July 2023

In the present study experimental observations of swirling fires were undertaken based on self-generated swirling flows to study some aspects of the whirling fires typically found in large urban and forest fires. The swirl was caused by channeling the entrainment flows caused by the fire itself located in a square enclosure with symmetrical open corner gaps. The stability characteristics in maintaining the integrity of the flame by the swirling flow were examined by modifying the channeled entrainment flows. Also studied were qualitative effects of different fuels, sizes of the fuel pan relative to that of the enclosure, and the wall gap sizes which permitted the generation of the swirling flows.
A 3-D Coupled Solution for the Flow and Fiber Orientation in Injection Molding of Fiber-Filled Systems
Authors: Kabanemi Kalonji K. , Hétu Jean-François , Garcia-Rejon Andrés
Published: July 2023

This paper describes a fully three-dimensional transient finite element method for calculating the flow behavior and fiber orientation during filling of injection molded parts. The fiber-fiber interaction is taken into account. The momentum and continuity equations are first solved with the viscoelastic stress treated as a fixed body force. The kinetic equation for the orientation tensor is then integrated with known kinematics using the standard Galerkin method. The calculation is performed on a time-dependent flow domain. Since the method is truly three-dimensional, singular regions such as the flow front or near injection gates and solid boundaries, where decoupled approximations are not valid, are naturally dealt with. The material anisotropy behavior is modeled by using the Doi-Doraiswamy-Metzner model. Numerical results, involving the Poiseuille flow and the filling of an end-gated plate, emphasizing the importance of the three-dimensional coupling calculations between the flow and orientation are presented.
On an Apparent Singularity in the Flow of Liquids Under High Shear Stress
Authors: Bair Scott , Khonsari M. M.
Published: July 2023

Examination of the equations governing the shear flow of laminar, incompressible, linearly viscous (Newtonian) liquids under high pressures reveals a singularity in the solution for the pressure gradient. This apparently unreported phenomenon is shown to occur in liquids whose viscosity, μ, increases exponentially with pressure, P, as μ = μoeαP, where α denotes the pressure-viscosity coefficient. For a two-dimensional configuration with the shearing action taking place in the x direction and with P = P(x,y), the singularity is shown to take place when: τyx=±1α1+α2τxxτyy, at which case both ∂p∂x and ∂p∂y→∞. The occurrence of such a singularity in the pressure gradient may have an important physical implication in lubrication flows particularly in concentrated contacts such as elastohydrodynamic lubrication of rolling element bearings and gears. Such a singularity may be the initiator of shear localization (shear bands) which have been recently observed experimentally.
Transient Response of Microchannel Heat Sinks in a Silicon Substrate
Authors: Rujano José R. , Rahman Muhammad M.
Published: July 2023

The transient conjugated heat transfer in forced convection for simultaneously developing laminar flow inside a microchannel heat sink is studied by solving the steady momentum equation and the transient energy equation. A parametric study is performed to understand the effects of channel depth and width, Reynolds number, spacing between channels and solid to fluid thermal conductivity ratio. Silicon as well as indium phosphide are used as wafer’s material. Step and pulsed variations of the heat load are analyzed. Results show that the time required for the heat transfer to reach steady state condition is longer for the system with larger D and S or smaller Re and W. Characteristics results for the fluid mean temperature at the exit, solid maximum temperature, local Nusselt number, and local heat flux are presented graphically as functions of position and time.
Thermoeconomic Analysis: A Criterion for the Selection of Cogeneration Systems
Authors: Luz-Silveira J. , Balestieri J. A. P. , Santos A. H. M. , Almeida R. A.
Published: July 2023

The economical viability of three cogeneration schemes as supplying alternatives for a hypothetical industrial process has been studied. A cost appropriation method based on Valero’s studies (1986) has been used. This method enables the determination of exergetic flows, the Second Law efficiency of equipment and the monetary costs of the products acquired by the industrial process (steam and electrical energy). The criterion adopted for the selection is the global cost of the supplied products to the industrial process as regarding in Brazilian conditions.
Thermodynamic Analysis of Injected Water Recovery Systems for the Humid Air Turbine (HAT) Cycle
Authors: Bidini Gianni , Desideri Umberto , Di Maria Francesco
Published: July 2023

The Humid Air Turbine (HAT) cycle is an inter-cooled gas turbine cycle, having an air-water mixing evaporator before the combustion chamber, and a heat recovering system for the exhaust gases. The considerable amount of water consumed in the mixing evaporator (about 1200–2400 m3 daily for a 100 MW unit), represents a significant drawback to the use of the HAT cycle as well as of other steam injected gas turbines. In fact, this means high operational costs for water treatment, and eventual legislative restrictions limiting the use of water, not to mention the environmental impact of the depletion of water resources.

The aim of this paper is to evaluate the changes in the performance of the HAT cycle when a water recovery system is added in the exhaust gases, and to determine the heat exchangers conditions for maximum water and heat recovery. Finally, the size of a surface condenser for water recovery is determined for a given HAT cycle power output.

The results show the possibility to recover up to 85% of the consumed water and up to 30% of input heat from the condensation of the water contained in the exhaust gas. The paper also examines all the thermodynamic processes in each cycle component from the viewpoint of recovering water from the exhaust gas. Since part of the water contained in the exhaust gas is due to the inlet air humidity and the combustion process, the relative amounts of water and their contributions to the overall heat recovery are also calculated.
Thermodynamic Analysis of High Temperature Fuel Cells: Methane Reforming
Authors: Call Frederick W.
Published: July 2023

The endothermic or exothermic processing of methane to a suitable fuel for fuel cell applications wastes exergy, the ability to produce electricity. The paper proposes a fuel cell process that converts (waste) heat (251 kW) into power (214 kW) while the methane (752 kW) is being reformed. Much more heat is processed than might be anticipated from the small values of enthalpy increase (37 kW) or the availability loss (36 kW) of the (endo-) thermochemical reaction. The resulting watergas (789 kW) can be used in an ordinary fuel cell, in co-generation, or as a chemical feed stock. A practical compromise is suggested and comparison is made to standard reforming methods.
Thermodynamic Evaluation of a Single-Flash Geothermal Power Plant in Nevada
Authors: Kanoglu Mehmet , Çengel Yunus A. , Turner Robert H.
Published: July 2023

First and second law analysis of a 12.5 MW single-flash design geothermal power plant in Nevada is performed using actual plant data, and alternatives are investigated to improve its performance. Exergy destruction throughout the plant is quantified and illustrated using an exergy cascade. The major source of exergy destruction is reinjection of brine after its separation from the steam. It accounts for 48.5% of total exergy destruction. The first and the second law efficiencies of the plant are calculated to be 5.7% and 21.6%, respectively, based on the exergy of the geofluid at downwell. These values seem to be very low. The analysis of alternative designs are based on the exergy analysis. Among the alternatives investigated, a double-flash design would increase the net power output by 4.5 MW (or 36%), depending on the secondary flash pressure chosen. The combined single-flash/binary design would increase the net power output by about 5.0 MW depending on the working fluid chosen.
Longitudinal Transition Maneuvers in an Automated Highway System
Authors: Connolly Thomas R. , Hedrick J. Karl
Published: July 2023

The control structure for automated vehicles in an Automated Highway System is based on the idea of multiple-surface sliding control. The “upper” surface determines a desired net torque while the “lower” surface determines the required throttle angle or brake pressure needed to achieve the desired torque. This paper presents an upper surface control law for performing longitudinal transition maneuvers. The maneuvers use desired velocity trajectories which are based on maintaining safety and comfort throughout the maneuver. The control law chosen is a sliding controller due to the non-linearities in the dynamics and the uncertainties in the parameters. Adaptive techniques were also implemented to help improve the velocity tracking. The controller was implemented on experimental vehicles and tested at highway speeds.
Worst-Case Evaluation Methods for Vehicle Control Systems
Authors: Ma Wen-Hou , Peng Huei
Published: July 2023

Worst-case evaluation method for vehicle control systems is studied in this paper. Depending on the control system information structure, we divide the worst-case scenario generation problems into four categories: one-player without preview, one-player with preview, two-player without preview, and two-player with preview. A passenger vehicle under automatic steering control was used as the target system to be analyzed. Numerical simulations and frequency domain analysis were performed to study the effectiveness of the proposed disturbance generation algorithms.
Theoretical Analysis of Punch Speed and Blank Holder Force Control in Deep Drawing Process of Strain-Rate-Sensitive Materials
Authors: Manabe Ken-ichi , Yoshihara Shoichiro , Nishimura Hisashi , Shibata Akinori
Published: July 2023

Various factors affecting the variable blank holder force (BHF) and punch speed in the circular cup deep-drawing process with forming-speed-dependent characteristics were analyzed in order to determine the optimal control conditions of the process and the effects on the permissible range of forming conditions. The isotropic blank material was assumed to exhibit strain hardening and strain-rate-sensitive characteristics given by σ = Kε˙mεn. Effects of material properties and process variables on the fracture and wrinkle limit BHF curves were simulated using an elementary analytical method. The simulated results show that the acceptable drawing range of highly strain-rate-sensitive materials strongly depends on the punch speed. It is confirmed theoretically that there is an optimal process control path in the acceptable range of the punch speed-BHF-drawing progress space even beyond the critical constant punch speed. Based on these results a new concept of optimal process control with variable punch speed and BHF control is proposed in order to reduce the forming time, improve the quality of the products and reduce the number of defective parts produced.
A Real Time Quintic Spline Interpolator for an Open Architecture Machine Tool
Authors: Wang Fu-Chung , Schofield Steven , Wright Paul K.
Published: July 2023

In this paper, we describe a new quintic spline interpolator for real time trajectory generation during free form curve machining on an Open Architecture machine tool platform. The research provides new capabilities for advanced CAD/CAM systems.

Complicated curves and shapes designed in a CAD system are usually represented by a set of discrete data points. Subsequently, for manufacturing by a CAM system, these data points need to be converted into tool paths for machining. Therefore, the paper presents a new interpolation method that interpolates the designated data points with a quintic spline curve for real-time tool path generation. The resultant curve, generated by the proposed interpolation method, is nearly arc-length parametrized and has C3 continuity. The near arc-length parametrization property makes the real time generation of the reference commands of the cutting tool path easier. The C3 continuity guarantees the smooth motion of continuous speed, acceleration and even jerk during the machining. The combined properties of this new interpolation method enable a new quintic spline interpolator to be developed for real time tool path generation.
Noise Optimal Control in a Fluid-Floated Magnetic Positioner
Authors: Ludwick Stephen J. , Trumper David L.
Published: July 2023

This paper describes the design of a noise-optimal controller in the context of an electromagnetically levitated motion control stage. In the stage, position is controlled in all six rigid-body degrees of freedom using electromagnets to provide the necessary forces. The moving element is surrounded by a fluid that forms squeeze film dampers between the moving and stationary portions of the stage. At the bandwidths of interest, the damping dominates the system dynamics, and so the plant is modeled as a mass-less damper. This stage provides the impetus for the development of a noise-optimal controller. Sensor noise and plant disturbance forces limit the achievable resolution of the stage. In order to understand this problem, we develop our analysis in the context of a single degree-of-freedom system. This is done in order to most simply show the key tradeoffs in this damper-dominated design. We then show how this model can be used in practice by quantifying the major noise sources present in our actual hardware and then applying this analysis to the control of the six degree-of-freedom stage. Experimental results from this stage verify the theoretical results.
Monitoring and Analysis of Ultraprecision Metal Cutting With Acoustic Emission
Authors: Chen Xuemei , Tang Jianshe , Dornfeld David
Published: July 2023

In the regime of ultraprecision metal cutting, process parameters such as chip thickness, tool-work contact, forces, etc. all become several orders of magnitude smaller than in conventional cutting. Very small variations in these quantities will affect significantly the surface integrity of the workpiece and the performance of the diamond tool. To achieve the specified ultra-precision accuracy systematically, an effective in-process micro-sensing and signal processing system is essential. In this paper, we demonstrate the sensitivity of acoustic emission to tool-work contact and chip thickness in ultraprecision machining. We also investigate the response of AE to the various energy dissipative effects involved in micro-cutting when the uncut chip thickness approaches the tool edge radius. A signal processing scheme utilizing wavelet transform that identifies the possible dominant cutting mechanism for a certain cutting state given the AE signals from that process was developed, and the implications in process monitoring and control are discussed.
Simulated Haptic Textures: Roughness
Authors: Minsky Margaret , Lederman Susan J.
Published: July 2023

We present a novel technique for simulating haptic surface texture using only lateral forces with a two-degree-of-freedom device. Using surfaces built by this technique, we investigate the psychophysics of texture perception, and more specifically, roughness. We find a relationship between lateral force and perceived roughness that could be used to provide controlled amounts of roughness in haptic-simulation environments.
The “Haptic Camera”: A Technique for Characterizing and Playing Back Haptic Properties of Real Environments
Authors: MacLean Karon E.
Published: July 2023

In some applications of simulated haptic feedback, it is necessary not only that the display feel stable and adequately realistic: it must resemble with high fidelity a particular real device, emulating the feedback supplied by a physical environment that does or will exist. An automated haptic characterization technique was developed in which the haptic display itself is used under tight position control to probe the real environment while measuring interaction forces. A model structure is assumed which may be nonlinear and globally discontinuous but piecewise continuous, and is refined for successively higher-order parameters by application of appropriately chosen position trajectories. A one degree-of-freedom linear-acting motor with 90 mm stroke, a peak force of 60 N and equipped with position and force sensors was used as both a probe and a force display.

This algorithm was tested on one real environment, a toggle switch with a nonlinear, compliance-dominated impedance. Because of the nature of the real device, only stiffnesses were extracted; this zero-order, piecewise linear model assumption provided a close fit to the measured trajectory with under 30 seconds of measurement and processing time. This was a substantial improvement in playback fidelity over that achieved by other characterization methods. Future work includes testing the algorithm on higher order systems.
An Input-Output Criterion for Linear Model Deduction
Authors: Walker Douglas G. , Stein Jeffrey L. , Ulsoy A. Galip
Published: July 2023

Model order deduction algorithms have been developed in an effort to automate the production of accurate, minimal complexity models of dynamic systems in order to aid in the design of these systems. Previous algorithms, MODA, and Extended MODA, deduce models independent of system inputs and outputs. FD-MODA uses frequency response methods to deduce models of a single input-output pair. In this paper, an input-output criterion based on controllability and observability is combined with the frequency based criterion used by MODA. The new model deduction algorithm, IO-MODA, compares the ratio of the adjacent diagonal values of the system gramian to a user specified threshold. The gramian is computed from a balanced realization of the system. IO-MODA generates an accurate multiple-input multiple-output model of minimum order with physically meaningful states. This model is called a proper MIMO model. An example problem is used to demonstrate this new model deduction algorithm.
Impact Dynamics in the Milling of Thin-Walled Structures
Authors: Davies M. A. , Balachandran B.
Published: July 2023

The development of reliable high-speed spindles and motion control systems has led to an increase in the industrial use of high-speed milling. One of the primary applications of this new technology is the manufacture of thin-walled aluminum components for aircraft. The flexibility of the workpieces, the high-spindle frequencies, and the inherent impact nonlinearities in the milling process can lead to complicated dynamic tool-workpiece interactions. An experiment was constructed to study the vibrations of a thin-walled part during milling. Time series, power spectra, autocorrelations, auto-bispectra, and phase portraits were examined. This data is indicative of the fact that stiffness nonlinearities due to the intermittent cut have a pronounced effect on the dynamics of the workpiece. Delay space reconstructions and pointwise dimension calculations indicate that the associated motions are characterized by a fractal geometry. The autobispectra indicate quadratic phase coupling at the spectral peaks associated with the cutter frequency. A phenomeno-logical model with impact nonlinearities was developed to explain the experimental results. The predicted results agree qualitatively with the experimental observations. The model predictions indicate that aperiodic motions are possible over a large range of parameter values. These results have implications for the prediction and control of vibrations in milling.
Stochastic Sliding Mode Control of a Target Tracking Mechanical System
Authors: Sun J. Q. , Xu Qing
Published: July 2023

An analysis of a target tracking mechanical system subject to random base excitations is presented in this paper. Nonlinear, stochastic sliding mode controls are proposed to minimize the random error of target tracking. Two special cases are studied. In the first case, it is assumed that all the system parameters are known and the state variables are measurable. A stochastic sliding mode control is then determined. This highly idealized example sheds some light on the effect of sliding mode control parameters on the reduction of response variance. The second case deals with a robust sliding mode control where some parameters of the mechanical system are assumed to fall in a known range of values. The proposed controls are proven stable in the mean square sense. The statistical aspects of the controlled system are studied by considering the first and second order moments of the state variables. The equations for these moments are derived and solved by using the method of Gaussian closure in order to investigate the variance reduction performance of the controls.
Resonant Dynamics of a Chain of Identical Linear Oscillators Coupled to a Nonlinear Oscillator
Authors: Banerjee Bappaditya , Bajaj Anil K. , Davies Patricia
Published: July 2023

A chain of N identical oscillators (spring-mass-damper systems) coupled to a nonlinear oscillator (a pendulum) is studied in this work. More specifically, the interesting case of 1:2 subharmonic internal resonance between the pendulum and some kth mode of the system, when there is also an external resonance with some rth harmonic excitation, is studied. It is found that for these conditions, the first-order approximation to the response of this N+1 degree-of-freedom system is ultimately governed by a system of four first-order equations. The method of harmonic balance is used to obtain these four first-order amplitude equations. The stability of the steady-state response, their bifurcation behavior and resonant dynamics are described. These responses can be used to evaluate the effectiveness of the pendulum as a vibration limiting device.
Characterization of Inelastic Deformation During the Transverse Loading of Weakly-Bonded Unidirectional Metal Matrix Composites
Authors: Neu Richard W. , Kroupa Joseph L.
Published: July 2023

A combined numerical and experimental analysis of a unidirectional titanium matrix composite (SCS-6/Timetal 21S) under a series of transverse loadings and unloadings is capable of separating the interfacial fiber-matrix bond strength into two distinct components: one associated with chemical bonding and the other with mechanical bonding. The influence of the mechanical bonding, which is the clamping due to the thermal residual stress state, is determined by finite element analysis with an imperfectly-bonded interface. The chemical bond strength is deduced by subtracting the mechanical bond strength component from the experimental response. Combined numerical and experimental analyses were conducted at two temperatures. At 25°C, the initial inelastic deformation from fiber-matrix separation is controlled by the mechanical component of the bond which is much larger than the chemical component; however, at 650°C, it is controlled by the chemical component. The mechanical bond strength is very dependent on temperature, whereas the chemical bond strength is only weakly dependent on temperature. In addition, the transverse response of unidirectional SCS-6/Timetal 21S was numerically determined for a wide range of temperatures (25°C to 815°C) and strain rates (8.33 × 10−4 1/s to 8.33 × 10−6 1/s) for both perfectly- and imperfectly-bonded cases.
Damage Accumulation Mechanisms in Thermal Barrier Coatings
Authors: Newaz G. M. , Nusier S. Q. , Chaudhury Z. A. , Wright K. P.
Published: July 2023

Spallation is a major failure condition experienced by thermal barrier coatings (TBCs) subjected to thermal and mechanical loads. Although evidence of spallation is substantiated and mechanistic models to describe the failure condition is prevalent in literature, the progressive nature of damage evolution leading to spallation has not been addressed adequately. In this paper, we investigated the damage evolution in partially stabilized zirconia TBC on Nickel-based single crystal superalloy, Rene N5. Thermal cycles were imposed on button specimens with Electron Beam - Plasma Vapor Deposition (EB-PVD) TBC coating. The bond coat was PtAl. The temperature range used was 200–1177C. Progressive damage evolution was tracked using microscopy on samples subjected to a series of thermal cycles. Fick’s law can describe the thermally grown oxide (TGO) buildup for early cycles. However, at higher number of thermal cycles, damage in the form of microcracks and their coalescence results in the loss of integrity of the TGO. Thus, both oxidation kinetics and damage appears to have significant roles to play as it relates to spallation. As these microcracks coalesce to form major delamination cracks or interlayer separation, the susceptibility for coating buckling is increased. The delamination cracks finally consume the TGO layer. The loss of TBC integrity from the bond coat and the substrate facilitates its buckling during cool down from elevated temperature. Our estimations show that a delamination crack length of about sixteen times the TBC thickness is needed for the current material system to initiate buckling. Progressive microcrack linking is a possible mechanism to develop such critical delamination crack lengths. Physical evidence of buckling was found in specimens prior to complete spallation.
Direct Measurements of Turbulent Boundary Layer Wall Pressure Wavenumber-Frequency Spectra
Authors: Abraham Bruce M. , Keith William L.
Published: July 2023

Direct measurements of streamwise wavenumber-frequency spectra of turbulent wall pressure fluctuations were made in an acoustically quiet water tunnel. A linear array of evenly spaced flush mounted pressure sensors was used to measure the wall pressure field at 48 streamwise locations. This array provided over 24 dB of resolution (sidelobe rejection) in the wavenumber domain, leading to an accurate estimate of the “convective ridge” and part of the subconvective and low wavenumber portions of the spectrum at discrete frequencies. Boundary layer parameters including the mean wall shear stress, boundary layer thickness, displacement thickness, and momentum thickness were derived from mean streamwise velocity measurements for 8,100 < Rθ < 16,700. Time and length scales derived from these parameters were used to nondimensionalize the measured spectra. The effectiveness of different scalings for nondimensionalizing the low and convective wavenumber regions at discrete frequencies were evaluated.
Sound Package Materials in Automobiles
Authors: Saha Pranab , Chahine John
Published: July 2023

Sound package materials have been used in automobiles for many years. Although the application of some of the key sound packages has not changed, the vehicle design and construction have changed significantly. Over the years, material and process development technology have changed, and health and environmental issues have raised different concerns. Global competition has also impacted the sound package development. These have provided challenges and opportunities to introduce new acoustical products and have forced the OEM to treat previously untreated noise paths with sound package materials. The goal is to achieve the desired interior acoustics in a car within bounds to meet customer requirements. This paper reviews all these factors and discusses some sound package material applications in some specific cases.
Design of a Train Separator for Hydraulic Capsule Pipeline Control
Authors: Du Hongliu , Nair Satish S.
Published: July 2023

Design of an important component for reliable functioning of hydraulic capsule pipelines [1–3] is discussed. A method for sizing the separator and predicting the spacing between capsules after the capsule train passes through the separator is developed. The proposed design has been implemented in hardware. Limited experimental results show that the capsules were separated as expected and the observed spacing between capsules matches the calculated values predicted by analytical methods.
Analyses of Containment Structures With Corrosion Damage
Authors: Cherry Jeffery L.
Published: July 2023

Corrosion damage to a nuclear power plant containment structure can degrade the pressure capacity of the vessel. For the low-carbon, low-strength steels used in containments, the effect of corrosion on material properties is discussed. Strain-to-failure tests, in uniaxial tension, have been performed on corroded material samples. Results from the tests were used to select strain-based failure criteria for corroded steel. Using the ABAQUS finite element analysis code, the capacity of a typical PWR Ice Condenser containment with corrosion damage has been studied. Multiple analyses were performed with the locations of the corrosion on the containment, and the amount of corrosion varied in each analysis.
Wheel Impact Detection: Cost Savings and Safety Through “Management by Prevention”
Authors: Tse Yan H. , Steets Paul G.
Published: July 2023

Defective railroad wheels in the form of spalling, shelling, slid flat and out-of-round condition impose heavy wheel impact load into railroad track structure and car components, causing millions of dollars damage to Conrail. Allowed to continue in service, these defective wheels occasionally can deteriorate to a cracking condition, eventually breaking to cause costly derailments. As one step in the quality process to implement “Management by Prevention”, Conrail has been installing wheel impact detectors, based on strain gage and microprocessor technology, at various main routes to detect defective wheels and remove them before they can cause further damage.

The key events leading to the adoption of wheel impact detectors to detect and remove defective wheels by Conrail and by the industry in general are chronologically outlined. Three alarm levels of wheel loads, 170 kips, 150 kips and 100 kips are adopted by Conrail to handle these defective wheels by degree of severity. The first alarm level at 170 kips requires the train to stop to inspect the questionable wheels. Both the first and second levels require the train speed to drop to 30 mph until the questionable car is set out. The third alarm level requires the car to be shopped as soon as the car is unloaded. The statistics of wheel load distribution as sensed by the wheel impact detectors is presented. The resulting savings from their removal are estimated to be close to $5 million a year for one site which only covers about 20% of the traffic. These savings do not include the avoidance of the potential cost of broken wheel derailments. To achieve even greater savings and safety, Conrail has established a five year plan to install three wheel impact detectors in addition to two existing ones to afford better coverage. With a total of five detectors, this coverage is increased to 64.1% of all traffic and the annual savings is estimated to be close to $16 million a year.
Burn-Off Simulation of a Railroad Roller Bearing
Authors: Anderson Gerald B. , Cline James E. , Smith Richard
Published: July 2023

As part of the Association of American Railroads’ (AAR) Bearing Research Program to improve track wayside and in-shop freight car roller bearing detection technology, a roller bearing burnoff test was conducted at the Transportation Technology Center in Pueblo, Colorado. The bearing research program was initiated to develop effective acoustic processing techniques for use in a new generation of wayside detection systems. Using new signal processing and detection techniques developed by the AAR, the characteristic frequencies of a defective bearing under thermal failure were identified.1 The analysis of the test data leads to several important observations on the characteristic features of acoustic and laser detection techniques for use in a new generation of wayside detection systems.
Life Cycle Issues in Composite Structure
Authors: Connolly Jerome
Published: July 2023

Composite structures offer significant advantages over equivalent metallic structure in terms of reduced weight and fatigue and corrosion resistance. These performance benefits are often compromised by increased acquisition and support costs, i.e. total life cycle costs. Life cycle issues should be thought of in terms of acquisition and support costs since these are important measures by which a vehicle is judged. Clearly advanced fighter aircraft have a premium on performance and consequently life cycle costs are secondary. However, military and commercial transports do not require such optimum performance and life cycle costs are a primary concern. In the commercial arena in particular, high life cycle costs on a vehicle can result in that vehicle being economically unfeasible.