bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of Composites in Aircraft Gas Turbine Engines: Critical Issues
Authors: Miller Robert J. 
Published: July 2023

Abstract
Actual and potential composite applications in commercial and military aircraft gas turbine engines range from low temperature graphite/polymer matrix composite (PMC) components at the front of the engine, such as, fan blades, vanes, struts and cases, to high temperature ceramic matrix composite (CMC) nozzle components. Currently the “building block” approach is primarily used in the development of composite components for gas turbine engines. Critical issues associated with the design of these composite structures for both commercial and military aircraft gas turbine engines are defined. Critical structural components for both commercial and military gas turbine engines are designed to meet strict safety-of-flight requirements established by the FAA and the Air Force/Navy, respectively. Key design requirements established for damage tolerance and durability are defined. Areas in which research and development efforts should be accelerated are identified. There are currently a number of ongoing major funded research and development programs involving industry, academia, and government agencies which are contributing significantly to some of the issues addressed. These programs are: (1) High Speed Research (HSR), (2) Affordable Composites for Propulsion (ACP), and (3) Advanced Composites Technology (ACT).
An Interaction Integral Formulation for Computing Stress Intensity Factors Along Curved Bimaterial Interface Cracks
Authors: Gosz Michael R. , Moran Brian , Dolbow John E. 
Published: July 2023

Abstract
Domain integrals for extracting mixed-mode stress intensity factors along curved, three-dimensional bimaterial interface cracks are derived. In the derivation, the asymptotic auxiliary fields for the plane problem of a bimaterial interface crack are imposed along a curved crack front. The general crack-tip interaction integral is then expressed in domain form which is more suitable for numerical computation. A consequence of imposing the auxiliary fields along a curved crack front is that the auxiliary stress fields do not satisfy equilibrium, and the auxiliary strain fields do not satisfy compatibility. It turns out that the terms which arise due to the lack of equilibrium and compatibility are not sufficiently singular to contribute to the crack tip interaction integral or to affect its path independence. It is crucial, however, to include them in the domain integral representations because the domain integrals involve fields which are not asymptotically close to the crack-tip. In the paper, we present two numerical examples. As a benchmark, we consider the problem of a penny-shaped interface crack embedded in a cylinder. The results for the complex stress intensity factor and phase angle are found to be in excellent agreement with the analytical solution. The problem of an elliptical crack embedded between two dissimilar isotropic materials, for which an analytical solution is not available, is also considered, and the results are discussed.
Elastic-Plastic Analyses of Multiple Site Damages in Aluminum Sheets Using Finite Element Alternating Method
Authors: Wang L. , Atluri S. N. 
Published: July 2023

Abstract
This paper presents elastic-plastic analyses of Multiple Site Damages (MSD) in aluminum sheets, which contain one large crack at the center with several small cracks in front of its tips, subjected to far field tension loads. The analyses is performed based on the T*-integral fracture parameter, using the recently developed elastic-plastic finite element alternating method. A T*-resistance curve is obtained from the numerical simulations of experiments of center-cracked panels containing single cracks, in the generation phase analyses. A number of numerical predictions are made in the application phase, using the T*-resistance curve obtained in the generation phase. The predicted curves of load versus crack-extension are compared with the experimental measurements obtained at National Institute of Standards and Technology (NIST). Good agreements are observed. Through this comparison, the present paper presents, for the first time, a truly validated energy based fracture criterion for the analysis of stable growth and link-up of multiple cracks in an MSD situation.
Aeroelastic Analysis of Helicopter Rotor Blades Incorporating Anisotropic Piezoelectric Twist Actuation
Authors: Wilkie W. Keats , Belvin W. Keith , Park K. C. 
Published: July 2023

Abstract
A simple aeroelastic analysis of a helicopter rotor blade incorporating embedded piezoelectric fiber composite, interdigitated electrode blade twist actuators is described. The analysis consists of a linear torsion and flapwise bending model coupled with a nonlinear ONERA based unsteady aerodynamics model. A modified Galerkin procedure is performed upon the rotor blade partial differential equations of motion to develop a system of ordinary differential equations suitable for dynamics simulation using numerical integration. The twist actuation responses for three conceptual full-scale blade designs with realistic constraints on blade mass are numerically evaluated using the analysis. Numerical results indicate that useful amplitudes of nonresonant elastic twist, on the order of one to two degrees, are achievable under one-g hovering flight conditions for interdigitated electrode poling configurations. Twist actuation for the interdigitated electrode blades is also compared with the twist actuation of a conventionally poled piezoelectric fiber composite blade. Elastic twist produced using the interdigitated electrode actuators was found to be four to five times larger than that obtained with the conventionally poled actuators.
Control of Bending and Twisting Vibration in Non-Isothermal Beams
Authors: Wetherhold Robert C. , Aldraihem Osama J. 
Published: July 2023

Abstract
Vibration control of a beam which experiences a slowly changing through-thickness temperature variation is considered. This temperature variation produces thermal moments and curvatures which are assumed to change slowly with respect to the vibration frequencies. By proposing a Lyapunov controller which relies on a definition of strain energy without thermal expansion terms, stability of vibration control and removal of thermal curvatures are assured. By proposing a Lyapunov controller based on strain energy including thermal expansion terms, stability is assured but the thermal curvatures remain. The effect of temperature on the sensor output is included. A laminated beam with full sensor (all mode) coverage is used to illustrate the method. The continuous system is simulated using a discretized (finite element) approximation, and the successful operation of both controllers is demonstrated. The effects of the host beam stiffness and the ratio of actuator thickness to host beam thickness are determined.
Sensor Instrumentation for Smart Materials and Structures
Authors: Claus Richard O. 
Published: July 2023

Abstract
This paper reviews recent progress in the development and testing of sensor instrumentation for smart materials and structures, with specific consideration of sensors based on optical fiber techniques. General classes of fiber-based sensor platforms for mechanical measurements are discussed, specifically including Fabry-Perot and grating-based devices. Extrinsic Fabry-Perot interferometric (EFPI) sensors are shown to be advantageous for applications involving embedding in materials and for use in particularly harsh environments, while gratings are shown to be useful in situations requiring distributed sensor multiplexing. The very recent development of long-period grating (LPG) sensors that overcome troublesome observable cross-sensitivity while allowing increased sensitivity and low-cost manufacturing is presented. Applications of fiber sensor instrumentation in recent smart structure demonstration articles is referenced.
Active Control of Transmission of Bandlimited Disturbances Into a Three-Dimensional Enclosure
Authors: Sampath Arun , Balachandran Bala 
Published: July 2023

Abstract
Experimental investigations into active control of bandlimited noise transmitted into the interior of a three-dimensional enclosure with a flexible wall are presented. In the different experiments, the frequency range of the bandlimited disturbance is chosen to encompass structural and/or enclosure resonances. The rigid boundaries of the enclosure are constructed from acrylic material, and the flexible boundary clamped along all the edges is constructed from aluminum material. Lead Zirconate Titanate (PZT) patches mounted symmetrically on the flexible wall are used as actuators. Polyvinylidene fluoride (PVDF) film patches mounted on the flexible wall are used as vibration sensors, and condenser microphones placed inside and outside the enclosure are used as acoustic sensors. Digital feedforward control schemes based on filtered-x gradient descent algorithms are implemented in the experiments to minimize a chosen performance function. Different performance functions are examined, and the results obtained in the corresponding cases are compared. It is observed from the experiments conducted thus far that better noise reduction results are obtained when only acoustic sensors are used than when either vibration sensors or a combination of acoustic and vibration sensors is used.
Active Aperture Antennas
Authors: Washington Gregory 
Published: July 2023

Abstract
Recent studies have shown that reflector surface adaptation can achieve performance characteristics on the order of phase array antennas without the complexity and cost. The work proposed in this study develops a class of antennas capable of variable directivity (beam steering) and power density (beam shaping). The actuation for these antennas is employed by attaching polyvinylidene fluoride (PVDF) film to a metalized mylar substrate. A voltage drop across the material will cause the material to expand or contract. This movement causes a moment which causes a moment to be developed in the structure which causes the structure to change shape. Several studies of flexible structures with PVDF films have shown that cylindrical antennas can achieve significant deflections and thereby offer beneficial changes to radiation patterns emanating from aperture antennas. In this study, relatively large curved actuators are modeled and a deflection vs. force relationship is developed. This relationship is then employed in simulations where the far field radiation patterns of an aperture antenna are manipulated.
On the Shape Control of Environmentally Responsive Composite With Embedded TiNi Alloy as Effector
Authors: Yoshida Hitoshi , Funaki Atsuo , Yano Shoichiro 
Published: July 2023

Abstract
Bi-directional Environmentally Responsive Composites (ERC) composed of TiNi alloy effectors and CFRTP (Carbon Fiber Reinforced Thermoplastic) were fabricated to investigate the temperature responses and a method of responsive shape control of ERC.
Response upon environmental alternations was defined as the response rate and the recovery rate corresponding to the change in environmental temperature. Responsive shape control was done by controlling for the curvature of ERC when the mechanical properties and the initial curvature of the effectors were given. When the curvatures of ERC at low and high temperatures were set, the corresponding equations were derived in order to calculate the initial curvature and flexural rigidity of the matrices. As a result, it was found that a bi-directional responsive ERC with superior performance could be made by appropriately choosing the properties, the geomatries and volume fractions of effectors and matrices. The ratios of experimental and calculating values are very close to 1.0, and the numerical results were fairly satisfactory.
Active Fracture Control of a Composite Material System With SMA Actuator and AE Sensor
Authors: Furuya Y. , Shimamoto A. , Tani J. , Qiu J. 
Published: July 2023

Abstract
An Active control of the material degradation (i.e. damage accumulation, crack, delamination etc.) in service time and furthermore, an active prevention system of final sudden failure of machinery components and structures are studied by using shape memory TiNi fiber reinforced epoxy matrix composite model. First, the basic experimental study on active suppression of stress intensity (K value) at the crack-tip is performed by using photoelastic material. This is because the compressive stress effect is induced by means of direct current joule heating of the prestrained TiNi fibers embedded in epoxy matrix. Next, as an expansion of this study, another composite material system with SMA actuator as well as acoustic emission (AE) sensor is fabricated in which a typical AE outbreaks is utilized as a trigger to control the strengthening the bulk composite. The shape memory shrinkage of TiNi fibers is controlled under the commands from a microcomputer linked with AE sensor. This type of SMA intelligent (smart) material systems will be applicable for the elongation of the lives of material components, prevention of the sudden failure and maintaining the safety of the machinery devices, vehicles and building structures.
Shape and Location Optimization of Piezoelectric Actuators in Active Control Systems
Authors: Yousefi-Koma Aghil , Vukovich George 
Published: July 2023

Abstract
An optimization procedure for finding the optimal shape and location of a piezoactuator for active control of smart structures is introduced. PZT piezoceramic is used as the actuator and PVDF piezofilm is employed as a strain rate sensor bonded onto a flexible structure. The modal method is used to model the dynamic system, and state space feedback control is employed. Three different optimization criteria are studied and discussed. In the criterion we look for a configuration of the piezoactuator which maximizes the overall damping ratio of the closed loop system. Minimization of the overall real part of eigenvalues of the controlled system is the second criterion. For the third criterion, we seek the minimum LQR cost function over possible shapes and locations. Simulation provides some interesting results: for instance it is shown that in the case of constant piezoactuator area, wider and shorter actuators are better than longer and narrower ones. The methodology introduced here can be easily used in the actual experimental design of piezoactuators.
An Investigation of Microstructure and Microdynamics of Fluid Flow in MEMS
Authors: Lanzillotto Ann-Marie , Leu Tzong-Shyng , Amabile Michael , Wildes Richard , Dunsmuir John 
Published: July 2023

Abstract
This paper reviews x-ray imaging, visualization and analysis technologies which were utilized in an investigation of microstructure and micromotion in fluidic microsystems. These systems include fluidic microvalves, silicon v-groove microchannels and capillary tubes. Specifically, we have visualized the 3-D internal microstructure of Redwood Microsystems Fluistor microvalves and EG&G IC Sensors bimetal microvalve using x-ray microtomography and a massively parallel supercomputer. In other experiments, microradiography was used to image fluid transport through the valves as well as actuation. To better understand the microdynamics of flow, we have also studied the displacement of fluids in Si v-grooves and found that capillarity effects may be dominant. Finally, we discuss methods to visualize and measure steady-state flow in microchannels through the use of emulsions. The detailed flow patterns are directly viewable by the motion of the droplets. Computer vision motion analysis is used to recover the corresponding flow fields and velocity profiles.
Using HTML for an Online Survey of Risk Perception: An Experience Study
Authors: Halstead-Nussloch Richard 
Published: July 2023

Abstract
It is desirable to discover more about how much risk people perceive in everyday life and actions. Because the Internet is growing so fast, a survey on the World Wide Web might be a possible way to meet this desire. This study investigated using such an Internet survey, administered through an Internet web server, HTML, and a web browser. The online risk-perception survey had fifteen paired-comparison questions. It can be reviewed and taken at URL:
http://www.sct.edu/sct/departments/cs/classes/webwork/rpsurvey.html
Each pair had one common member, namely “Driving for an hour on suburban roads and highways.” The common member of the pair was always presented first. Two classes at Southern Polytechnic were invited to take the survey. Six responses were received from the 25 potential respondents. The low response-rate (24%) and overall results indicate that using HTML surveys on the web is more suitable for conveniently automating only the data collection rather than automating the total administration of a risk-perception survey. It is recommended that, within limits, surveys on the web can be an effective tool for assessing risk perception.
A Process to Quantify and Optimize the Effectiveness of Maintenance on Unavailability and Risk
Authors: Vesely W. E. 
Published: July 2023

Abstract
A process is described for utilizing available maintenance and failure data collected at nuclear power plants to quantify the effectiveness of maintenance on equipment reliability and availability. The methodology which is applied was developed under the sponsorship of the U.S. Nuclear Regulatory Commission (NRC) to help support the NRC’s Maintenance Rule. The process was applied and demonstrated using plant maintenance data for various equipment, such as diesels, motor operated valves and check valves. The applications show how maintenance can be optimized to maximize equipment reliability and availability while at the same time reducing required resources.
Building a Marketplace for Cross-Departmental Change
Authors: Sturdivant Maggie H. , Arsenault Frank J. 
Published: July 2023

Abstract
As the current decade opened, the Department faced the need to establish a standards basis for all of its work and the lack of a commonly accepted, standards-based management approach. The one-size-fits-all standards applied to production facilities had proven to be inappropriate for application to the diverse, complex, and sometimes undefined work of the Department’s revised mission. The Department Standards Committee was established as a high level, open marketplace for ideas — a Department-wide forum for discussion and decision. For its technical work, the Committee draws upon teams of voluntary participants from across the complex to provide a broad spectrum of experience and perspective in addressing issues such as cooperative engagement in the identification of Work Smart Standards, stakeholder involvement, and the attributes of effective documentation and implementation. The current expanding application of Work Smart Standards represents the practical results of this innovative effort.
National Training Program Efforts for Work Smart Standards
Authors: Carnes William E. , Peppers Kathleen S. 
Published: July 2023

Abstract
The Department of Energy recognized the need to establish a standards based, instead of expert based, way of performing its work. The Department Standards Committee was established as the high level, umbrella for developing the criteria and assisting in establishing this fundamental change throughout the Department. This paper describes the process and outcomes that Standards Process Action Team 8 (Training) applied to develop a needs analysis and method for effectively explaining the change of practices and processes within the Department. That process is based on the five step Instructional Systems Design model.
Singular Solutions of Interfacial Stresses in Multilayered Structures
Authors: Yin Wan-Lee 
Published: July 2023

Abstract
A general analysis methodology is developed to obtain accurate elasticity solutions of the singular stress fields associated with free edges and interfaces in multilayered structures under thermo-mechanical loads. Approximate solutions based on finite element or variational methods are used to provide traction boundary conditions on a circular path encircling the singularity. The singular elasticity solution of the region interior to the path is then determined in terms of eigenfunction expansion and by using boundary collocation. Results for a bilayer beam under a temperature load demonstrate that the interfacial stresses may be significantly contributed by non-singular eigenfunctions. Hence full elasticity solutions of the present type, rather than asymptotic solutions, may be required to assess the criticality and mode ratio of the interfacial actions across critical regions of the interface.
Tension-Tension Fatigue of Copper Thin Films
Authors: Read David T. 
Published: July 2023

Abstract
Tension-tension, load-controlled fatigue results extending to over 100,000 cycles for electron-beam-evaporated copper are reported. The specimen is fabricated as a single tensile coupon with hundreds of grains across the width but one or few through the thickness, supported on a silicon frame. These specimens had measured values of Young’s modulus lower than bulk polycrystalline values, but had high values of the yield and ultimate strengths. Closed-loop feedback control of the piezoelectric actuators allowed load-controlled fatigue tests with a cycle duration of 15 s. Stress-endurance results for this set of copper films are reported and compared to previous results.
Contribution of Thermal Stresses to Delamination of Coatings From Optical Fibers
Authors: Aloisio Charles J. , King Wilton W. 
Published: July 2023

Abstract
Sometimes the polymer coating on an optical fiber is observed to have separated from the fiber over (usually) a small portion of the interface. Irregularities on the capstans and sheaves of draw, rewind, coloring and cabling machines can initiate such delaminations. Subsequent growth would not be anticipated under the condition of radial compressive stress that might be expected for a coating shrinking over a relatively rigid fiber as the composite cools during manufacture. And compressive stress is indeed found at the interface when a single-layer coating is used. However, for a two-layer system, having a high-modulus secondary over a low-modulus primary (for improved protection against microbending), the different rates of thermal expansion can lead to radial tension at the silica/primary interface, and this tension can “drive” the growth of delaminations.
A principal result of this study is that the analysis predicts the primary coating although rubbery, to be approximately in a state of uniform hydrostatic tension. This tensile stress is of substantial magnitude because of constraints imposed by the relatively stiff secondary coating and by the fiber. The existence of significant radial tension at the fiber surface is consistent with experimental observations of induced delaminations, which are seen to grow long after cessation of external disturbances.