bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Autonomous System for the Active Control of Noise on a High Speed Patrol Craft
Authors: Dignan M. , Schudel G. , Sutterlin M. , Kewley D. 
Published: July 2023

Abstract
An autonomous active noise control system has been developed to reduce low frequency noise in the aft berthing space of a high speed patrol craft. The system controls both high amplitude propeller blade-rate harmonic noise, as well as broadband noise caused by propeller cavitation and machinery. A local control strategy using an adaptive feedback algorithm provides a quiet zone at the head of each bunk. One system, containing a loudspeaker, microphones, and control electronics, is mounted at the head end of each bunk. The only external connection to the system is a power cable. Noise reductions of up to 20 dB at tones and 8, 15, and 5 dB in the 31, 63, and 125 Hz octave bands respectively have been measured at the head position of the bunks. Overall A-weighted level reductions of up to 6 dB have also been measured.
Estimation of the Fuzzy Substructure Model Parameters Using the Mean Power Flow Equation of the Fuzzy Structure
Authors: Soize Christian 
Published: July 2023

Abstract
This paper presents a theoretical approach for identifying the dimensionless mean coefficient of participating fuzzy mass which is the main unknown parameter of the type I or II fuzzy law previously introduced by the author. This method is based on the use of the associated power flow equation, each power term being identified by using a global statistical energy analysis of the fuzzy structure (master structure with its fuzzy substructures). Identification is then carried out by solving a nonlinear constrained optimization problem. An example is given to illustrate the theoretical results.
Using Composite Materials for Noise Attenuation in Automobiles
Authors: Raichel Daniel R. 
Published: July 2023

Abstract
An overview is rendered of the criteria that must be met in the use of composite materials for reducing NVH (noise-vibration-harshness) in automotive vehicles. Previous work in structural mechanics provide the foundation for defining composite complex moduli, and. hence, loss tangents of fiber and particulate composite materials as functions of the constituent (i.e., fiber and matrix) properties. Specific materials can be cited as being primary candidates for NVH control in vehicles, primarily through structural stiffening, and these can also serve other functions such as promoting vehicular lightness and providing for passenger protection. The field remains wide open for the introduction of new types of composites and structural rheological matrices.
Space-Time Analysis of the Flow-Induced Vibration of a Solid Containing an Embedded Cylindrical Shell
Authors: Hull Andrew J. , Abraham Bruce M. 
Published: July 2023

Abstract
This paper develops a model of a viscoelastic solid that contains an embedded cylindrical shell through which fluid flows at low Mach number. The model output corresponds to the displacement that a beamformed, steered array of sensors would measure in wavenumber and frequency. The solid and the shell are modeled using elasticity equations of isotropic mediums. The fluid is modeled with two pressure terms: one that represents the acoustic pressure field and one that represents the normal forces of the turbulent boundary layer on the inner wall of the cylindrical shell. The fluid equations are coupled to the solid equations by conservation of momentum. The spatial (or wavenumber) response of the array and the array elements are also included in the model. All the model terms are assembled into a single integral equation which is numerically evaluated at various frequencies. The work is verified with an experiment in which gravity-fed water is passed through a piece of surgical tubing that is contained in the block. Displacement measurements of the free surface of the block are made with an eight-element array, and the results are compared to the theoretical model. It is shown that the model and the experiment are in good agreement.
Growth and Propagation of Acoustic Waves of Nonuniform Sound Speed Within a Plane-Walled Enclosure
Authors: Kuprowicz Nicholas J. , Petrykowski John C. , Eloe Paul W. 
Published: July 2023

Abstract
The propagation of acoustic waves through nonuniform temperature fields may suffer distortion due to local sound speed variations. This paper considers the case of the generation and propagation of acoustic waves through a nonuniform temperature field where the spatial variations are caused by eddy current heating of a fluid layer. Numerical solutions to the variable coefficient inhomogeneous wave equation are presented for the case where the fluid is excited in the transverse direction and the adjoining walls are acoustically hard. Progressive and dispersive waves can be clearly distinguished in the numerical results with a dispersive wave speed value within 1.5% of theory. In addition, the progressive waves are shown to propagate along curved characteristics with the curvature being related to the severity of the sound speed gradient. Several eddy current heating applications are described in which propagation of acoustic waves is significantly altered by the nonuniform sound speed profile.
Effect of an Annular Inlet Guide on the Performance of Low-Speed Centrifugal Fans
Authors: Vadari Viswanathan R. , Ruff Gary A. , Reethof Gerhard 
Published: July 2023

Abstract
Understanding the complex flow in the inlet and scroll of low-speed centrifugal fans is required to improve fan aerodynamic and acoustic performance. Previous investigators have documented the presence of a strong separation region at the inlet of a centrifugal fan. In this study, a simple annular inlet guide (AIG) was designed to reduce the size and strength of the separation region, thereby improving the flow quality entering the impeller and reducing noise. Preliminary inlet guide designs resulted in a reduction of 6 dB at the blade passing frequency and a 10 dB reduction at its second harmonic. A reduction of 3 dB in the broadband frequency range of 0 to 2000 Hz was also obtained without loss of aerodynamic efficiency. Based on static pressure measurements made in the exhaust duct, the AIG was found to redistribute the flow uniformly over the width of the impeller.
A Modified Secondary Source Method for Characterizing Pump Acoustic Source Impedance in Hydraulic Systems
Authors: Chen Chuan-Chiang , Hastings Mardi C. 
Published: July 2023

Abstract
Hydraulic pumps generate flow ripples which interact with the hydraulic circuit and cause pressure pulsations (fluid-borne noise). This kind of noise is a major source of structural vibration and airborne noise. In order to study the noise and vibration in hydraulic systems, the pump source impedance must be characterized.
In general, the pump source impedance is independent of the interaction between the pump and circuits connected to it. Former researchers [1,2,3,4] measured acoustic pressures along the transmission line at different locations and used plane-wave propagation theory to find the source impedance. However, the acoustic pressures used in previous research are dependent on the dynamic response of the circuits as well as the pump. Edge and Johnston [5,6] developed the ‘secondary source’ method to evaluate the source characteristics of hydraulic pumps. They used a secondary source to excite the pump at two different frequencies. The pump source impedance (termination impedance for the second source) could then be estimated. Since the impedance obtained from their method is for different frequencies than the harmonic frequencies of the pump, they used a suitable model along with the experimental results to find the impedance of the pump at the desired harmonic frequencies.
In this paper, a new method is proposed using a ‘modified secondary source’ method which is achieved by use of two experimental configurations. By using the principle of superposition for a linear system, the pump impedance can be found from addition of the impedances obtained from the two setups. The proposed method will be able to cover the whole frequency range without using a mathematical model for the pump.
Sound and Vibration in Composite Tubes of Variable Cross Section
Authors: McAleenan Michael G. , Nagem Raymond J. 
Published: July 2023

Abstract
To investigate the coupling between sound production and wall vibration in composite tubes of variable cross section, a set of composite cones with varying wall material and thickness was manufactured and tested experimentally. The approach undertaken was to optimize the relationship between cross sectional radial vibrations and structural stiffness. Employing Webster’s variation of the wave equation as a basis for a theoretical analysis, a second generalized equation was derived to include the effects of surface vibrations onto the standing wave pattern in the composite tube. Methods for solving this differential equation analytically are discussed, as are assumptions to arrive at a general solution for the natural frequency mode and shapes.
The focus of the experimental research was to produce such composite cones, excite standing waves in the cones at particular frequencies, and record the acoustic radiation and the corresponding wall oscillations for each. Carbon, Kevlar and wood veneer were chosen as materials for the composite. To reduce the influence of other factors that effect acoustical properties, each cone was laid up over a single mold. In addition, pre-impregnated fabrics were used to insure a consistent volume fraction, and the sinusoidal source and mechanical procedures were held constant.
The results suggest that composite tubes of variable cross section can be designed to obtain a coupling between the standing wave and wall vibrations to produce a specific sound quality.
An Automatic Shut-Off Valve for Hydraulic Accumulators
Authors: Song Jinchun , Zhou Shichang , Liu Lipeng 
Published: July 2023

Abstract
This paper introduces an automatic shut-off valve device used in conjunction with a hydraulic accumulator that compensates for leakage in hydraulic accumulator circuits. This device shuts off automatically to prevent the pressurized oil inside the accumulator from draining out whenever the pressure of the circuit drops to zero. Therefore, it saves the time and energy of recharging the accumulators.
Differential PWM Operated Solenoid Valves in the Pilot Stage of Mini Excavators: Modeling and Identification
Authors: Tafazoli S. , Peussa P. , Lawrence P. D. , Salcudean S. E. , de Silva C. W. 
Published: July 2023

Abstract
For computer control of the link movements in a mini excavator, the original pilot stage has to be modified. In our previous work (Peussa et al., 1995), switching on/off valves were used in the pilot stage, as an interface between the main valve and electronics. It was investigated that Differential Pulse Width Modulation (DPWM) can be used to generate the required pilot pressure. Modeling and identification of the proposed DPWM operated pilot stage is studied in this paper. Both parametric and non-parametric approaches are employed for identification. An estimated linear model is obtained for the new pilot system and its validity is checked via various tests. According to the results, the modified pilot stage has linear dynamics and is quite reliable.
Improved Simulation of Ratcheting in Straight Pipes
Authors: Hassan Tasnim , Zhu Yimin , Matzen Vernon C. 
Published: July 2023

Abstract
It is well known that ratcheting can cause failure in piping components or systems subjected to seismic or other cyclic loads. Commercial finite element codes cannot accurately simulate the ratcheting responses recorded in tests on piping components and systems. The reason for this can be traced to inadequate constitutive models in the existing analysis codes. To overcome this deficiency, we have incorporated an improved cyclic plasticity model, based on the Armstrong-Frederick kinematic hardening rule in conjunction with the Drucker-Palgen plastic modulus equation, into an ANSYS user subroutine. The analysis results for straight pipes subjected to constant internal pressure and quasi-static cyclic bending obtained from the modified ANSYS code are compared to experimental data, as well as to results from ABAQUS and the original ANSYS code. The simulations from the modified ANSYS are satisfactory and show a significant improvement over the original ANSYS and the ABAQUS codes.
Cyclic Material Properties Tests Supporting Elastic-Plastic Analysis Development
Authors: Hodge Scott C. , Minicucci Jay M. 
Published: July 2023

Abstract
Correlation studies have shown that hardening models currently available in the ABAQUS finite element code (isotropic, kinematic) do not accurately capture the inelastic strain reversals that occur due to structural rebounding from a rapidly applied transient dynamic load. The purpose of the Cyclic Material Properties Test program was to obtain response data for the first several cycles of inelastic strain reversal from a cyclic properties test. This data is needed to develop elastic-plastic analysis methods that can accurately predict strains and permanent sets in structures due to rapidly applied transient dynamic loading. Test specimens were cycled at inelastic strain levels typical of rapidly applied transient dynamic analyses (0.5% to 4.0%). In addition to the inelastic response data, cyclic material properties for high yield strength (80 ksi) steel were determined including a cyclic stress-strain curve for a stabilized specimen.
Two test methods, the Incremental Step Method and the Companion Specimen Method, were used to determine cyclic properties. The incrementally decreasing strain amplitudes in the first loading block of the Incremental Step Method test is representative of the response of structures subjected to rapidly applied transient dynamic loads. The inelastic strain history data generated by this test program will be used to support development of a material model that can accurately predict inelastic material behavior including inelastic strain reversals. Additionally, this data can be used to verify material model enhancements to elastic-plastic finite element analysis codes.
Parallel Contact Detection Algorithm for Transient Solid Dynamics Simulations Using Pronto3D
Authors: Attaway Stephen W. , Hendrickson Bruce A. , Plimpton Steven J. , Gardner David R. , Vaughan Courtenay T. , Heinstein Martin W. , Peery James S. 
Published: July 2023

Abstract
An efficient, scalable, parallel algorithm for treating material surface contacts in solid mechanics finite element programs has been implemented in a modular way for MIMD parallel computers. The serial contact detection algorithm that was developed previously for the transient dynamics finite element code PRONTO3D has been extended for use in parallel computation by devising a dynamic (adaptive) processor load balancing scheme. 1
Advanced Materials and Structures for Transport Aircraft
Authors: Janicki Gerry 
Published: July 2023

Abstract
The growth predicted in the commercial transport aircraft market by the three leading airframe manufacturers indicates that there is a one trillion dollar market encompassing over 13,000 aircraft over the next twenty years. The ability to capture a significant portion of this business will be dependent on the ability of a company to offer technologically advanced products at an affordable price. The McDonnell Douglas Corporation has established the Advanced Transport Aircraft Systems Division to develop and implement advanced technology in future transport aircraft products. McDonnell Douglas through Douglas Aircraft Company has produced over 17,000 aircraft since the early 1930’s. A key element of capturing the future market is the incorporation of technology advancements into future products in a manner that reduces the acquisition and operating costs for the airline customers. Structures and materials technology has an impact on both the manufactured cost and the direct operating cost.
Hurdles in Technology Transfer Between Industries
Authors: Barron James H. 
Published: July 2023

Abstract
It has long been the goal of structural composites producers to achieve aerospace quality composites using automotive production methods. It was hoped that by drawing on the best of the two industries, the goal could be achieved. However, too often, when put together, the two seem to be speaking different languages. This paper will discuss experiences of the author with interactions in automotive, aerospace, and industrial industries and attempts to exchange technologies between them.
An Aircraft Company’s Venture Into Non-Traditional Composite Structure: Bridge Decks, Windmills, Pedestrian Bridge, Transit Bus
Authors: Banuk Ron 
Published: July 2023

Abstract
In 1993 Northrop Corporation began to look at the potential for acquiring new business outside of the aerospace industry in the areas of composite infrastructure and surface transportation. In the field of windmills a typical design problem called for the construction of a 2000-lb blade to withstand one billion fatigue cycles over a 30-year life and be manufactured for $5/lb. The design would include an intricate all-composite root rib fitting. Design criteria for a pedestrian footbridge is shown to include a 90-ft span, bullet proof sides, fastenerless assembly, and a cost about $1000/ft. In the field of surface transportation a tank treadway needs a fastenerless damage tolerant design while the tank sponsons require the impact resistance afforded by thermoplastic materials. In another manufacturing activity bridge decking is being designed for damage tolerance to a hole in the presence of local tire contact stresses.
Offshore Structures: The Environmental, Economic and Structural Design Drivers
Authors: Mickelson Craig S. , Anderson Jeffrey J. 
Published: July 2023

Abstract
Composite structures are becoming more attractive to the offshore oil industry as weight becomes a critical design criteria in deep waters. Composites’ high strength to weight ratio offers potentially large weight reductions with comparable or enhanced performance for many applications. A team lead by Northrop Grumman Marine Systems (formerly Westinghouse Marine Division) consisting of DeepStar, ABB Vetco Gray, Offshore Technology Research Center, Reading and Bates and Hexcel (formerly Hercules) supported by NIST is currently developing one such offshore application, a composite drilling riser. This paper describes the design drivers for a composite drilling riser capable of operating at a 6000 foot water depth. The design drivers are categorized into three areas: environmental, structural and economic and directly determine the material selection, material property allowables, composite lay-up and composite to metal termination design.
The Development of Composites for Automotive Structures
Authors: Jeryan Richard 
Published: July 2023

Abstract
The automotive use of polymer composite materials offers the potential for significant benefits to both the consumer and the manufacturer. The materials and their manufacturing methods continue to be developed and composites are being applied in a widening array of structural and nonstructural parts of cars and trucks. The technical and business issues that face these applications are under development by the automotive manufacturers, materials suppliers, universities and government-supported consortia.
Composites are a mixture of several materials on a macroscopic level; they have characteristics that cannot be attained from the individual constituents. Automotive composite materials have high strength and stiffness fibers imbedded in a lower strength, lower stiffness, but easily manufactured, matrix. In polymer composites, the fibers are typically glass and the matrix is a thermoplastic or thermoset polymer. Composites exhibit a low density and a high specific strength, and can yield significant weight reduction when used in primary and secondary automotive components.
Characterization of Dynamic Ductile Fracture Using High Speed Infrared and Visible Optics
Authors: Singh Raman P. , Rosakis Ares J. , Ravichandran Guruswaminaidu 
Published: July 2023

Abstract
An experimental investigation has been conducted to study dynamic crack initiation in precracked ductile 304 stainless steel specimens. The specimens are subjected to dynamic three point bend loading by impacting them in a drop weight tower. This impact results in deformation followed by fracture initiation.
During the dynamic deformation and failure process the time history of the temperature and deformation fields around the crack tip are recorded experimentally. The transient temperatures are recorded using high speed infrared detectors, while the deformation fields are obtained using Coherent Gradient Sensing (CGS) in conjunction with high speed photography. The experimentally obtained temperature variation is then used to extract the time history of the dynamic J-integral, Jd(t). This is the first time that a non-contact temperature measurement is used to evaluate Jd(t). The applicability of this technique is currently being validated through comparison with the simultaneously performed optical measurements of the deformation field using CGS.
Constraint Fracture in Simulated Weldments
Authors: Anderson D. D. , Jackson J. H. , Epstein J. S. , Ganti S. , Parks D. M. 
Published: July 2023

Abstract
Simulated under-matched butt weldments have been fabricated using commercially pure titanium (CP Ti) as an interleaf material diffusion bonded to a higher strength 6Al-4V titanium (6Al-4V Ti). Four-point bend bars were constructed where-by the only changing geometric feature is the thickness of the CP Ti interleaf which varied from 12 to 1.7 mm. The CP Ti and 6Al-4V Ti elastic moduli are 112.3 and 115.1 MPa while the yield stresses are 366 MPa and 896 MPa respectively. A through-crack was inserted in the center of the CP Ti interleaf. Due to the close moduli, the elastic T constraint terms do not change as the CP Ti interleaf thickness is varied. However, under plastic loading, the thickness of the interleaf has a large effect on the local plastic fields surrounding the crack tip as well as the initiation J values. Using a hybrid approach with moire interferometry and finite element methods, it has been found that the higher strength 6Al-4V Ti acts to constrain the crack tip plastic zone. The net result of this constraint is a reorientation of plastic flow in the CP Ti interleaf from 90 to 45 and 135 degrees and a mean stress 2.8 times larger that the flow stress. To understand the effect of the hydrostatic constraint on the initiation process in the CP Ti interleaf, a series of double interleaf tensile bars have been developed to obtain stress-strain curves of the CP Ti interleaf under varied constraint states. These tensile specimens indicate that for the highly constrained CP Ti interleafs, that the mode of fracture initiation is due to a form of cleavage initiating at the titanium carbide stringers.
Basic Research Issues in Aerodynamics, Structural Dynamics, and Control of Turbine Engine High Cycle Fatigue
Authors: Greitzer Edward M. , Paduano James D. , Epstein Alan H. , Weisshaar Terrence A. 
Published: July 2023

Abstract
This paper summarizes basic research issues which can enable improved methodologies for High Cycle Fatigue mitigation in gas turbine engines. The paper is drawn from the results of a recent AFOSR Workshop on High Cycle Fatigue, which brought together a national community of industry, government, and academic researchers specifically to define these issues.