bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamics of Free Surface and Pure Elongational Flows of Liquid Crystalline Polymers
Authors: Wang Qi , Forest M. Gregory , Zhou Hong 
Published: January 2022

Abstract
The performance properties of many polymers are dominated by the molecular alignment induced during processing by the elongational flow component, that is, the diagonal component of the velocity gradient tensor. Here we discuss two idealizations of this flow-microstructure interaction. We first summarize our recent studies of biaxial nematic patterns and phase transitions (Forest and Wang, 1998a) of lyotropic liquid crystalline polymers (LCPs) in response to imposed elongational flows. We show axisymmetric biaxial nematic patterns coexist with homogeneous biaxial patterns characterized by Rey (Rey, 1995). All biaxial patterns in unidirectional stretching flows are unstable, whereas planar stretching induces candidate stable biaxial nematic patterns. Non-homogeneous biaxial patterns have potential core defects, and two special director alignments are selected by imposing a finite-pressure condition along the axis of flow symmetry. The role of director dynamics in response to flow perturbations is described, and in particular new, elongation-induced, director instabilities are revealed, extending seminal stability and phase transition results (Khokhlov and Semenov, 1982; See et al., 1992; Bhave et al, 1993; Rey, 1995; Hu and Ryskin, 1992). We then examine two special solution families of the governing equations for free surface, axisymmetric, cylindrical LCP fiber flows, following analogous Newtonian results of Segur et al. (Segur et al., 1997). The cylindrical free surface only accommodates uniaxial orientation, and from these ideal transient solutions we analyze the linearized stability of the coupled flow and microstructure in the LCP thin-filament approximation (Forest et al, 1997).
Rheology of Discontinuous Fiber Arrays in Elongation
Authors: Creasy T. S. , Advani S. G. 
Published: January 2022

Abstract
This paper presents a two-fluid shear cell model that may apply to the long-discontinuous-fiber melt system made from AS4 carbon/poly-ether-ketone-ketone. As a 370°C melt at rest, PEKK forms a thermotropic liquid crystal structure. An LDFMS extended in the direction of the fibers generates a magnified local shearing strain rate through relative fiber motion. The boundary between the LCP and isotropic fluids could be a function of the fiber volume fraction, the generated shear strain rate, and the nucleation strength of the fiber surface. The two-cell model shows some of the consequences of generating a two fluid system within the LDFMS. The experimental data in this paper demonstrate the LCP character of PEKK and the nucleation effects of the AS4 fibers.
A Fully Non-Linear Theory of Electro-Magneto-Hydrodynamics
Authors: Ko Hyung-Jong , Dulikravich George S. 
Published: January 2022

Abstract
A number of analytical models exist for both electro-hydrodynamics (EHD), the study of fluid flows containing electric charges under the influence of an electric field and negligible magnetic field, and magneto-hydrodynamics (MHD), the study of fluid flows containing no free electric charges that are under the influence of a magnetic field and no electric field. At the present, there are no practical yet consistent models for the combined electro-magneto-hydrodynamic (EMHD) effects which most often occur in actual situations. This work represents an attempt to develop such a fully consistent analytical model for multi-dimensional, steady and unsteady, compressible and incompressible flows of electrically conducting fluids under the simultaneous or separate influence of externally applied and internally generated steady or unsteady electric and magnetic fields. The approach is based on the fundamental laws of continuum mechanics and thermodynamics with all assumptions clearly stated and consistently applied. The resulting second order EMHD model allows for non-linear polarization and magnetization of the medium. The new model is therefore superior to the existing EMHD models and represents a tractable set of equations suitable for detailed numerical discretization and integration.
Model Recognition and Simulation of an E/H Steering Controller on Off-Road Equipment
Authors: Wu D. , Zhang Q. , Reid J. F. , Qiu H. , Benson E. R. 
Published: January 2022

Abstract
An automated E/H steering controller is essential for autonomous off-road equipment. This paper presents a methodology for designing the E/H steering controller through a combination of testing and simulation. The steering kinematic model provides the steering linkage gain between the hydraulic actuator and the front wheel. The model makes it possible to close the steering control loop based on the signal of the hydraulic steering actuator rather than the front wheel. Test results were used to identify the non-linear and dynamic characteristics of the original E/H steering system. A Matlab model of E/H steering controller was developed based on the experimental test results.
Life-Cycle Assessment of Oil ‘Hydraulic’ Systems for Environmentally-Sensitive Applications
Authors: Burrows Clifford R. , Hammond Geoffrey P. , McManus Marcelle C. 
Published: January 2022

Abstract
Life-cycle assessment (LCA) techniques have been used in order to evaluate the environmental impact of conventional oil ‘hydraulic’ systems in an ecologically-sensitive application; that of mobile forestry machinery typical of modem European design. A single-grip ‘harvester’ employed for logging and a ‘forwarder’ that subsequently transports the felled and cut-to-length timber out of the forest are analysed. The results of this indicative LCA provide insights into the relative magnitude of the complex range of environmental impacts arising from fluid power systems and their parent vehicles in the forestry context. It also suggests areas for future research, principally on the impact of diesel fuel and hydraulic oil (including their additives) on the forest ecosystem, on the balance between local, regional and global environmental effects, and on the developing methods of LCA itself.
Investigation of the Effects of Swashplate Angle and Suction Timing on the Noise Generation Potential of an Axial Piston Pump
Authors: Wicke Volker , Edge Kevin A. , Vaughan Nicholas D. 
Published: January 2022

Abstract
The paper presents theoretical work carried out with the simulation program Bathfp. Models simulating the dynamic behaviour of axial piston pumps have been extended to investigate piston forces for different valve plate timings and for different swashplate angles. These forces have then been used to calculate the mean and fluctuating components of the moment functions. Since the forces and moments together are the most important inputs causing structure borne noise, the influence of the swashplate angle on the structure borne noise could be investigated. The influence of the suction port timing on both structure borne and fluid borne noise potential is also discussed.
Nonlinear Adaptive Learning for Electrohydraulic Control Systems
Authors: Zheng Danian , Havlicsek Heather , Alleyne Andrew 
Published: January 2022

Abstract
This investigation presents the application of an existing adaptive learning rule to the position control of a hydraulic cylinder driven by an electrohydraulic proportional valve. The system is representative of many types of Manufacturing applications including Injection Molding, Metal Forming and Industrial Presses which perform the same operation repeatedly for many cycles. The system contains several major nonlinearities that limit the ability of simple controllers in achieving satisfactory performance. These nonlinearities include: valve deadzones, valve flow saturation, and cylinder seal friction. Furthermore there is a significant compliance in the system due to the hose length between the valve and the cylinder. The learning algorithm iteratively determines an appropriate feedforward signal to be used in conjunction with simple feedback in order to track a predetermined reference signal. The algorithm is presented along with simulation and experimental results.
A Study of Pneumatic Pipes Modeling
Authors: Bideaux E. , Scavarda S. 
Published: January 2022

Abstract
In fluid power systems, lines or pipes can have a predominant effect on dynamics. Although many studies have been carried out on hydraulic pipe modeling, there are only a few existing approaches for such problems in pneumatics. This paper proposes a basic work for modeling of pneumatic pipes. After presenting the state of the art situation and the nature of this problem, we have proposed two ways of modeling pneumatic pipes. The first one consists of a discretization scheme based on an upwind finite differencing scheme. This method has advantages but can lead to erroneous results in the case of a predominance of the convection effect when the direction of flow changes rapidly. We propose a method for solving such difficulties. We also propose a second method which is based on a finite volume approach. This type of model represents the convection effect better and we will prove its robustness through several examples. Before concluding, in order to validate our propositions, we compare experimental trails to the results given by the simulation of the two methods.
Stochastic Turbulent Fields for Acoustic Numerical Simulations
Authors: Bailly Christophe , Blanc-Benon Philippe 
Published: January 2022

Abstract
The goal of this paper is to show that stochastic turbulent fields can be used in acoustic numerical simulations when only some statistical properties of turbulence are required. The turbulent field is achieved by synthesizing a collection of Random Fourier Modes (RFM) at each point in space. An extension of the RFM method to include a time evolution and spatial inhomogeneous statistics is suggested. Then two applications of the RFM are given for acoustic numerical simulations. The first deals with the atmospheric sound propagation through turbulence over large distances. The second one concerns generation and radiation of noise for subsonic flow at high Reynolds number.
The Influence of Leading Edge Separation on the Unsteady Response of a Thin Airfoil
Authors: Lynch Denis A. , Minniti Robert J. , Mueller Thomas J. 
Published: January 2022

Abstract
An experimental investigation of the influence of a leading edge separation region on the unsteady aerodynamic problem for thin, symmetric airfoils exposed to periodic gusting was performed in a subsonic indraft wind tunnel. Two leading edge shapes for the airfoil were used to examine the influence of flow separation both in the unsteady velocity and pressure fields. It is shown that flow separation near the leading edge causes a sharp increase in the unsteady RMS velocity and unsteady surface pressure variation associated with the gust frequency. This also causes a departure from the expectation that the gust information is convected downstream by the freestream in the velocity field. In the absence of such a separation region, velocity and surface pressure results closely resemble inviscid theoretical predictions and expectations. Accurate prediction of unsteady pressure is crucial in estimating the acoustic production of the system.
Anechoic Box Method for Measurement of Industrial Sound
Authors: Huang Xiubao , Balligand Hélène 
Published: January 2022

Abstract
A new method is described to measure the free field sound pressure level in a non-anechoic test laboratory for industrial equipment. The method, called anechoic box method, uses a small anechoic box to house the microphone, instead of using a conventional large semi anechoic room to house the large size machinery. A window opening on one wall of the box faces the sound source and all other walls (five sides) are closed. The noise source within the field of view of the microphone gives an equivalent free field sound pressure level in a non-anechoic industrial environment when the noise source is positioned exactly at the window. This method is also capable of isolating unwanted noise sources. Experimental results based on a 2000 Hz noise source demonstrate the effectiveness of isolation by field of view and show consistent results when field of view is changed systematically.
Low Velocity Impact Characterization of Neat Vinyl Ester 411-350 Resin System
Authors: Motuku M. , Janowski G. M. , Vaidya U. K. , Mahfuz H. , Jeelani S. 
Published: January 2022

Abstract
The room temperature impact response of DERAKANE 411-350 vinyl ester neat resin system (unreinforced matrix) has been investigated as a function of sample thickness and impact energy level. Vinyl ester resins are of interest in ballistic applications such as in armored vehicles. The response of neat resin to impact loading was investigated using the impact load histories (load-time and load-deflection traces), impact plots and fractography analysis. The maximum load or peak contact force, energy to maximum load, total energy and deflection at maximum load were found to increase in a nearly parabolic manner with increase in impact energy level, whereas time-to-maximum load or impact duration at the peak load decreased linearly. Total energy-to-impact energy ratio changed in a step-wise manner with impact energy. The slope of the load-deflection (load-time) traces, which is related to the impact modulus or relative stiffness of the material, increased with impact energy level and sample thickness. The change of slope with impact energy level and sample thickness indicated the dependence of impact modulus on the impact energy level and target geometry. The threshold impact energy levels, which were associated with the onset of catastrophic matrix failure and extensive tensile strength losses, were identified from the impact plots. Multiple radial cracking, perforations in the form of a truncated cone at the point of impact and support induced damage were identified as the dominant failure characteristics.
High Frequency Vibration Analysis Performed by a Statistical Energy Analysis Formulation and an Energy Finite Element Formulation
Authors: Vlahopoulos Nickolas , Garza-Rios Luis Octavio , Nelson Richard K. 
Published: January 2022

Abstract
The Energy Finite Element Analysis (EFEA) offers significant advantages in the areas of model generation, interpretation of results, and definition of design variables for parametric analyses, with respect to the established Statistical Energy Analysis (SEA). A theoretical overview and comparison of the two methods is presented first. A published marine application is analyzed, and comparison of the results offers an initial validation of the EFEA. Numerical models for a fishing boat are generated for both methods and utilized for further comparison between the two formulations. The applicability of the EFEA in the marine field is demonstrated and its benefits are discussed.
Parallel Computation of Harmonic Waves Using Domain Decomposition: Part 2 — Numerical Implementation and Applications
Authors: Susan-Resiga Romeo F. , Atassi Hafiz M. 
Published: January 2022

Abstract
A numerical implementation of the Domain Decomposition (DD) method for parallel computation of time-harmonic waves is presented. The Finite Element method on unstructured mesh is employed to discretize the boundary-value problem. A nonover-lapping mesh partitioning is used to build an overlapping domain decomposition. The algorithm also defines the new subdomain boundaries, other than the original boundaries of the global computational domain, on which transmission conditions are introduced. The independent subdomain problems can be solved concurrently, one problem per processor, on a parallel computer. The iterative scheme used to update the subdomain transmission conditions is computationally efficient and only swaps the nodal values in the overlapping region between adjacent subdomains. For exterior problems, the communication required to update the conditions on the outer boundary is substantially reduced by employing a modified Dirichlet-to-Neumann (DtN) map with truncated support. Numerical results are presented for a radiation model problem. It is shown that the DtN nonreflecting conditions eliminate spurious reflections and that the iterative scheme leads to a continuous global solution. The DD algorithm also has a very good convergence rate and significantly reduces memory requirement in comparison with a direct solver.
Coupled-Mode Formulation of Acoustic Disturbances in Ducts of Variable Cross-Section With Baffled Ends
Authors: Pierce Allan D. , Cleveland Robin O. 
Published: January 2022

Abstract
Computational techniques are discussed for predicting acoustically induced flow within ducts whose cross-sectional dimensions vary continuously with axial distance along the duct. A formulation is introduced in which both the acoustic pressure and the axial component of the fluid velocity are expanded in terms of the local cross-sectional modal eigenfunctions, these depending implicitly on axial distance. A variational principle is derived and used to derive a set of coupled ordinary differential equations for the modal coefficients. A theory is also developed for the excitation of the field within the duct when a plane wave is incident at the baffled open end of the duct, the other end being closed. A potential application is in the design of an acoustic sensor that makes use of microclectromechanical sensor (MEMS) technology.
Experimental Analysis and Reduction of Alternator Noise
Authors: DiSalvo Michael J. , Wu Sean F. 
Published: January 2022

Abstract
This paper presents the analysis of alternator noise radiation from a passenger vehicle. Experimental data show that the noise spectra contain both narrow- and broad-band sounds, and the overall sound pressure level (SPL) from an unloaded alternator can be as high as 90 dB(A) with the engine running from 3,800 to 5,000 rpm (alternator speed from 11,400 to 15,000 rpm). The overall SPL values seem to be relatively independent of the current output. Results show that only at very low speeds the alternator noise levels increase with the current, and level off as the current increases. At high speeds, the noises are independent of the current. This is because at high speeds the alternator fan noise is so predominant that it masks all other noise sources. When the fans are removed, the overall SPL decreases by 15 to 20 dB (A). A closer look at the fans reveals that they not aerodynamically suited to run at such high speeds. The blades have large inclination angles, poor profiles, contain rough edges and sharp corners. Once the modified fans are installed, the overall SPL values are reduced by 5 dB (A) over the entire speed range. Flow measurements indicate that the cubic feet per minute (CFM) values for the redesigned fans are increased by 47% over the original fans. Furthermore, a working prototype on a two-speed accessory drive system is designed and fabricated. This accessory drive system allows the alternator to run at the optimum speed when the engine is idling, and switches to lower speeds as the engine speeds increase. With this accessory drive system, the alternator can deliver the desired current output with minimum noise radiation.
A Wave Approach for the Free Vibration Analysis of Axially Loaded, Rotating Timoshenko Shaft Systems
Authors: Tan Chin A. , Kang Bongsu 
Published: January 2022

Abstract
A systematic approach for the free vibration analysis of a rotating Timoshenko shaft system subjected to axial forces is presented in this paper. The system has multiple point discontinuities such as elastic supports, rotor masses, and cross-sectional changes. Wave reflection and transmission matrices are employed to characterize the wave motions between the sub-spans of the shaft system. These matrices are combined with the field transfer matrices expressed in wave forms to obtain the characteristic equation in a straight-forward manner. The solutions are exact since effects of attenuating wave components are included in the formulation. The wave propagation-based matrix algebra leads to recursive algorithms which are suitable for computer coding. Three examples are presented to illustrate the numerical procedure.
Estimating the Probability Distribution of von Mises Stress for Structures Undergoing Random Excitation: Part 2 — Example Calculations
Authors: Segalman Dan , Reese Garth , Field Richard , Fulcher Clay 
Published: January 2022

Abstract
The primary purpose of finite element stress analysis is to estimate the reliability of engineering designs. In structural applications, the von Mises stress due to a given load is often used as the metric for evaluating design margins. For deterministic loads, both static and dynamic, the calculation of von Mises stress is straightforward [2]. For random load environments typically defined in terms of power spectral densities, however, the deterministic theory normally applied to compute RMS acceleration, displacement, or stress tensor responses cannot be applied directly to calculate the probability distribution of von Mises stress, a nonlinear function of the linear stress components. Recently methods have been developed to solve this problem [4]. Those methods and are applied here to an example structure.
Control of Rolling in Ships by Means of Active Fins Governed by a Neural-Network Controller
Authors: Liut Daniel A. , Mook Dean T. , VanLandingham Hugh F. , Nayfeh Ali H. 
Published: January 2022

Abstract
A method to reduce the rolling motion of a ship in a seaway by means of actively controlled fins is described. The method is based on a multidisciplinary simulation: 1) the motion of the ship in a seaway is simulated by a numerical model called LAMP (Large-Amplitude-Motion Program), which is based on a source-panel method to model the flowfield around the ship, 2) the forces on the fins are simulated by a general unsteady vortex-lattice method, and 3) the commands to the fins are generated by a neural network. The ship is considered to be a rigid body and the complete equations of motion are integrated numerically in the time domain so that the motion of the ship and the complete flowfield are calculated simultaneously and interactively. The neural network controlling the fins can be progressively trained by a new moment-matching strategy. The results show substantial reductions in roll.
Active Vibration Control of Smart Composite Beams With Embedded Optical Fiber Sensor and ER Fluid
Authors: Leng Jinsong , Asundi A. , Liu Yanju 
Published: January 2022

Abstract
This paper proposes the use of an fiber optic sensor (FOS) and electrorheological (ER) fluid actuator in the vibration active monitoring of smart composite structures. The intensity modulated fiber optic vibration sensor is developed following the face coupling theory. The characteristics of this optical fiber vibration sensor have been tested. The experimental results show that the new type intensity modulated optical fiber vibration sensor has higher sensitivity to measure the vibration frequency. At same time, our experimental investigations are focused on evaluating the elastodynamic response characteristics of a beam fabricated in an electrorheological fluid. It is noted that the most significant change in the material properties of ER fluid is the change of material stiffness and damping, which varies with the electric field intensity imposed upon ER fluid. Finally, the vibration of smart composite beam with embedded intensity modulated optical fiber vibration sensor and electrorheological fluids can be detected and controlled actively.