A hybrid method for broadband vibroacoustic simulations

2021 ◽  
Vol 263 (4) ◽  
pp. 2812-2821
Author(s):  
Jared Miller ◽  
Scott D. Sommerfeldt ◽  
Jonathan D. Blotter ◽  
David C. Copley
Keyword(s):  
Hybrid Method ◽  
High Frequency ◽  
Low Frequency ◽  
Energy Response ◽  
High Frequency Response ◽  
Modal Response ◽  
Listening Tests ◽  
Limited Frequency ◽  
Acoustic Responses ◽  
Vibrating Systems

Many methods for simulating acoustic responses of vibrating systems are only suitable for limited frequency ranges, providing either an accurate low frequency or high frequency response. A hybrid method is presented to combine a low frequency modal response and a high frequency statistical energy response to obtain a unified broadband response. The method is designed to produce an auralizable response. An experimental setup is used to validate the method. Listening tests are conducted to assess the realism of the auralizations compared to measurements. The listening tests confirm that the method is able to produce realistic auralizations, subject to a few limitations.

Prediction of High Frequency Sonic Boom Noise Transmission Into Buildings Using a Hybrid Analytical-Ray Tracing Approach

2012 ◽  
Author(s):  
Joseph M. Corcoran ◽  
Marcel C. Remillieux ◽  
Ricardo A. Burdisso
Keyword(s):  
Ray Tracing ◽  
High Frequency ◽  
Acoustic Radiation ◽  
Low Frequency ◽  
Sonic Boom ◽  
Acoustic Transmission ◽  
Frequency Method ◽  
Low Frequencies ◽  
Sonic Booms ◽  
Acoustic Responses

As part of the effort to renew commercial supersonic flight, a predictive numerical tool to compute sonic boom transmission into buildings is under development. Due to the computational limitations of typical numerical methods used at low frequencies (e.g. Finite Element Method), it is necessary to develop a separate approach for the calculation of acoustic transmission and interior radiation at high frequencies. The high frequency approach can then later be combined with a low frequency method to obtain full frequency vibro-acoustic responses of buildings. An analytical method used for the computation of high frequency acoustic transmission through typical building partitions is presented in this paper. Each partition is taken in isolation and assumed to be infinite in dimension. Using the fact that a sonic boom generated far from the structure will approximate plane wave incidence, efficient analytical solutions for the vibration and acoustic radiation of different types of partitions are developed. This is linked to a commercial ray tracing code to compute the high frequency interior acoustic response and for auralization of transmitted sonic booms. Acoustic and vibration results of this high frequency tool are compared to experimental data for a few example cases demonstrating its efficiency and accuracy.

A Study of the Response of a Small Porous Chamber to Forced Oscillation

1966 ◽  
Vol 88 (1) ◽  
pp. 25-32
Author(s):  
R. L. Peskin ◽  
E. Martinez
Keyword(s):  
Phase Angle ◽  
High Frequency ◽  
Gas Flow ◽  
Low Frequency ◽  
Pressure Change ◽  
Analytical Investigation ◽  
Frequency Curve ◽  
Cylindrical Chamber ◽  
Gas Damping ◽  
Vibrating Systems

An analytical investigation of the pressure response to forced volume oscillations of a shallow cylindrical chamber with a porous end is undertaken. Investigation is in the frequency domain. Both infinite and finite-length chambers are considered. The irreversible gas flow introduces a frequency-dependent phase angle between volume and pressure change. Pressure leads volume at low frequency, and the phase angle becomes zero at high frequency. Curve characteristics suggest applications such as gas damping of vibrating systems.

FREQUENCY-TUNABLE DUAL-BAND PRINTED ANTENNA EQUIPPED WITH COAXIALSPLIT BALANCING UNIT

2019 ◽  
pp. 60-64
Author(s):  
S. A. Alekseytsev ◽  
A. P. Gorbachev
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Dipole Antenna ◽  
Dual Band ◽  
Radiation Characteristics ◽  
High Frequency Response ◽  
Maximum Value ◽  
Linear Behavior ◽  
Lumped Elements ◽  
Frequency Tunable

In this paper, we present initial design of dual-band dipole antenna which able to perform when shifting high frequency band by inserting of inductive element between high-, and low-frequency dipole arms. Responses of high frequency and bandwidth at –10 dB level on the inductivity are presented in the paper. The maximum value of inductivity to be inserted is about hundreds of nH, hence, it can be implemented by microstrip lines. It is also possible to use lumped elements. Approximations of such responses with polynomials power two and lower are presented in the paper. It is shown, that the bandwidth of the S11 below –10 dB high frequency response has approximately linear behavior, so that can be used when carrying out experimental verifying of the numerical simulations. When simulating radiation characteristics the Russian standard FAF‑4D substrate was used, which can operate at frequencies up to 8–10 GHz.

Nonlinear behaviour of the Mack mode in a hypersonic boundary layer

2019 ◽  
Vol 872 ◽  
pp. 74-99 ◽  
Author(s):  
Stuart A. Craig ◽  
Raymond A. Humble ◽  
Jerrod W. Hofferth ◽  
William S. Saric
Keyword(s):  
Boundary Layer ◽  
High Frequency ◽  
Low Frequency ◽  
Nonlinear Behaviour ◽  
Hypersonic Boundary Layer ◽  
Bispectral Analysis ◽  
Frequency Wave ◽  
Number Range ◽  
High Frequency Response ◽  
Quadratic Phase

Mack-mode waves are measured in a hypersonic boundary layer using high-frequency focusing schlieren deflectometry. Experiments are performed using a $5^{\circ }$ flared cone at $0^{\circ }$ angle of attack in the low-disturbance Mach 6 Quiet Tunnel at Texas A&M University across a free-stream unit Reynolds number range of $7.8\times 10^{6}~\text{m}^{-1}\leqslant \mathit{Re}^{\prime }\leqslant 11.0\times 10^{6}~\text{m}^{-1}$. The high-frequency response of the measurement system allows harmonics and other nonlinear behaviour to be measured. Mack-mode waves and several harmonics are clearly observed at a frequency of $f_{0}\approx 250~\text{kHz}$. Bispectral analysis is used to show that these waves undergo several quadratic phase-coupled sum and difference interactions with themselves to produce harmonics, as well interact with a relatively low-frequency wave that results in amplitude modulation. Bispectral analysis is used to highlight these interactions.

scholarly journals A Review of the Research and Development of High-Frequency Measurement Technologies Used for Nonlinear Dynamics of Drillstring

2021 ◽  
Vol 2021 ◽  
pp. 1-27
Author(s):  
Lixin Li ◽  
Jin Wang ◽  
Yingmei Yu ◽  
Yifei Xing ◽  
Fengyan Zhang ◽  
...  
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Frequency Measurement ◽  
Research Perspective ◽  
Frequency Measurements ◽  
High Frequency Response ◽  
Lithology Identification ◽  
New Findings ◽  
High Efficient ◽  
Drilling Cost

High-frequency measurements can provide much more new insights for drillstring dynamics compared to traditional instruments, leading to a new realm of understanding of drillstring behaviors in great detail than before. In this paper, data acquisition tools with high-frequency sample rates and the data processing are introduced. Based on high-frequency data, progress of drilling dynamics is summarized, including new understandings of low-frequency drillstring dynamics, high-frequency torsional oscillations (HFTOs), and high-frequency axial oscillations (HFAOs) and new findings for the coupling of vibrations and motions, as well as models and simulation methods to deeply comprehend high-frequency dynamics of drillstring. High-frequency measurements have been used for enabling drillers to improve drill performance, especially for field decision making, BHA selection, and bit design, usually through the ways of minimizing vibrations to obtain high-efficient drilling conditions, the high-frequency response near bit can also be used for lithology identification during drilling. Though there still exists a gap between research perspective and drilling practice, the industry of high-frequency measurements has gotten off a good start, which has huge potential to avoid nonproductive time thereupon reducing drilling cost in the future.

Vibration Mitigation With a Multi-Axial Magnetorheological Mount

2009 ◽  
Author(s):  
Walter Anderson ◽  
The Nguyen ◽  
Mohammad Elahinia
Keyword(s):  
Frequency Response ◽  
High Frequency ◽  
Low Frequency ◽  
Hybrid Vehicles ◽  
Experimental Results ◽  
Small Displacement ◽  
Frequency Range ◽  
Mr Fluid ◽  
High Frequency Response ◽  
Hydraulic Hybrid

This paper presents a multi-axial magnetorheological (MMR) mount. An MMR mount has been developed for use with hydraulic hybrid vehicles (HHV). Like hybrid electric vehicles (HEV), HHV provides better fuel economy. An inherent problem to hydraulic hybrid vehicles is vibration of the hydraulic pump-motor (P/M). This vibration can be classified as shock loading for initial start-up, and periodic vibration over a large frequency range. The latter vibration opportunity can be classified as having large displacement at low frequency and small displacement at high frequency. This requires a stiff mount for the low frequency response and a soft mount for the high frequency response. A single axis magnetorheological (MR) mount has previously been developed and studied by the same group. This was done to develop an understanding of the MR fluid and to discover the limitations of such a mount. Models to predict the experimental results have also been generated. These models show a good correlation to the experimental results. Then, the model has been enhanced from the single axis mount to a multi-axial. This was done by examining the 3-D CAD model to develop the different boundary conditions for the simulation. With a multi-axial magnetorheological mount, damping and stiffness can be altered to yield acceptable transmissibility over the frequency range. This is achieved through the use of an inertia track paired with a pseudo-decoupler. These features are commonly found in a passive hydraulic mount; however through the use of MR fluid, the downfalls of the hydraulic mount can be mitigated, e.g. performance deterioration outside of notch frequency. Additionally, a magnetorheological mount is semi-active so there is an inherent stability to the mount. The MMR mount uses elastomer and MR fluid to achieve the static stiffness to support the P/M and achieve low dynamic stiffness for the high frequency response, which is necessary for a good isolator. The advantages of the use of a multi-axial magnetorheological mount are as follows: fewer mounts are required, stability when compared to an active mount, less power required when compared to an active mount, better isolation when compared to pure elastomeric and passive hydraulic mounts. A model for a multi-axial magnetorheological mount has been developed and simulated. For the purposes of this study, elastomer has been considered to have a linear dynamic response. Additionally, the shock response of the mount has not been considered. Future work includes manufacturing a multi-axial MR mount to verify the simulation results.

scholarly journals Modal Analysis of a Small Smooth Kart Tire - Numerical and Experimental Determination

2018 ◽  
Vol 23 (No 3, September 2018) ◽  
pp. 362-369
Keyword(s):  
Finite Element ◽  
Frequency Response ◽  
Modal Analysis ◽  
High Frequency ◽  
Experimental Testing ◽  
Contact Problems ◽  
Explicit Finite Element ◽  
High Frequency Response ◽  
Modal Response ◽  
Testing Frequency

The modal analysis of a kart tire was performed using the Abaqus/explicit finite element numerical software and the results obtained were validated by experimental testing. Frequency response functions, damping ratios, and modal shapes are the driving parameters for analysis. The investigation shows a very useful modal response of the kart tire such that a high frequency response function of approximately 301 Hz to 630 Hz was obtained for both the finite element solutions and experimental results. These results are much higher than that of the conventional tires therefore making it an excellent tire-type material that can be used for further analysis and study of tire-road contact problems, air-pumping, and noise radiation.

scholarly journals A hybrid method for vibroacoustic coupling

2008 ◽  
pp. 689-699
Author(s):  
Emeline Sadoulet-Reboul ◽  
Alain Le Bot ◽  
Joël Perret-Liaudet
Keyword(s):  
Radiative Transfer ◽  
Hybrid Method ◽  
High Frequency ◽  
Low Frequency ◽  
Energy Sources ◽  
High Frequency Range ◽  
Engine Compartment ◽  
Frequency Range ◽  
Transfer Method

hybrid method is proposed to study the noise radiated in the high frequency range by a gearbox inside an engine compartment. Due to its elastodynamic characteristics, the vibratory behaviour of the transmission lies in the low frequency range. However, the noise radiated is rather in the high frequency range facing the size of the acoustical cavity. Thus the proposed hybrid method allows to couple a low-frequency vibratory approach to the radiative transfer method used for the high frequency acoustical calculation. The coupling is realized through equivalent energy sources introduced on the surface of the vibrating structure.

Simulations of high-resolution images of amorphous silicon films

1986 ◽  
Vol 44 ◽  
pp. 544-545
Author(s):  
G. Y. Fan ◽  
J. M. Cowley
Keyword(s):  
Electron Microscope ◽  
High Frequency ◽  
Fourier Transformation ◽  
Amorphous Materials ◽  
Low Frequency ◽  
Chromatic Aberration ◽  
Structure Information ◽  
Frequency Components ◽  
High Resolution Images ◽  
Spatial Frequency Spectrum

It is well known that the structure information on the specimen is not always faithfully transferred through the electron microscope. Firstly, the spatial frequency spectrum is modulated by the transfer function (TF) at the focal plane. Secondly, the spectrum suffers high frequency cut-off by the aperture (or effectively damping terms such as chromatic aberration). While these do not have essential effect on imaging crystal periodicity as long as the low order Bragg spots are inside the aperture, although the contrast may be reversed, they may change the appearance of images of amorphous materials completely. Because the spectrum of amorphous materials is continuous, modulation of it emphasizes some components while weakening others. Especially the cut-off of high frequency components, which contribute to amorphous image just as strongly as low frequency components can have a fundamental effect. This can be illustrated through computer simulation. Imaging of a whitenoise object with an electron microscope without TF limitation gives Fig. 1a, which is obtained by Fourier transformation of a constant amplitude combined with random phases generated by computer.

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