Modeling perforates in mufflers using two-ports

One of the main sources of noise of a vehicle is the engine where its noise is usually damped by means of acoustic mufflers. A very common problem in the modeling of automotive mufflers is that of two flow ducts coupled through a perforate. A new segmentation approach is developed here based on two-port analysis techniques, in order to model perforated pipes using general two-port codes, which are widely available. Examples are given for simple muffler configurations and the convergence of the technique is investigated based on the number of segments used. The results are compared with closed form solutions form the literature. Finally, an analysis of a complicated multichamber perforated muffler system is presented. The two-port simulation results show good agreement with both the measurements, and the simulations using the classical four-port elements.

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Closed-Form Solutions for Eigenbuckling of Rectangular Mindlin Plate

International Journal of Structural Stability and Dynamics ◽

10.1142/s0219455415500790 ◽

2016 ◽

Vol 16 (08) ◽

pp. 1550079 ◽

Cited By ~ 6

Author(s):

Yufeng Xing ◽

Wei Xiang

Keyword(s):

Closed Form ◽

Present Method ◽

Separation Of Variables ◽

Mindlin Plate ◽

Rectangular Plates ◽

Closed Form Solutions ◽

Simply Supported ◽

Major Development ◽

First Time ◽

Good Agreement

This paper studies the eigenbuckling of Mindlin plate with two adjacent edges clamped and the remaining edges simply supported or clamped by using the separation of variables method, and the concise and explicit closed-form solutions are obtained for the first time. The cases involving free edges can also be dealt with if there are two opposite edges simply supported. The closed-form solutions are in good agreement with the existing solutions, thus the validity of present method and accuracy of the obtained solutions are verified. This paper proves to be a major development of analytical method since it has long been acknowledged that the eigenbuckling of rectangular plates without two parallel edges simply supported are not amenable to analytical solutions.

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Simulating Univariate and Multivariate Tukey g-and-h Distributions Based on the Method of Percentiles

ISRN Probability and Statistics ◽

10.1155/2014/645823 ◽

2014 ◽

Vol 2014 ◽

pp. 1-10 ◽

Cited By ~ 4

Author(s):

Tzu Chun Kuo ◽

Todd C. Headrick

Keyword(s):

Closed Form ◽

Numerical Integration ◽

Method Of Moments ◽

Data Generation ◽

Shape Parameters ◽

Distribution Fitting ◽

Closed Form Solutions ◽

Nonnormal Distributions ◽

Simulation Results ◽

Family Of Distributions

This paper derives closed-form solutions for the g-and-h shape parameters associated with the Tukey family of distributions based on the method of percentiles (MOP). A proposed MOP univariate procedure is described and compared with the method of moments (MOM) in the context of distribution fitting and estimating skew and kurtosis functions. The MOP methodology is also extended from univariate to multivariate data generation. A procedure is described for simulating nonnormal distributions with specified Spearman correlations. The MOP procedure has an advantage over the MOM because it does not require numerical integration to compute intermediate correlations. Simulation results demonstrate that the proposed MOP procedure is superior to the MOM in terms of distribution fitting, estimation, relative bias, and relative error.

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Bond-Slip Relationship for EB-FRP Joints by Including Free End Slip

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.368-370.1031 ◽

2013 ◽

Vol 368-370 ◽

pp. 1031-1038

Author(s):

Kang Liu

Keyword(s):

Closed Form ◽

Response Curve ◽

Experimental Results ◽

Identification Procedure ◽

Bond Slip ◽

Closed Form Solutions ◽

Theoretical Results ◽

Good Agreement

Closed form solutions are derived in this work by including free end slip, relating free end and loaded end slips to bond resistance, as well as relating slip or strain at any position to free end slip. To identify the bond-slip relationship, indirect analytical identification from load-slip response curve is used. Using the identification procedure developed in this paper, very good agreement between the theoretical solutions and experimental results was observed, which validates the theoretical results derived in this work.

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Modeling Support Loss in Torsional Mode Vibrations of a Micromechanical Disk Resonator with Two L-Shaped Support Beams

Engineering, Technology & Applied Science Research ◽

10.48084/etasr.984 ◽

2017 ◽

Vol 7 (1) ◽

pp. 1353-1357

Author(s):

M. Bagheri ◽

A. Bijari ◽

M. Imanparast ◽

M. Raghebi

Keyword(s):

Closed Form ◽

Quality Factor ◽

Natural Frequencies ◽

Ansys Software ◽

Disk Resonator ◽

Torsional Mode ◽

Form Equation ◽

Simulation Results ◽

Horizontal Support ◽

Good Agreement

In this paper, a new micromechanical disc resonator with two L-shaped horizontal support beams in torsional mode vibrations has been proposed. The proposed micromechanical resonator has been studied in the field of natural frequencies and support loss. In order to verify the findings of natural frequencies, the analytical results are compared to the simulation results given by ANSYS software. A good agreement between analytical and simulation results is shown. In addition a closed-form equation for support loss quality factor in torsional mode vibrations of the proposed micromechanical resonator is presented. The results show that using L-shaped support beams can improve the support loss quality factor up to two times.

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A NEW CLOSED FORM SOLUTION FOR DYNAMIC STABILITY ANALYSIS OF ROLLING AIRFRAMES HAVING ONE PAIR ON-OFF ACTUATOR

Aviation ◽

10.3846/aviation.2021.13832 ◽

2021 ◽

Vol 25 (2) ◽

pp. 92-103

Author(s):

Jalal Karimi

Keyword(s):

Stability Analysis ◽

Closed Form ◽

Dynamic Stability ◽

Linear Theory ◽

Closed Form Solution ◽

Form Solution ◽

Control Surface ◽

Closed Form Solutions ◽

Forcing Term ◽

Simulation Results

In this paper, the dynamic stability analysis of a rolling airframe actuated by one pair ON-OFF actuator using linear theory is presented via developing a new closed form solution. The effect of discontinuous forcing term on rolling airframe stability is studied. In contrast to tricyclic motion with constant forcing term (constant non-homogeneous term) in which only the amplitude of nutation and precession is affected, it is found that ON-OFF control affects both amplitude and phase of nutation and precession motions. In the case of discontinuous control surface, there are two sources for resonance instability. Finally, through simulation results of closed form solutions, a comparison between airframe’ response to ideal and real ON-OFF command is achieved. The effect of ON-OFF control on angular motion is also evaluated.

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Induced drag of wings in ground effect

The Aeronautical Journal ◽

10.1017/aer.2016.106 ◽

2016 ◽

Vol 120 (1234) ◽

pp. 1867-1890 ◽

Cited By ~ 3

Author(s):

P.J. Mantle

Keyword(s):

Aspect Ratio ◽

Closed Form ◽

Original Work ◽

Ground Effect ◽

Air Gap ◽

Closed Form Solutions ◽

End Plate ◽

Induced Drag ◽

Lift And Drag ◽

Good Agreement

ABSTRACTThis paper provides a set of closed form solutions for the lift and drag of wings flying in ground effect both with and without end plates. The developed theories are based on observations of several independent sources of controlled model tests over ground planes and over water and on previous theories prepared by researchers from the original work by Prandtl and Wieselsberger to the present day. The theories developed cover wings of varying aspect ratio, thickness to chord ratios and angle of attack. The results for wings with end plates include the effect of ground (or surface) clearance height, end plate depth and air gap depths beneath the wings or end plates. Good agreement is found between the developed theory and test.

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