The Effect of Direct Field Component on a Statistical Energy Analysis (SEA) Model

2013 ◽  
Vol 471 ◽  
pp. 279-284 ◽  
Author(s):  
Azma Putra ◽  
Al Munawir ◽  
W.M.F.W. Mohamad ◽  
J.I. Mohammad
Keyword(s):  
Field Component ◽  
Energy Analysis ◽  
Complex Structure ◽  
Sound Field ◽  
Injection Technique ◽  
Statistical Energy Analysis ◽  
Coupling Loss ◽  
Model Assumption ◽  
Power Injection ◽  
Acoustic Space

Statistical Energy Analysis (SEA) is a well-known method to analyze the flow of acoustic and vibration energy in a complex structure. The structure is divided into subsystems where the energy in each of the subsystem is assumed to be reverberant. This study investigates the application of SEA model in a 'damped' acoustic space where the direct field component from the sound source dominates the total sound field rather than a diffuse field in a reverberant space which the SEA model assumption is based on. A measurement was conducted in a scaled room divided into two acoustic spaces separated by a partition with an opening. Absorbent materials were installed on the room walls and the power injection technique was implemented to obtain the coupling loss factor (CLF) of the system. It is found that correction of the direct field component from the subsystem energy improves the prediction of the CLF of the system.

scholarly journals Pengaruh dari Direct Field Component pada Ruang Akustik dengan menggunakan SEA Model

2019 ◽  
Vol 5 (2) ◽  
Author(s):  
Al Munawir ◽  
Herri Darsan ◽  
Murhaban Murhaban
Keyword(s):  
Field Component ◽  
Model Comparison ◽  
Energy Analysis ◽  
Complex Structure ◽  
Sound Field ◽  
Coupling Loss ◽  
Model Assumption ◽  
Reflection Measurement ◽  
Acoustic Space ◽  
Good Agreement

Statistical Energy Analysis (SEA) is a well-known method to analyze the flow of acoustic and vibration energy in a complex structure. This study investigates the application of the corrected SEA model in a non-reverberant acoustic space where the direct  field component from the sound source dominates  the total  sound  field rather than  a diffuse field in a reverberant space which the  classical SEA model assumption is based on. A corrected SEA model is proposed where the direct field component in the energy is removed and the power injected in the subsystem considers only the remaining power after the loss at first reflection.  Measurement is conducted a box divided into two rooms separated by a partition with an opening where the condition of reverberant and non-reverberant can conveniently be controlled. In the case of a non-reverberant space where acoustic material was installed inside the wall of the experimental box, the signals are corrected by eliminating the direct field component in the measured impulse response. Using the corrected SEA model, comparison of the coupling loss factor (CLF) with the theory shows good agreement.

Effect of junction type on the vibroacoustic response of a system of plates

2021 ◽  
Vol 263 (2) ◽  
pp. 3953-3962
Author(s):  
Marcell Treszkai ◽  
Daniel Feszty
Keyword(s):  
Experimental Data ◽  
Energy Analysis ◽  
Steel Plates ◽  
Statistical Energy Analysis ◽  
Coupling Loss ◽  
Frequency Range ◽  
Reference Case ◽  
Power Injection ◽  
Challenging Tasks ◽  
Junction Type

Modelling of junctions is one of the most challenging tasks in vibroacoustics, especially for Statistical Energy Analysis (SEA), where the results heavily depend on the damping (DLF) and coupling loss factors (CLF). Also, it is an interesting question to determine that to what extent does the DLF or CLF contribute to the overall vibroacoustic characteristics of a structure? The aim of this paper is to investigate via measurements and SEA simulations the effect of the ratio of DLF and CLF on the response of a system for various junctions, such as riveting, bolting, line and point welding, between two steel plates. Loss matrices are determined experimentally by the Power Injection Method in the 200-1600 Hz frequency range. The simulation was performed in the ESI VA One software by using its analytical CLF formulations and compared to experimental data. For the reference case, a bended plate structure was considered, representing an ideal junction between two subsystems. This was equipped with damping foils to ensure the same weight and then compared to the results from other joints. Results showed that increasing the CLF could be more effective than focusing on increasing the DLF.

Prediction of Transient Vibration Envelopes Using Statistical Energy Analysis Techniques

1990 ◽  
Vol 112 (1) ◽  
pp. 127-137 ◽  
Author(s):  
M. L. Lai ◽  
A. Soom
Keyword(s):  
Loss Factor ◽  
Energy Analysis ◽  
A Priori ◽  
Coupled Systems ◽  
Time Varying ◽  
Statistical Energy Analysis ◽  
Coupling Loss ◽  
Transient Vibration ◽  
Coupled Plates ◽  
Coupling Loss Factor

The prediction, by the statistical energy analysis (SEA) method, of transient vibration envelopes for coupled systems is investigated. The relation between the time-varying energy transferred between two coupled subsystems and time-varying energies of the subsystems is studied numerically and experimentally. These studies indicate that time-varying energy transmitted between two subsystems is related to the subsystem energies by an apparent time-varying coupling loss factor. It is shown that the apparent coupling loss factor approaches the asymptotic (or steady-state) coupling loss factor as response energies and transferred energies are integrated over progressively larger times. Both the apparent time-varying coupling loss factor and the asymptotic coupling loss factor, determined experimentally, are used in energy balance equations to predict the time-varying vibration envelopes of a system of two point-coupled plates and the results are compared. Although overall response predictions are similar, considerable differences are noted in individual frequency bands. However, no general method for a priori determination of the apparent time-varying coupling loss factor is suggested.

Formulation of SEA parameters using mobility functions

1994 ◽  
Vol 346 (1681) ◽  
pp. 477-488 ◽  
Keyword(s):  
Dynamic Systems ◽  
Energy Analysis ◽  
Statistical Energy Analysis ◽  
Coupling Loss ◽  
Coupled Subsystems ◽  
Power Inputs ◽  
Complex Structural ◽  
General Mobility ◽  
Power And Energy ◽  
Loss Factors

Statistical energy analysis SEA formulates the dynamic response of a system in terms of power and energy variables. The SEA parameters include power inputs; damping loss factors; which control the power dissipated within the system; and coupling loss factors, which control the power transmitted between coupled subsystems. One of the great difficulties in using SEA is the calculation of these parameters. In this paper sea parameters are formulated using general mobility functions. Simplifications that result from averaging the parameters either over frequency or over an ensemble of dynamic systems are presented. These simplifications make it possible to apply SEA to very complex structural-acoustic systems.

scholarly journals Coupling strength assumption in statistical energy analysis

2017 ◽  
Vol 473 (2200) ◽  
pp. 20160927 ◽  
Author(s):  
T. Lafont ◽  
N. Totaro ◽  
A. Le Bot
Keyword(s):  
Coupling Strength ◽  
Energy Flow ◽  
Energy Analysis ◽  
Flow Direction ◽  
Statistical Energy Analysis ◽  
Coupling Loss ◽  
Indirect Coupling ◽  
Random Forces ◽  
Statistical Ensembles ◽  
Coupled Plates

This paper is a discussion of the hypothesis of weak coupling in statistical energy analysis (SEA). The examples of coupled oscillators and statistical ensembles of coupled plates excited by broadband random forces are discussed. In each case, a reference calculation is compared with the SEA calculation. First, it is shown that the main SEA relation, the coupling power proportionality, is always valid for two oscillators irrespective of the coupling strength. But the case of three subsystems, consisting of oscillators or ensembles of plates, indicates that the coupling power proportionality fails when the coupling is strong. Strong coupling leads to non-zero indirect coupling loss factors and, sometimes, even to a reversal of the energy flow direction from low to high vibrational temperature.

Inter-Modal Couplings between Two Sea Subsystems with an Arbitrary Interface

2011 ◽  
Vol 130-134 ◽  
pp. 824-828
Author(s):  
Lin Ji ◽  
Zhen Yu Huang
Keyword(s):  
Energy Analysis ◽  
Simple Technique ◽  
Dynamic Stiffness ◽  
Statistical Energy Analysis ◽  
Coupling Loss ◽  
Simple Manner ◽  
Modal Density ◽  
Modal Coupling ◽  
Coupling Stiffness ◽  
High Modal Density

A simple technique is introduced to estimate the inter-modal coupling relations of two Statistical Energy Analysis (SEA) subsystems connected via an arbitrary interface. Based on a subsystem modal approach, the dynamic stiffness matrix of a generic built-up system is derived analytically. The coupling stiffness terms between any pair of subsystem modes can then be determined in explicit expressions. Under the proper SEA conditions, e.g. each subsystem has a high modal density and the couplings between SEA subsystems are sufficiently weak, these inter-modal coupling stiffness expressions can be greatly simplified. The results can then be easily accommodated within the standard SEA modeling procedure to predict the SEA response of generic built-up systems in a simple manner. Theoretical applications are made to estimate the SEA coupling loss factors between two subsystems connected by two rigid points.

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