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.

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.

Mechanical Power Flow Between Stiffened Plates and Viscoelastic Discrete Systems

1986 ◽  
Vol 108 (2) ◽  
pp. 155-164 ◽  
Author(s):  
E. Goldfracht ◽  
G. Rosenhouse
Keyword(s):  
Power Flow ◽  
Energy Analysis ◽  
Power Transmission ◽  
Discrete Systems ◽  
Vibration Energy ◽  
Stiffened Plates ◽  
Statistical Energy Analysis ◽  
Frequency Range ◽  
Lower Frequency Range ◽  
Fundamental Theorems

In this paper we primarily discuss a theory of power transmission and vibration energy distribution of dynamically loaded structures. The loads are random and the system comprises linked elements, which consist of machine-supported stiffened plates. Fundamentally, the theory is deterministic, but in addition it uses some features of the SEA. In fact, the analysis is intended to verify fundamental theorems of the Statistical Energy Analysis in the lower frequency range.

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.

Prediction on Coincidence Effect of Sound Insulation of a Wall

2011 ◽  
Vol 99-100 ◽  
pp. 354-357
Author(s):  
Xian Feng Huang ◽  
Jun Liu ◽  
Yan Yang
Keyword(s):  
Building Materials ◽  
Energy Analysis ◽  
Sound Insulation ◽  
Light Weight ◽  
Statistical Energy Analysis ◽  
Frequency Range ◽  
Single Leaf ◽  
Comparison Results ◽  
Coincidence Effect ◽  
Sound Environment

Coincidence effect which occurs in a certain frequency range will impairs the sound insulation of walls. For the purpose to predict the phenomenon of coincidence effect that is unlikely predicted theoretically by the mass law, the Statistical Energy Analysis (SEA) theory are adopted in studying coincidence effect of sound insulation of the light weight single-leaf wall. The comparison among predicted by SEA, by mass law and measured was performed. Therefore, the comparison results show that sound insulation prediction by SEA is more precise and agrees with the measured date. Moreover, the coincidence effect and its effect on sound insulation were predicted by SEA. Eventually, it is likely to select appropriate building materials and configuration to achieve a better sound environment theoretically.

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.

scholarly journals Study on Noise Prediction and Reduction in Coupled Workshops Using SEA Method

2011 ◽  
Vol 2011 ◽  
pp. 1-8
Author(s):  
Ye Lei ◽  
Jie Pan ◽  
Meiping Sheng
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Noise Reduction ◽  
Reasonable Agreement ◽  
Energy Analysis ◽  
Noise Prediction ◽  
Statistical Energy Analysis ◽  
Sound Energy ◽  
Significant Element

A theoretical model for predicting noise reduction in coupled workshops is presented by using statistical energy analysis (SEA) method. An opening between the coupled workshops is considered into the theoretical model properly. The leakage issue is dealt with in the process of SEA modeling. An experiment is also carried out. A reasonable agreement between the prediction of noise reduction and the experimental data is observed. Moreover, it is concluded from the simulations that the sound energy transmit through the opening was the most important way to affect the noise reduction and the leakage is a significant element to influence the effect of noise treatment.

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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