Overview of AutoSEA2

2000

Statistical Energy Analysis (SEA) [1-4] has a long history in building acoustics and since the large NASA projects in the early sixties it has been recognised as a worthwhile method. However, it is only recently that it has become generally available through convenient, commercial software. The solutions of the SEA equations for power balance in structures are normally undemanding. Instead, demands on the software are routines for the evaluation of parameters needed for devising these equations. The procedures are generally based on asymptotic formulations for high frequencies and large structures supporting diffuse wave fields, available for a number of generic elements such as beams, thin-walled plates and shells and air volumes. Elements can be coupled at points, along (straight) lines and (plane) surfaces, where the coupling coefficients are normally found from "wave-approach" calculations. Some software has extended these formulations; yet, a major obstacle for the application of SEA to engineering structures is the lack of routines for the evaluation of SEA parameters.

This Phase I report explores the feasibility of using Energy Finite Element Analysis (EFEA) methods for structural acoustic applications. Using both Statistical Energy Analysis (SEA) and experimental results as benchmarks, the steady-state power flow capabilities EFEA software are demonstrated. Results obtained via the power flow finite element approach are generally in good agreement with those obtained elsewhere. Development and implementation of capabilities for predicting reverberant interior and underwater-radiated noise (including machinery- and flow-related) are also discussed. A number of recommendations are outlined concerning further improvements to the EFEA software that would enhance its attractiveness as a provisional tool for EFEA. The ideal implementation would be a hybrid system of EFEA and SEA for the analysis and understanding of ship noise and vibration. The EFEA approach would be appropriate for structureborne energy flow in and around the source, where the vibra...

Structural and Multidisciplinary Optimization, 2018

The main objective of this paper is to perform design sensitivity analysis of two right angle coupled plates, connected by various joint connections, to determine an optimum coupling loss factor (CLF) using optimization in the statistical energy analysis (SEA) framework. The theoretical analysis of obtaining such optimum CLFs can be used during the design stage of a dynamic system to specify the right type of joint. First-and second-order sensitivity analysis using theoretical equations of CLFs of two right angle plates in the SEA framework, coupled to form welded, riveted, and bolted connections, is presented in the audible frequency range. These sensitivities were determined using both analytic (direct differentiation) and finite difference methods; the sensitivities computed by the analytic method agree well with the finite difference method, indicating that the direct differentiation method can be directly used to predict variation in the CLF and the corresponding response of coupled plates joined by various joint connections. The sensitivity analysis also gives a feasible region in terms of frequency range for the determination of optimum values of CLF by selecting the right type of joint at the design stage based on its stiffness. The study presented in this paper will be very useful at the drawing board stage of designing vibro-acoustic systems to reduce vibration or noise of such systems by giving a definite direction for the modification of design parameters, thus eliminating expensive experimentation; it will be helpful in arriving at the optimum values of CLF that would eventually reduce the vibro-acoustic response of dynamic systems with a large number of subsystems connected by welded, riveted, and bolted joints.

Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2019

The Statistical Energy Analysis (SEA) approach has largely been used in vibro-acoustic modelling to predict the averaged energy in coupled vibrating structures and acoustic cavities. The average is performed over an ensemble of nominally identical built-up systems where random responses are observed at high frequencies after excitation. Over the years, this approach has been extended to predict the energy variance employing the statistics of the Gaussian Orthogonal Ensemble, and numerical and experimental evidence has supported the predictions of the mean and variance of energy of coupled vibrating structures. However, little experimental evidence is found to validate the prediction of the variance of energy in coupled structural-acoustic systems. In this work, the mean and variance of energies predicted from a statistical energy analysis model have been validated with experimental measurements on a structural-acoustic system, comprised by a flat thin plate coupled to an enclosed ac...

Proc IMechE Part C: J Mechanical Engineering Science, 2016

In industries, the use of appropriate junctions between components is of paramount interest. Coupling loss factor is one of the important parameters in statistical energy analysis for vibroacoustic analysis of complicated structures in drawing board stage. The values of coupling loss factor were calculated and compared for different junctions. The screwed and bolted junctions were examined for thin rectangular plates of same size. The energy level difference method was used to find coupling loss factors because of its simplicity. These experimentally found coupling loss factors were later compared with analytical solutions. It is noticed that the analytical results are in good agreement with experimental results. It is also observed that coupling loss factor for bolted junction are relatively high than that for screwed junction.

Most of the currently available numerical prediction techniques for the analysis of steady-state dynamic vibro-acoustic problems can be classified as being either deterministic or statistical approaches. The Finite Element Method (FEM), the most popular deterministic technique, is limited to the low-frequency range due to its sensitivity to interpolation and pollution errors. The statistical methods, of which the Statistical Energy Analysis (SEA) is most know, are limited to the high-frequency range due to their underlying assumptions. Between the low-and high-frequency ranges there is a relatively wide mid-frequency-range, in which some of the structural subsystems fulfill the requirements for the statistical approach and some others do not (yet). Recently, a hybrid deterministic-statistical framework which combines FE and SEA models has been developed by Shorter and Langley. However, the computational load associated with the FE models still limits the use of this method. In this ...

Sound And Vibration, 2005

Journal of Sound and Vibration, 1995

An efficient method is presented for the prediction of structure-borne sound transmission in large welded ship structures. SEA (Statistical Energy Analysis) is used, and the equations used for the SEA parameters are also presented. Traditionally, the SEA method requires a great deal of work when steel structures are modelled. It is almost impossible to prepare models manually for large structures

2018

This is a Master´s Thesis written at the Geophysical Institute at the University of Bergen. The work represents the end of a Master in Renewable Energy. The aim of this project has been to develop a tool and a method for ship energy analysis including emissions, efficiency and costs. The complexity of the tool made it necessary to cooperate with several sponsors and partners. Researcher Tjalve Magnusson Svendsen from Prototech AS has been the man supervisor for the student through the project. The results are a product of a close cooperation between the student and Mr. Svendsen. The student is grateful for all the help provided, and for the understanding and advises given through the two semesters. Without Mr. Svendsen the result would not have been what it is. Many thanks to Tjalve Magnusson Svendsen and Prototech AS. Professor Peter M. Haugan from Geophysical Institute has been supporting the project as a cosupervisor through the two semesters. Peter has been a supportive contributor for the results presented. Mr. Haugan has also been very helpful in arranging the study trip to Tokyo and giving advises in report writing. Without Mr. Haugan the result would not have been what it is. Many thanks to Peter M. Haugan. R&D Manager Kristian Voksøy Steinsvik from Havyard Design & Solutions AS has been supporting the project as the second co-supervisor. The student had the pleasure of spending several periods in Havyard´s offices to cooperate with Havyard to develop the tool. Mr. Steinsvik has also been a key partner in developing the method used in the tool by advises and support. Without Mr. Steinsvik the result would not have been what it is. Many thanks to Kristian Voksøy Steinsvik. The University of Bergen has provided help, support and advises for the project since the beginning. Several professors, scientists and engineers currently working for the Geophysical institute has been willing to answer question, share knowhow and give advises to the student. Senior Executive Officer Elisabeth Aase Saether has been very helpful during the two years at the university. The student is really grateful for the two years he has been student at the Geophysical Institute at the University of Bergen. The BKK-UiB cooperation has supported the project with 50 000 NOK. Without these funds, much of the work in this master´s thesis would not have been possible. In addition to the 50 000 NOK from the BKK-UiB cooperation, Hordaland County Council has supported the project with 9000 NOK. The student is very grateful for the funds granted from these two contributors. Havyard Design & Solution AS has also been supporting the project with advisors, data, technical equipment and funds for travelling. Many thanks to the management in Havyard Design & Solutions AS for all help and support during these two semesters. Norsk Fisketransport AS allowed the student to spend 10 days onboard the Live Fish Carrier NFT Steigen. The generosity of Norsk Fisketransport AS and the excellence and hospitality of the crew on board NFT Steigen helped the student improve the method and the tool. It was 10 educational days in good company. A special thanks to Captain Kent Sjåvik for being service minded, hospitable and willing to answer questions. Lars Kolle, author of the book "Håndbok for prosjektering av brennstofføkonomisk fartøy" donated the student a copy of the book. Many thanks to Mr. Kolle for his generousity. Assistant Professor Svein Anond Anondsen donated the book "SIN 0501-Marin Teknikk 1", which played an important role in the ship design part of the tool. Many thankts to Mr.

Journal of The Brazilian Society of Mechanical Sciences and Engineering, 2003

The coupling loss factors are of critical importance when building and solving Statistical Energy Analysis (SEA) models. This paper proposes a methodology to numerically estimate these factors for frame-type structures. The estimated factors are compared with those obtained through analytical expressions for frame structures, where members are joined at right angles. The example used to verify the proposed technique consists of two infinite beams connected at a right angle modeled via the Spectral Element Method (SEM) using throw-off elements. It is shown that the obtained coupling loss factors compare very well with the analytical expressions that may be derived for this simple right-angle connection case. By using the SEM approach, the coupling loss factors can be obtained for arbitrary frame structure connections, thus facilitating the analysis via SEA.