scholarly journals HYDROELASTIC RESPONSE ANALYSIS OF IRREGULAR-SHAPED LARGE FLOATING STRUCTURES USING BOUNDARY ELEMENT-FINITE ELEMENT HYBRID MODEL

2002 ◽  
Vol 67 (555) ◽  
pp. 201-208 ◽  
Author(s):  
Takuji HAMAMOTO ◽  
Kenichi FUJITA
Keyword(s):  
Finite Element ◽  
Boundary Element ◽  
Hybrid Model ◽  
Response Analysis ◽  
Floating Structures ◽  
Hydroelastic Response

scholarly journals A Coupled Smoothed Finite Element-Boundary Element Method for Structural-Acoustic Analysis of Shell

2017 ◽  
Vol 42 (1) ◽  
pp. 49-59 ◽  
Author(s):  
Wanyi Tian ◽  
Lingyun Yao ◽  
Li Li
Keyword(s):  
Finite Element ◽  
Boundary Element Method ◽  
Frequency Response ◽  
Boundary Element ◽  
Acoustic Analysis ◽  
Response Analysis ◽  
Frequency Response Analysis ◽  
Acoustic Problem ◽  
Element Boundary ◽  
Element Method

Abstract Nowadays, the finite element method (FEM) - boundary element method (BEM) is used to predict the performance of structural-acoustic problem, i.e. the frequency response analysis, modal analysis. The accuracy of conventional FEM/BEM for structural-acoustic problems strongly depends on the size of the mesh, element quality, etc. As element size gets greater and distortion gets severer, the deviation of high frequency problem is also clear. In order to improve the accuracy of structural-acoustic problem, a smoothed finite-element/boundary-element coupling procedure (SFEM/BEM) is extended to analyze the structural-acoustic problem consisting of a shell structure interacting with the cavity in this paper, in which the SFEM and boundary element method (BEM) models are used to simulate the structure and the fluid, respectively. The governing equations of the structural-acoustic problems are established by coupling the SFEM for the structure and the BEM for the fluid. The solutions of SFEM are often found to be much more accurate than those of the FEM model. Based on its attractive features, it was decided in the present work to extend SFEM further for use in structural-acoustic analysis by coupling it with BEM, the present SFEM/BEM is implemented to predict the vehicle structure-acoustic frequency response analysis, and two numerical experiments results show that the present method can provide more accurate results compared with the standard FEM/BEM using the same mesh. It indicates that the present SFEM/BEM can be widely applied to solving many engineering noise, vibration and harshness (NVH) problems with more accurate solutions.

Hydrodynamic Behavior of Truss Pontoon Mobile Offshore Base Platform

2016 ◽  
Author(s):  
Somansundar Sakthivel ◽  
Panneer Selvam Rajamanickam ◽  
Nagan Srinivasan
Keyword(s):  
Bending Moment ◽  
Offshore Structures ◽  
Elastic Behavior ◽  
Response Analysis ◽  
Vertical Acceleration ◽  
Floating Structures ◽  
Operational Conditions ◽  
Box Structure ◽  
Mobile Offshore Base ◽  
Hydroelastic Response

Very Large Floating Structures (VLFS) are highly specialized floating structures with variety of applications ranging from airport strips to floating motels offshore ports etc. Their economic design is based on their hydro-elastic behavior due to wave environmental forces. VLFS are extra large in size and mostly extra long in span and for that reason they are mostly modularized into several smaller structures and integrated. VLFSs may be classified into two broad categories, namely the semi-submersible type and the pontoon-type. The former type of VLFSs having their platform raised above the sea level and supported by columns resting on submerged pontoons and can minimize the effects of wave actions. In open sea, where the wave heights are relatively large, the semi-submersible VLFSs are preferred. On the other hand, the pontoon-type VLFS is a simple flat box structure floating on the sea surface. It is very flexible compared to other kinds of offshore structures, and so its elastic deformations are more important than their rigid body motions. The critical problem is the longitudinal bending moment of the long floating vessel in waves/current environment. Most of the present available VLFS designs are not economical for applications in hostile ocean. This paper presents hydrodynamic analysis carried out on an innovative VLFS called truss pontoon Mobile Offshore Base (MOB) platform concept proposed by Srinivasan [1]. The concept uses a strong deck with strong longitudinal beams to take care of the needed bending moment of the vessel for the survival, standby and operational conditions of the wave. At the submerged bottom just above the keel-tank top, a simple open-frame truss-structure is used instead of a heavy shell type pontoon. Thus the truss-pontoon provides the necessary flow transparency for the reduction of the wave exciting forces and consequently the heave motions and the vertical acceleration. Numerical analysis of truss pontoon MOB platform is carried out using HYDroelastic Response ANalysis (HYDRAN). Responses of the isolated scaled module in waves are obtained from these numerical tools and compared with published literature. Unconnected two modules and three modules are analysed using HYDRAN and the responses are compared with the isolated module. The proposed concept yielded lesser responses as compared to semisubmersible conventional MOB platform.

scholarly journals Design Optimization for Structural-Acoustic Problems Using FEM-BEM

2002 ◽  
Author(s):  
Kyung K. Choi ◽  
Jun Dong ◽  
Nam Ho Kim
Keyword(s):  
Finite Element ◽  
Design Optimization ◽  
Boundary Element ◽  
Noise Level ◽  
Optimization Problems ◽  
Design Sensitivity ◽  
Response Analysis ◽  
Element Analysis ◽  
Structural Dynamic ◽  
Structural Part

A structural-acoustic design optimization of a vehicle is presented using finite element and boundary element analyses. The steady-state dynamic behavior of the vehicle is calculated from the finite element frequency response analysis, while the sound pressure level within the acoustic cavity is calculated using the boundary element analysis. A reverse solution procedure is employed for the design sensitivity calculation using the adjoint variable method. An adjoint load is obtained from the acoustic boundary element re-analysis, while the adjoint solution is calculated from the structural dynamic re-analysis. The evaluation of pressure sensitivity only involves a numerical integration process for the structural part. Two design optimization problems are formulated and solved. It has been shown that the structural weight is saved when the noise level is maintained, and the weight needs to increase in order to reduce the noise level in the passenger compartment.

Application of the Boundary Element Method and Modal Analysis to Tire Acoustics Problems

1993 ◽  
Vol 21 (2) ◽  
pp. 66-90 ◽  
Author(s):  
Y. Nakajima ◽  
Y. Inoue ◽  
H. Ogawa
Keyword(s):  
Finite Element ◽  
Boundary Element Method ◽  
Boundary Element ◽  
Acoustic Radiation ◽  
Traffic Noise ◽  
Noise Prediction ◽  
Prediction System ◽  
Tire Noise ◽  
Acoustic Contribution ◽  
Element Method

Abstract Road traffic noise needs to be reduced, because traffic volume is increasing every year. The noise generated from a tire is becoming one of the dominant sources in the total traffic noise because the engine noise is constantly being reduced by the vehicle manufacturers. Although the acoustic intensity measurement technology has been enhanced by the recent developments in digital measurement techniques, repetitive measurements are necessary to find effective ways for noise control. Hence, a simulation method to predict generated noise is required to replace the time-consuming experiments. The boundary element method (BEM) is applied to predict the acoustic radiation caused by the vibration of a tire sidewall and a tire noise prediction system is developed. The BEM requires the geometry and the modal characteristics of a tire which are provided by an experiment or the finite element method (FEM). Since the finite element procedure is applied to the prediction of modal characteristics in a tire noise prediction system, the acoustic pressure can be predicted without any measurements. Furthermore, the acoustic contribution analysis obtained from the post-processing of the predicted results is very helpful to know where and how the design change affects the acoustic radiation. The predictability of this system is verified by measurements and the acoustic contribution analysis is applied to tire noise control.

Hybrid Reduced Model of Rotor

2013 ◽  
Vol 60 (3) ◽  
pp. 319-333
Author(s):  
Rafał Hein ◽  
Cezary Orlikowski
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Hybrid Model ◽  
Rotor System ◽  
Reduced Model ◽  
Order Model ◽  
Gyroscopic Effect ◽  
Reduced Models ◽  
Rigid Finite Element Method ◽  
Low Order

Abstract In the paper, the authors describe the method of reduction of a model of rotor system. The proposed approach makes it possible to obtain a low order model including e.g. non-proportional damping or the gyroscopic effect. This method is illustrated using an example of a rotor system. First, a model of the system is built without gyroscopic and damping effects by using the rigid finite element method. Next, this model is reduced. Finally, two identical, low order, reduced models in two perpendicular planes are coupled together by means of gyroscopic and damping interaction to form one model of the system. Thus a hybrid model is obtained. The advantage of the presented method is that the number of gyroscopic and damping interactions does not affect the model range

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