Summary
We introduce a coupled finite and boundary element formulation for acoustic scattering analysis over thin shell structures. A triangular Loop subdivision surface discretisation is used for both geometry and analysis fields. The Kirchhoff-Love shell equation is discretised with the finite element method and the Helmholtz equation for the acoustic field with the boundary element method. The use of the boundary element formulation allows the elegant handling of infinite domains and precludes the need for volumetric meshing. In the present work the subdivision control meshes for the shell displacements and the acoustic pressures have the same resolution. The corresponding smooth subdivision basis functions have the C1 continuity property required for the Kirchhoff-Love formulation and are highly efficient for the acoustic field computations. We redverify the proposed isogeometric formulation through a closed-form solution of acoustic scattering over a thin shell sphere. Furthermore, we demonstrate the ability of the proposed approach to handle complex geometries with arbitrary topology that provides an integrated isogeometric design and analysis workflow for coupled structural-acoustic analysis of shells. This article is protected by copyright. All rights reserved.

We present an isogeometric analysis technique that builds on manifold-based smooth basis functions for geometric modelling and analysis. Manifold-based surface construction techniques are well known in geometric modelling and a number of variants exist. Common to most is the concept of constructing a smooth surface by blending together overlapping patches (or, charts), as in differential geometry description of manifolds. Each patch on the surface has a corresponding planar patch with a smooth o...

The interaction between thin structures and incompressible Newtonian fluids is ubiquitous both in nature and in industrial applications. In this paper we present an isogeometric formulation of such problems which exploits a boundary integral formulation of Stokes equations to model the surrounding flow, and a non linear Kirchhoff–Love shell theory to model the elastic behavior of the structure. We propose three different coupling strategies: a monolithic, fully implicit coupling, a staggered, el...

Abstract This paper presents a novel automatic polycube construction algorithm using centroidal Voronoi tessellation (CVT) based surface segmentation. Given a smooth surface triangle mesh, we segment triangles into six clusters in the surface normal space while satisfying the constraints of polycube construction. A bijective mapping between the input mesh and polycube surfaces is then built via a planar domain parameterization. We develop a new harmonic boundary-enhanced centroidal Voronoi tesse...

#2Johan Christensen(DTU: Technical University of Denmark)H-Index: 26

Last. Andrea Alù(University of Texas at Austin)H-Index: 112

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Acoustic metamaterials can manipulate and control sound waves in ways that are not possible in conventional materials. Metamaterials with zero, or even negative, refractive index for sound offer new possibilities for acoustic imaging and for the control of sound at subwavelength scales. The combination of transformation acoustics theory and highly anisotropic acoustic metamaterials enables precise control over the deformation of sound fields, which can be used, for example, to hide or cloak obje...

Last. Jörg Peters(UF: University of Florida)H-Index: 29

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Geometrically continuous (Gk) constructions naturally yield families of finite elements for isogeometric analysis (IGA) that are Ck also for non-tensor-product layout. This paper describes and analyzes one such concrete C1 geometrically generalized IGA element (short: gIGA element) that generalizes bi-quadratic splines to quad meshes with irregularities. The new gIGA element is based on a recently-developed G1 surface construction that recommends itself by its a B-spline-like control net, low (l...

Last. Jan Zapletal(Technical University of Ostrava)H-Index: 7

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We consider the shape optimisation of high-voltage devices subject to electrostatic field equations by combining fast boundary elements with multiresolution subdivision surfaces. The geometry of the domain is described with subdivision surfaces and different resolutions of the same geometry are used for optimisation and analysis. The primal and adjoint problems are discretised with the boundary element method using a sufficiently fine control mesh. For shape optimisation the geometry is updated ...

Last. Michael A. Scott(BYU: Brigham Young University)H-Index: 27

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In this paper we present a new method termed Truncated Hierarchical Catmull–Clark Subdivision (THCCS), which generalizes truncated hierarchical B-splines to control grids of arbitrary topology. THCCS basis functions satisfy partition of unity, are linearly independent, and are locally refinable. THCCS also preserves geometry during adaptive hh-refinement and thus inherits the surface continuity of Catmull–Clark subdivision, namely C2C2-continuous everywhere except at the local region surrounding...

In this paper we couple collocated Boundary Element Methods (BEM) with unstructured analysis-suitable T-spline surfaces for solving a linear Boundary Integral Equation (BIE) arising in the context of a ship-hydrodynamic problem, namely the so-called Neumann–Kelvin problem, following the formulation by Brard (1972) and Baar and Price (1988). The local-refinement capabilities of the adopted T-spline bases, which are used for representing both the geometry of the hull and approximating the solution...

#1Leilei Chen(USTC: University of Science and Technology of China)H-Index: 11

#2Changjun Zheng(USTC: University of Science and Technology of China)H-Index: 15

Last. Haibo Chen(USTC: University of Science and Technology of China)H-Index: 17

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Abstract A coupling algorithm based on the finite element method (FEM) and the wideband fast multipole boundary element method (wideband FMBEM) is proposed for acoustic fluid–structure interaction simulation and structural–acoustic design sensitivity analysis by using the direct differentiation method. The wideband fast multipole method (FMM), which is developed by combining the original FMM and the diagonal form FMM, is used to accelerate the calculation of the matrix–vector products in boundar...

An isogeometric boundary element method based on T-splines is used to simulate acoustic phenomena. We restrict our developments to low-frequency problems to establish the fundamental properties of the proposed approach. Using T-splines, the computer aided design (CAD) and boundary element analysis are integrated without recourse to geometry clean-up or mesh generation. A regularized Burton–Miller formulation is used resulting in integrals which are at most weakly singular. We employ a collocatio...

An isogeometric Galerkin approach for analysing the free vibrations of piezoelectric shells is presented. The shell kinematics is specialised to infinitesimal deformations and follow the Kirchhoff-Love hypothesis. Both the geometry and physical fields are discretised using Catmull-Clark subdivision bases. It provides the required C1 continuous discretisation for the Kirchhoff-Love theory. The crystalline structure of piezoelectric materials is described using an anisotropic constitutive relation...

#1Yonghong Wu(BIT: Beijing Institute of Technology)H-Index: 63

#2Chunying Dong(BIT: Beijing Institute of Technology)H-Index: 19

Last. Fei Sun(BIT: Beijing Institute of Technology)H-Index: 17

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Abstract The problems of Acoustic-Structural Interaction (ASI) are commonly encountered in the simulation of the thin-walled structures immersed in the fluid. This interaction can affect the acoustic properties of the fluid and the dynamic characteristics of the structure. In this paper, a Non-Uniform Rational B-Splines (NURBS)-based Isogeometric Finite Element (FE) - Boundary Element (BE) symmetric coupling method is developed to study the ASI problems and the free vibration of the elastic stru...

Last. C. G. Politis(UWest: University of the West)H-Index: 8

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Abstract In this paper an Isogeometric Boundary Element Method for three-dimensional lifting flows based on Morino’s (Morino and Kuo, 1974) formulation is presented. Analysis-suitable T-splines are used for the representation of all boundary surfaces and the unknown perturbation potential is approximated by the same T-spline basis used for the geometry. A novel numerical application of the so-called Kutta condition is introduced that utilises the advantages of isogeometric analysis with regard t...

Abstract This paper addresses the susceptibility of finite element models to uncertainty in frequency ranges with relatively high modal density, particularly in the con- text of vibroacoustic analysis. The principal idea is based on a stochastic fi- nite element method (FEM) technique called Craig-Bampton stochastic method (CBSM). It is a parametric Monte Carlo simulation (MCS) approach that can be performed at a fraction of the otherwise potentially impractical computational cost, due to the us...

#1H.S. Yang(BIT: Beijing Institute of Technology)H-Index: 3

#2Chunying Dong(BIT: Beijing Institute of Technology)H-Index: 19

Last. Yonghong Wu(BIT: Beijing Institute of Technology)H-Index: 63

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Abstract In this paper, a three-dimensional (3D) isogeometric finite element (FE) and boundary element (BE) coupling approach based on non-uniform rational B-splines (NURBS) is developed to simulate the deformed body. Based on the geometric exactness and higher smoothness of isogeometric analysis (IGA), NURBS discretization is applied to the approximation of geometric representation, displacement field and traction field simultaneously. An improved power series expansion method (M-PSEM) is used ...

#1Yonghong Wu(BIT: Beijing Institute of Technology)H-Index: 63

#2Chunying Dong(BIT: Beijing Institute of Technology)H-Index: 19

Last. H.S. Yang(BIT: Beijing Institute of Technology)H-Index: 3

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Abstract In this paper, Finite Element-Indirect Boundary Element (FE-IBE) coupling approach based on the Isogeometric Analysis (IGA) framework is proposed to deal with Acoustic-Structural Interaction (ASI) problems. Numerical simulation of thin-walled structures is carried out by using isogeometric Reissner-Mindlin shell theory. The isogeometric indirect boundary element method (IBEM) is used to simulate the fluid domain, and the coupling formula is established by connecting the primary variable...

Abstract Isogeometric boundary element method is a computer simulation algorithm that can directly utilize the data of a geometric model represented by its surface. Catmull-Clark subdivision surfaces are a widely used technique in 3D computer graphics to construct complicated geometries. In the present work, we combine Catmull-Clark subdivision surfaces with isogeometric boundary element method to simulate acoustic propagation in semi-infinite domains. The present method can produce fast and hig...

An isogeometric approach for solving the Laplace–Beltrami equation on a two-dimensional manifold embedded in three-dimensional space using a Galerkin method based on Catmull–Clark subdivision surfaces is presented and assessed. The scalar-valued Laplace–Beltrami equation requires only $C^0 continuity and is adopted to elucidate key features and properties of the isogeometric method using Catmull–Clark subdivision surfaces. Catmull–Clark subdivision bases are used to discretise both the geomet...

#1Leilei Chen(Xinyang Normal University)H-Index: 11

#2Chuang Lu(USTC: University of Science and Technology of China)H-Index: 1

Last. Changjun Zheng(Hefei University of Technology)H-Index: 15

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A novel boundary element method based on subdivision surfaces is applied to simulate wave scattering problems governed by the Helmholtz equation. The Loop subdivision scheme widely used in the CAD ...

#1Yonghong Wu(BIT: Beijing Institute of Technology)H-Index: 63

#2Chunying Dong(BIT: Beijing Institute of Technology)H-Index: 19

Last. H.S. Yang(BIT: Beijing Institute of Technology)H-Index: 3

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Abstract This paper introduces two NURBS (Non-Uniform Rational B-Splines)-based Isogeometric FE (Finite Element)-BE (Boundary Element) coupling approaches, i.e. DCM (Directed Coupling Method) and SICM (Symmetric-Iterative Coupling Method), to solve the structural-acoustic interaction problems. IGA (IsoGeometric Analysis) can eliminate the substantial geometrical errors and time-consuming meshing steps. Meanwhile, CAD (Computer Aided Design) only makes use of surface representations to model geom...