Acoustic Finite Element Method Research Articles

Study on the Simulation of Radial Tire Vibration Noise

This article takes the sizing 195/65R15 as an example and establishes a 3D tire FE model to simulate the tire in the steady rolling process through Pro/E and Abaqus software. The vibration accelerations of nodes were extracted from tire surface, which can be transferred into acoustic boundary conditions to calculate the tire vibration noise by acoustic finite element method and acoustic infinite element method. This paper provides a new method which calculates the tire vibration noise and predicts the tire noise characteristics in the conceptual design phase.

Specification of Realistic Boundary Conditions for the FE Simulation of Low Frequency Sound Fields in Recording Studios

The room acoustic design of the low frequency characteristics of control and recording rooms in studio facilities still poses a challenging task to acoustic designers and consultants. Due to the low density of eigenmodes at frequencies below the Schroeder frequency, the statistical assumptions underlying geometrical acoustics theory do not hold for this frequency range. Consequently simulation methods such as 'raytracing' or the 'mirror-image-method' cannot supply reliable results here. On the other hand analytical solutions for the wave equation of the sound field in enclosed spaces are generally restrained to rather simple room geometries and boundary conditions. Therefore numerical methods such as the finite element method (FEM) are promising contenders for the simulation of low frequency sound fields in arbitrarily shaped rooms with complex boundary conditions. In the course of this study the FEM was used to simulate the low frequency sound field in the control room of a recording studio in Munich, Germany. The results are compared to measurements in the real room in order to evaluate the performance of the simulation. Special attention is paid to a realistic representation of the acoustic characteristics of the room boundaries in the model and the limitations of an impedance approach are discussed. It is made clear, that the Achilles' heel of room acoustic FEM simulations appears to be the realistic boundary specification and that further work has to focus on the identification or development of robust and reliable measurement or modelling techniques to determine the acoustic characteristics of the various materials on the room boundaries.

Fluid-structure coupled analysis of underwater cylindrical shells

Underwater cylindrical shell structures have been found a wide of application in many engineering fields, such as the element of marine, oil platforms, etc. The coupled vibration analysis is a hot issue for these underwater structures. The vibration characteristics of underwater structures are influenced not only by hydrodynamic pressure but also by hydrostatic pressure corresponding to different water depths. In this study, an acoustic finite element method was used to evaluate the underwater structures. Taken the hydrostatic pressure into account in terms of initial stress stiffness, an acoustical fluid-structure coupled analysis of underwater cylindrical shells has been made to study the effect of hydrodynamic pressures on natural frequency and sound radiation. By comparing with the frequencies obtained by the acoustic finite element method and by the added mass method based on the Bessel function, the validity of present analysis was checked. Finally, test samples of the sound radiation of stiffened cylindrical shells were acquired by a harmonic acoustic analysis. The results showed that hydrostatic pressure plays an important role in determining a large submerged body motion, and the characteristics of sound radiation change with water depth. Furthermore, the analysis methods and the results are of significant reference value for studies of other complicated submarine structures.

Dynamic response of deformable structures subjected to shock load and cavitation reload

The dynamic response of deformable structures subjected to shock load and cavitation reload has been simulated using a multiphase model, which consists of an interface capturing method and a one-fluid cavitation model. Fluid–structure interaction (FSI) is captured via a modified ghost fluid method (Liu et al. in J Comput Phys 190: 651–681, 2003), where the structure is assumed to be a hydro-elasto-plastic material if subjected to a strong shock load. Bulk cavitation near the structural surface is captured using an isentropic model (Liu et al. in J Comput Phys 201:80–108, 2004). The integrated multiphase model is validated by comparing numerical predictions with 1D analytical solutions, and with numerical solutions calculated using the cavitation acoustic finite element (CAFE) method (Sprague and Geers in Shocks vib 7:105–122, 2001). To assess the ability of the multiphase model for multi- dimensions, underwater explosions (UNDEX) near structures are computed. The importance of cavitation reloading and FSI is investigated. Comparisons of the predicted pressure time histories with different explosion center are shown, and the effect on the structure is discussed.

A thermo-electro-mechanical coupling study of Csaw motions and an application to the ultrasonic spherical motors by TEM–FEM

This paper carries out thermo-electro-mechanical element study of anisotropic and piezoelectric curved surface acoustic waves (Csaw) in uniform materials, and dispersed Csaw of inlaid electrode metals, particularly for a novel type of miniature ultrasonic spherical saw motors. An electro-thermo-mechanical acoustic finite element method is chosen with temperature variation introduced and electric potential condensed, its convergence is verified for mechanical vibration spectrums and piezoelectric surface wave velocities. The coupled acoustic influences of Euler angles and temperature gradients in addition to implanted electrode heights and surface curvatures are evaluated on the piezoelectric surface waves. Numerical results are provided for consistent evaluations, and several conclusions with attained curves are drawn to investigate the electromechanically controlled standing wave drive mechanism.

Simulation-based analysis of acoustic absorbent lining subject to normal plane wave incidence

The performance of an acoustic absorbent lining can be significantly enhanced by introducing holes inside the lining. Its performance is dependent on the material properties, thickness of layers as well as the size and distribution of holes. In this paper, a simulation-based design approach that combines the acoustic finite element method (FEM) and acoustic duct method (ADM) with a multi-variable optimization technique is proposed for the design synthesis of the acoustic absorbent lining. The proposed method treats a single cell of a periodic acoustic absorbent lining in isolation. The cell may contain a set of holes. Two acoustic ducts are attached at opposing faces of the isolated cell. FEM model is built for the cell and these two acoustic ducts. The reflection and transmission characteristics of acoustic absorbent lining are calculated simultaneously using the acoustic duct theory. The zero-order optimization method is applied to optimize the various design variables, such as Young's modulus of the material, damping loss factors and the diameters of cylindrical holes, etc., to achieve the desirable acoustic performance of the absorbent lining at a single frequency of interest. The proposed method is validated against analytical solutions for a homogeneous acoustic absorbent lining. Numerical examples for the linings with different optimized results are presented to demonstrate the performance of the optimized absorbent lining.

Comparison of the acoustic finite element method and the acoustic boundary element method for interior noise prediction

Comparisons are made of the acoustic finite element method versus the acoustic boundary element method for predicting interior noise in an enclosure. The theoretical formulation of both methods is summarized, and applications are presented of the interior noise prediction in a rectangular box and in the passenger compartment of an automotive vehicle. The accuracy of the predicted results and the computational performance of the acoustic finite element method versus the acoustic boundary element method are compared. The relative advantages and disadvantages of each method are discussed.