Solution of coupled poroelastic/acoustic/elastic wave propagation problems using automatic hp-adaptivity

http://www.utc.fr/~chazotje/publis/Articles/Julien_JSV2.pdf

A mixed "Biot-Shell" analytical model for the prediction of sound transmission through a sandwich cylinder with a poroelastic core

Given the quest for mass reduction while preserving proper vibration and acoustic comfort levels in industrial machinery and vehicles, lightweight poroelastic materials have gained a lot of importance. Often, these materials are applied in a multilayered configuration, which can consist of a number of acoustic, elastic, viscoelastic and poroelastic layers. Among these, poroelastic materials are the main focus of this paper. A poroelastic material comprises two constituents, being the elastic solid constituent, also called the frame, and the fluid filling the voids. Depending on the frequency range of interest, the motion of both constituents can be strongly coupled. Poroelastic materials can dissipate energy very effectively by structural, thermal and viscous means. Considerable research effort has been put in the development of robust models and prediction techniques which are capable of accurately describing the damping phenomena of these materials. After a broad introduction, this paper reviews the most commonly used models, ranging from simple empirical relations to detailed models accounting for the coupled behaviour of both phases and the CAE modelling techniques currently being applied for the analysis of the time-harmonic vibro-acoustic behaviour of these materials. Commonly used methods, such as the Finite Element Method and the Transfer Matrix Method which are mainly fitted for low-freqency and high-frequency applications, respectively, are discussed as well as extensions to improve their efficiency and applicability. The two final sections pay special attention to the promising Wave Based Method, a Trefftz-based technique, the application range of which was recently extended towards poroelastic problems.

Modelling Techniques for Vibro-Acoustic Dynamics of Poroelastic Materials

This paper presents the low frequency acoustic properties of a new proposed elastic metamaterial, which is arranged in the axial coordinate. The band structures, transmission spectra, and eigenmode displacement fields of this metamaterial are different from previous elastic metamaterial structures. Numerical calculation results show that the first order band gap of the radial flexible elastic metamaterial plate is below 10 Hz. A multiple-vibration coupling mechanism is proposed to explain the low frequency band gaps. By changing the geometrical dimensions h 1, h 2, b 1, and b 1 of the centre part, the location and width of the low frequency band gaps can be varied easily. The effects of density and Young's modulus are also discussed in detail. In summary, the radial flexible elastic metamaterial plate can restrain low frequency vibration, owing to which it can potentially be used to protect infrasound, generate filters, and design acoustic devices.

https://iopscience.iop.org/article/10.1088/0022-3727/49/43/435501/pdf

Low frequency band gaps below 10 Hz in radial flexible elastic metamaterial plate

Optimal negative stiffness inertial-amplifier-base-isolators: Exact closed-form expressions

Dynamic stiffness of hollowed cylindrical rubber vibration isolators — The wave-guide solution

New modelling tools intended to contribute to the development of components for quieter vehicles are developed. The tools are based on continuum models for wave propagation in poro– and visco–elastic media. By using geometric attributes of the studied components, the computational cost may be radically decreased compared to traditional methods. By assigning known analytical functions for one or two of the spatial directions, the spatial dimension of the remaining numerical problem is reduced. This reduction of spatial dimensions is performed in two di↵erent ways. The first one treats wave propagation in infinitely extended homogeneous and hollowed cylindrical rods, or wave guides, consisting of visco–elastic media. The wave solutions obtained are then used to model rubber vibration isolators of finite length by mode–matching the fields to the radial boundary conditions of interest. The second one is a method for modelling rotationally symmetric multilayered structures consisting of poro–elastic, elastic and fluid domains. By using a harmonic expansion for the azimuthal spatial dependence, the original three–dimensional problem is split up into several, much smaller, two– dimensional ones, radically decreasing the computational load.Moreover, using a mixed measurement/modelling approach, the audible frequency range characteristics of a viscous damper from a truck is studied, illustrating the influence of the rubber bushings by which it is attached to surrounding structures.The modelling approaches presented in this thesis are intended as tools aiding the design process of new vehicles, enabling new technology striving for more sustainable vehicle concepts. More specifically, the tools aim to improve the modelling of sound and vibration properties which are often penalised when seeking new, more sustainable vehicle designs.

Weak formulation of Biot's equations in cylindrical coordinates with harmonic expansion in the circumferential direction

Transverse, tilting and cross-coupling stiffness of cylindrical rubber isolators in the audible frequency range—The wave-guide solution

A vibro-acoustic reduced order model using undeformed coupling interface substructuring - Application to rubber bushing isolation in vehicle suspension systems

A weak form of the anisotropic Biot's equation represented in a cylindrical coordinate system using a spatial Fourier expansion in the circumferential direction is presented. The original three dim ...

Martin Östberg

Papers

Dynamic stiffness of hollowed cylindrical rubber vibration isolators — The wave-guide solution

Weak formulation of Biot's equations in cylindrical coordinates with harmonic expansion in the circumferential direction

Transverse, tilting and cross-coupling stiffness of cylindrical rubber isolators in the audible frequency range—The wave-guide solution

A vibro-acoustic reduced order model using undeformed coupling interface substructuring - Application to rubber bushing isolation in vehicle suspension systems

Weak forms for modelling of rotationally symmetric, multilayered structures, including anisotropic poro-elastic media