Wave sensitivity analysis for periodic and arbitrarily complex composite structures

Purpose: This paper presents the development of a numerical continuum-discrete approach for computing the sensitivity of the waves propagating in periodic composite structures. The work can be directly employed for evaluating the sensitivity of the structural dynamic performance with respect to geometric and layering structural modifications. Design/methodology/approach: A structure of arbitrary layering and geometric complexity is modelled using solid FE. A generic expression for computing the variation of the mass and the stiffness matrices of the structure with respect to the material and geometric characteristics is hereby given. The sensitivity of the structural wave properties can thus be numerically determined by computing the variability of the corresponding eigenvalues for the resulting eigenproblem. The exhibited approach is validated against the FD method as well as analytical results. Findings: An intense wavenumber dependence is observed for the sensitivity results of the sandwich structure. This exhibits the importance and potential of the presented tool with regard to the optimization of layered structures for specific applications. The model can also be used for computing the effect of the inclusion of smart layers such as auxetics and piezoelectrics. Originality/value: The paper presents the first continuum-discrete approach specifically developed for accurately and efficiently computing the sensitivity of the wave propagation data for periodic composite structures irrespective of their size. The considered structure can be of arbitrary layering and material characteristics as FE modelling is employed

GUIDED WAVE PROPAGATION IN THERMAL MEDIA THROUGH THE SEMI ANALYTICAL FINITE ELEMENT METHOD

In this paper, the issue of the estimation of wave propagation characteristics in thermal media is dealt with. A formulation, named the Thermal Semi Analytical Finite Element, based on the semi analytical finite element approach coupled with the thermal effect is offered. Temperature variations affect the mechanical properties of the waveguide. The question of dispersion curves and group velocities is studied. This study is expected to be of use in the sensitivity analysis of guided waves for wave propagation in thermal environment. Comparisons between numerical and analytical results are given to show the effectiveness of the proposed approach

Structural energy flow optimization through adaptive shunted piezoelectric metacomposites

International audienceIn this article, a numerical approach for modeling and optimizing two-dimensional smart metacomposites is presented. The proposed methodology is based on the Floquet-Bloch theorem in the context of elastodynamics including distributed shunted piezoelectric patches. The dedicated numerical technique is able to cope with the multimodal wave dispersion behavior over the whole first Brillouin zone for periodically distributed two-dimensional shunted piezomechanical systems. Some indicators allowing the optimization of the shunt impedance for specific performance objectives are presented and applied for illustration purposes on the design of an adaptive metacomposite with specific functionalities. In order to validate the strategy, the designed metacomposite is integrated in a support structure, and a full three dimensional model is derived to illustrate the efficiency of the approach

Integrated and Distributed Adaptive Metacomposites for vibroacoustic control of Aerospace Structures

International audienceResearch activities in smart materials and structures represent a significant potential for technological innovation in mechanics and electronics. The necessity of controlling vibroacoustic behavior of industrial systems motivates a broad research effort for introducing active or passive technologies to control noise and vibrations. New processes are now available which allow active transducers and their driving electronics to be directly integrated into otherwise passive structures. This new approach could allow fine control of the material physical behavior for implementing new functional properties that do not exist in nature. In this sense, we can speak of "integrated distributed adaptive metacomposites" that merges with the notion of programmable material. Through two different examples dealing with active acoustical impedance and elastodynamical interface, this paper presents used theoretical tools for designing specific applications of this new technology

Computation of 2D vibroacoustic waves dispersion for optimizing acoustic power flow in interaction with adaptive metacomposites

International audienceThis paper presents an integrated methodology for optimizing vibroacoustic energy flow in interaction between an adaptive metacomposite made of periodically distributed shunted piezoelectric material glued onto passive plate and open acoustic domain. The computation of interacting Floquet-Bloch propagators is also used to optimize vibroacoustic behavior. The main purpose of this work is first to propose a numerical methodology to compute the fluid-structure multi-modal wave dispersions. In a second step, optimization of electric circuit is used to control the acoustic power flow. 3D standard computation is used to confirm the efficiency of the designed metacomposite in terms of acoustic emissivity and absorption

Dynamics of stochastic and periodic structures in mid-frequency range

International audiencea hybridization of the Wave Finite Element Method (WFEM) with the Generalised Polynomial Chaos Expansion (GCE). The WFE is a spectral method dealing with wave propagation in periodic structure. This method proved its efficiency in different domains; structural vibration, non-destructive testing, etc. However, the WFE is limited to deterministic media. Knowing that uncertainties affect dynamic behavior in Mid- and High frequencies, the combination of WFE and GCE is used to predict the effect of uncertainties on the dynamic response of periodic media. The uses of the GCE is based on the iso-probabilistic transformations for usuel distributions to Gaussian one to use the Hermite-Chaos expansion.The presented approach is validated for two periodic waveguides connected through a junction with uncertain parameters. The obtained results are verified vs Monte Carlo simulations

Sensitivity analysis of complex engineering systems: Approaches study and their application to vehicle restraint system crash simulation

Restricted by high calculation cost of single engineering model run and large number of model runs for sampling-based Sensitivity Analysis (SA), qualitative SA are used for parameter study of the Vehicle Restraint System (VRS) and quantitative SA of such models has always been a challenge. Sequential approaches are proposed for SA of complex systems and the SA of a VRS is realized: sampling-based SA methods are discussed; SA of a simple three points dynamic bending test model is realized, the aims are to compare different two-level screening methods and put into practice the sequential SA; crash test FE model of a VRS is created and used for SA; influential uncertain parameters of the VRS are identified qualitatively through screening analyses (SA with Two-level screening and Morris Analysis), and Sobol' indices are used to quantify the influence of influential parameters with Kriging metamodeling. The uncertain parameters which contribute the most to robustness of the VRS are identified and their influences are quantified by combining screening analyses and Sobol' Indices

Adaptive metacomposites : design strategy and experimental validation

International audienceRecent advances in modeling of multiphysics periodic systems allow designers to investigate new concepts for vibroacoustic absorption. In this work, we present a strategy to design adaptive metacomposites, namely host structures with periodic piezoelectric patches shunted with semi-passive electric circuits, together with experimental implementation

Conception et développement d'un système d'inspection par ondes guidées pour la détection des défauts dans les tubes

Le système d'inspection conçu permet d'acquérir des signaux de mesure sur une canalisation et de fournir des indications sur la localisation des défauts avec des idées sur leurs natures. Le générateur des ondes guidées permet l'émission des ondes de torsion et la réception des échos réfléchis. Certains outils de traitement du signal pour le filtrage et l'analyse des signaux enregistrés sont utilisés dans le but d'éliminer les bruits de fonds et les parasites pour extraire les informations les plus pertinentes

Multi-modal wave propagation in smart structures with shunted piezoelectric patches

International audienceThe propagation of wave modes in elastic structures with shunted piezoelectric patches is dealt with in this work. The wave finite element approach, which is based on the finite element method and periodical structure theory, is firstly developed as a prediction tool for wave propagation characteristics in beam like structures, and subsequently extended to consider shunted piezoelectric elements through the diffusion matrix model (DMM). With these numerical techniques, reflection and transmission coefficients of propagating waves in structures with shunted piezoelectric patches can be calculated. The performance of shunted piezoelectric patches on the control of wave propagation is investigated numerically with the DMM. Forced response of the smart structure can also be calculated, and based on which the time response of the structure can be obtained via an inverse discrete fourier transform approach. These general formulations can be applied to all types of slender structures. All these numerical tools can facilitate design modifications and systematic investigations of geometric and electric parameters of smart structures with shunted piezoelectric elements