Morvan Ouisse

Institut FEMTO-ST | FEMTO ST · Department of Applied Mechanics

The pressure-based, current-driven impedance control technique known as “Electroacoustic Absorption” has offered new horizons for room modal equalization at low frequencies, steerable anomalous reflection, acoustic transmission attenuation and non-reciprocal wave propagation. Nevertheless, its level of performance is strongly limited by stability c...

The perfect absorption of bending waves by thermally tunable subwavelength absorbers is analytically and experimentally demonstrated in this work for a reflection problem in beams. These absorbers are local resonators located at the end of a semi-infinite beam and consist of thin blades covered with a layer of Shape Memory Polymer (SMP), the stiffn...

The design and the grazing flow aeroacoustical characterization of a 2D active liner based on an array of electroacoustic absorbers are presented in this paper. The strategy stands on a pressure-based, current-driven digital architecture for impedance control with both local and non local architectures. A wind tunnel test rig is used for the in-flo...

Abstract This study presents a sensitivity analysis methodology used for electric motor design. This innovative approach evaluates both global effects of parameter variations in their design range and of parameter deviations in their tolerance intervals on design objectives. For the purpose of robust optimisation, this method helps to select the mo...

Elastic guided wave focusing is of great interest for applications such as vibroacoustic control, energy harvesting, or Structural Health Monitoring. Different strategies allow generation of this effect, GRadient-INdex devices in particular exploit medium with varying properties such as thickness to reproduce an adequate refractive index profile as...

Shape memory alloys (SMAs) are a group of metallic alloys capable of sustaining large inelastic strains that can be recovered when subjected to a specific process between two distinct phases. Regarding their unique and outstanding properties, SMAs have drawn considerable attention in various domains and recently became appropriate candidates for or...

This paper reviews the damping characteristics of plant fiber composites (PFCs) with particular attention regarding their performance with respect to that of synthetic fiber composites (SFCs). Indeed, PFCs have become increasingly popular in many application fields. Their specific characteristics when compared to those of synthetic fibers, such as...

The design of lightweight and stiff structures with attractive vibration damping properties is a major issue in mechanical engineering. The insertion of Acoustic Black Holes (ABH) in a beam is a technique that consists in locally reducing its thickness at the end and coating it with a visco-elastic film. The reflection coefficient of the resulting...

The work describes the out-of-plane properties of a curved wall honeycomb structure evaluated using analytical models and finite elements techniques. Out-of-plane properties are calculated using a theoretical approach based on energy theorems and validated using a full-scale finite element technique to simulate transverse shear tests. The effects o...

The inclusion of vibroacoustic treatments at early stage of product development through the use of poro-elastic media with periodic inclusions, which exhibit proper dynamic filtering effects, is a powerful strategy for the achievement of lightweight sound packages and represents a convenient solution for manufacturing aspects. This can have differe...

This paper aims at consolidating research dealing with vibroacoustics of periodic media. The main goal of this work is to develop and to validate tools for the design of global vibroacoustic treatments based on periodic patterns, allowing passive control of acoustic paths in layered concepts. To this aim, some enhancements are introduced to the sta...

The SALUTE project aims at evaluating performance of metacomposites for acoustic smart lining in grazing turbulent flow. Theoretical and numerical investigations are carried out for designing innovative specimen. A specific focus is placed in the realization of prototypes for evaluating the metacomposite liner performances in 2D and 3D liners, its...

Rotors of asynchronous machines can be subjected to risk of failure due to vibratory fatigue. This is caused by the way electric motors are powered. Pulse Width Modulation (PWM) is the control strategy of the traction chain. This signal is composed by a fundamental and numerous harmonics of voltage and current that induce harmonics on the torque si...

The application of shift cell technique is presented and discussed for periodic porous media described with equivalent fluid models: as it can be found in literature, it consists in a reformulation of classical Floquet-Bloch (F-B) conditions, in which the phase shift of the boundary conditions, related to wave propagation, is integrated into the pa...

The aim of this work is to propose an indicator, based on the info-gap approach, which assesses the robustness of the dynamic response of the model of a structure to lack of knowledge in the associated eigensolutions. The info-gap uncertainty model for the eigensolutions is constructed mode by mode based on a set of experimentally identified eigens...

Structural periodic design is a powerful approach to achieve lightweight structures that can be manufactured in a costefficient manner. Periodic media exhibit specific dynamic filtering effects that can be used for advanced vibroacoustic design. How periodic concepts can improve the broadband vibroacoustic signature and performance is still an open qu...

In this paper, some guidelines are provided in order to predict at which frequency the 1st performance peak (related to periodicity effects: half of the wavelength = periodicity dimension) appears, together with its amplitude, as functions of the unit cell dimensions. Conversely, also the link between the unit cell dimensions and the 1st performanc...

This paper is focused on the identification of the in-plane elastic constants of a new design of auxetic (negative Poisson's ratio) honeycomb configuration with curved cell walls by using analytical and numerical homogenization techniques. The sensitivity of the elastic constants is determined against the various cell geometry parameters. Good agre...

This chapter is dedicated to the dynamical mechanical thermal analysis of shape-memory polymers. Temperature obviously plays a major role in the mechanical properties of these materials; hence, the understanding of the physical phenomena driving the shape-memory effect is of first importance for the design of practical applications in which shape-m...

The work describes the wave propagation in a periodic structure formed by a linear spring-mass chain with local Duffing non-linear resonators. The wave propagation of the system isstudied using the Floquet-Bloch theorem combined with a perturbation approach to iden-tify the dispersion relations in the nonlinear periodic structure. The theoretical m...

This paper studies a new type of smart metamaterial consisting of piezoelectric actuators and digital synthetic impedance circuits (digital circuits). The digital circuit contains a micro-controller. By programming the micro-controller, the circuit can establish any desired impedance between the terminals of the connected piezoelectric patch, there...

We present a first experimental characterization of our ultra-compact, ultra-stable laser. The heart of the apparatus is an original Fabry-Perot cavity with a 25 mm length and a pyramidal geometry, equipped with highly-reflective crystalline coatings. The cavity, along with its vacuum chamber and optical setup, fits inside a 30 L volume. We have me...

Phononic Crystals (PCs) are artificial materials with extensive application in the aerospace and aeronautical industries since they introduce frequency stop-bands (frequency ranges where wave cannot freely propagates). In this investigation 2D periodic and quasi-periodic pattern: instead of strictly repeating a pattern, a certain degree of irregula...

Periodic structures found a big interest in engineering applications because they introduce frequency band effects, due to the impedance mismatch generated by periodic discontinuities in the geometry, material or boundary conditions, that can improve the vibroacoustic performances. However, the presence of defects or irregularity in the structure,...

The periodic structures have various applications in vibroacoustic engineering fields since they introduce frequency band effects due to the periodic discontinuities in the geometrical or material configurations: this can lead to increased performances. This paper is focused on the analysis of quasi-periodic structures: instead of using strictly re...

For the last two decades, the development of conducting polymers (CP) as artificial muscles, by materials researchers and chemists, has made establishing a reliable and repeatable synthesis of such materials possible. CP-based milli-robots were mostly unknown in soft robotics, however, today, they play a vital role in robotics and smart materials f...

We theoretically, numerically and experimentally demonstrate the acoustic isolator effect in a one-dimensional waveguide with direction-dependent controlled boundary conditions. A theoretical model is used to explain the principle of nonreciprocal propagation in boundary-controlled waveguides. Numerical simulations are preformed on a reduced model...

The use of periodic media as passive mechanical and acoustic vibration filters has become a research topic of great interest. The classic cores dynamic characteristics have been widely studied and only for very few configurations revealed partial Bragg bandgaps using simple beam models. In this paper, an innovative negative Poisson's ratio cellular...

Smart metamaterials consisting of piezoelectric materials are promising structures with new functionalities. Previous studies usually use shunt circuitry composed of analog elements or active feedback control strategies with sensors and actuators to control the piezoelectric materials. The shunt circuitry is simple since it uses the same piezoelect...

The vast majority of structures introduce symmetry in one or two dimensions, which can be a periodicity in the case of constructing several identical unit cells. Periodic structures have found a big interest in engineering applications because they introduce frequency band effects, due to the impedance mismatch generated by periodic discontinuity i...

The main advantage of designing sound packages with periodic arrangements is that they can provide a combination of absorption effects, resonance effects and wave interferences effects. This offers different applications in transportation (aeronautics, space, automotive, railway), energy and civil engineering sectors, where both weight and space, a...

Acoustic performances of two concepts based on the integration of an elastic membrane in the front wall of a cavity and Helmholtz resonator embedded in a melamine matrix are studied. Membranes are made of acrylic material, this latter is first characterized with a uniaxial test in order to extract the mechanical properties needed to model the membr...

In this paper, we theoretically, numerically and experimentally demonstrate the acoustic isolator effect in a 1D waveguide with direction dependent controlled boundary conditions. A theoretical model is used to explain the principle of non reciprocal propagation in boundary controlled waveguides. Numerical simulations are carried out on a reduced m...

This paper presents a system matrices identification approach directly from the real-time measured structural responses. Based on the experimental modal analysis, the identified system matrices are expected to represent the system behaviours as same as the experimentally measured ones. Due to the fact that the system matrices, i.e. the mass, stiffn...

One dimensional active metamaterials with broadband controllable bending stiffness are studied in this paper. The key unit of the active metamaterials is composed of a host beam and piezoelectric patches bonded on the beam surfaces. These patches serve as sensors or actuators. An appropriate feedback control law is proposed in order to change the b...

Acoustic Black Holes are innovative solutions to damp vibrations through the use of power-law profiles in flexural beams and plates. However practical implementations of the concept are limited due to the finiteness of the thickness at the end of the beam. In this paper, it is proposed to add a viscoelastic layer on the ABH and control its mechanic...

Smart composite structures, which are able to modify their mechanical properties with respect to their environment (e.g. active vibration control), to interact with other structures (e.g. mechatronic) or with human beings (e.g. Human-Machine Interaction), are widely used in the modern industrial fields (e.g. aerospace), due to the intensification o...

The composite structures embedding piezoelectric implants are developed due to their abilities of modifying mechanical properties according to the environment, of keeping their integrity, of interacting with human beings or with other structures. One way to functionalize a mechanical device consists in embedding the transducers inside the final com...

Stop bands in auxetic periodic structures including resonators are investigated in this paper. In aerospace field, sandwich panels like honeycombs are mainly used for their structural properties, and can present some advantages for vibroacoustics control. Auxetic structures seem to give enhanced properties for wave propagation control, and have bee...

In this paper, an adaptive phononic crystal slab based on the combination of metallic parts and highly dissipative polymeric interfaces is designed. Cylindrical pillars are composed of shape memory polymer and aluminium deposited periodically on the aluminium slab. The mechanical properties of the polymer depend on both temperature and frequency an...

The system identification technology is essentially an inverse procedure, starting from the experimentally measured response, to construct mass, stiffness, and damping matrices of the structure. However, the measurement inevitably contains uncertainties, which significantly impact the identified system characteristics, especially for damping terms....

The typical model updating techniques mainly focus on calibrating the model parameters , e.g. Young's modulus and density, while being inefficient for the model form error due to the inevitable approximation and simplification during numerical modeling. In this paper, an integrated model updating approach for both uncertain material parameters and...

Special Issue on Uncertainty Management in Complex Multiphysics Structural Dynamics (SI Number: SI032B) ASCE-ASME Journal of Risk and Uncertainty in Engineering Systems, Part B: Mechanical Engineering

Periodic structures are well known for the possibility to exhibit band gap effects. This work aims at investigating vibration behaviors of quasi-periodic structures. In this paper, the quasi-periodic structure is defined as a type of beam with an impedance mismatch generated by Fibonacci orders with non-symmetrical translation in geometry, acting a...

This paper starts with the presentation of the shift cell technique, which allows the description of the propagation of all existing waves starting from the unit cell through a quadratic eigenvalue problem. Its major advantage is that it allows the implementation of any frequency dependence and damping in the problem: this is a fundamental advantag...

Sandwich panels are widely used in applications where high stiffness and low weight structures have become an asset, such as the aerospace segment. The environment in which those panels are used produce uncomfortable vibrations in the low-mid range which also may induce inefficiency. This hybrid cellular core obtained with a Kirigami derived techni...

In the growing field of origami engineering, self-folding is of a high regard. The latter is regularly used by nature as an efficient approach for autonomous growing and reorganizing. In this work, we present a self-folding approach based on Electro-Active Polymer (EAP), especially Conductive Polymers (CP). This approach proposes lightweight, compa...