Najib Kacem

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

PhD., Ing.

About

116
Publications
33,191
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1,395
Citations
Introduction
Graduated in 2006 with an Arts et Métiers ParisTech engineering diploma. He joined the French Alternative Energies and Atomic Energy Commission to prepare for a Ph.D that he completed in 2010. He subsequently undertook a post-doctoral research position at the University of Geneva. Since September 2011, he is Associate Professor at the University of Franche-Comté. His area of expertise and research interests include MEMS/NEMS, Nonlinear Dynamics, Energy Harvesting, and Smart Systems.
Additional affiliations
September 2011 - present
University of Franche-Comté
Position
  • Professor (Associate)
September 2010 - August 2011
International University in Geneva (IUN)
Position
  • Research Associate
January 2010 - August 2010
Institut National des Sciences Appliquées de Lyon
Position
  • Research Associate
Education
January 2007 - December 2009
September 2003 - September 2006
Ecole Nationale Supérieure d'Arts et Métiers
Field of study
  • Applied Mechanics

Publications

Publications (116)
Chapter
Rott’s pendulum is a two degrees of freedom system having two-to-one internal resonance. The objective of this work is to demonstrate that the Rott’s pendulum can be attached to a rotating system in order to transfer kinetic energy between the rotation applied to the pendulum and an electromagnetic generator linked to its main axis. In fact, the in...
Article
Rotating systems accumulate a substantial quantity of kinetic energy while in operation, however, it is arduous to extract that energy when the transduction mechanism is embedded in the rotating body. In this paper, it is proposed that the use of a pendulum system attached to an electromagnetic generator, can be an efficient solution to extract the...
Article
In this paper, the equation of motion of graphenelike topological gyroscopic metamaterials under acceleration is derived, and the influence of the external acceleration on the band structure is investigated. The calculated results of band structure under acceleration of 1g are in good agreement with the experimental results reported in the literatu...
Article
Full-text available
The demand for detecting minute mass in biology and chemistry promotes the research of high sensitivity and strong robustness mass sensor based on MEMS resonators in the past few decades. The nonlinear behaviors are introduced to improve sensitivity, frequency stability, and resolution etc. However, the bifurcation configuration will become sophist...
Article
Full-text available
In this paper, the design of large-scale quasi-periodic Vibration Energy Harvesters (VEH) is optimized to enhance the harvested power of an electromagnetic mode localized structure. This work aims to optimize the output power by employing the energy localization phenomenon in a large-scale periodic configuration by introducing the minimum number of...
Article
In this work, we consider MEMS devices made of mechanically coupled microbeams under electric actuation. We conduct an experimental study to identify the occurrence of veering and then investigate its dynamic response for different electric actuations. A slight change in the DC voltage bias from the veering point is observed to affect significantly...
Article
Full-text available
In this paper, we develop a new approach in order to understand the origin of the quadrature error in MEMS gyroscopes. As the width of the flexure springs is a critical parameter in the MEMS design, it is necessary to investigate the impact of the width variations on the stiffness coupling, which can generate a quadrature signal. To do so, we devel...
Article
Full-text available
Mode-localized sensor with amplitude ratio as output metric has shown excellent potential in the field of micromass detection. In this paper, an asymmetric mode-localized mass sensor with a pair of electrostatically coupled resonators of different thicknesses is proposed. Partially distributed electrodes are introduced to ensure the asymmetric mode...
Article
The high-order mode localization in electrostatically coupled microbeams with distributed electrodes has been theoretically investigated and then introduced in high sensitivity mass sensor. A reduced-order model of such sensor considering geometric and electrostatic nonlinearity is established to analyze the complex influences of coupling strength,...
Conference Paper
Full-text available
A novel dual-mass accelerometer is proposed while exploiting the phenomenon of mode localization in two electrostatically coupled resonators with an adjustable coupling strength. The external inertial forces are transmitted differentially to the resonators in term of axial load change through the two levering mechanisms, breaking the balanced state...
Article
A novel dual proof mass accelerometer is proposed by introducing mode localization in two electrostatically coupled resonators. The levering mechanism is utilized to amplify the inertial force applied axially to the two weakly coupled resonators. The dynamic model considering the electrostatic and mechanical nonlinearities is established and solved...
Article
This letter demonstrates the linear dynamic range enhancement of a mode-localized microelectromechanical systems sensor based on two weakly coupled cantilevers under electrostatic actuation resulting in a repulsive force. An analytical model is proposed to design the sensor, and the expression of the electrostatic force is obtained using a finite e...
Preprint
Full-text available
Mode-localization sensor with amplitude ratio as output metric has shown excellent potential in the field of micro-mass detection. In this paper, an asymmetric mode -localized mass sensor with a pair of electrostatically coupled resonators of different thickness is proposed. Partially distributed electrodes are introduced to ensure the asymmetric m...
Research
Full-text available
Website for overall conference series: https://event.asme.org/IDETC-CIE | Details for this Micro and Nano-Systems (MNS) conference: https://cdn.filestackcontent.com/zQLrrroZSEWQUh7g7eio?MNS%20Descriptions.pdf
Article
Full-text available
In this paper, the effects of initial deflection on the static and dynamic behaviors of circular capacitive transducers are experimentally investigated. The obtained results are in good agreement with numerical simulations. It is shown that the initial deflection has a major impact on the static response of the resonator by shifting the pull-in vol...
Article
Full-text available
In this paper we study a generic model of a nonlinear quasiperiodic vibration energy harvester (VEH) based on electromagnetic transduction. The proposed device consists of multiple moving magnets guided by elastic beams and coupled by repulsive magnetic forces. A system of two degrees-of-freedom (DOFs) with tunable nonlinearity and mode localizatio...
Article
Full-text available
We present a mode localized mass sensor prototype based on a hybrid system excited at a fixed frequency slightly below the resonances. Indeed, we show, both theoretically and experimentally, that this condition yields higher sensitivities and similar sensitivity ranges than that of resonance peak tracking while being less time consuming than a clas...
Article
In this letter, non-linearity and energy localization are experimentally tuned in an electromagnetic vibration energy harvester in order to enhance its output performances. The non-linear device consists of two moving magnets guided by elastic beams and coupled by a repulsive magnetic force. The mechanical non-linearity is introduced by considering...
Article
In order to overcome mode aliasing limitation in linear mode-localized sensors, we demonstrate in this Letter both theoretically and experimentally how to tune the electrostatic nonlinearity and exceed the ultimate sensitivity reachable in the linear regime. A mass sensor composed of two coupled micro-cantilevers with different lengths is considere...
Article
Full-text available
An ultrasensitive mass sensor is proposed by combining the benefits of mode localization and nonlinear dynamics in two clamped–clamped microbeams of different lengths. The coupling electrostatic stiffness between the two resonators can be tuned for modulating sensitivity, and the actuation voltage applied to the shorter beam can be adjusted in orde...
Article
In this paper, we present a fully tunable system able to generate mode localization between a 170 000 Q-factor quartz crystal microbalance at 1 MHz and a digital device (Field Programmable Gate Array) simulating in real time the presence of an identical and weakly-coupled second resonator. Indeed, this method allows to precisely select each paramet...
Article
Comparing to linear vibration absorbers, nonlinear energy sinks (NESs) have attracted worldwide attention for their intrinsic characteristic of targeted energy transfer (TET) or energy pumping (EP) in a relatively wide frequency range. Unfortunately, they are highly dependent on the vibration amplitude to be attenuated, and will play its role only...
Conference Paper
This paper investigates the mass sensing in a mode-localized sensor composed of two weakly coupled MEMS cantilevers with lengths 98μm and 100μm. The two resonators are connected by a coupling beam near the fixed end, and the shortest cantilever is electrostatically actuated with a combined AC-DC voltage. The DC actuation voltage is tuned to compens...
Conference Paper
A multimodal electromagnetic vibration energy harvester based on a nonlinear quasi-periodic system is proposed. The multimodal approach and the nonlinearity are implemented in order to improve the output performances of the studied device. The present study investigates a periodic system composed of two weakly coupled magnets and mechanically guide...
Article
This paper presents a sensor using the mode localization phenomenon to detect a mass perturbation. It is composed of two cantilevers with different lengths and connected by a coupling beam. The short cantilever is electrostatically actuated and by changing the applied DC voltage, we can reduce its stiffness and reach the veering point, which corres...
Article
In this article, an original approach to model the squeeze film effects in capacitive circular microplates is developed. The nonlinear von Kármán plate theory is used while taking into consideration the electrostatic and geometric nonlinearities of the clamped edge microplate. The fluid underneath the plate is modeled using the nonlinear Reynolds e...
Article
The present paper investigates the implementation of the energy localization phenomenon for enhancing the output harvesting performance. Also in this paper, a linear electromagnetic vibration energy harvester with weakly-magnetic coupling is proposed. The designed device is two degree-of-freedom oscillators, which functionalizes the energy localiza...
Chapter
The present study investigates the modeling of the vibration energy localization from a nonlinear quasi-periodic system. The periodic system consists of n moving magnets held by n elastic structures and coupled by a nonlinear magnetic force. The quasi-periodic system has been obtained by mistuning one of the n elastic structures of the system. The...
Article
Full-text available
A multimodal vibration energy harvesting in a periodic system is proposed. The multimodal approach and the nonlinearity are implemented in order to improve the performances of the studied device. The periodic system, based on electromagnetic transduction, consists of two weakly coupled magnets mechanically guided by two elastic beams. The quasi-per...
Article
Full-text available
In order to investigate the effects of geometric imperfections on the static and dynamic behavior of capacitive micomachined ultrasonic transducers (CMUTs), the governing equations of motion of a circular microplate with initial defection have been derived using the von Kármán plate theory while taking into account the mechanical and electrostatic...
Article
Most of the vibration sources, which could be used for energy harvesting, are vertical and very low frequency (e.g. human movement, vehicle transportation, etc…). Under those conditions and while considering the size constraints, usual vibration energy harvesters (VEHs) underperform due to the combined effect of gravity, mechanical damping and the...
Article
A new piezoelectric actuated nonlinear mass sensor is proposed by using the snap-through phenomenon of a compressed bistable beam to enhance the sensitivity and resolution, which can be used to weigh or detect threshold mass by tracking the bifurcation frequency shift. According to the nonlinear finite element modeling technique, the nonlinear dyna...
Conference Paper
In the field of mass sensing, there is an ever growing interest in the development of ultrasensitive MEMS devices for agro-food, environment, safety or health. Within this context, mode localization in an array of coupled resonators has been studied and implemented for a few years due to its high sensitivity to mass perturbation. However, this phen...
Conference Paper
Full-text available
This paper presents a nonlinear analytical model of MEMS mass sensor, which is composed of two cantilevers of 98 µm and 100 µm length, 20 µm width and 1.3 µm thick. They are connected by a coupling beam and only the shortest cantilever is actuated by a combined AC-DC voltage. The DC voltage is used to equilibrate the system and the phenomenon of mo...
Conference Paper
We investigate the effects of squeeze air film and initial deflection on the resonance frequencies and modal damping of capacitive circular microplates. The equation of motion of a circular microplate, which are derived from the von kármán plate theory, coupled with the Reynolds equation are discretized using the Differential Quadrature Method (DQM...
Conference Paper
Vibration Energy Harvesters (VEHs) are devices used to collect mechanical energy from the surrounding environment to supply low power electronic systems such as Wireless Sensor Nodes. In this paper, we introduce an electromagnetic VEH model and a semi-analytical method called Moment Equation Copula Closure (MECC) that is compared to Monte Carlo sim...
Article
Full-text available
The contributions put forth by this paper first include the design and testing of a new high performance electromagnetic vibration energy harvester based on an optimized electromagnetic structure and a friction-less compliant folded-beam suspension. Then, High Static Low Dynamic (HSLD) stiffness principle is used to reduce the resonance frequency o...
Conference Paper
Full-text available
Vibration energy harvesters (VEHs) provide an efficient solution for implementing self-sustained low power microelectromechanical systems. When operating linearly, unimodal VEHs have a narrow operating bandwidth. Consequently, their performances can be significantly reduced if the VEH resonance frequency and the excitation frequency do not coincide...
Conference Paper
Full-text available
The effect of disorder on the collective dynamics of two coupled nonlinear pendulums is investigated in this paper. The disorder is introduced by slightly perturbing the length of some pendulums in the nearly periodic structure. A generic discrete analytical model combining the multiple scales method and a standing-wave decomposition is proposed an...
Article
Full-text available
In the present paper, a quasi-periodic vibration energy harvester with magnetic coupling is proposed using the benefits of the energy localization. The proposed quasi-periodic system consists of moving magnets held by elastic structures and coupled by a magnetic force. The mistuning of the device can be achieved by changing either the linear mechan...
Article
Full-text available
A mechanical periodic structure in presence of component perturbations can be a seat of a localization of vibration energy. In fact, it is well known that mistuned components have larger response levels than those of perfect components. This results in a localized energy, which can be tapped via harvesting devices. In this study, the dynamic behavi...
Article
Full-text available
Vibration energy harvesting by exploiting the multimodal approach in a quasi-periodic system is proposed. The quasi-periodic system, based on electromagnetic transduction, consists of two weakly coupled magnets mechanically guided by two elastic beams. Mistuning is achieved by varying the mechanical stiffness of one of the beams. These imperfection...
Article
The evaluation of damping in the assembled structures presents a real challenge. Indeed, because of the nonlinear behavior of the dissipation and their localization in interfaces, the equations of motion of a dynamic system involve coupling terms. These coupling terms are generally neglected, in engineering applications, by the community because of...
Conference Paper
In this article, we investigate the nonlinear static and dynamic behavior of a clamped circular microplate in presence of imperfections. By taking in account the von K` armàn nonlinear-ity, the geometrical imperfections lead to a significant delay in static pull-in occurrence. Numerical simulations are performed in the frequency domain to study the...
Conference Paper
The collective nonlinear dynamics of electrostatically coupled nanobeams under parametric excitation is modeled and investigated , while including the main sources of nonlinearities up to the fifth order. The normalized nonlinear differential equations are solved using secular perturbation theory. Numerical simulations have been performed using the...
Conference Paper
Full-text available
In this paper, we propose a nonlinear multimodal vibration energy harvesting method using an array of coupled levitated magnets. This approach is validated with an experimental prototype of two magnets. The advantage of this device is the combination of the benefits of nonlinearities and modal interactions in order to enlarge the bandwidth and incr...
Conference Paper
Full-text available
The collective dynamics of a chain of coupled pendulums is investigated under simultaneous external and parametric excitation. The purpose of this study is to track the frequency response of the considered system in term of bifurcation topology with respect to the excitation amplitudes and structural imperfections. The equations of motion are deriv...
Conference Paper
Full-text available
Intrinsic Localized Modes (ILMs) or solitons are investigated in periodic arrays of coupled nonlinear resonators under simultaneous external and parametric excitations. The method of multiple scales is employed, transforming the dimensionless equations of motion into a damped driven Nonlinear Schrödinger (NLS) equation. Exact stationary soliton sol...
Article
Full-text available
Perfect structural periodicity is disturbed in presence of imperfections. The present paper is based on a realistic modeling of imperfections, using uncertainties, to investigate the robustness of the collective nonlinear dynamics of a periodic coupled pendulums chain. A generic discrete analytical model combining multiple scales method and standin...
Article
Purpose The purpose of this paper is to develop robust metamodels, which allow propagating parametric uncertainties, in the presence of localized nonlinearities, with reduced cost and without significant loss of accuracy. Design/methodology/approach The proposed metamodels combine the generalized polynomial chaos expansion (gPCE) for the uncertain...
Conference Paper
Full-text available
It is known that, when the mechanical coupling between the components is weak, small imperfections in a periodic structure can induce vibration localization. Stochastic analysis of near-periodic coupled pendulums chain is discussed in this paper. Perfect periodicity of the system is disturbed by varying randomly the length of one of the pendulums w...
Article
We propose a multiphysics model to investigate the nonlinear dynamics of two coupled nanocantilevers under electrostatic actuation and 1:1 internal resonance (IR). We demonstrate that the region below the first pull-in instability is governed by the veering phenomenon between the modes. IR conditions are analyzed in the veering region and the modul...
Article
The paper focuses on a MEMS mass detection sensor using mode localization and electrostatic actuation to counterbalance the manufacturing defects. The sensor is composed of two cantilevers with different lengths, connected together with a weak mechanical spring. A DC voltage is applied on the shortest beam so that the system is balanced when no mas...
Article
Capacitive micromachined ultrasonic transducers (CMUTs) are microelectromechanical systems used for the generation of ultrasounds. The fundamental element of the transducer is a clamped thin metallized membrane that vibrates under voltage variations. To control such oscillations and to optimize its dynamic response it is necessary to know the modal...
Article
The nonlinear dynamics of a weakly coupled pendulums chain is investigated under primary resonance. The coupled equations governing the nonlinear vibrations are normalized and transformed into a set of coupled complex algebraic equations using the multiple scales method coupled with standing wave decomposition. A model reduction method is proposed...
Article
Dynamic range improvement based on geometric nonlinearity and initial deflection is demonstrated with imperfect circular microplates under electrostatic actuation. Depending on design parameters, we prove how the von Kármán nonlinearity and the plate imperfections lead to a significant delay in pull-in occurrence. These promising results open the w...
Conference Paper
In order to ensure more realistic design of nonlinear periodic structures, the collective dynamics of a coupled pendulums system is investigated under parametric uncertainties. A generic discrete analytical model combining the multiple scales method, the perturbation theory and a standing-wave decomposition is proposed and adapted to the presence o...
Conference Paper
The collective dynamics of an array of periodic two dimensional (2D) coupled pendulums under harmonic horizontal base excitation is investigated. The coupled differential equations governing the nonlinear vibrations of the considered system have been solved using an analytical-numerical solving procedure , based on the multiple scales method couple...
Conference Paper
Full-text available
We study wave propagation in a damped driven discrete nonlinear two-dimensional (2D) periodic structure. The considered system is composed of identical spherical particles and subjected to harmonic horizontal base excitation, where its collective nonlinear dynamics is caused by the Hertzian contact law and the applied compressive load. The coupled...
Conference Paper
Full-text available
To achieve robust design, in presence of uncertainty, nonlinearity and structural periodicity, a metamodel combining the Latin Hypercube Sampling (LHS) method for uncertainty propagation and an enriched Craig-Bampton Component Mode Synthesis approach (CB-CMS) for model reduction is proposed. Its application to predict the time responses of a stocha...
Conference Paper
Full-text available
The collective nonlinear dynamics of electrostatically coupled microbeams under parametric excitation is modeled and investigated, while including the main sources of nonlinearities up to the fifth order. The nonlinear equations of motion are solved using secular perturbation theory coupled with standing wave decomposition. Numerical simulations ha...
Conference Paper
Full-text available
Linear VEH has been widely studied and is well understood, several researchers proposed to add nonlinear cubic stiffness to enhance its performances and especially to widen its frequency band under harmonic excitation. Because most of the real life vibrations are random by nature, the behavior of nonlinear VEH under white noise excitation has been...
Conference Paper
We investigate the nonlinear dynamics of magnetically coupled beams for multi-modal vibration energy harvesting. A multi-physics model for the proposed device is developed taking into account geometric and magnetic nonlinearities. The coupled nonlinear equations of motion are solved using the Galerkin discretization coupled with the harmonic balanc...
Article
We propose a multi-modal vibration energy harvesting approach based on arrays of coupled levitated magnets. The equations of motion which include the magnetic nonlinearity and the electromagnetic damping are solved using the harmonic balance method coupled with the asymptotic numerical method. A multi-objective optimization procedure is introduced...