Hadi Madinei

Swansea University | SWAN · College of Engineering

This paper aims to investigate the pull-in phenomenon of functionally graded (FG) capacitive nanocantilevers subjected to an electrostatic force and thermal moment due to an applied voltage and thermal shock considering the intermolecular force within the framework of nonlocal elasticity theory to account for the small scale effect. The FG nano-bea...

This paper deals with the effect of the intrinsic material length-scale parameter on the stability and natural frequency of a rectangular micro-plate for two different cases; fully clamped and fully simply supported. A variational formulation based on Hamilton’s principle and the modified couple stress theory is used to obtain the nonlinear governi...

Nano molecular adsorption of bio particles made it possible to design and produces of some micro sensors that can sense some vital characteristics of a patient. In this paper, electromechanical characteristics of such a device are investigated and a novel suggestion is made to increase its sensitivity. The device is a micro-cantilever beam submerge...

This paper deals with the study of structural noise in a capacitive MEMS microphone, which consists of a fully clamped circular micro-plate. The micro-plate is subjected to a bias DC voltage and sound pressure waves. Due to the nonlinearity and displacement dependency of the electrostatic force, the amplitude of the applicable bias DC voltage has s...

This paper deals with the study of parametric oscillation of an electrostatically actuated microbeam using variational iteration method. The paper considers a micro-beam suspended between two conductive micro-plates, subjected to a same actuation voltage. The nonlinear governing differential equation of motion about static equilibrium position usin...

The study presents a novel approach for stochastic nonlinear model updating in structural dynamics, employing a Bayesian framework integrated with Markov Chain Monte Carlo (MCMC) sampling for parameter estimation by using an approximated likelihood function. The proposed methodology is applied to both numerical and experimental cases. The paper com...

The study presents a novel approach for stochastic nonlinear model updating in structural dynamics, employing a Bayesian framework integrated with Markov Chain Monte Carlo (MCMC) sampling for parameter estimation by using an approximated likelihood function. The proposed methodology is applied to both numerical and experimental cases. The paper com...

This research investigates the feasibility of mass sensing in piezoresistive MEMS devices based on catastrophic bifurcation and sensitivity enhancement due to the orientation adjustment of the device with respect to the crystallographic orientation of the silicon wafer. The model studied is a cantilever microbeam at the end of which an electrostati...

In this paper, we propose an active control method to adjust the resonance frequency of a capacitive energy harvester. To this end, the resonance frequency of the harvester is tuned using an electrostatic force, which is actively controlled by a voltage source. The spring softening effect of the electrostatic force is used to accommodate the domina...

The objective of the present study is to examine the effect of nonlinearity on the efficiency enhancement of a capacitive energy harvester. The model consists of a cantilever microbeam underneath which there is an electret layer with a surface voltage, which is responsible for the driving energy. The packaged device is exposed to unwanted harmonic...

The impetus of the present study is to examine the effect of nonlinearity on the efficiency enhancement of a capacitive energy harvester. The model consists of a cantilever microbeam underneath which there is an electret layer with a surface voltage, which is responsible for the driving energy. The packaged device is exposed to unwanted harmonic me...

The objective of this study is to investigate the sensitivity of the Equivalent Dynamic Stiffness Mapping (EDSM) identification method to typical types of inaccuracy that are often present during the identification process. These sources of inaccuracy may include the presence of noise in the simulated/measured data, expansion error in the estimatio...

Nonlinear localization approaches are used not only for detecting the exact location of the nonlinear elements in mechanical structures, but they are also exploited in order to find any possible flaws such as cracks in Structural Health Monitoring (SHM) applications. This study aims to develop a localization method to determine the location of loca...

This study explores heat-induced nonlinear vibration of a functionally graded (FG) capacitive nanobeam within the framework of nonlocal strain gradient theory (NLSGT). The elastic FG beam, which is firstly deflected by a DC voltage, is driven to vibrate about its deflected position by a periodic heat load. The nano-structure, which consists of a cl...

Dynamic properties of the contact interfaces in joints and mechanical connections have a great influence on the overall dynamic properties of assembled structures. Uncertainty and nonlinearity are two major effects of contact interfaces which introduce challenges in accurate modeling. Randomness in surface roughness quality, surface finish and cont...

Contact interfaces are one of the main sources of variability in the dynamic properties of assembled structures. This variability is due to the randomness in the surface roughness quality and the nonlinear mechanism such as slip. It can also affect the dynamic behaviour of the joints both in linear and nonlinear regions. It is possible to measure t...

Identification of structural nonlinearities has been of great interest over recent decades. In addition, due to high cost and time requirements, it is not practical to have complete experimental measurements. This study is initially focused on the localisation of structural nonlinearities using an approach based on spatially incomplete experimental...

In this paper, a finite element model is coupled to an homogenisation theory in order to predict the energy harvesting capabilities of a porous piezoelectric energy harvester. The harvester consists of a porous piezoelectric patch bonded to the root of a cantilever beam. The material properties of the porous piezoelectric material are estimated by...

This paper proposes the use of an electrostatic device to improve the performance of MEMS piezoelectric harvesters in the presence of manufacturing uncertainties. Different types of uncertain parameters have been considered and randomised according to their experimentally measured statistical properties. It has been demonstrated that manufacturing...

This paper investigates the use of an electrostatic device to improve the performance of MEMS piezoelectric harvesters in the presence of geometric and structural variabilities due to the manufacturing process. Different types of uncertain parameters including material and geometric uncertainties have been considered. The variability of these param...

In this paper, a homogenised finite element model is developed to predict the energy harvesting capabilities of a porous piezoelectric energy harvester. The harvester consists of a porous piezoelectric patch bonded to a cantilever beam. The material properties of the porous piezoelectric material are estimated by the Mori-Tanaka homogenisation meth...

A new formulation for calculating the steady-state responses of multiple-degree-of-freedom (MDOF) non-linear dynamic systems due to harmonic excitation is developed. This is aimed at solving multi-dimensional nonlinear systems using linear equations. Nonlinearity is parameterised by a set of ‘non-linear control parameters' such that the dynamic sys...

This paper investigates the use of a MEMS energy harvester with adjustable resonance frequency to improve the performance of MEMS harvesters in the presence of manufacturing uncertainties. Model parameters which are subject to considerable variability have been selected and standard Monte Carlo simulation (MCS) is used for uncertainty propagation....

This paper investigates the use of electrostatic forces for vibration control of MEMS devices. A micro beam subject to electrostatic loading is considered. The electrostatic forces cause softening nonlinearity and their amplitudes are proportional to the square of applied DC voltages. An optimization problem is set up to minimize the vibration leve...

Micro Electro Mechanical Systems for vibration energy harvesting have become popular over recent years. At these small length scales electrostatic forces become significant, and this paper proposes a hybrid cantilever beam harvester with piezoelectric and electrostatic transducers for narrow band base excitation. One approach would be to just combi...

In this paper an adaptive tuned piezoelectric vibration based energy harvesting system based on the use of electrostatic device is proposed. The main motivation is to control the resonance frequency of the piezoelectric harvester with the DC voltage applied to the electrostatic system in order to maximize the harvested power. The idea is demonstrat...

This paper deals with the study of bifurcational behavior of a capacitive microbeam actuated by asymmetrically located electrodes in the upper and lower sides of the microbeam. A distributed and a modified two degree of freedom (DOF) mass-spring model have been implemented for the analysis of the microbeam behavior. Fixed or equilibrium points of t...

This paper deals with the study of structural noise in a capacitive MEMS microphone, which consists of a fully clamped circular micro-plate. The micro-plate is subjected to a bias DC voltage and sound pressure waves. Due to the nonlinearity and displacement dependency of the electrostatic force, the amplitude of the applicable bias DC voltage has s...