- Dr Asanedit
Magnetorheological elastomers (MRE) are smart composite materials by which their mechanical properties, such as stiffness, are changed under a magnetic field. In this article, the introduction of a variable stiffness coupling (VSC) fitted... more
Magnetorheological elastomers (MRE) are smart composite materials by which their mechanical properties, such as stiffness, are changed under a magnetic field. In this article, the introduction of a variable stiffness coupling (VSC) fitted within a shaft for torsional vibration isolation that would adapt and change its attenuation frequency range is presented. The VSC concept on torsional vibration isolation is tested experimentally. MRE samples with 40% volume fraction are fabricated and manufactured using a 3D mold design and fixed within a coupling in a shaft to investigate the magnetic field effect on the torsional rigidity. Impact hammer test is conducted along with an accelerometer to obtain the transmissibility factor analysis. Results show that the vibration level decreases when the magnetic field increases. The 1st natural frequency of the system happened at 26 Hz and moved to 28 Hz when the applied current increases from 0 mT to 12.38 mT. MRE torsional stiffness increased f...
Research Interests:
The measurement of blood glucose levels is essential for diagnosing and managing diabetes. Enzymatic and nonenzymatic approaches using electrochemical biosensors are used to measure serum or plasma glucose accurately. Current research... more
The measurement of blood glucose levels is essential for diagnosing and managing diabetes. Enzymatic and nonenzymatic approaches using electrochemical biosensors are used to measure serum or plasma glucose accurately. Current research aims to develop and improve noninvasive methods of detecting glucose in sweat that are accurate, sensitive, and stable. The carbon nanotube (CNT)-copper oxide (CuO) nanocomposite (NC) improved direct electron transport to the electrode surface in this study. The complex precipitation method was used to make this NC. X-ray diffraction (XRD) and scanning electron microscopy were used to investigate the crystal structure and morphology of the prepared catalyst. Using cyclic voltammetry and amperometry, the electrocatalytic activity of the as-prepared catalyst was evaluated. The electrocatalytic activity in artificial sweat solution was examined at various scan rates and at various glucose concentrations. The detection limit of the CNT-CuO NC catalyst was ...
Research Interests:
Research Interests:
Research Interests:
One of the significant symptoms in Parkinson’s disease is resting tremor. Resting tremor occurs when the muscle is relaxed, causing the limb to shake. Rhythmic muscle movement of the patients commonly happens within the range of 4 Hz to 6... more
One of the significant symptoms in Parkinson’s disease is resting tremor. Resting tremor occurs when the muscle is relaxed, causing the limb to shake. Rhythmic muscle movement of the patients commonly happens within the range of 4 Hz to 6 Hz. Thus, reducing this type of tremor will help improve patients’ quality of life. In this paper, to suppress resting tremors, an intelligent glove was designed utilizing the concepts of vibrations and gyro effect. A rotating brass disc attached to the glove creates a gyroscopic effect of the smart glove. Therefore, the disc will do their utmost to stay upright and counter any input forces instantaneously by providing the counterforce. A reduction of more than 50 % with the intelligent glove is also shown.
Research Interests:
Parkinson’s disease is a central nervous system disorder, whose effects and symptoms are evident in the physical movement and appearance of the patient. The frequency range of 2–10 Hz is mostly where the balanced muscles movement of the... more
Parkinson’s disease is a central nervous system disorder, whose effects and symptoms are evident in the physical movement and appearance of the patient. The frequency range of 2–10 Hz is mostly where the balanced muscles movement of the patients happens. This paper seeks to create a wearable device that is capable of suppressing these tremors within a specific frequency range by examining the system with and without dynamic vibration absorber (DVA) is done for three main positions, normal, short, and long positions; so that the stiffness and the natural frequency changes. The dynamic vibration absorber, tremor suppression will be achieved. The dynamic vibration absorber is set to be a spring-mass system. From the findings of the experimental studies realizing such a device is possible and that varying the absorber parameters of the device can achieve different levels and degrees of tremor suppression. The proposed DVA showed more than 60% of the vibration suppression. The proposed method is reliable for vibrations suppression for tremors of Parkinson’s disease and it is simple without using multiple devices so that it is more comfortable for patients.
Research Interests:
A stable voltage supply is important for the proper operation of electronic devices. Stability is characterized by the ability of the voltage output to stay constant and ripplefree regardless of how much load is connected to the circuit.... more
A stable voltage supply is important for the proper operation of electronic devices. Stability is characterized by the ability of the voltage output to stay constant and ripplefree regardless of how much load is connected to the circuit. There is a brief discussion on how much inaccuracy is caused by voltage supplies which are prone to voltage fluctuations due to switching phenomenon taking place in the circuit, load fluctuations or temperature changes
Research Interests:
The active suppression of structural vibration is normally achieved by either feedforward or feedback control. In the absence of a suitable reference signal feedforward control cannot be employed and feedback control is the only viable... more
The active suppression of structural vibration is normally achieved by either feedforward or feedback control. In the absence of a suitable reference signal feedforward control cannot be employed and feedback control is the only viable approach. Conventional feedback control algorithms (e.g. LQR and LQG) are designed on the basis of a mathematical model of the system and ideally the performance of the system should be robust against uncertainties in this model. The aim of this paper is to numerically investigate the robustness of LQR and LQG algorithms by designing the controller for a nominal system, and then assessing (via Monte Carlo simulation) the effects of uncertainties in the system. The ultimate concern is with the control of high frequency vibrations, where the short wavelength of the structural deformation induces a high sensitivity to imperfection. It is found that standard algorithms such as LQR and LQG are generally unfeasible for this case. This leads to a considerati...
Research Interests:
The aim of this project was to carry out fundamental investigation on the nano-powder assisted wire EDM fabrication process for micro mirror. The WEDM machine at International Islamic University Malaysia was used. Different quantity and... more
The aim of this project was to carry out fundamental investigation on the nano-powder assisted wire EDM fabrication process for micro mirror. The WEDM machine at International Islamic University Malaysia was used. Different quantity and size of conductive nano-powder will be used along with the dielectric liquid to improve the surface quality of micro mirror. The surface roughness and optical reflectivity will be investigated thoroughly with standard equipment which will corelated with the various process parameters. The target of roughness of surface around Ra(50nm). Successful completion of the project will lead to characterization of new type of nano-powder assisted WEDM process.
Research Interests:
Research Interests:
Energy harvesting has been around for centuries in the form of windmills, watermills and passive solar power systems. It is not only restricted to the natural resources but it has widen the tapping source to utilise the vibration which... more
Energy harvesting has been around for centuries in the form of windmills, watermills and passive solar power systems. It is not only restricted to the natural resources but it has widen the tapping source to utilise the vibration which happen all around us. In the last decade, beam with piezoceramic patches have been used as a method to harverst energy. An energy harvester system modelled in this paper consist of unimorph piezoelectic cantilever beam with a tip mass. It generates electric current or voltage from the piezoelectric strain effect due to base excitation. This paper is aimed at developing a mathematical model of unimorph cantilever beam with piezoelectric harvester by using Euler- Bernoulli beam theory. The step by step analytical solution and the simulation result are shown in the form of voltage around the natural frequencies.
Research Interests:
In order to ensure a constant voltage source, we employ line regulation, load regulation and ripple rejection. These are often small deviations in the input voltage. A spike or surge is a sudden large deviation in the circuit that usually... more
In order to ensure a constant voltage source, we employ line regulation, load regulation and ripple rejection. These are often small deviations in the input voltage. A spike or surge is a sudden large deviation in the circuit that usually only lasts for a very short period of time, for example lightning surges. This characteristic means that regulator circuits designed for line regulation and ripple rejection may not be able to handle the large load of a surge and may not be able to respond fast enough to make any meaningful difference [1]. Spikes are extremely damaging to a circuit since the voltage of a spike such as a lightning surge can be thousands of times the intended voltage of the circuit
Research Interests:
Vertically Aligned Carbon Nanotubes (VACNTs) has captured attention by the researchers because of their flexibility and other attractive engineering properties. They are promising to be used as a functional bulk material in MEMS as well... more
Vertically Aligned Carbon Nanotubes (VACNTs) has captured attention by the researchers because of their flexibility and other attractive engineering properties. They are promising to be used as a functional bulk material in MEMS as well [1]. VACNT array (CNT forest) is known to be the darkest material on Earth because of their unique absorption index. However, this author has shown and explained that tip bent carbon nanotube forest can reflect light like mirror [2].This paper reports that selectively tip bent CNT forest act as an anisotropic mirror, and this property can be exploited to fabricate CNT-based flexible angle sensor that is first of its kind. In this report, we presented a method that can bend the tips of the CNT inside a VACNT array as described in Fig. 1(a). A rigid cylindrical tool rolls over the CNT forest to bend and align the CNTs in the direction of the tool motion. The alignment of the CNTs after process can be observed in Fig. 1(b). Later optical characterizatio...
Research Interests:
Research Interests:
This research describes a resonance principle-based low power Wireless Power Transfer (WPT) system. The reflective impedance model is derived to evaluate the resonance coupling between coils. Additionally, Cockroft Walton voltage boosting... more
This research describes a resonance principle-based low power Wireless Power Transfer (WPT) system. The reflective impedance model is derived to evaluate the resonance coupling between coils. Additionally, Cockroft Walton voltage boosting circuit is incorporated to boost up the received voltage to the appropriate level, instead of using traditional conditioning circuits. The prototype model, operating at 130 kHz, is demonstrated experimentally and analysed graphically to validate the performance of designed circuit. For an overall span of 100 mm coil separation distance, the maximum efficiency of 60% with no load and 36% loaded system, is observed at a distance of 55 mm with the approximate (e.g., manual) axial orientation of coils. It can be supported widely for the portable electronic products and biomedical devices. As an added contribution, the WPT circuit were enabled by a password security feature using an arduino nicrocontroller.Â
Research Interests:
This paper presents the new coil design strategy for Wireless Power Transfer (WPT) applications. In order to produce better power transfer efficiency for remotely located load, hybrid approach is proposed using two different coils such as... more
This paper presents the new coil design strategy for Wireless Power Transfer (WPT) applications. In order to produce better power transfer efficiency for remotely located load, hybrid approach is proposed using two different coils such as conical and spiral. Hybrid approach refers the coil model by engaging conical as a transmitter and spiral as a receiver in a single system. The field pattern of conical coil is cumulative so that better magnetic field is possible at the bottom side for high directivity. In contrast, the spiral coil produces distributive field pattern so that the field distribution is uniform. Taking advantage of these two different behaviors, better power efficiency would be achieved by reducing power loss in the coil zone. For this hybrid approach, Finite Element Method (FEM) based conical and spiral coils were developed and simulated to determine field patterns and their value. Two different prototypes (Conical and spiral) were experimented with fixed spiral load coil to validate the performance of the hybrid approach. The output load coil voltage and efficiency plots were made based on the measurement, for analyzing the system performance. It is recorded the efficiency of 72% with the optimum distance 10cm and biasing voltage 10V respectively. The results from simulation as well as experiment confirms that hybrid approach could support significantly to reduce power loss and increase the relative operative distance.
Research Interests:
Mechanical systems with rotary machines or rotating elements experience torsional vibration, which may lead to an extreme damage and wear. Conventionally, to isolate these undesirable structural vibrations, passive elastomer or torsional... more
Mechanical systems with rotary machines or rotating elements experience torsional vibration, which may lead to an extreme damage and wear. Conventionally, to isolate these undesirable structural vibrations, passive elastomer or torsional dampers are used. However, these passive vibration isolators are not adaptive to varying oscillation frequencies in real time. Due to the need for a real time adaptability and controllable stiffness, the research and development of a smart material called magnetorheological elastomer (MRE) is of interest. This paper presents the mathematical modelling and development of MRE with its implication in torsional vibration control. Based on the model and through experimental studies, the properties of the MRE such as stiffness and transmissibility factor in regard to varying magnetic fields are investigated. The change in magnetic field is achieved by changing the amount of applied current. It is found out that the stiffness of MRE increases with increasing magnetic field and consequently modifies system’s natural frequency. This allows shift in the transmissibility curve to achieve minimum transmissibility factor in the applications involving varying frequency.
Research Interests:
Research Interests:
This paper is a preliminary work to explore the feasibility of cubic silicon carbide on silicon wafers with integrated proof mass as horizontal cantilever with vertical displacement. The reason of harvesting ambient vibration energy is to... more
This paper is a preliminary work to explore the feasibility of cubic silicon carbide on silicon wafers with integrated proof mass as horizontal cantilever with vertical displacement. The reason of harvesting ambient vibration energy is to convert mechanical energy produces by piezoelectric into useful electrical energy. The collectable energy is useful for powering the low-power devices. Theoretically, the resonant phenomena are a special characteristic in order to optimize the generated output power. The natural frequency of the cantilever can to be tuned with difference proof masses. Another parameter considered in this paper is the damping ratio. Throughout analytical study, small damping ratio will enhance the output power of the piezoelectric energy harvester (PEH). This paper will present a mathematical modelling approach and the simulation validation.
Research Interests:
Research Interests:
The control of broadband steady state vibration amplitude of a multi-mode system is presented. This objective is achieved using an Active Dynamic Vibration Absorber (ADVA). The stiffness property of the ADVA is adaptively tuned to... more
The control of broadband steady state vibration amplitude of a multi-mode system is presented. This objective is achieved using an Active Dynamic Vibration Absorber (ADVA). The stiffness property of the ADVA is adaptively tuned to attenuate the vibration of the multi-mode system at resonance. The ADVA detects the excitation frequency of the multi-mode system and calibrates its stiffness property to give the required stiffness for that mode. To implement the ADVA, a prototype model with low modal frequencies is designed. The equations of the steady state response of the multi-mode system with the attached ADVA are derived. The behavior of the prototype model when the ADVA is attached to different locations is used to determine the optimal location of the ADVA. The simulation result shows a reduction in the broadband of the multi-mode system. The result of the implementation of the ADVA reveals a 46%, 73% and 97% vibration amplitude reduction at first, second and third mode of the mul...
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Harvesting energy from ambient structural vibration using piezoelectric materials gained massive interest in the past decade. Piezoelectric harvesters can be incorporated in many applications; however, one of the main challenges to become... more
Harvesting energy from ambient structural vibration using piezoelectric materials gained massive interest in the past decade. Piezoelectric harvesters can be incorporated in many applications; however, one of the main challenges to become widely adopted is to optimize their design for maximum energy harvesting. In this paper, we investigated energy harvesting from a piezoelectric patch that is attached to a non-deterministic thin plate vibrating in bending. Energy harvesting from six patch shapes (differing in the number of edges) was examined through a coupled-field finite element model. The thin plate was simply supported with nominal geometry and material properties. The plate’s dynamics were randomized by randomly distributing point masses on its bottom surface; this made the plate a non-deterministic subsystem. The design optimization was performed by changing the shape of the piezoelectric patch and analyzing the ensemble response of the electrical potential across the piezoel...
Research Interests:
Recently, many researchers are interested with Free Space Optics (FSO) communication since its deliver wireless data transmission between transceivers. One of the key challenges with FSO systems is maintaining alignment between... more
Recently, many researchers are interested with Free Space Optics (FSO) communication since its deliver wireless data transmission between transceivers. One of the key challenges with FSO systems is maintaining alignment between transceivers. Since the beam signal is transmitted through the free space, the optical signal propagation is affected by atmospheric turbulence and pointing error. Hence, tracking system is required to reduce or eliminate the misalignment between the transmitter and receivers. In order to implement this system, a prototype model perform experiments is required. This research project and grant aims to develop/fabricate the required prototype model to study the implementation of tracking system
Research Interests:
Research Interests:
AC voltage supplies are commonly available in our residential or induSlIial envilllfllllent. however in consumer electronics the supply required is always DC voltage ~upply. Many devices employed for sensitive electronic operations. such... more
AC voltage supplies are commonly available in our residential or induSlIial envilllfllllent. however in consumer electronics the supply required is always DC voltage ~upply. Many devices employed for sensitive electronic operations. such as fine-luning and control. require an almost perfect DC voltage level which is normally obtained from Ihe available AC supply. However, mainlllining a perfectly constant voltage in the cUe of a supply is a challenging task to accomplish. The solution for this dilemma is 10 take thc AC voltage lind lectify it into a DC voltage supply (Scllaefer, 1%5; Baliga, 2010). To that end. many such circuits have been constructed. Here we explore a few rectifiers lIl1d discuss their mcthud ofopemtion
Research Interests:
Micro-Wire Electro-discharge machining (-WEDM) is a nonconventional machining technology which is extensively used for metal based micro fabrication process. This is a non-contact machining process where material removal is taken place... more
Micro-Wire Electro-discharge machining (-WEDM) is a nonconventional machining technology which is extensively used for metal based micro fabrication process. This is a non-contact machining process where material removal is taken place by electro-thermal action. -WEDM process is difficult to be applied for semiconductor material like Silicon (Si). In this paper a new approach is proposed for machining polished Si (p-type, resistivity 1-50 -cm) wafer. In this method, initially Si workpiece is coated with a conductive material (gold for this study) and then -WEDM operation is carried out. Finally, after WEDM operation, the conductive layer is removed from the polished Si substrate without damaging the substrate. WEDM process stability was found to be improved (up to 60 times for certain machining condition) if coated Si wafer is used as compared to uncoated Si workpiece. Material removal rate was also found to be increased by a good margin (~ 100% maximum) for coated Si wafer. Ove...
Research Interests:
Piezoelectric (PZT) shunt damping is an effective method to dissipate energy from a vibrating structure; however, most of the applications focus on targeting specific modes for structures vibrating at low-frequency range, i.e.... more
Piezoelectric (PZT) shunt damping is an effective method to dissipate energy from a vibrating structure; however, most of the applications focus on targeting specific modes for structures vibrating at low-frequency range, i.e. deterministic substructure (DS). To optimally attenuate structures vibrating at high-frequency range, i.e. non-deterministic substructure (Non-DS) using a PZT shunt damper, it is found that the impedance of the PZT patch’s terminal needs to be the complex conjugate of its inherent capacitance paralleled with the impedance ‘faced’ by its non-deterministic host structure underline moment actuation. The latter was derived in terms of estimation of the effective line moment mobility of a PZT patch on a Non-DS plate by integrating the expression of driving point moment mobility of an infinite thin plate. This paper conducts a parametric investigation to study the effect of changing the size, quantity and configuration of the PZT patch to the performance of the opti...
Research Interests:
Research Interests:
This paper introduces the improved parameter estimation of Magnetorheological fluid (MRF) damper models for varying input current. The models being studied for the estimation are Bingham model, Simple Bouc-Wen model, Modified Bouc-Wen... more
This paper introduces the improved parameter estimation of Magnetorheological fluid (MRF) damper models for varying input current. The models being studied for the estimation are Bingham model, Simple Bouc-Wen model, Modified Bouc-Wen model, Hyperbolic Tangent Function model, and Nonlinear Biviscous model. In estimating the parameters of the models, a comparison between the simulation and the experimental results are made. The mathematical equations of each parameter are established as a function of the input current through curve fitting method. In order to optimize the estimation, the mathematical equations are divided into two range. It is found out that the model with the least value of parameter estimation error is Modified Bouc-Wen.
December 2004 recorded a tragic scene of human suffering caused by Asian Tsunami disaster. Due to fault displacement within the convergent boundary zone between the Indian oceanic plate and the Eurasia continental plate, an earthquake... more
December 2004 recorded a tragic scene of human suffering caused by Asian Tsunami disaster. Due to fault displacement within the convergent boundary zone between the Indian oceanic plate and the Eurasia continental plate, an earthquake results large tsunamis disaster which killed over 165,000 people in early January 2005. Relatively, only few animals have been reported dead, which revives speculation that animals somehow sense impending disaster [1]. In March 11, 2011, a 9.0 magnitude of earthquake had strike Japan which tolls 10,000 deaths.Estimated more than 434,000 people are homeless and live in shelter. The government of Japan stated that damaged due to this disaster could cause up to $310 billion, making it the most costly natural disaster recorded. Debate was over the scope for predicting or warning of a tsunami. In this scene, it is noted thatmany animals moved inland to safety before the first wave strike [1-5]. Eyewitness said that elephants screamed and ran for higher grou...
Research Interests: Engineering and IIUM
A basic analysis of inductive coils and its parameter calculations are presented. The simulations of mutual inductance, coupling factor calculations are demonstrated with graphical analysis. Three different lab-scale coil models such as... more
A basic analysis of inductive coils and its parameter calculations are presented. The simulations of mutual inductance, coupling factor calculations are demonstrated with graphical analysis. Three different lab-scale coil models such as square, circular and rectangular coils are wounded to evaluate the magnetic field by experiment, to validate the performance of Wireless Power System (WPT). In the open literature, circular coils are employed in most of the works, but few works have been reported in the parameter analysis. Further investigations on parameter exploration seems as a prerequisite for magnetic field measurement by estimating the parameters such as mutual inductance(M), coupling factor(k), magnetic flux(Φ) and magnetic field(B). It helps us to select the coils according to the applications. In this work, it is observed that circular performs well than other shaped coils in terms of parametrical analysis which are mentioned above. The simulation, and experimental results a...
Research Interests:
Research Interests:
This paper presents recent mechatronics technology that can help to implement predictive maintenance by combining intelligent and predictive maintenance instrument. Vibration Fault Simulation System (VFSS) is an example of mechatronics... more
This paper presents recent mechatronics technology that can help to implement predictive maintenance by combining intelligent and predictive maintenance instrument. Vibration Fault Simulation System (VFSS) is an example of mechatronics system. The focus of this study is the prediction on the use of critical machines to detect vibration. Vibration measurement is often used as the key indicator of the state of the machine. This paper shows the choice of the appropriate strategy in the vibration of diagnostic process of the mechanical system, especially rotating machines, in recognition of the failure during the working process. In this paper, the vibration signature analysis is implemented to detect faults in rotary machining that includesimbalance, mechanical looseness, bent shaft, misalignment, missing blade bearing fault, balancing mass and critical speed. In order to perform vibration signature analysis for rotating machinery faults, studies have been made on how mechatronics technology is used as predictive maintenance methods. Vibration Faults Simulation Rig (VFSR) is designed to simulate and understand faults signatures. These techniques are based on the processing of vibrational data in frequency-domain. The LabVIEW-based spectrum analyzer software is developed to acquire and extract frequency contents of faults signals. This system is successfully tested based on the unique vibration fault signatures that always occur in a rotating machinery.
Research Interests:
Research Interests:
Energy harvesting has experienced significant attention from researchers globally. This is due to the quest to power remote sensors and portable devices with power requirements of tens to hundreds of μW. Hence, ambient vibration energy... more
Energy harvesting has experienced significant attention from researchers globally. This is due to the quest to power remote sensors and portable devices with power requirements of tens to hundreds of μW. Hence, ambient vibration energy has the potential to provide such power demands. Thus, cantilever beams with piezoelectric materials have been utilized to transduce mechanical energy in vibrating bodies to electrical energy. However, the challenge is to develop energy harvesters that can harvest sufficient amount of energy needed to power wireless sensor nodes at wide frequency bandwidth. In this article, piezoelectric energy harvester (PEH) beams with coupled magnets are proposed to address this issue. With macro fiber composite as the piezoelectric transducer, mathematical models of different system configurations having magnetic couplings are derived based on the continuum based model. Simulations of the system dynamics are done using numerical integration technique in MATLAB software to study the influence of magnetic interactions in generating power and frequency bandwidth due to base excitations at low frequency range. Experimental results comparing conventional system and the proposed piezoelectric beam configurations with coupled magnets are also presented. Finally, the optimal beam separation distance between the magnetic oscillator and PEH is presented in this work.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Active vibration control of the first three modes of a vibrating cantilever beam using piezoelectric patches is examined in this paper. A model based on Euler-Bernoulli beam equation is adopted and extended to the case of three bonded... more
Active vibration control of the first three modes of a vibrating cantilever beam using piezoelectric patches is examined in this paper. A model based on Euler-Bernoulli beam equation is adopted and extended to the case of three bonded piezoelectric patches which act as sensor, actuator and exciter respectively. The sensor and the actuator are collocated to achieve a minimum phase. A compensated inverse PID controller has been designed and developed to damp these modes. Simulation studies are carried using MATLAB. ...
Research Interests:
Ordinary fixed controllers designed based on nominal parameters do not take into account the uncertainties present in and around the system and hence lose their effectiveness when subjected to uncertainties. To overcome this, a robust... more
Ordinary fixed controllers designed based on nominal parameters do not take into account the uncertainties present in and around the system and hence lose their effectiveness when subjected to uncertainties. To overcome this, a robust control system that accommodates uncertainties is crucial. Structural uncertainties could alter mass, damping and stiffness matrices of a system which in turn perturb its eigenvalues. Based on this, uncertainties in mass, damping and stiffness matrices are represented in terms of changes in eigenvalues. In this paper, an analytical solution for estimating the changes in eigenvalues of a plate–like structure when subjected to structural uncertainties is derived. The derived changes in eigenvalues are represented in terms of changes in mass and stiffness. The variation in eigenvalues obtained from analytical solution is then compared with numerical simulation. Based on the results obtained, the proposed estimation technique can aid in the design of robust controller for vibration control.
Research Interests:
In rotating machinery, unattenuated excessive torsional vibration leads to damage and excessive wear. This type of vibration, which is transferred from one structure to another can be estimated using torsional transmissibility factor... more
In rotating machinery, unattenuated excessive torsional vibration leads to damage and excessive wear. This type of vibration, which is transferred from one structure to another can be estimated using torsional transmissibility factor (TTF). The value of the TTF describes the ratio of output to input and reaches its peak at the natural frequency. Hence, the ability to vary coupling stiffness of two rotating shafts will allow the control of the TTF towards better performance and preventions from fatigue loading. Traditionally, passive rubbers are used as a flexible coupling in between two shafts. However, the constant passive stiffness of the material limits its performance. To address this issue, an adaptive coupling based on magnetorheological elastomer (MRE) is proposed to achieve better TTF at varying frequencies. Mathematical modelling, simulation study and experimental results of MRE for torsional vibration isolation are presented in this work. Natural frequency obtained from th...
Research Interests:
This project presents an innovation to be developed in wheelchairs used nowadays to provide its users with better life quality, elevates the level of their ambitions and to enable them to overcome today’s special needs obstacles in... more
This project presents an innovation to be developed in wheelchairs used nowadays to provide its users with better life quality, elevates the level of their ambitions and to enable them to overcome today’s special needs obstacles in different fields. As engineers, it is our role to contribute to finding answers to the world’s dilemmas through applying a detailed analysis of the issue addressed and what are the possible solutions to it based on the knowledge obtained through our academic and experimental experience. Wheelchair users are suffering from discrimination in different aspects of life, such as work opportunities, usage of public facilities and many other life aspects. The standing wheelchair with built-in climate control system will introduce a new horizon for its users in the search of social equality and achievement. The mechanism to be developed is made of 4 different subsystems that demonstrate different mechanical engineering disciplines, which are mainly mechanical mec...
Magnetorheological Elastomer (MRE) is a type of smart composite material consisting of a polymer matrix embedded with ferromagnetic particles. In the presence of an external magnetic field, its mechanical properties, such as stiffness,... more
Magnetorheological Elastomer (MRE) is a type of smart composite material consisting of a polymer matrix embedded with ferromagnetic particles. In the presence of an external magnetic field, its mechanical properties, such as stiffness, changes make it attractive in vibration isolation applications. Unwanted vibration in machines can cause severe damage and machine breakdown. In Qatar, the extraction of the natural gas from the ground requires sophisticated drilling machines. In this work, a semi-active vibration isolator using MRE is proposed for a potential application in a drilling system to isolate the torsional vibration. MRE was fabricated with a 35% mass fraction (MF) consisting of silicon rubber and iron particles. It was fitted with aluminum couplers and attached to the shaft (drill string) to study its efficiency in vibration isolation under a magnetic field. Two tests were conducted on the drilling prototype setup used in this work; the first test was a hammer impact test....