CERES :: Browsing by Author "Zhu, Meiling"

Browsing by Author "Zhu, Meiling"

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Open Access
Analyses of Power Output of Piezoelectric Energy-Harvesting Devices Directly Connected to a Load Resistor Using a Coupled Piezoelectric-Circuit Finite Element Method
(IEEE Institute of Electrical and Electronics, 2009-07-31T00:00:00Z) Zhu, Meiling; Worthington, Emma; Njuguna, James A. K.
A coupled piezoelectric-circuit finite element model (CPC-FEM) is proposed for the first time to study the power output of a vibration-based piezoelectric vibration-based piezoelectric energy harvesting devices (EHDs) that is directly connected to a resistive load. Special focus is given to the effect of the resistive load value on the vibrational amplitude of the piezoelectric EHDs, and thus on the current, voltage, and power generated by the EHDs. In the literature, these outputs are widely assumed to be independent of the resistive load value for the reduction in complexity of modelling and simulation. The presented CPC-FEM uses a cantilever with sandwich structure and a seismic mass attached to the tip to study the following load characteristics of the EHD as a result of changing the resistive load value: (1) the electric outputs of the EHD: current through and voltage across the resistive load, (2) the power dissipated by the resistive load, (3) the vibration amplitude of tip displacement of the cantilever, and (4) the shift in resonant frequency of the cantilever. Investigation results shows significant dependences of the vibration characteristics of the piezoelectric EHDs on the externally connected resistive load are found, rather than independence as previously assumed in most literature. The CPC-FEM is capable of predicting the generated power output of the EHDs with different resistive load value while simultaneously calculating the effect of the resistive load value on the vibration amplitude. The CPC-FEM is invaluable for validating the performance of designed EHDs before fabrication and testing, thereby reducing the recurring costs associated with repeat fabrication and trials. In addition, the proposed CPC-FEM is potentially useful in device designs optimisations for maximal power generation.
Open Access
Are the 1D and 2D constitutive equations of piezoelectric materials right?
(2007-06-14T00:00:00Z) Zhu, Meiling; Kirby, Paul B.
Open Access
Characterization of a rotary piezoelectric energy harvester based on plucking excitation for knee-joint wearable applications
(Institute of Physics, 2012-05-31T00:00:00Z) Pozzi, Michele; Zhu, Meiling
Wearable medical and electronic devices demand a similarly wearable electrical power supply. Human-based piezoelectric energy harvesters may be the solution, but the mismatch between the typical frequencies of human activities and the optimal operating frequencies of piezoelectric generators calls for the implementation of a frequency up-conversion technique. A rotary piezoelectric energy harvester designed to be attached to the knee-joint is here implemented and characterized. The wearable harvester is based on the plucking method of frequency up-conversion, where a piezoelectric bimorph is deflected by a plectrum and permitted to vibrate unhindered upon release. Experiments were conducted to characterize the energy produced by the rotary piezoelectric energy harvester with different electric loads and different excitation speeds, covering the range between 0.1 and 1 rev s −1 to simulate human gait speeds. The electrical loads were connected to the generator either directly or through a rectifying bridge, as would be found in most power management circuits. The focus of the paper is to study the capability of energy generation of the harvester for knee-joint wearable applications, and study the effects of the different loads and different excitation speeds. It is found that the energy harvested is around 160–490 {µJ} and strongly depends on the angular speed, the connected electric loads and also the manufacturing quality of the harvester. Statistical analysis is used to predict the potential energy production of a harvester manufactured to tighter tolerances than the one presented here.
Open Access
Contact Analysis and Mathematical Modeling of Traveling Wave Ultrasonic Motors
(IEEE Institute of Electrical and Electronics, 2004-11-01T00:00:00Z) Zhu, Meiling
An analysis of the contact layer and a mathematical modeling of traveling wave ultrasonic motors (TWUM) are presented for the guidance of the design of contact layer and the analyses of the influence of the compressive force and contact layer on motor performance. The proposed model starts from a model previously studied but differs from that model in that it adds the analysis of the contact layer and derives the steady-state solutions of the nonlinear equations in the frequency domain, rather than in the time domain, for the analyses of vibrational responses of the stator and operational characteristics of the motor. The maximum permissible compressive force of the motor, the influences of the contact layer material, the thickness of the contact layer, and the compressive force on motor performance have been discussed. The results show that by using the model, one can understand the influence of the compressive force and contact layer material on motor performance, guide the choice of proper contact layer material, and calculate the maximum permissible compressive force and starting voltage.
Open Access
Coupled piezoelectric-circuit FEA to study influence of a resistive load on power output of piezoelectric energy devices
(2012-08-01) Zhu, Meiling; Worthington, Emma; Njuguna, James A. K.; Schmid, Ulrich
This paper presents, for the first time, a coupled piezoelectric-circuit finite element model (CPC-FEM) to analyze the power output of vibration-based piezoelectric energy harvesting devices (EHDs) when connected to a resistive load. Special focus is given to the effect of the resistive load value on the vibrational amplitude of the piezoelectric EHDs, and thus on the current, voltage, and power generated by the EHDs, which are normally assumed to be independent of the resistive load in order to reduce the complexity of modelling and simulation. The CPC-FEM presented uses a cantilever with the sandwich structure and a seismic mass attached to the tip to study the following load characteristics of the EHD as a result of changing the load resistor value: (1) the electric outputs of the EHD: current and voltage, (2) the power dissipated by the resistive load, (3) the vibration amplitude of tip displacement, and (4) the shift in resonant frequency of the cantilever. Significant dependences of the characteristics of the piezoelectric EHDs on the externally connected resistive load are found, rather than independency, as previously assumed in most literature. The CPC-FEM is capable of predicting the generated power output with different resistive load values while simultaneously considering the effect of the resistor value on the vibration amplitude. The CPC-FEM is invaluable for validating the performance of a device before fabrication and testing, thereby reducing the recurring costs associated with repeat fabrication and trials, and also for optimizing device design for maximal power-output generation.
Open Access
Design analysis and fabrication of a mobile energy harvesting device to scavenge bio-kinetic energy.
(Cranfield University, 2014-05) Daniels, Alice Charlotte Hilda; Zhu, Meiling; Tiwari, Ashutosh
The increasing prevalence of low power consumption electronics brings greater potential to mobile energy harvesting devices as a possible power source. The main contribution of this thesis is the study of a new piezoelectric energy harvesting device, called the piezoelectric flex transducer (PFT), which is capable of working at non- resonant and low frequencies to harvest bio-kinetic energy of a human walking. The PFT consists of a piezoelectric element sandwiched between substrate layers and metal endcaps, the endcaps are specifically designed to amplify the axial force load on the piezoelectric element, instead of conventional designs of piezoelectric energy harvesters that focus on utilising resonant frequency in order to increase power harvested. This thesis presents the analyses, design, prototyping and characterisation of the PFT using a coupled piezoelectric-circuit finite element model (CPC-FEM) to show the energy harvesting capability of the proposed and developed novel device to harvest bio-kinetic energy. Prior to the study of the new PFT, an initial focus was given to a traditional Cymbal device to investigate its potential as a bio-kinetic energy harvesting device. To gain an understanding, effects of geometrical parameters and material properties of the device on its energy harvesting capability were studied and in doing so issues and problems were identified with the traditional Cymbal device for use as a bio-kinetic energy harvesting device. Its structural materials were not able to withstand higher than a 50N applied load and it was proposed that a small adhesion area connection in a fundamental part of the structure may have been at high risk of delamination. In order to study these, the CPC-FEM model was developed using the commercial software of ANSYS and validated by experimental methods. Later, based on a modelling and experimental study, a novel PFT was proposed and implemented to overcome the issues and problems of the traditional Cymbal device. For this initial study, the Cymbal was analysed by studying how key dimensional parameters affect the energy harvesting performance of the Cymbal. In addition to this, how piezoelectric material properties affect the energy harvesting performance were studied using the developed CPC-FEM model through comparisons of different piezoelectric materials and their electrical performances to aid with selecting high power producing materials for the final PFT design. It was found that (1) d₃₁ is a more dominant material property over other material properties for higher power output, (2) Figure of Merit (FOM) was more linear related to the power output than either the k₃₁ or the d₃₁, and (3) εᵀ r₃₃ had some role when the materials have an identical d₃₁; a lower ε ᵀ₃₃ was preferred. A combined FOM with d₃₁ parameters is recommended for selection of piezoelectric material for a higher power outputs. The design of the new PFT is partly based on the traditional Cymbal however, the new PFT has more potential for withstanding higher forces due to an addition of substrate layers that reduced delamination risks. Using a similar approach to designing the traditional Cymbal, the new PFT was designed and tested with force frequencies of less than 5Hz and forces of up to 1kN. In the design process, the validated CPC-FEM was used 1) to analyse then utilise correlations between geometric parameters and power outputs, and 2) to ensure structural integrity by monitoring mechanical stress in the PFT. The PFT was retrofitted into a shoe and the harvested power was used to power an in-house developed wireless sensor module whilst the subject with a body weight of 760N was wearing the shoe and ran at 3.1mph (equivalent to 1.4Hz on the shoe), the PFT produced an average maximum power of 2.5mW over 2MΩ load and the power produced is able to power the wireless module approximately every 10 seconds.
Open Access
Design and implementation of a wireless sensor communication system with low power consumption for energy harvesting technology
(2012-02-02T00:00:00Z) Marsic, Vlad; Zhu, Meiling; Williams, Stewart W.
This paper presents the design and implementation of a wireless sensor communication system with a low power consumption for integration with energy harvesting technology, that can be employed in energy autonomous wireless sensor communication applications. The design and implementation focus on three levels: hardware, software and data transmission. The resulted system is able to satisfy all the theoretical and practical requirements in order to be included in a wireless sensor structure that is able to give the device self-powered autonomy, due to a smart inter-correlated management of the energy resources.
Open Access
Design and testing of piezoelectric energy harvesting devices for generation of higher electric power for wireless sensor networks
(2009-10-01T00:00:00Z) Zhu, Meiling; Worthington, Emma
This paper reports our design and testing results on the electric output performance of a vibration-based piezoelectric energy harvesting device (PEHD). The PEHD is a cantilever with a sandwich structure and seismic mass attached to the tip. The geometric parameters of the device are based on optimization design with a volume of around 1cm3 and at a targeted resonant frequency of 80-100 Hz. A maximum output power of 370μW at 15.5 volts into a 325kΩ resistive load is generated at the resonant frequency of 87Hz and under an acceleration of 0.23g. Quite remarkably, this power is a very encouraging power figure that gives the prospect of being able to power a wider range of applications than is currently possible in wireless sensor networ
Open Access
Design study of piezoelectric micro-machined mechanically coupled cantilever filters using a combined finite element and microwave circuit analysis.
(Elsevier Science B.V., Amsterdam., 2006-02-01T00:00:00Z) Zhu, Meiling; Kirby, Paul B.
A new mechanical filter structure is presented which comprises two silicon cantilevers mechanically coupled by a silicon linkage with thin film piezoelectric transducers providing electrical input and output signals. The resonance behaviour of such a structure results in a band-pass filter response, having a band-width determined by the frequency separation between the closely spaced in-phase and out-of-phase vibrational modes of the two coupled cantilevers. A detailed configuration design analysis, filter simulation and optimisation of performance is undertaken using a new modelling approach combining microwave circuit theory and finite element analysis to evaluate the generalised (A, B, C and D) and scattering (S) circuit parameters of the filter. Two significant features of the filters have emerged from the derived analyses and simulations: (1) with correct design filter Q-values can reach several thousand which is much higher than the Q-values (80) of uncoupled cantilevers, (2) the Q-value is determined by the configuration of the silicon linkage and so is under the designer's control. The position and length of the linkage that give optimum Q and minimum insertion loss are determined.
Open Access
Design, modelling and testing of a novel energy harvesting device
(Cranfield University, 2009-09) Longana, Marco Luigi; Zhu, Meiling; Njuguna, James
This work is a feasibility study to develop a novel energy harvesting device. Energy harvesting devices capture energy in various forms from the surrounding and transform it into usable electrical energy. These devices do not require any refuelling or recharging and are virtually a never ending source of energy. The energy harvesting devices rely on di erent mechanisms of energy conversion, depending on the energy source. This work focuses on conversion of mechanical energy from vibrations into electric energy using piezoelectric materials. Most of the existing devices are shaped like a cantilever beam, thus limiting the tunability to a single resonance frequency. It is believed that by modifying the geometry of the energy harvesting device and applying a pre-load to the active material (piezoelectric), a variable tunability can be achieved. Also, the application of an axial compressive pre-load helps to further increase the power output of the device. Therefore, in this present work, the performance of a simply supported beam shaped energy harvesting device is investigated both numerically and experimentally. For the numerical analyses nite element simulations are carried out using ANSYS. An electro-mechanical model of the simply supported beam has been developed through a series of approaching models with increasing complexity, starting from an analytical solution. The nal three-dimensional model was used as a base to create a model of the beam that has been used during the experimental tests. Shape optimization studies were carried out on this nite element model to analyse the power output of the device. It has been observed, through pre-stressed modal analyses, that the axial pre-load decreases the resonance frequency of the beam, thereby giving the beam the ability to be tuned. Also,it has been observed that an optimisation of the beam footprint shape can increase the power output by almost 40%.The experimental work focussed on the investigation of the harmonic behaviour of the simply supported beam under di erent pre-load conditions. It was observed that the experimental results were in disagreement with the nite element simulations and also with the reference literature. The disagreement was identi ed to be due to the hinge design that does not ensure the alignment of the two tips of the beam and therefore the application of a perfectly axial pre-load. From the work presented here it emerges that the possibility to develop a simply supported beam shaped energy harvesting device that rely on the application of an axial pre-load to obtain tunability and an higher power output is promising. The nite element simulations gave good results on the beam behaviour and on the possibility to further increase its output by optimising the shape of its footprint. The experimental work allowed to identify the hinge design as a problem area to design a pro table device.
Open Access
Dimensional reduction study of piezoelectric ceramics constitutive equations from 3-D to 2-D and 1-D
(IEEE Institute of Electrical and Electronics, 2008-11-01T00:00:00Z) Zhu, Meiling; Leighton, Glenn J. T.
The accurate performance evaluation is crucial to the design and development of macro/micro sized piezoelectric devices, and key to this is the proper use of the stiffness/compliance and piezoelectric coefficients of the piezoelectric ceramics involved. Although the literature points out effective piezoelectric coefficients: and for thin film materials, and reduced dimensionality of equations for bulk material, the elastic and piezoelectric coefficients remain unchanged from the 3D equations in most of the reported macro/micro sized device’s 1D and 2D analyses involving the e form of the constitutive equations. This leads to variations between numerically predicted and experimental results in most devices. In order to understand effects of the dimensional reduction from 3D to 2D and 1D on stiffness/compliance and piezoelectric coefficients, this paper derives the 2D and 1D constitutive equations from the 3D equations with focus upon the discussion of often required device configurations for sensor and actuator design and analysis. Two modified coefficients are proposed, termed reduced and enhanced and these enable better understanding of effects of the dimensional reduction and also effects on the design and analysis of sensors and actuator
Open Access
Enhanced piezoelectric energy harvesting powered wireless sensor nodes using passive interfaces and power management approach
(Cranfield University, 2014) Giuliano, Alessandro; Zhu, Meiling
Low-frequency vibrations typically occur in many practical structures and systems when in use, for example, in aerospaces and industrial machines. Piezoelectric materials feature compactness, lightweight, high integration potential, and permit to transduce mechanical energy from vibrations into electrical energy. Because of their properties, piezoelectric materials have been receiving growing interest during the last decades as potential vibration- harvested energy generators for the proliferating number of embeddable wireless sensor systems in applications such as structural health monitoring (SHM). The basic idea behind piezoelectric energy harvesting (PEH) powered architectures, or energy harvesting (EH) more in general, is to develop truly “fit and forget” solutions that allow reducing physical installations and burdens to maintenance over battery-powered systems. However, due to the low mechanical energy available under low-frequency conditions and the relatively high power consumption of wireless sensor nodes, PEH from low-frequency vibrations is a challenge that needs to be addressed for the majority of the practical cases. Simply saying, the energy harvested from low-frequency vibrations is not high enough to power wireless sensor nodes or the power consumption of the wireless sensor nodes is higher than the harvested energy. This represents a main barrier to the widespread use of PEH technology at the current state of the development, despite the advantages it may offer. The main contribution of this research work concerns the proposal of a novel EH circuitry, which is based on a whole-system approach, in order to develop enhanced PEH powered wireless sensor nodes, hence to compensate the existing mismatch between harvested and demanded energy. By whole-system approach, it is meant that this work develops an integrated system-of-systems rather than a single EH unit, thus getting closer to the industrial need of a ready- to-use energy-autonomous solution for wireless sensor applications such as SHM. To achieve so, this work introduces: Novel passive interfaces in connection with the piezoelectric harvester that permit to extract more energy from it (i.e., a complex conjugate impedance matching (CCIM) interface, which uses a PC permalloy toroidal coil to achieve a large inductive reactance with a centimetre- scaled size at low frequency; and interfaces for resonant PEH applications, which exploit the harvester‟s displacement to achieve a mechanical amplification of the input force, a magnetic and a mechanical activation of a synchronised switching harvesting on inductor (SSHI) mechanism). A novel power management approach, which permits to minimise the power consumption for conditioning the transduced signal and optimises the flow of the harvested energy towards a custom-developed wireless sensor communication node (WSCN) through a dedicated energy-aware interface (EAI); where the EAI is based on a voltage sensing device across a capacitive energy storage. Theoretical and experimental analyses of the developed systems are carried in connection with resistive loads and the WSCN under excitations of low frequency and strain/acceleration levels typical of two potential energy- autonomous applications, that are: 1) wireless condition monitoring of commercial aircraft wings through non-resonant PEH based on Macro-Fibre Composite (MFC) material bonded to aluminium and composite substrates; and wireless condition monitoring of large industrial machinery through resonant PEH based on a cantilever structure. shown that under similar testing conditions the developed systems feature a performance in comparison with other architectures reported in the literature or currently available on the market. Power levels up to 12.16 mW and 116.6 µW were respectively measured across an optimal resistive load of 66 277 kΩ for an implemented non-resonant MFC energy harvester on aluminium substrate and a resonant cantilever-based structure when no interfaces were added into the circuits. When the WSCN was connected to the harvesters in place of the resistive loads, data transmissions as fast as 0.4 and s were also respectively measured. By use of the implemented passive interfaces, a maximum power enhancement of around 95% and 452% was achieved in the two tested cases and faster data transmissions obtained with a maximum percentage improvement around 36% and 73%, respectively. By the use of the EAI in connection with the WSCN, results have also shown that the overall system‟s power consumption is as low as a few microwatts during non- active modes of operation (i.e., before the WSCN starts data acquisition and transmission to a base station). Through the introduction of the developed interfaces, this research work takes a whole-system approach and brings about the capability to continuously power wireless sensor nodes entirely from vibration-harvested energy in time intervals of a few seconds or fractions of a second once they have been firstly activated. Therefore, such an approach has potential to be used for real-world energy- autonomous applications of SHM.
Open Access
Experimental characterisation of macro fibre composites and monolithic piezoelectric transducers for strain energy harvesting
(2012-07-06) Pozzi, Michele; Canziani, Alfredo; Durazo-Cardenas, Isidro; Zhu, Meiling; Tribikram, Kundu
Compact and lightweight energy harvesters are needed to power wireless sensor nodes (WSNs). WSNs can provide health monitoring of aircraft structures, improving safety and reducing costs by enabling predictive maintenance. A simple solution, which meets the requirements for lightness and compactness, is represented by piezoelectric generators fixed to the surface of the wing (i.e. the wing skin). Such piezoelectric patches can harvest the strain energy available when the wing is flexed, as occurs, for example, in the presence of gust loading. For this study, monolithic piezoelectric sheets and macro fibre composite (MFC) generators were fixed to plates made of two materials commonly used for aircraft wing skin: Al-2024 aluminium alloy and an epoxy-carbon fibre composite. The plates then underwent harmonically varying loading in a tensile testing machine. The power generation of the harvesters was measured at a selection of strain levels and excitation frequencies, across a range of electrical loads. The optimal electrical load, yielding maximum power extraction, was identified for each working condition. The generated power increases quadratically with the strain and linearly with the frequency. The optimal electrical load decreases with increasing frequency and is only marginally dependent on strain. Absolute values of generated power were highest with the MFC, reaching 12mW (330μW/cm2) under 1170μstrain peak-to-peak excitation at 10Hz with a 66kΩ load. Power generation densities of 600μW/cm2were achieved under 940μstrain with the monolithic transducers at 10Hz. It is found that MFCs have a lower power density than monolithic transducers, but, being more resilient, could be a more reliable choice. The power generated and the voltage outputs are appropriate for the intended applic
Open Access
Harvesting energy from the dynamic deformation of an aircraft wing under gust loading
(2012-07-06) Pozzi, Michele; Guo, Shijun J.; Zhu, Meiling; Tribikram, Kundu
Weight reduction and maintenance simplification are high in the agenda of companies and researchers active in the aerospace sector. Energy harvesters are being investigated because they enable the installation of wireless sensor nodes, providing structural health monitoring of the aircraft without additional cabling. This paper presents both a weight-optimized composite wing structure and a piezoelectric harvester for the conversion of mechanical strain energy into electrical energy. Finite elements modelling was used for the minimum- weight optimisation within a multi-constraints framework (strength, damage tolerance, flutter speed and gust response). The resulting structure is 29% more compliant than the original one, but is also 45% lighter. A strain map was elaborated, which details the distribution of strain on the wing skin in response to gust loading, indicating the optimal locations for the harvesters. To assess the potential for energy generation, a piezoelectric harvester fixed to a portion of the wing was modelled with a multi-physics finite elements model developed in ANSYS. The time-domain waveforms of the strain expected when the aircraft encounters a gust (gust frequencies of 1, 2, 5 and 10 Hz were considered) are fed into the model. The effects of harvester thickness and size, as well as adhesive thickness, were investigated. Energy generation exceeding 10 J/m2in the first few second from the beginning of the gust is predicted for 100μ-thick harvesters. The high energy density, low profile and weight of the piezoelectric film are greatly advantageous for the envisaged application
Open Access
Low power consumption wireless sensor communication system integrated with an energy harvesting power source
(2013-01-22T00:00:00Z) Marsic, Vlad; Giuliano, Alessandro; Zhu, Meiling
This paper presents the testing results of a wireless sensor communication system with low power consumption integrated with an energy harvesting power source. The experiments focus on the system's capability to perform continuous monitoring and to wirelessly transmit the data acquired from the sensors to a user base station, for realization of completely battery-free wireless sensor system. Energy harvesting technologies together with system design optimization for power consumption minimization ensure the system's energy autonomous capability demonstrated in this paper by presenting the promising testing results achieved following its integration with structural health monitoring and body area network applications.
Open Access
Multi-level and multidisciplinary optimisation of microelectromechanical systems
(Cranfield University, 2012-10) Farnsworth, Michael; Tiwari, Ashutosh; Zhu, Meiling
A comparative investigation into the role multi-level and multidisciplinary design optimisation can play in the automated design synthesis of microelectromechanical systems (MEMS) is presented. Microelectromechanical systems are a field grown out of the integrated circuit industry, with the goal of developing smart micro devices which can interact with the environment in some form. They promise to revolutionise our present day lifestyles as much as the integrated circuit has done in recent decades. The complexity in fabrication, the delicacy in size that each device encompasses and the multidisciplinary nature means design synthesis is a highly complicated process. Current challenges stemming from their design include the high levels of computational cost required in their modeling and analysis, and the often increasing complexity of design through the coupling of multiple components and devices into a functioning system. The development of automated design synthesis tools and methodologies to aid MEMS design is therefore important to overcome these challenges in order to accommodate the growing field of MEMS as it expands into more and more areas and continues opening up to more and more applications. An update of the current state of the art in automated MEMS design synthesis and optimisation is first presented, utilizing state of the art multi-objective evolutionary algorithms over five separate MEMS design optimisation case studies. The field of multilevel and multidisciplinary optimisation is critically reviewed and discussed with respect to their application to MEMS design synthesis and optimisation. The outcome is twofold, with the construction of both a novel multidisciplinary optimisation algorithm tailored towards MEMS design and a set of multi-level design optimisation strategies. This thesis next outlines and develops a novel modular soft computing framework to house the multi-objective, multi-level and multidisciplinary design optimisation strategies. In order to evaluate both the current state of the art in automated MEMS design synthesis and the multi-level and multidisciplinary optimisation strategies outlined a hierarchical MEMS bandpass filter case study has been constructed. Incorporating a novel state of the art electrical equivalent modelling and design synthesis approach, six novel design problems structured around the MEMS bandpass filter were developed and formed the basis for the comparative study to follow. Finally both the current state of the art in automated MEMS design synthesis, multiobjective evolutionary algorithms, and the outlined and developed multi-level and multidisciplinary optimisation strategies are applied to the six design problems developed. Comparative analysis and discussion is then given, showing a marked improvement in MEMS design synthesis for the multi-level and multidisciplinary optimisation strategies over the current state of the art methodology.
Open Access
A multi-objective and multidisciplinary optimisation algorithm for microelectromechanical systems
(2017-09-14) Farnsworth, Michael; Tiwari, Ashutosh; Zhu, Meiling; Benkhelifa, Elhadj
Microelectromechanical systems (MEMS) are a highly multidisciplinary field and this has large implications on their applications and design. Designers are often faced with the task of balancing the modelling, simulation and optimisation that each discipline brings in order to bring about a complete whole system. In order to aid designers, strategies for navigating this multidisciplinary environment are essential, particularly when it comes to automating design synthesis and optimisation. This paper outlines a new multi-objective and multidisciplinary strategy for the application of engineering design problems. It employs a population-based evolutionary approach that looks to overcome the limitations of past work by using a non-hierarchical architecture that allows for interaction across all disciplines during optimisation. Two case studies are presented, the first focusing on a common speed reducer design problem found throughout the literature used to validate the methodology and a more complex example of design optimisation, that of a MEMS bandpass filter. Results show good agreement in terms of performance with past multi-objective multidisciplinary design optimisation methods with respect to the first speed reducer case study, and improved performance for the design of the MEMS bandpass filter case study.
Open Access
Optimization design of multi-material micropump using finite element method
(Elsevier Science B.V., Amsterdam., 2009-01-15T00:00:00Z) Zhu, Meiling; Kirby, Paul B.; Wacklerle, M.; Herz, M.; Richter, M.
This paper presents a micropump fabricated from low-cost materials with specific goal of cost reduction. The micropump does not require any valve flap and comprises of one plastic pump polyether-ether-ketone (PEEK) body, one metal diaphragm, and three piezoelectric ceramics to form piezoelectrically actuated diaphragm valves. The valve actuation simplifies micropump structural designs and assembly processes to make the pump attractive for low cost bio-medical drug delivery applications. A detailed optimization design of geometric parameters of the piezoelectrically actuated diaphragm is undertaken by use of 3D finite element method (FEM) to maximize piezoelectric actuation capability and ensure actuation reliability. An optimized geometric dimensional design: the ratio of thicknesses between the piezoelectric ceramics and the metal diaphragm, and the lateral dimension of the piezoelectric ceramic, is obtained through simulations. Based on the optimized design, a good agreement has been reached between simulated and measured strokes of the micropumps. The tested results show that the micropump has a high pump flow rate for air, up to 39 ml/min, and for water up to 1.8ml/min, and is capable of ensuring diaphragm’s maximum stress and strain is within material strength for reliable wor
Open Access
Performance testing of a low power consumption wireless sensor communication system integrated with an energy harvesting power source
(2012-11-30T00:00:00Z) Marsic, Vlad; Giuliano, Alessandro; Pozzi, Michele; Zhu, Meiling; Williams, Stewart W.; Yurish, S.
This paper presents the performance testing results of a wireless sensor communication system with low power consumption integrated with a vibration energy harvesting power source. The experiments focus on the system’s capability to perform continuous monitoring and to wirelessly transmit the data acquired from the sensors to a user base station, completely battery-free. Energy harvesting technologies together with system design optimisation for power consumption minimisation ensure the system’s energy autonomous capability demonstrated in this paper by presenting the promising testing results achieved following its integration with Structural Health Monitoring (SHM) and Body Area Network (BAN) applications.
Open Access
Piezoelectric Energy Harvesting: Enhancing Power Output by Device Optimisation and Circuit Techniques
(Cranfield University, 2010-03-31) Worthington, Emma; Zhu, Meiling; Kirby, Paul B.
Energy harvesting; that is, harvesting small amounts of energy from environmental sources such as solar, air flow or vibrations using small-scale (≈1cm 3 ) devices, offers the prospect of powering portable electronic devices such as GPS receivers and mobile phones, and sensing devices used in remote applications: wireless sensor nodes, without the use of batteries. Numerous studies have shown that power densities of energy harvesting devices can be hundreds of µW; however the literature also reveals that power requirements of many electronic devices are in the mW range. Therefore, a key challenge for the successful deployment of energy harvesting technology remains, in many cases, the provision of adequate power. This thesis aims to address this challenge by investigating two methods of enhancing the power output of a piezoelectric-based vibration energy harvesting device. Cont/d.