Electro-mechanical coupling properties of band gaps in an with periodically attached “spring-mass” resonators

The model of a locally resonant (LR) epoxy/PZT-4 phononic crystal (PC)nanobeam with “spring-mass” resonators periodically attached to epoxy is proposed. The corresponding band structures are calculated by coupling Euler beam theory, nonlocal piezoelectricity theory and plane wave expansion (PWE) method. Three complete band gaps with the widest total width less than 10GHz can be formed in the proposed nanobeam by comprehensively comparing the band structures of three kinds of LR PC nanobeams with resonators attached or not. Furthermore, influencing rules of the coupling fields between electricity and mechanics,“spring-mass” resonator, nonlocal effect and different geometric parameters on the first three band gaps are discussed and summarized. All the investigations are expected to be applied to realize the active control of vibration in the region of ultrahigh frequency.

Design and Analysis of Electro-mechanical Hybrid Anti-lock Braking System for Hybrid Electric Vehicle Utilizing Motor Regenerative Braking

Braking on low adhesion-coefficient roads, hybrid electric vehicle＇s motor regenerative torque is switched off to safeguard the normal anti-lock braking system （ABS） fimction. When the ABS control is terminated, the motor regenerative braking is readmitted. Aiming at avoiding permanent cycles from hydraulic anti-lock braking to motor regenerative braking, a novel electro-mechanical hybrid anti-lock braking system using fuzzy logic is designed. Different from the traditional single control structure, this system has a two-layered hierarchical structure, The first layer is responsible for harmonious adjustment or interaction between regenerative system and anti-lock braking system. The second layer is responsible for braking torque distribution and adjustment. The closed-loop simulation model is built. Control strategy and method for coordination between regenerative and anti-lock braking are developed. Simulation braking on low adhesion-coefficient roads with fuzzy logic control and real vehicle braking field test are presented. The results from simulating analysis and experiment show braking performance of the vehicle is perfect, harmonious coordination between regenerative and anti-lock braking function, significant amount of braking energy can be recovered and the proposed control strategy and method are effective.

Analysis Method and Principle of Dual-mode Electro-mechanical Variable Transmission Program

Automotive industry,as an important pillar of the national economy,has been rapidly developing in recent years.But proplems such as energy comsumption and environmental pollution are posed at the same time.Electro-mechanical variable transmission system is considered one of avilable workarounds.It is brought forward a kind of design methods of dual-mode electro-mechanical variable transmission system rotational speed characteristics and dual-mode drive diagrams.With the motor operating behavior of running in four quadrants and the speed characteristics of the simple internal and external meshing single planetary gear train,four kinds of dual-mode electro-mechanical transmission system scheme are designed.And the velocity,torque and power characteristics of one of the programs are analyzed.The magnitude of the electric split-flow power is an important factor which influences the system performance,so in the parameters matching design,it needs to reduce the power needs under the first mode of the motor.The motor,output rotational speed range and the position of the mode switching point have relationships with the characteristics design of the planetary gear set.The analysis method is to provide a reference for hybrid vehicles＇ design.As the involved rotational speed and torque relationships are the natural contact of every part of transmission system,a theory basis of system program and performance analysis is provided.

Numerical Simulation of Dynamic Electro-Mechanical Response of Ionic Polymer-Metal Composites

Ionic Polymer-Metal Composites （IPMC） is an emerging class of Electro-Active Polymer （EAP） materials. IPMC has attractive features, such as high sensitivity and light weight, which are useful for developing novel designs in the fields of bionic actuators, artificial muscles and dynamic sensors. A Finite Element （FE） model was developed for simulating the dynamic electro-mechanical response of an IPMC structure under an external voltage input. A lumped Resisto^Capacitor （RC） model was used to describe the voltage-to-current relationship of a Nation IPMC film for the computation of electric field intensity. Moreover, the viscoelastic property of the IPMC film was considered in the model and the non-uniform bending behavior was also taken into account. Based on the proposed model and the assumption that the thicknesses of the two electrodes are the same and uniform, the optimal coating thickness of the IPMC electrode was determined. It was demonstrated that the dynamic electro-mechanical response of the IPMC structure can be predicted by the proposed FE model, and the simulation results were in good agreement with the experimental findings.

ELECTRO-MECHANICAL COUPLING ANALYSIS OF MEMS STRUCTURES BY BOUNDARY ELEMENT METHOD

In this paper,we present the applications of Boundary Element Method(BEM) to simulate the electro-mechanical coupling responses of Micro-Electro-Mechanical systems(MEMS). The algorithm is programmed in our research group based on BEM modeling for electrostatics and elastostatics.Good agreement is shown while the simulation results of the pull-in voltages are compared with the theoretical/experimental ones for some examples.

Analysis of piezoelectric ceramic multilayer actuators based on an electro-mechanical coupled meshless method

This paper presents an efficient meshless method for analyzing cracked piezoelectric structures subjected to mechanical and electrical loading. In this method, an element free Galerkin （EFG） formulation, an enriched basic function and some special shape functions that contain discontinuous derivatives are employed. Based on the moving least squares （MLS） interpolation approach, the EFG method is one of the promising methods for dealing with problems involving progressive crack growth. Since the method is meshless and no element connectivity data are needed, the burdensome remeshing procedure required in the conventional finite element method （FEM） is avoided. The numerical results show that the proposed method can yield an accurate near-tip stress field in an infinite piezoelectric plate containing an interior hole. In another example studying a ceramic multilayer actuator, the proposed model was found to be accurate in the simulation of stress and electric field concentrations arround the abrupt end of an internal electrode.

Fuzzy Sliding Mode Control Based on Longitudinal Force Estimation for Electro-mechanical Braking Systems using BLDC Motor

This paper focuses on the controller design using fuzzy sliding mode control(FSMC)with application to electro-mechanical brake(EMB)systems using BLDC Motor.The EMB controller transmits the control signal to the motor driver to rotate the motor.The torque distribution of motors is studied in this paper actually.Firstly,the model of the EMB system is established.Then the state observer is developed to estimate the vehicle states including the vehicle velocity and longitudinal force.Due to the fact that the EMB system is nonlinear and uncertain,a FSMC strategy based on wheel slip ratio is proposed,where both the normal and emergency braking conditions are taken into account.The equivalent control law of sliding mode controller is designed on the basis of the variation of the front axle and rear axle load during the brake process,while the switching control law is adjusted by the fuzzy corrector.The simulation results illustrate that the FSMC strategy has the superior performance,better adaptability to various types of roads,and shorter braking distance,as compared to PID control and traditional sliding mode control technologies.Finally,the hardware-in-loop(HIL)experimental results have exemplified the validation of the developed methodology.

Study of Piezoresistive Micro Electro-Mechanical Accelerometer Design Platform

According to the inland micro electro-mechanical system （MEMS） process technique level, a design platform of piezoresistive micro electro-mechanical accelerometer is given. This platform is much more adaptable to the inland designer compared with the current MEMS CAD software. The design flow is presented in detail, and the key techique in the platform is analyzed amply. The structure design methodology is exemplified in the design of a piezoresistive accelerometer, and the accelerometer is the optimized structure for the given performance requirements. The accelerometer is now being manufactured.

Analytical Modelling and Experiment of Novel Rotary Electro-Mechanical Converter with Negative Feedback Mechanism for 2D Valve

The manufacturing of spiral groove structure of two-dimensional valve(2D valve)feedback mechanism has shortcomings of both high cost and time-consuming.This paper presents a novel configuration of rotary electro-mechanical converter with negative feedback mechanism(REMC-NFM)in order to replace the feedback mechanism of spiral groove and thus reduce cost of valve manufacturing.In order to rapidly and quantitative evaluate the driving and feedback performance of the REMC-NFM,an analytical model taking leakage flux,edge effect and permeability nonlinearity into account is formulated based on the equivalent magnetic circuit approach.Then the model is properly simplified in order to obtain the optimal pitch angle.FEM simulation is used to study the influence of crucial parameters on the performance of REMC-NFM.A prototype of REMC-NFM is designed and machined,and an exclusive experimental platform is built.The torque-angle characteristics,torque-displacement characteristics,and magnetic flux density in the working air gap with different excitation currents are measured.The experimental results are in good agreement with the analytical and FEM simulated results,which verifies the correctness of the analytical model.For torque-angle characteristics,the overall torque increases with both current and rotation angle,which reaches about 0.48 N·m with 1.5 A and 1.5°.While for torque-displacement characteristics,the overall torque increases with current yet decrease with armature displacement due to the negative feedback mechanism,which is about 0.16 N·m with 1.5 A and 0.8 mm.Besides,experimental results of conventional torque motor are compared with counterparts of REMC-NFM in order to validate the simplified model.The research indicates that the REMC-NFM can be potentially used as the electro-mechanical converter for 2D valves in civil servo areas.

An Electro-Mechanical Controller for Adjusting Piston Pump Stroke On-the-Go for Site-Specific Application of Crop Nutrients

Nutrient application systems are designed to apply a relatively uniform amount of a fertilizer to agricultural fields. However, considerable variation in soil texture and other characteristics often occurs within and across production fields, which could have a major impact on fertilizer management strategies. Therefore, uniform application of a fertilizer over the entire field can be both costly and environmentally unsound. Due to their rugged and fool-proof design, crankshaft type piston pumps are widely used in agriculture. The on-the-go outlet flow of these pumps can only be varied by changing the drive shaft speed for each pump stroke setting. But only a limited range of flow rates can be achieved by changing the drive shaft speed. There is a need for an electronic controller, which can adjust the pump stroke on-the-go, for real-time, variable-rate application of crop nutrients. The Clemson “Electro-me-chanical controller for adjusting pump stroke on-the-go” was designed to replace the current manual stroke adjustment system on positive displacement piston pumps. This affordable system can be retrofitted on most John Blue - piston pumps for real-time adjustment of the pump stroke and can be controlled using pre-described position sequences (map-based) or real-time sensor commands (such as optical, pressure, and flow sensors) combined with fertilizer calculation algorithms. In addition, it can adjust pump stroke manually, using an eclectic dial from the tractor’s cab.

Development of a Portable Electro-Mechanical Educational Model for Variable Rate Center Pivot Irrigation Technology

Center pivot irrigation systems usually apply a relatively uniform amount of water to fields that are often inherently variable, which could lead to significant waste of water and energy. To address this issue, our team is now developing an Intelligent Center Pivot (ICP) by integrating sensor-based irrigation scheduling with variable rate irrigation technology. However, before this technology can be applied in commercial production, it is necessary to educate growers about its practicality and potential benefits. The objective of this study was to develop a portable tabletop intelligent center pivot model (ICPDemo) to demonstrate and promote adoption of the ICP technology. This paper describes an ICPDemo constructed in 2014, including the design specifications, electro-mechanical design, control strategy, and performance. The ICPDemo has performed according to design specifications and is successfully being used to demonstrate the benefits and effectiveness of ICP technology for irrigation scheduling.

Investigation of the Electro-Mechanical Behavior of Hybrid Polyaniline/Graphene Nanocomposites Fabricated by Dynamic Interfacial Inverse Emulsion Polymerization

This paper describes a study on electrical resistivity under loading of polyaniline (PANI)/graphene nanocomposite powders and compacts. The composites were prepared by an in-situ interfacial dynamic inverse emulsion polymerization technique under sonication of aniline in the presence of graphene sheets in chloroform. During polymerization the graphene nanoplatelets are coated with PANI and are well dispersed both in the polymeric suspension and then in the dried polymer matrix as evidenced by cryogenic transmission electron microscopy (Cryo-TEM) and high resolution scanning microscopy (HRSEM). The presence of graphene nanoplatelets lowers the electrical resistivity of the polyaniline by two orders of magnitude for both the powder and the compact composites as demonstrated by their electrical resistance measurements conducted under loading. The lowest measured electrical resistivity values were 5 Ω·cm for 33% wt. graphene powder and 8 Ω·cm for 41% wt. graphene compacted composites. Cyclic electrical measurements under loading showed a distinct reproducible dependence of the bulk resistivity vs. applied pressure. This repetition is a key component for electro-mechanical sensors. To the authors’ best knowledge, this is the first report on polymerization of aniline in presence of graphene by the in-situ interfacial dynamic inverse emulsion polymerization technique and also the first report on cyclic electrical measurements under pressure of PANI/graphene nanocomposites.

Approach for Cost Determination of Electro-Mechanical Equipment in Ror Shp Projects

Electricity is one of the most widely used forms of energy. Being a renewable source of energy small hydropower is considered as an environment—friendly and cheap source of electricity. The installation cost of the small hydropower project depends mainly on two parts—civil works and electromechanical equipment. One of the most important element on the recovery of a small hydro-power plant is the electromechanical equipment (turbine-alternator). The present paper intends to develop a correlation to determine the cost based on the cost influencing parameters as power and head using three different methods, namely;sigma plot method, linest method and logest method. An attempt has also been made to identify the best correlation among the three models closer to the actual cost of electro-mechanical equipment as collected from recently developed projects.

Source free unsupervised domain adaptation for electro-mechanical actuator fault diagnosis

A common necessity for prior unsupervised domain adaptation methods that can improve the domain adaptation in unlabeled target domain dataset is access to source domain data-set and target domain dataset simultaneously.However,data privacy makes it not always possible to access source domain dataset and target domain dataset in actual industrial equipment simulta-neously,especially for aviation component like Electro-Mechanical Actuator(EMA)whose dataset are often not shareable due to the data copyright and confidentiality.To address this problem,this paper proposes a source free unsupervised domain adaptation framework for EMA fault diagnosis.The proposed framework is a combination of feature network and classifier.Firstly,source domain datasets are only applied to train a source model.Secondly,the well-trained source model is trans-ferred to target domain and classifier is frozen based on source domain hypothesis.Thirdly,nearest centroid filtering is introduced to filter the reliable pseudo labels for unlabeled target domain data-set,and finally,supervised learning and pseudo label clustering are applied to fine-tune the trans-ferred model.In comparison with several traditional unsupervised domain adaptation methods,case studies based on low-and high-frequency monitoring signals on EMA indicate the effectiveness of the proposed method.

Electro-mechanical offset measurements of beam position monitors

Purpose The absolute beam position measurement in the booster and storage ring of the high energy photon source(HEPS)requires the offset between the electrical and mechanical centers of the beam position monitor(BPM).Method Traditionally,an RF signal is sent to an antenna or stretched wire aligned with the vacuum chamber,and the signal at each electrode is measured.Conversely,a replacement method using a vector network analyzer,which was proposed by Lambertson,does not involve mechanical alignment and can be used for electrical offset determination.Results and conclusions The electro-mechanical offsets of booster BPMs of the HEPS were measured using the Lambertson method.The result shows good agreement with the stretched wire method within a 30μm error.

Inner damage identification and residual strength assessment of a 3D printed tunnel with marble-like cementitious materials using piezoelectric transducers

Quantitative damage identification of surrounding rock is important to assess the current condition and residual strength of underground tunnels.In this work,an underground tunnel model with marble-like cementitious materials was first fabricated using the three-dimensional(3D)printing technique and then loaded to simulate its failure mode in the laboratory.Lead zirconate titanate piezoelectric(PZT)transducers were embedded in the surrounding rock around the tunnel in the process of 3D printing.A 3D monitoring network was formed to locate damage areas and evaluate damage extent during loading.Results show that as the load increased,main cracks firstly appeared above the tunnel roof and below the floor,and then they coalesced into the tunnel boundary.Finally,the tunnel model was broken into several parts.The resonant frequency and the peak of the conductance signature firstly shifted rightwards with loading due to the sealing of microcracks,and then shifted backwards after new cracks appeared.An overall increase in the root-mean-square deviation(RMSD)calculated from conductance signatures of all the PZT transducers was observed as the load(damage)increased.Damage-dependent equivalent stiffness parameters(ESPs)were calculated from the real and imaginary signatures of each PZT at different damage states.Satisfactory agreement between equivalent and experimental ESP values was achieved.Also,the relationship between the change of the ESP and the residual strength was obtained.The method paves the way for damage identification and residual strength estimation of other 3D printed structures in civil engineering.

铌酸锂表面波器件基底最佳切割方向

为在表面波器件设计时选择基底的最佳切割方向,推导表面波压电增劲晶体声学基本方程和表面波边界条件方程,使用循环迭代法,对铌酸锂晶体最佳退耦的声弧矢yz平面计算了沿不同方向的电自由条件表面波声速与电短路条件表面波声速.在此基础上计算了机电耦合系数,并确定最大机电耦合系数的方向为基底的最佳切割方向.计算结果表明,铌酸锂晶体作为表面波器件基底的最佳切割方向为164°y切.

缓冲层和外部电阻抗对薄膜体声波谐振器频率特性的影响(英文)

通过在AlN薄膜体声波谐振器上引入压电缓冲层和外部电阻抗来调节谐振器的频率特性,在考虑了缓冲层和外部电阻抗后,得到薄膜谐振器的输入电阻抗公式,并用来描述器件的机电行为。通过计算阻抗-频率谱评估了薄膜谐振器的频率特性和有效机电耦合系数k2eff,研究了缓冲层和外部电阻抗包括电阻、电感、电容对薄膜谐振器的阻抗-频率谱的影响。计算结果表明,外部电阻抗的引入可根本上改变薄膜谐振器的共振频率,且对k2eff有重要的影响。

Electro-mechanical Modeling of Wind Turbine and Energy Storage Systems with Enhanced Inertial Response

In this paper,a coordinated control scheme for wind turbine generator(WTG)and supercapacitor energy storage system(ESS)is proposed for temporary frequency supports.Inertial control is designed by using generator torque limit considering the security of WTG system,while ESS releases its energy to compensate the sudden active power deficit during the recovery process of turbine rotor.WTG is modeled using the fatigue,aerodynamic,structure,turbulence(FAST)code,which identifies the mechanical loadings of the turbine and addresses electro-mechanical interactions in the wind energy system.A damping controller is augmented to the inertial control to suppress severe mechanical oscillations in the shaft and tower of the turbine during frequency supports.Furthermore,the result of small-signal stability analysis shows that the WTGESS tends to improve the stability of the whole multi-energy power grid.The major contributions of this paper will be validated by utilizing the proposed control method that combines the grid support capability and maintaining the integrity of structural design of the turbine for normal operations.

A modified similitude analysis method for the electro-mechanical performances of a parallel manipulator to solve the control period mismatch problem

Due to the discrete feature and performance limitation of the numerical controller,the control period sometimes cannot meet the constraints of the scaled model in similitude analysis,which brings the control period mismatch problem.The traditional similitude analysis methods are not able to solve this problem since the controller is treated as continuous system in these methods.This paper proposes a modified similitude analysis method to solve the control period mismatch problem,and the electro-mechanical performances of a 2-DOF parallel manipulator is predicted.Based on the model of dynamic and control system,most of the similitude laws are derived by taking the controller as continuous system.Then the transfer function of the controller in discrete form is established,and the similitude law related to control period is derived to figure out the cause of mismatch problem.The modified method,named long period equivalent,is proposed to solve the mismatch problem by using the least square method and superposition principles.Finally,the scaled model of the parallel manipulator is determined based on the modified similitude analysis method.