Electromechanical Characteristics Research Articles

Research on mechanical resonance of Precise cable drive systems

Precise cable drive is a light, concise and efficient spatial friction flexible transmission mode, which has the characteristics of flexible layout, lightweight and miniaturization. It is a good choice for Acquiring tracking and pointing applications (ATPs). But the cable drive mechanism (CDM) is easy to cause large-scale speed oscillation in the process of performing tasks as cable compliance. This paper focused on the mechanical resonance in a practical full-closed loop positioning control system. A dynamic model with the electro-mechanical and rigid-flexible coupling characteristics is proposed, which is capable to analyze the global influence factors on speed oscillation. The parametric sensitivities have been conducted to investigate the effects of design parameters on mechanical resonance.

Electromechanical modelling and stress analysis of RF MEMS capacitive shunt switch

This paper presents the simulation results as well as calculated results of a proposed RF MEMS shunt switch with Electro-mechanical modelling and stress gradient characteristics. The analysis is done with three membrane structures such as plane beam, incorporated with and without perforations, and non-uniform meander type beam, these are simulated in the COMSOL Multi-physics tool. The various model analysis are carried out for different values of residual stress gradients such as different structures, materials, and beam thickness. The analysis are characterized that the higher values of stress gradient are not desirable for switching action. By analyzing all the results we have observed that the stress analysis for the non-uniform meandered type switch obtained maximum stress of 35.6 MPa, and center deflection of 0.06 MPa/μm, the deformations of the beam which is the least among the considered switches.

Electromechanical coupling modeling and motor current signature analysis of bolt loosening of industrial robot joint

Since loosening of the bolt connection reduce the stability and working accuracy of industrial robot joint, developing and applying new detection methods to provide effective and reliable diagnosis is still a challenging task. In this study, a detection method for bolt loosening of industrial robot joint based on electromechanical modeling and motor current signature analysis (MCSA) is proposed. Firstly, a dynamics model is established based on the electromechanical coupling characteristics of the robot joint servo system, and the bolt loosening factor in the model is equivalent to the variations of support stiffness. The vibration performance of the system due to bolt loosening is analyzed, and the dynamical equations show the coupling relationship between the motor current and bolt loosening. Then according to the traits of motor current variation, this study proposes to utilize the time–frequency features of the motor current to detect loosening. The energy concentrated time–frequency representation (TFR) is obtained by the synchrosqueezing transform (SST) method, and then time–frequency ridges are extracted. The features of the time–frequency ridges are adopted as indicators of the bolt loosening. The support vector machine (SVM) classifier is utilized to identify the loosening of bolts. The simulated motor current signal analysis shows that the SST can highlight the current transients caused by bolt loosening. The bolt loosening experiment is conducted on the single-degree-of-freedom servo joint test bench, and the results prove the effectiveness of the proposed method.

A Study on the Electro-Hydraulic Coupling Characteristics of an Electro-Hydraulic Servo Pump Control System

Electro-hydraulic servo pump control belongs to an electro-hydraulic coupling motion control system, which involves the mutual penetration and integration of mechanical, hydraulic, electrical, control, and other disciplines, as well as the time-varying, uncertain, multisource, and multifield problems of the internal and external excitation of the system, which makes the electro-hydraulic servo pump control system have the characteristics of a complex model, strong coupling, nonlinearity, and time-variation, resulting in the low accuracy and poor dynamic characteristics of the system. This paper takes a servo motor quantitative pump hydraulic cylinder load as the main dynamic line; divides the electro-hydraulic servo pump control system into a motor pump unit, a hydraulic transmission unit and a power output unit; analyzes its electromechanical coupling characteristics, pressure flow coupling characteristics, and mechanical–hydraulic coupling characteristics, respectively; studies the multiparameter characteristics of the system under the electromechanical–hydraulic coupling conditions; and summarizes the influence laws between the parameters. Finally, through a MATLAB/Simulink simulation, it provides a theoretical basis and guidance for high-performance control of the system.

Design, Fabrication, Structure Optimization and Pressure Sensing Demonstration of COC Piezoelectret Sensor and Sensor Array.

This study reported on the design and fabrication of a pseudo-piezoelectric material (piezoelectret) from cyclic olefin copolymer (COC) based on a micropillar structure. The fabrication feasibility of such structure was explored and piezoelectret with the good piezoelectric activity (characterized by quasi-static piezoelectric coefficient d33) was demonstrated. Response surface method with a central composite design was employed to investigate the effects of the structure parameter on the piezoelectric coefficient d33. An optimal structure design was obtained and was validated by experiments. With the optimal design, d33 can reach an exceptional high value of ~9000 pC/N under low pressure. The charging process and the electrical and electromechanical characteristics were further investigated by experimentation and modeling. We further demonstrated the scalability of the fabrication process and demonstrated the application of these sensors in position specific pressure sensing (pressure mapping).

Graphene‐Based Composite Foams with Tunable Porosity for Ultra‐Sensitive Low‐Pressure Applications

AbstractComposite foam sensors presenting promising applications in pressure sensors require seamless integration of conductive additives, simplicity of manufacturing with minimum footprint, and consistent performance with optimum mechanical properties. Here, a resistive‐type foam sensor based on polyvinyl alcohol (PVA) containing high loading of water‐based graphene slurry (30 vol%) developed by in situ condensation is presented. The composite foam sensor exhibits an open‐cell structure with high electrical conductivity (13.3 × 10–2 S m−1), high sensitivity (S = 8.2 ± 0.7 for pressure <1 kPa), and minimum response time (8 ms). The effect of processing on porosity and the corresponding disparity in the electromechanical performance of the foam sensors is witnessed. A systematic method to evaluate the mechanical properties of foam sensors as per foam standards is described. In addition to assessing the electromechanical properties, the graphene‐based foam sensor is calibrated for the first time. The calibration curve and accuracy of the foam sensor are correlated to their morphology. Synthesis and facile integration of graphene in composites, their mechanical, electromechanical characteristics, and calibration of sensors are demonstrated. Furthermore, it is shown that the sensors can empower human‐machine interface systems using a custom‐developed user interface.

Conversion of Mechanical Energy to Electrical Energy Using Piezoelectric Materials for Bicycle Lane Lighting Systems

This study examined the electromechanical characteristics of piezoelectric materials, which constitute a compact renewable energy source; these materials can convert mechanical energy (such as pressure or a cumulative impact) in the form of mechanical stress to electricity. This study further explored systems that require moderate energy and utilize piezoelectric materials to create an energy-generating floor. The electrical characteristics of these piezoelectric materials were studied, including the feasibility of installing them as a power source for road lighting, particularly cycling lanes. Furthermore, the effects of riders’ weights and cycling speeds were investigated. The results indicate that the electric power generated is adequate for the installation of these materials and can thus help improve visibility in the event of insufficient lighting.

Retracted: Analysis of Electromechanical Characteristics in Air-Core Integrated Linear Synchronous Motor for EDS Maglev Train With Pitching Operation Condition

Propulsion, levitation and guidance characteristics are the key technology of electro-dynamic suspension Maglev train. An air-core integrated linear synchronous motor with asymmetric primary combined coils is introduced, which can not only simultaneously realize the propulsion, levitation and guidance performances, but also analyze the electromagnetic performance variation of linear synchronous motor under pitching condition. The novel three-dimensional analytical method is proposed for analyzing the transient electromechanical characteristics of the linear synchronous motor. Firstly, the topology structure and operation principle of the linear synchronous motor with pitching attitude are proposed. Secondly, the three-dimensional analytical methods and expressions of electromechanical characteristics are obtained by equivalent circuit method and Fourier decomposition method, such as levitation force, guidance force, propulsion force and pitching torque, etc. Finally, the three-dimensional electromechanical characteristics of the linear synchronous motor are calculated under pitching operation conditions in high-speed maglev train, and the correctness of the analytical theory is verified by the finite element analysis and measured data of on-board motor.

Novel Surfactant-Induced MWCNTs/PDMS-Based Nanocomposites for Tactile Sensing Applications.

The paper presents the use of surfactant-induced MWCNTs/PDMS-based nanocomposites for tactile sensing applications. The significance of nanocomposites-based sensors has constantly been growing due to their enhanced electromechanical characteristics. As a result of the simplified customization for their target applications, research is ongoing to determine the quality and quantity of the precursor materials that are involved in the fabrication of nanocomposites. Although a significant amount of work has been done to develop a wide range of nanocomposite-based prototypes, they still require optimization when mixed with polydimethylsiloxane (PDMS) matrices. Multi-Walled Carbon Nanotubes (MWCNTs) are one of the pioneering materials used in multifunctional sensing applications due to their high yield, excellent electrical conductivity and mechanical properties, and high structural integrity. Among the other carbon allotropes used to form nanocomposites, MWCNTs have been widely studied due to their enhanced bonding with the polymer matrix, highly densified sampling, and even surfacing throughout the composites. This paper highlights the development, characterization and implementation of surfactant-added MWCNTs/PDMS-based nanocomposites. The prototypes consisted of an optimized amount of sodium dodecyl sulfonate (SDS) and MWCNTs mixed as nanofillers in the PDMS matrix. The results have been promising in terms of their mechanical behaviour as they responded well to a maximum strain of 40%. Stable and repeatable output was obtained with a response time of 1 millisecond. The Young’s Modulus of the sensors was 2.06 MPa. The utilization of the prototypes for low-pressure tactile sensing applications is also shown here.

Numerical Evaluation of the Influence of the Outlet Nozzle Diameter of a Piezoelectric Gas Injector on Its Flow Properties

The paper presents the results of flow analyses of a piezoelectric gas injector with pulse action. The conceptual solution, due to the use of a piezoelectric actuator, is characterized by shorter opening and closing times. This promotes the precision of fuel dosing. It also meets current trends in environmental protection. The innovation in the injector under study is the use of a beam actuator comprising three layers, two active and one passive. The electromechanical characteristics of the converter were determined based on the method in which the actuator is treated as a bent beam with a locally implemented piezoelectric segment. Based on such assumptions, the deformation shape of the actuator and, as a result, the opening degree of the injector valve were determined. Flow studies were carried out using Computational Fluid Dynamics (CFD) in the ANSYS Fluent environment. The RANS (Reynolds-averaged Navier–Stokes) approach and the k-ω SST turbulence model were adopted. The solution was sought based on the standard SIMPLE scheme and polyhedral mesh. It allowed the determination of the flow characteristics of the analysed injector, with variable valve lift and outlet nozzle diameter.

Piezoelectric properties and related parameters of novel 1–2–2 composites based on single crystals of the PZN–xPT type

High-performance 1–2–2 composites based on domain-engineered relaxor-ferroelectric single crystals are analyzed, which demonstrate strong electromechanical coupling and large energy-harvesting characteristics. The role of the single-crystal rods and laminar polymer matrix is highlighted. A large anisotropy of the piezoelectric charge coefficients d 3j* and electromechanical coupling factors k 3j* is observed in specific volume-fraction ranges, with proposed dependence diagrams. The effective parameters of composites with parallelepiped-shaped rods are compared to similar parameters for composites based on cylindrical rods, with good agreement between parameters. These novel composites can be used in piezoelectric sensors, actuators, transducers, and energy-harvesting devices.

Structural features and electrophysical properties of the “piezoceramic-polymer” composites

Composites of a mixed type, consisting of porous piezoceramics particles in a polymer matrix, were produced and studied. A fabrication technique of such composites with 0–3 and 1–3 connectivities suitable for 3D printing method was presented. Their dielectric, electromechanical, and piezoelectric characteristics were measured. Dependences of dielectric permittivity on the number of layers of piezoceramic particles in the composite sample and on the ratio between the particle size and piezoelement thickness were presented. Single layer composites with appropriate ratio of the sample thickness and piezoelectric particles diameter demonstrated piezoelectric and electromechanical properties close to those of the initial piezomaterials.

Electromechanical losses and dispersion in textured piezoceramics based on layered bismuth-containing compositions

This article presents the results of experimental study of the frequency dependences of complex electromechanical characteristics of layered ferroelectrics based on bismuth-containing compounds with a perovskite-like structure. Textured ceramics of the composition 0.9Na0.5Bi4.5Ti4O15-0.1PbNb0.5Cr0.5O3 were prepared by uniaxial hot pressing method with a special sintering conditions. Experimental disk-shaped samples were cut from the hot-pressed blocks and polarized parallel (E ǁ P) and perpendicular (E ⊥ Р) to the pressing axis (P). Complex electromechanical parameters of textured piezoceramics and their frequency dependences in the frequency range up to 50 MHz were measured and analyzed using PRAP iterative automatic method.

Development and research of induction heating system in technological complexes of oil transportation

The problem of development and research of an induction system for heating viscous non-conductive liquids during transportation through pipelines is considered. A specific feature of the research object is the combination of the processes of heating a laminar fluid flow in a cylindrical inductor and mixing in a three-phase inductor - mixer. Research of interrelated electromagnetic, thermal and electromechanical processes in heating and stirring systems has been carried out. The results of a numerical calculation of electromagnetic and thermal fields and the electromagnetic moment of rotation of the rotor in a heated liquid are presented. A relationship has been established between the thermal power released in the elements of the system and the power used to rotate the rotor. The electromechanical (control) characteristics of the induction mixer are given. It is shown that with an appropriate choice of design and operating parameters of the induction system, it is possible to find the required ratio between the thermal power released in the elements of the system and the power used to stir the liquid. The results of the research are intended to solve the problems of designing the design of induction systems for heating viscous liquids and effective control of the heating process.

Structural Design and Test of a Piezoelectric Flextensional Transducer for Passive Detection of Frogmen

A piezoelectric flextensional transducer was designed using the finite element method (FEM) for the passive detection of underwater frogmen. By studying the main performance parameters of sonar transducers for the detection of frogmen around the world, this paper presents the advantages of active and passive sonar in this task and proposes a passive method for the detection of frogmen. Subsequently, a Cymbal transducer was selected considering the needs of the research. After introducing the principles and methods of the FEM analysis, the acoustic and electromechanical characteristics of the Cymbal transducer were verified under the influence of structural dimensions, e.g., resonance frequency, conductance, and susceptance. The electromechanical performance of the Cymbal transducer was simulated with a FEM to study how it is affected by static water pressure and processing errors and to demonstrate the feasible application of the Cymbal transducer in practical applications. In the end, a Cymbal prototype was tested to verify that the designed Cymbal transducer performs in compliance with the requirements and can be used for the passive detection of underwater frogmen with open-circuit breathing.

Investigation and Calculation of Electric Scooter Electromechanical Characteristics

The design of an electric scooter is presented. The advisability of using an inverted motor with an external rotor, which is part of the wheel, is shown. Permanent magnets producing a large number of pole pairs are installed on the rotor inner surface facing the air gap. With such design, low scooter motion speeds can be obtained without the need of using mechanical gearboxes. The choice of the rotor main dimensions based on the specific tangential force is considered. The stator consists of a core body with a winding, usually a three-phase one. In scooter motors, it is advisable to use a concentrated winding with a fractional q, which is wound around the tooth to form a separate coil on it, belonging to one of the phases. In such winding, the end turns do not intersect; its end-winding parts are much shorter than they are in distributed windings. The stator winding is powered by an inverter controlled synchronously with the rotor rotation. The considered electromechanical converter is nothing but a conventional synchronous machine. Constant torque operation is not typical for the scooter motor. When the user changes the scooter operation mode, for example, in changing over to another track section, all processes develop similarly to those that take place in conventional DC motors. To confirm this, the calculation of the motor is given, and its parameters are determined. An algorithm for calculating the scooter mechanical and performance characteristics has been developed.

A Versatile Model for Describing Energy Harvesting Characteristics of Composite-Laminated Piezoelectric Cantilever Patches.

Vibration-based energy harvesters consisting of a laminated piezoelectric cantilever have recently attracted attention for their potential applications. Current studies have mostly focused on the harvesting capacity of piezoelectric harvesters under various conditions, and have given less attention to the electromechanical characteristics that are, in fact, crucial to a deeper understanding of the intrinsic mechanism of piezoelectric harvesting. In addition, the current related models have mostly been suitable for harvesting systems with very specific parameters and have not been applicable if the parameters were vague or unknown. Drawing on the available background information, in this study, we conduct research on a vibration-based cantilever beam of composite-laminated piezoelectric patches through an experimental study of its characteristics as well as a modeling study of energy harvesting. In the experimental study, we set out to investigate the harvesting capacity of the system, as well as the electromechanical (voltage/current-strain and power-strain relationships) characteristics of the cantilever harvester. In addition, we summarize some pivotal rules with regard to several design variables, which provide configuration design suggestions for maximizing energy conversion of this type of harvesting system. In the modeling study, we propose a coupled electromechanical model with a set of updated parameters by using an optimization program. The preceding experimental data are used to verify the superiority of the model for accurately predicting the amount of harvested energy, while effectively imitating the characteristics of a cantilever harvesters. The model also has merit since it is suitable for diversified harvesters with vague or even unknown parameters, which cannot be dealt with by using traditional modeling methods. Overall, the experimental study provides information on a comprehensive way to enhance the harvesting capacity of piezoelectric cantilever transducers, and the modeling study provides a wide scope of applications for cantilever harvesters even if precise information is lacking.

Impact of an interface electrode charge and materials polarization to a conductive interface crack

A charged interface electrode and a conductive interface crack between different piezoelectric half-spaces with an arbitrary polarization direction under out-of-plane mechanical loading and in-plane electrical field are considered. An analytical method is used based upon the presentations of the electromechanical characteristics through sectionally-analytic vector-functions with the following formulation and solution of the combined Dirichlet-Riemann boundary value problem. Special attention is devoted to the formulation of the Gauss theorem for the electrode, which permits to take into account its charge. The expressions for stress, electric field, electric displacement jumps and the energy release rate (ERR) are found in a simple analytical form. The numerical results show the dependence of the ERR on the electrode charge, on the intensity of the electric field and on the directions of the polarization of the piezoelectric materials. It is particularly found that due to the appropriate choice of these parameters, the maximum value of the ERR for the crack can be substantially reduced, which mitigates the threat of crack propagation.

Research on performance of a laboratory-scale SAG mill based on DEM-EMBD

To explore the performance of a semi-autogenous (SAG) mill under different working conditions, in this paper, the working process of the laboratory-scale SAG mill is taken as the research object. Firstly, the electrical system and multi-body dynamics model (EMBD) of the SAG mill are established, the rock discrete element method (DEM) analysis model is obtained based on the multi-sphere filling method, and then the DEM-EMBD coupling model is created, and its effectiveness is verified through actual experiments. Secondly, the influences of fraction of critical speed, lifter face angle, and rock shape on particle motion characteristics, particle collision energy, and mill torque are studied by the method of DEM-EMBD coupling method. The results show that the particle motion characteristics are mainly determined by fraction of critical speed and lifter face angle. Particle collision energy is mainly determined by lifter face angle and rock shape. Further, when the SAG mill runs at a low speed, the lifter face angle and rock shape become the main influencing factors of the mill torque, and the fraction of critical speed becomes the dominant factor with a high running speed of the SAG mill. Finally, the electromechanical characteristics of the SAG mill are analysed, and the results show that the fluctuation of motor load torque, current, and SAG mill speed in the start-up stage is much larger than that in the stable running stage. The fraction of critical speed and the lifter face angle have a greater impact on the electromechanical characteristics, while the rock shape has little influence on the electromechanical characteristics as a whole.

Mechanical Energy Harvesting System from the Human Arm Movement for Continuous Blood Pressure Measurement

Background: In this article, an approach to harvesting electrical energy from a mechanically excited piezoelectric element has been described. Three PMN-xPT compositions were used with x taking the values of 0.31, 0.33, and 0.35 in order to study the most important properties of piezoelectric PMN-PT in energy harvesting. Objectives: This study uses a detailed analysis of three Relaxer (1-x)PMN-xPT ceramic compositions, emphasizing the influence of content on piezoelectric, dielectric, and electromechanical characteristics. Methods: Prototypes have been made and characterized, validating these energy thresholds. From this comparative analysis of the three compositions, it was found that PMN-35PT has the highest recoverable energy density. On the other hand, the pressure change in the radial artery was calculated using the pressure sensitivity of the sensor and systolic and diastolic characteristic points in the pressure pulse wave (PPW). Results: The results show that piezoelectric, dielectric, and electromechanical properties are all directly associated with chemical composition and that the examined ceramics outperform their PZT counterparts, making them very suitable for energy harvester systems and sensing device applications. Therefore, the structure developed is an external patch of 5x3cm², placed on the arm and able to recover 3.46 mW for PMN-35PT during human walking. Conclusion: Results indicate that the suggested method demonstrated reliable accuracy of systolic blood pressure (SBP). The technology has the potential to be used for long-term continuous blood pressure monitoring. The piezoelectric sensor was placed on the skin above the radial artery and measured for 10 sec to obtain the continuous pressure waveform.