Mechanical Output Performance Research Articles

Influence of contact characteristics of joint surface on vibration performance of the giant magnetostrictive transducer

The giant magnetostrictive transducer is a transducer device that realizes magneto-mechanical energy conversion. Each mechanical component is connected by the joint surface to realize the transmission of ultrasonic vibration energy. To ensure the efficient transmission of energy, the influence of the contact characteristics of the joint surface on the output stability of the transducer is studied. According to the contact conditions between the mechanical joint surfaces of the giant magnetostrictive ultrasonic transducer (GMUT), the key factors affecting the mechanical vibration performance of the ultrasonic system are obtained by analyzing the vibration transmission characteristics of the joint surfaces. The influence of different joint surface contact characteristics (JSCT) on the amplitude–frequency curve of the transducer is analyzed by the ANSYS software. Simulations and experiments have been conducted to verify the predicted results. As the preload force increases, the natural frequency of the transducer increases, but the growth rate decreases. The natural frequency of the double-rod GMUT with a small joint surface area is slightly higher in the optimal output mode shape, while its amplitude is significantly larger. The optimal prestress for the GMUT with different-sized joint surfaces is 3–5 MPa. This paper acquires the JSCT under a high-frequency vibration condition, reveals the influence of the joint surface on the mechanical output performance of the GMUT, and can provide a theoretical basis for the design and analysis of the rotary ultrasonic vibration processing system.

Hidden regulator-based rotational triboelectric nanogenerator with tracing optimal working condition

The research on the rotational triboelectric nanogenerators (R-TENGs) is actively conducted by numerous groups, but its friction-based operation mechanism makes it challenging to simultaneously ensure electrical performance (including output voltage and power) and mechanical performance (such as stability and durability). In this study, a physically intelligent Hidden regulator-assisted design-based R-TENG (HR-TENG) is developed based on the self-adaptive mechanical kinetic design. The relationships between engaged forces and the output performance of R-TENG are investigated, and the normal force acting on the contact interface is unveiled as a hidden core of the output performance of R-TENG. Here, HR-TENG traces the optimal working conditions in real-time according to input energy conditions by itself with spontaneously adjusted friction by controlling the normal force with mechanically self-adjustable components. HR-TENG can be operated in a wide range of conditions of input energy source, and exhibit self-adaptive electrical performance while maintaining mechanical performance depending on the input energy conditions without human intervention. The behaviors of the mechanically self-adjustable components depending on the operation of HR-TENG are analyzed theoretically and experimentally based on kinetic dynamics, and the effect of the normal force on the electrical and mechanical output performances is investigated. The average coefficient of inner friction of HR-TENG is 0.27, and the maximum output voltage and peak power are 254 V and 0.726 mW, respectively. As a proof-of-concept demonstration, the electrical output of HR-TENG under a wide range of input wind conditions (wind speed of 4–22 m/s) is investigated, and the real-time tracing ability of HR-TENG to the optimal working conditions in the continuously changing wind environment is analyzed. The kinetic design of HR-TENG with the hidden regulator (normal force), which affects multiple direct factors of electrical and mechanical performances, can be introduced to various R-TENGs as a key strategy, and thus, it can be expected to serve as a design guideline for futuristic physical intelligence-assisted smart energy harvesters.

A Low-Voltage Cylindrical Traveling Wave Ultrasonic Motor Incorporating Multilayered Piezoelectric Ceramics.

In-plane bending traveling wave ultrasonic motors (USM), which are compact in structure and flexible in design, have been widely applied in biological engineering, optical engineering, and aerospace engineering. However, the high driving voltage and complicated driving circuit of this kind of USM restrict their further miniaturization and electromechanical integration in these applications and bring some potential safety hazards. To solve this problem, a low-voltage-driving traveling wave USM incorporating cofired multilayer piezoelectric ceramics was proposed in this work. Four cofired piezoelectric ceramics were strategically designed to excite two orthogonal third-order in-plane bending modes with the same frequency of the USM. The principles of traveling wave synthesis and low-voltage-driving of the USM were deduced, and the stator dynamic design and transient dynamic simulation were carried out by finite-element method. The microproperties of cofired piezoelectric multilayer ceramics, the vibration characteristics of the stator, and the mechanical output performance of the USM were tested by experiments. The results indicated that the motor can work as low as 5 [Formula: see text]. A long stroke with a maximum forward and reverse rotational speeds of 187.7 and 176.6 r/min were obtained, respectively, and a maximum stalling torque of 4.8 mN · m at 47.3 kHz under 15 [Formula: see text] was achieved. The results showed that the proposed USM is small, low in driving voltage, and high in torque output, which has promising applications in aerospace, biomedicine, and other fields that require a lightweight and integration of driving devices.

A novel hybrid mode linear ultrasonic motor with double driving feet.

A novel standing wave linear ultrasonic motor with double driving feet based on longitudinal-bending coupling mode is designed in this study. The motor adopts the bonded-type structure, and four pieces of piezoelectric ceramics on a metal beam are divided into two groups. Two voltages with 90° phase difference are applied to two groups of Pb-based lanthanumdoped zirconate titanates ceramics, respectively. Then the first longitudinal and second bending modes generated are superimposed on the stator, which can produce elliptical motion trajectories on the driving feet. The excitation method and driving mechanism of the motor are illustrated in detail. A finite model of the stator is established in the ANSYS parametric design language interface, and the operating mode of the stator and motion trajectories on the driving feet are discussed. The prototype is fabricated, and its impedance characteristics and mechanical output performance are tested. The results show that the maximal no-load velocity of the motor is ∼147.78 mm/s under a voltage of 200V and a preload of 3 N. The maximum thrust force is ∼1.1 N when the voltage and preload are 200V and 6 N, respectively.

Improving the performance of ultrasonic motors in low-pressure, variable-temperature environments

Ultrasonic motor (USM) performance is dependent on the tribological characteristics of the interface between a stator and rotor, which are sensitive to ambient environments and driving parameters. Thus, the effects of vacuum and temperature on the mechanical output performance and energy conversion efficiency of a traveling wave rotary ultrasonic motor 60 (TRUM-60) with a novel micro-dimpled PI-based friction material and optimized input parameters were systematically investigated for the first time. The degree of vacuum had a negligible effect on the performance of the TRUM-60, whereas temperature influenced its mechanical output torque, rotational speed, and output power. The results can aid in the design of USM devices for aerospace applications.

Numerical Analysis and Experimental Investigation on a Novel Piezoelectric-Actuated Rail-Type Mobile Platform

A novel piezoelectric-actuated rail-type mobile platform is proposed in this article, which has potential application in the inspection and maintenance tasks of the Tokamak vacuum vessel as it holds good environmental adaptability to extreme environments, such as strong magnetic fields, high vacuum, and high temperature. The rail-type piezoelectric-actuated mobile platform consists of a rail and a framed piezoelectric actuator operating with two orthogonal bending vibrations. The framed piezoelectric actuator moves on the rail by friction. At first, a semianalytical model is created for the framed piezoelectric actuator utilizing the transfer matrix method in order to reveal its dynamic behavior. Then, the prototype of the proposed framed piezoelectric actuator is manufactured and assembled, and its vibration characteristics are measured to verify the feasibility of the developed transfer matrix model. Additionally, the mechanical output performances of the rail-type mobile platform prototype are investigated experimentally, and it is observed that the maximum speed of the mobile platform prototype reached 384.68 mm/s when the amplitude of the driving voltage is 400 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pp</sub> , its maximum load-weight to self-weight ratio reached 7.6 when the excitation voltage is 300 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pp</sub> , its maximum output force is about 1.8 N under the excitation voltage of 400 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pp</sub> , and the minimum displacement resolution is 4 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> m when operated in the stepping mode. Finally, the extreme environment (temperature: 0–120 °C and vacuum: 3×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−3</sup> –10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> Pa) tests are carried out to measure the output performances of the mobile platform prototype. The results show that the platform prototype is capable of carrying loads in a high-temperature and high-vacuum environment.

Development of a Small Two-Dimensional Robotic Spherical Joint Using a Bonded-Type Piezoelectric Actuator

Piezoelectric actuator (PEA) is one of the most promising candidates for the robotic joints to realize high-resolution linear or rotary motions. In this article, a small 2-D robotic spherical joint using a bonded-type PEA was proposed to achieve the high-resolution rotary motions around two orthogonal axes. The configuration and operating principle of the robotic spherical joint were first formulated. Then theoretical analyses were carried out to design the PEA, and a prototype of the joint was fabricated. Finally, a series of tests were performed to verify the theoretical results and investigate the mechanical output performances of the joint. The experimental results revealed that maximum rotary velocities of 1.03 rad/s around the X- axis and 1.14 rad/s around the Y -axis were achieved under voltage of 400 Vp-p and frequency of 750 Hz. Meanwhile, the displacement resolutions were tested to be about 4.64 μ rad around the X- axis and 4.76 μ rad around the Y- axis. The proposed joint with small size and compact structure could accomplish the 2-D precision rotary motion with merits of high resolution and large motion range.

3D printing and dynamic modeling of a polymer-based bimodal piezoelectric motor

Owing to characteristics of single-step fabrication and rapid prototyping, 3D printing have potential applications in processing piezoelectric motors with complex structures. In this paper, a 3D printed resin-based bimodal piezoelectric motor is proposed. Four slots of the motor are designed to reduce the influence of large damping caused by polymer’s viscoelastic and enhance mechanical properties. Considering the viscoelasticity and internal structure of the stator, a dynamic model based on the proposed motor is developed. Furthermore, parameters of these slots are optimized using the Taguchi method. Prototypes are fabricated and experimentally investigated. The results demonstrate that the first longitudinal mode and the second bending mode are 17 765 Hz and 18 006 Hz respectively, which are consistent with the analytical model results. Under the voltage of 300 Vpp, the maximum no-load speed and maximum driving load of the slotted motor are 200 r min−1 and 20 g with a speed of 6 r min−1, respectively. Compared with the motor without slots, the speed and load capacity are increased by 25% and 33%. Therefore, the motor with slots exhibits better mechanical output performance.

Development of a two-DOF inertial rotary motor using a piezoelectric actuator constructed on four bimorphs

A new two-DOF inertial rotary motor using a two-dimensional piezoelectric actuator (PEA) constructed on four bimorphs was developed in this work. The theoretical analyses and finite element method (FEM) simulation were accomplished to design the two-dimensional PEA. The stick-slip mechanism was utilized to implement the rotary motions of the motor. Then the mechanical output performances of the motor were tested and compared with previous work. The experimental results indicated that the maximum rotary velocities of the motor were 263.26 mrad/s around X axis and 268.48 mrad/s around Y axis under voltage of 210 Vp-p and frequency of 630 Hz, respectively. The angular displacement resolutions of 6.27 μrad around X axis and 6.34 μrad around Y axis were achieved under voltage increment of 2.5 V, respectively. This new motor held the advantages of smaller size and larger output speed. This motor could be applied to precision attitude adjustment systems by virtue of its compact size, high resolution and large rotary motion space.

Traveling Wave Type Multi-Degree-of-Freedom Spherical Ultrasonic Motor with Built-in Stators

A multi-degree-of-freedom spherical ultrasonic motor with built-in traveling wave stators is proposed, and each traveling wave stator can be controlled independently, the three-degree-of-freedom movement of the spherical rotor is realized by the coordinated control of the three traveling wave stators and the spatial arrangement of the support structures. The motor also has a built-in pre-pressure adjustment structure, which can adjust the pre-pressure of three stators at the same time and make them the same size. The structure and working principle of the motor are expounded in detail. The structure and working principle of the motor are expounded in detail. The finite element method is used to analyze the modal of the traveling wave stator, and the transient trajectory of the driving part is simulated. Finally, the working principle was verified on the prototype, and the mechanical output performance of the prototype was tested: when the excitation voltage of the motor is 400 V and the preload is 100 N, the maximum speed is 45.6 rad/min, the maximum speed output torque is 1.265 Nm; the maximum deflection angle is 43°, and the maximum deflection speed is 56.3 rad/min, the maximum deflection torque is 1.76 Nm, achieves high torque and multiple-degrees-of-freedom. The motor has the advantages of large output force, high integration, and adjustable preload.

A Novel Piezoelectric Inchworm Actuator Driven by One Channel Direct Current Signal

A novel piezoelectric inchworm actuator driven by one channel dc signal is developed in this article to simplify excitation signal of the inchworm actuators, and the clamping force of the developed actuator is generated by a dc motor and two permanent magnets. The piezoelectric stack is excited by a sensing signal, which is generated by the separate photoelectric sensor to detect the position of the rotational permanent magnets. A mathematical model is established to predict the motion of the slider. The prototype of the proposed piezoelectric actuator is fabricated, and mechanical output performance is measured. At a voltage of 75 V and frequency of 3.2 Hz, the average output step is 0.241 μm under no-load conditions. The proposed inchworm actuator can be operated by just one channel dc signal and the output displacement is stable, which provides a new idea for the integration design of the piezoelectric actuators in the future.

A Review on the Flexure-Based Displacement Amplification Mechanisms

Multifarious flexure-based displacement amplifiers have been proposed and studied in the past decades, showing importance in many industrial fields, such as bioengineering, optical instruments, and semiconductor technology. Displacement amplifiers provide precise motion and large stroke through a simple and low-cost way compared with other piezoelectric actuators. Those merits have opened a door for new and advanced micro devices with unprecedented performance. This paper aims to proffer a comprehensive review on the design, modeling, characteristics, and applications of flexure-based displacement amplifiers, following by pointing out the inherent drawbacks in this research area such as amplification ratio limit, parasitic motion, low lateral stiffness, low natural frequency, and discussing existing solutions and some potential research directions in those topics. Finally, a summary is concluded and the future development perspectives of the displacement amplifiers are discussed. This review contributes to giving a comprehensive understanding of the displacement amplifier, which provides guidance on designing new displacement amplifiers for improving their mechanical output performance. It is also expected to be instrumental for related researchers to understand displacement amplifiers, and to successfully select and design for specific applications.

A review of recent studies on non-resonant piezoelectric actuators

Abstract Various non-resonant piezoelectric actuators have been emerged in recent decades and they have been applied successfully in many industrial fields, such as medical apparatuses, optical instruments and semiconductor technologies. They are generally classified into three categories according to their different working principles: the direct drive type, the inertial drive type and the inchworm type, respectively. The main contribution of this work is to provide a comprehensive review of recent studies on the non-resonant type piezoelectric actuators. In this review, the operating principles, some representative designs, performance analyses and practical applications of each type of non-resonant piezoelectric actuators are provided. Finally, a summary is concluded and the future development perspectives of these non-resonant type piezoelectric actuators are discussed. This review contributes to giving a comprehensive understanding of the non-resonant type piezoelectric actuators. It also provides guidance on designing new piezoelectric actuators for improving their mechanical output performances.

Development of a Two-Dimensional Linear Piezoelectric Stepping Platform Using Longitudinal-Bending Hybrid Actuators

A novel two-dimensional (2-D) linear piezoelectric stepping platform using two parallel longitudinal-bending hybrid piezoelectric actuators is proposed in this paper. The proposed platform is moved in the X -direction by combing the vertical and horizontal bending motions of the parallel actuators, whereas the movement in the Y- direction is realized by the vertical bending and longitudinal hybrid motions. The platform is designed and its operating principles in two orthogonal directions are described. The finite-element method simulations are performed to verify the operating principles of the 2-D platform. Two piezoelectric actuators are fabricated and a prototype of the platform is assembled. The measured results of mechanical output performance indicate that the velocities of the platform are 101.7 and 124.2 μm/s in X - and Y- directions when the voltage and frequency are ${\text{400}\,\text{V}}_{{\text{p-p}}}$ and 5 Hz, respectively, which verifies the feasibility of the proposed mechanism for the 2-D stepping platform.

A Two-Dimensional Wireless and Passive Sensor for Stress Monitoring.

A new two-dimensional wireless and passive stress sensor using the inverse magnetostrictive effect is proposed, designed, analyzed, fabricated, and tested in this work. Three pieces of magnetostrictive material are bonded on the surface of a smart elastomer structure base to form the sensor. Using the external load, an amplitude change in the higher-order harmonic signal of the magnetic material is detected (as a result of the passive variation of the magnetic permeability wirelessly). The finite element method (FEM) is used to accomplish the design and analysis process. The strain-sensitive regions of the tension and torque are distributed at different locations, following the FEM analysis. After the fabrication of a sensor prototype, the mechanical output performance is measured. The effective measurement range is 0–40 N and 0–4 N·M under tension and torque, respectively. Finally, the error of the sensor after calibration and decoupling for Fx is 3.4% and for Tx is 4.2% under a compound test load (35 N and 3.5 N·M). The proposed sensor exhibits the merits of being passive and wireless, and has an ingenious structure. This passive and wireless sensor is useful for the long-term detection of mechanical loading within a moving object, and can even potentially be used for tracing dangerous overloads and for preventing implant failures by monitoring the deformation of implants in the human body.

Improved energy conversion efficiency of the ultrasonic motor with surface texture

PurposeThis paper aims to investigate the effect of frictional materials and surface texture on the energy conversion efficiency and the mechanical output performance of the ultrasonic motor (USM).Design/methodology/approachA newly designed testing system was set up to measure the mechanical output performance of the USM. The influence of different frictional materials on the output performance of the USM was studied under the same assembly process and parameters. The surface texture was fabricated by laser ablation processing. The effects of surface texture and input parameters on the energy conversion efficiency and mechanical output performance of the USM were studied.FindingsThe results show that polyimide (PI) composites as frictional material can significantly improve the output performance of the USM compared to polytetrafluoroethylene (PTFE) composites. When the pre-load is 240 N, the energy conversion efficiency of the USM using textured PI composites as frictional material can reach 41.93 per cent, increased by 29.21 per cent compared to PTFE composites, and the effective output range of the USM is increased to 0.7-1.1 N m. Besides, the pre-load and surface texture have a great influence on the output performance of the USM.Originality/valuePI composites can improve the mechanical output performance of the USM. Surface texture can also improve the interface tribological properties and the energy conversion efficiency based on the advanced frictional materials, which will contribute to the increment of the output performance of the USM under the same input conditions.

Design and experimental evaluation of a novel stepping linear piezoelectric actuator

A novel stepping piezoelectric actuator is proposed and tested in this work to achieve the linear driving with long stroke and high resolution. The proposed piezoelectric actuator contains four piezoelectric stacks located in U-shape: two of them are set horizontally, whereas the other two are placed vertically. The actuating principle of the U-shaped actuator is analyzed: two piezoelectric stacks are used to control the clamping state of the runner, while the linear stepping motion is achieved by the other two stacks. A double-level screws structure, which not only gives enough preload, but also protects the piezoelectric stacks from lateral forces, is proposed and used to make the piezoelectric stacks work under a reliable condition. An equivalent model is developed for the calculation of the clamping force of the piezoelectric actuator. The equivalent model is based on a concept of converting structures related to clamping forces into springs with certain elastic coefficients. Static analysis is performed by finite element method (FEM) to get the equivalent coefficients of the structures. A prototype is fabricated and the experimental studies are carried out to validate the actuating principle and obtain the mechanical output performances. Experimental results show that the maximum driving force of the prototype is 13.2 N and the maximum velocity is 47.6 μm/s.

A novel L-shaped linear ultrasonic motor operating in a single resonance mode.

In this study, a large thrust linear ultrasonic motor using an L-shaped stator is described. The stator is constructed by two mutually perpendicular rectangular plate vibrators, one of which is mounted in parallel with the slider to make the motor structure to be more compact. The symmetric and antisymmetric modes of the stator based on the first order bending vibration of two vibrators are adopted, in which each resonance mode is assigned to drive the slider in one direction. The placement of piezoelectric ceramics in a stator could be determined by finite element analysis, and the influence of slots in the head block on the vibration amplitudes of driving foot was studied as well. Three types of prototypes (non-slotted, dual-slot, and single-slot) were fabricated and experimentally investigated. Experimental results demonstrated that the prototype with one slot exhibited the best mechanical output performance. The maximum loads under the excitation of symmetric mode and antisymmetric mode were 65 and 90 N, respectively.

A novel piezoelectric actuator with two operating modes

A novel piezoelectric actuator with two operating modes is proposed and tested in this work, whose unique feature is that it has different mechanical output performances under two bending resonance frequencies. The proposed actuator is fabricated by bonded eight pieces of lead zirconate titanate ceramic plates on an aluminum alloy beam symmetrically. When the ceramic plates are excited by signals with resonance frequency of the first bending mode of the actuator, two bending vibrations will be superimposed to form elliptical movements on the two driving tips, which is the first operating mode. The other operating mode can be realized easily by changing the working frequency to the second bending mode of the actuator. These two operating modes are calculated and compared in detail. The prototype achieves a maximum no-load speed of 171 mm/s and maximum thrust force of 0.6 N using the first operating mode, whereas these two values are increased to be about 208 mm/s and 0.76 N under the second operating mode. The weight of the proposed piezoelectric actuator is about 17.7 g, and the maximum force weight ratio is tested to be about 42.9 N/kg.

An I-shape linear piezoelectric actuator using resonant type longitudinal vibration transducers

Resonant type longitudinal vibration transducers are used in this work to construct a linear piezoelectric actuator with four driving feet. Totally three longitudinal transducers are integrated in I-shape to form the proposed actuator, which contains one vertical transducer and two horizontal transducers. These three transducers vibrate under longitudinal modes with certain temporal sequence, whose vibrations are superimposed in the actuator to generate elliptical motions on the four driving feet. The three transducers are tuned to be suitable dimensions, under which they have very close 1st longitudinal resonance frequencies; the working frequency of the piezoelectric actuator is designed to be about 31.3kHz. The vibration coupling problem between the longitudinal transducers are studied by calculating the motion trajectories of the four feet. It is found that the temporal shift of the longitudinal vibrations can be used to tune the movement trajectories; the four feet can get nearly the same vertical displacements under a phase shift of 105°. At last, the vibration characteristics and mechanical output performances of a prototype are measured. The working frequency of the prototype, the maximum speed, and the maximum thrust force are measured to be 33.15kHz, 1563mm/s, and 158.2N, respectively.