Orthogonal Bending Vibrations Research Articles

Study on a novel omnidirectional ultrasonic cavitation removal system for Microcystis aeruginosa

Microcystis aeruginosa, as a typical alga, produces microcystin with strong liver toxicity, seriously endangering the liver health of human and animals. Inhibiting the bloom of the Microcystis aeruginosa in lakes becomes a significant and meaningful work. Ultrasonic cavitation is currently considered to be the most environmentally friendly and effective method for the removal of Microcystis aeruginosa. However, the commercialized ultrasonic algae removal systems require multi-Langevin transducers to achieve omnidirectional ultrasonic irradiation due to the single irradiation direction of the Langevin transducer, resulting in the complex design and high energy consumption. To achieve a low-cost, simple structure, and high-efficiency algae removal system, a novel omnidirectional ultrasonic cavitation removal system for Microcystis aeruginosa is proposed. The proposed system is major composed of a novel omnidirectional ultrasonic transducer, which generates the omnidirectional ultrasonic irradiation by its shaking-head motion coupled by two orthogonal bending vibration modes. Modal simulation, sound field simulation, and cavitation bubble radius simulation are first carried out to optimize the geometric sizes of the proposed transducer and verify the correctness of the omnidirectional ultrasonic irradiation principle. Then the vibration characteristics of the transducer prototype are measured by vibration tests and impedance tests. Finally, the feasibility and effectiveness of the proposed omnidirectional ultrasonic removal system for Microcystis aeruginosa are evaluated through the algae removal experiments. The experimental results exhibit that the algal cells damaged by ultrasonic irradiation from the proposed system do not have the ability to self-repair. In addition, the algal removal rates reached 55.41% and 72.97% after 30 min of ultrasonic treatment when the corresponding ultrasonic densities are 0.014 W/mL and 0.021 W/mL, respectively. The proposed omnidirectional ultrasonic algae removal system significantly simplifies the configuration and reduces energy consumption, presenting the potential promise of algae removal and environmental protection.

Design and Dynamic Simulation of a Novel Traveling Wave Linear Ultrasonic Motor

To overcome the problem of frequency consistency and simplify the design process of linear ultrasonic motor, a novel traveling wave linear ultrasonic motor with a ring-type stator is proposed in this paper. The combination of two orthogonal bending vibration modes with the same order is selected as the operating mode of the motor. A traveling wave along the side of the stator is utilized to drive the slider to move linearly. The stator adopts a ring symmetrical structure, which can effectively ensure that the resonance frequencies of the two vibration modes are consistent. Thus, we do not need to tune the frequencies of the two vibrations by constantly adjusting the shape of the stator or designing complex clamping parts to fix the stator without making any influence on the vibrations. Meanwhile, a three-dimensional finite element model of the motor is built. Using the model, we obtain the elliptical motion trajectories of the stator driving surface, the output performance of the motor, the sticking-slipping-separation contact characteristic between the stator and the slider and fabricate and measure a prototype of the proposed motor.

Theoretical modeling and experimental investigation on a novel screwed-type piezoelectric focusing mechanism for space cameras

Traditional focusing mechanisms for space cameras are driven by a stepper motor with transmission parts, holding the disadvantages of complex structure, low space utilization, electromagnetic interference, and difficulty in self-locking. In order to overcome the above defects, a novel screwed-type piezoelectric focusing mechanism is proposed for space cameras. A screwed-type piezoelectric actuator with a hollow tube stator and rotor is proposed to directly drive a focusing lens to achieve a variation in the focal length. The stator with internal thread operates with two orthogonal bending vibrations and drives the rotor with thread to achieve linear motion by friction. An axial pre-pressure adjustment structure is designed to improve the output performance of the screwed-type piezoelectric actuator in a weightless environment. In order to reveal the dynamic characteristics of the stator and to determine its physical dimensions, an electromechanical coupling model is created using the transfer matrix method. A prototype of the stator is fabricated, and its vibration characteristics were tested to confirm the correctness of the developed theoretical model. In addition, the mechanical output characteristics of the screwed-type piezoelectric actuator prototype are experimentally evaluated. The experimental results shown that: 1. The maximum axial load weight to actuator weight ratio reaches 4.8 under peak-to-peak excitation voltages of 100 Vp-p; and 2. the actuator prototype can operate in high-temperature (100 °C) and high-vacuum (1.5 × 10-3 Pa) environments. Finally, the feasibility of the screwed-type piezoelectric focusing mechanism is experimentally demonstrated. The minimum displacement resolution of the mechanism prototype reaches 5.01 μm when the duty ratio is 1.20%, and the mechanism focuses on the image located at 3300 mm. The proposed piezoelectric focusing mechanism can realize high-precision linear positioning without transmission parts, and can realize self-locking without power, presenting the potential application in space cameras.

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.

The design and experiment of a novel ultrasonic motor based on the combination of bending modes

This paper presents a new-type linear ultrasonic motor which takes advantage of the combination of two orthogonal bending vibration modes. The proposed ultrasonic motor consists of eight pieces of PZT ceramic plates and a metal beam that includes two cone-shaped horns and a cylindrical driving foot. The finite element analyses were finished to verify the working principle of the proposed motor. The mode shapes of the motor were obtained by modal analysis; the elliptical trajectories of nodes on the driving foot were obtained by time-domain analysis. Based on the analyses, a prototype of the proposed motor was fabricated and measured. The mechanical output characteristics were obtained by experiments. The maximal velocity of the proposed motor is 735mm/s and the maximal thrust is 1.1N.

A High-Power Linear Ultrasonic Motor Using Bending Vibration Transducer

To overcome the modal degeneration problem that commonly exists in the design of ultrasonic motors (USMs) using composite vibration modes, a high-power linear USM using a bending vibration transducer is proposed in this paper. In this new design, two orthogonal bending vibration modes with the same order are superimposed in the motor and generate elliptical motions at the two driving feet. Square cross-section structure is adopted by the motor to ensure that the two bending modes have the same resonance frequency. After the introduction of the working principle, the motor is analyzed by using finite-element method. A prototype motor is fabricated and measured. Typical output of the prototype is a no-load speed of 1527 mm/s and a maximum thrust force of 50 N at a voltage of 200 Vrms. This study verifies the feasibility of the proposed design and provides a way to improve the output power of USMs.

An Experimental Method to Determine Circumferential Chamfered Position for a Langevin-Type Stator

A langevin-type ultrasonic motor works using two orthogonal bending vibration modes. However, due to the influence of machining error, heterogeneous materials, especially the screw stress unevenness along the circumferential direction, the modal frequencies of two vibration modes are different, which will affect motor performance. Earlier research only deals with the axial position to chamfer to reduce the frequency difference, and think vibration direction consistent with excitation direction. While experimental results show that these two directions are generally different. By using Finite Element Method (FEM), a square-base stator is simulated, and the relationship is obtained qualitatively between the extreme value amplitude point and the extreme value bending moment of inertia of the stator. At last, an experimental method is presented to determine the maximum vibration amplitude position of a cylinder ultrasonic motor when the excitation angle changes in the range (-90,90].

A High Power Linear Ultrasonic Motor Using a Bending Bolt-Clamped Transducer

Based on the concept of forming elliptical movements on the two leading ends of a beam by the superimposing of two orthogonal first-order bending modes, a high power linear ultrasonic motor using a bending bolt-clamped transducer is proposed in this study. Two groups of bending PZT located at the wave loop of the bending vibration are excited by alternating voltages with the transducer's bending resonance frequency to accomplish the generations of the two orthogonal bending vibrations. The symmetrical setting of the PZT elements makes the two driving feet have the same elliptical movement trajectory. Elastic supporting is accomplished by thin beams machined on the two sides of each horn. The electromechanical coupling factors of the motor are calculated; the movement trajectories of the diving feet are simulated. After the fabrication of a prototype, its vibration characteristics and mechanical ability are tested. The proposed motor achieves a maximum speed of 1309 mm/s and a maximum thrust force of 45 N.

Vibrations of H+(D+) in stoichiometric LiNbO3 single crystal

A first principles quantum mechanical calculation of the vibrational energy levels and transition frequencies associated with protons in stoichiometric LiNbO(3) single crystal has been carried out. The hydrogen contaminated crystal has been approximated by a model one obtains by translating a supercell, i.e., a cluster of LiNbO(3) unit cells containing a single H(+) and a Li(+) vacancy. Based on the supercell model an approximate Hamiltonian operator describing vibrations of the proton sublattice embedded in the host crystal has been derived. It is further simplified to a sum of uncoupled Hamiltonian operators corresponding to different wave vectors (ks) and each describing vibrations of a quasi-particle (quasi-proton). The three dimensional (3D) Hamiltonian operator of k=0 has been employed to calculate vibrational levels and transition frequencies. The potential energy surface (PES) entering this Hamiltonian operator has been calculated point wise on a large set of grid points by using density functional theory, and an analytical approximation to the PES has been constructed by non-parametric approximation. Then, the nuclear motion Schrödinger equation has been solved by employing the method of discrete variable representation. It has been found that the (quasi-)H(+) vibrates in a strongly anharmonic PES. Its vibrations can be described approximately as a stretching, and two orthogonal bending vibrations. The theoretically calculated transition frequencies agree within 1% with those experimentally determined, and they have allowed the assignment of one of the hitherto unassigned bands as a combination of the stretching and the bending of lower fundamental frequency.

A rotary ultrasonic motor using bending vibration transducers

A rotary ultrasonic motor using bending vibration transducers is proposed. In each transducer, two orthogonal bending vibrations are superimposed and an elliptical trajectory is generated at the driving foot. Typical output of the prototype is a no-load speed of 58 rpm and maximum torque of 9·5 Nm under an exciting voltage of 200 V(rms).

A Linear Ultrasonic Motor Using Bending Vibration Transducer with Double Driving Feet

A linear ultrasonic motor using bending vibration transducer with double driving feet was proposed. The motor consists of two exponential shape horns located on the two leading ends. Two orthogonal bending vibrations are superimposed in the motor and generate elliptical trajectories at the driving feet. The motion trajectories of the driving feet were deduced. Transient analysis was developed to gain the vibration characteristics of motor. A prototype motor was fabricated and measured. Typical output of the prototype is no-load speed of 990 mm/s and maximum thrust force of 12 N at a voltage of 150 Vrms.

A miniaturization of the multi-degree-of-freedom ultrasonic actuator using a small cylinder fixed on a substrate

Multi-degree-of-freedom ultrasonic actuator has been studied for robot arms and multidimensional precision table and so on because of its simple structure, silent operation, and holding force. In this study, we aim to miniaturize multi-degree-of-freedom ultrasonic actuator for fabrication on a substrate. This actuator consists of a stainless steel cylinder and a PZT ring. The cylinder is fixed on a substrate and the PZT ring is glued to the substrate near the cylinder. The 1st longitudinal vibration and the 2nd bending vibration are simultaneously excited in the cylinder to make elliptical motion at the top of the cylinder and a ball rotor placed on the cylinder rotates because of the friction force. Length of the cylinder was decided so as to tune the resonance frequency of the 1st longitudinal vibration to the 2nd bending one. Actuator performances are evaluated experimentally using a 14 mm height and 7 mm diameter stainless steel cylinder with a 0.5 mm thickness PZT ring. The rotation about the cylinder axis is tested using the two orthogonal bending vibrations with 90° phase difference. Also, the rotation about horizontal axes were investigated using the combination of the longitudinal vibration and one of two bending vibrations. We measured the rotation speed of a steel ball and obtained 15.8 rps using a 6 mm diameter ball rotor.