Orthogonal Vibration Modes Research Articles

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.

Design of a Semi-Oval Shaped Ultrasonic Motor

A low voltage drive linear ultrasonic motor with a semi-oval shaped stator is proposed in this paper. In the stator, two multilayer piezoelectric actuators are clamped in the holder of the stator by pre-stressing to excite a semi-oval ring. The semi-oval shaped stator is designed to have normal vibration and tangential vibration modes, thus these two orthogonal mechanical vibration modes of the stator can be excited to generate elliptical motion at the contact point of the stator. In design of the motor, ANSYS finite element analysis software was used in this study to accomplish the design and analysis. A prototype motor was fabricated and measured. For single phase signal driving, typical output of the prototype is a no-load speed of 88 mm/s and maximum thrust force of 1.96 N at a voltage of 16 Vp. For two sine wave signals driving, typical output of the prototype is a no-load speed of 106 mm/s and maximum thrust force of 3.33 N at a voltage of 16 Vp.

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 New Two-Axis Optical Scanner Actuated by Piezoelectric Bimorphs

A two-axis optical scanner was designed and fabricated from stainless-steel substrate and piezoelectric sheets. Metal substrate with four cantilevers was bonded with eight piezoelectric sheets forming four bimorphs to enable two-axis scanning of the mirror. With a 5 mm × 5 mm square mirror, following scanning angles and frequencies were achieved at two orthogonal vibration modes: 35.2° at 861.5 Hz with a driving voltage of 100 Vp-p and 10.9° at 2485 Hz with a driving voltage of 200 Vp-p. The developed technique offers alternative to MEMS scanners providing scanning ability with large mirror size and scanning angles at middle frequency range.

Noncontact friction force microscopy based on quartz tuning fork sensors

Noncontact friction force microscopy (NC-FFM) measures the damping of the resonant oscillation of an atomic force microscope (AFM) tip that vibrates parallel to the sample surface at a controlled distance. By exploiting the two fundamental orthogonal vibration modes of a quartz tuning fork, such technique can be realized by all-piezoelectric sensing by simultaneously employing an AFM noncontact mode for distance control. The low noncontact-mode vibration amplitude used increases the effective interaction time for shear measurement. Application to polymeric samples shows that the dissipation contrast of NC-FFM is higher than that of the corresponding noncontact-mode phase imaging.

Origins of isotopomeric polymorphism

The complex formed between 4-methylpyridine and pentachlorophenol (4MPPCP) crystallises in a triclinic space group. If the same complex is synthesized from deuterated pentachlorophenol, it crystallizes in an entirely different monoclinic polymorph. Using solid-state NMR of samples synthesized with a full range of deuteration levels, crystallized from solution or the melt, and in the presence or absence of seeds, we have confirmed that the isotopomers indeed have different thermodynamically stable crystal structures. The roots of this phenomenon of isotopomeric polymorphism apparently lie in the differences in hydrogen bonding between the polymorphs. The triclinic form has a relatively short hydrogen bond. High-field solid-state NMR shows both the 1H chemical shift and the 2H electric quadrupole coupling of the hydrogen involved in the bond to be strongly temperature-dependent, indicating a low-lying excited state of the hydrogen bond longitudinal vibration. Inelastic neutron scattering of isotopomers of 4MPPCP has allowed us to identify the three orthogonal vibrational modes of the hydrogen in the hydrogen bond, at 29.7, 145, and 205 meV (240, 1168, and 1651 cm−1). The longitudinal mode is the lowest in energy, and it indicates a slightly asymmetric low-barrier double-well potential. Intrinsic to such potentials is a very small difference in zero-point energies (ZPEs) between the protonated and deuterated forms. As a contrast, the monoclinic form has a comparatively normal hydrogen bond, in which the proton and deuteron ZPEs should be different by approximately 500 cm−1. A scenario can be envisaged where the triclinic protonated form is lower in energy than the monoclinic protonated form, but the triclinic deuterated form is higher in energy than the monoclinic deuterated form. This evidently accounts for the difference in relative stabilities of the two forms upon isotope substitution. Revised version of a paper presented at the International Conference ‘Isotopes 2005 Bath’, 27 June to 1 July 2005, Bath, UK.

Vibrational coherent quantum computation

A long-lived coherent state and non-linear interaction have been experimentally demonstrated for the vibrational mode of a trapped ion. We propose an implementation of quantum computation using coherent states of the vibrational modes of trapped ions. Differently from earlier experiments, we consider a far-off resonance for the interaction between external fields and the ion in a bidimensional trap. By appropriate choices of the detunings between the external fields, the adiabatic elimination of the ionic excited level from the Hamiltonian of the system allows for beam splitting between orthogonal vibrational modes, production of coherent states and non-linear interactions of various kinds. In particular, this model enables the generation of the four coherent Bell states. Furthermore, all the necessary operations for quantum computation such as preparation of qubits, one-qubit and controlled two-qubit operations, are possible. The detection of the state of a vibrational mode in a Bell state is made possible by the combination of resonant and off-resonant interactions between the ion and some external fields. We show that our read-out scheme provides highly efficient discrimination between all the four Bell states. We extend this to a quantum register composed of many individually trapped ions. In this case, operations on two remote qubits are possible through a cavity mode. We emphasize that our remote-qubit operation scheme does not require a high quality factor resonator: the cavity field acts as a catalyst for the gate operation.

Single-phase drive of a circular ultrasonic motor

A method of single-phase drive of an ultrasonic rotary motor is proposed where the vibration mode of a circular stator is rotated by a single-phase source. If a small mass is attached to the circular ring vibrator, the degenerate doublets of the vibration mode are perturbed and separated into two orthogonal vibration modes with different resonance frequencies. The two modes can be excited with a phase difference of 90° by a single-phase source if the amount of the mass is appropriate. This causes the rotation of the vibration mode. The proposed method is successfully studied theoretically and compared well experimentally.

Ultrasonic motors using piezoelectric ceramic multimode vibrators

The development is reported of an ultrasonic motor using piezoelectric ceramic multimode vibrators consisting of circular or annular plates in which degenerate horizontal vibration modes of the same or different form are used. Two orthogonal nonaxisymmetric vibration modes were used in the same-form case, and the combination of a nonaxisymmetric vibration mode and a radial vibration mode was used in the different-forms case. Some details of the motor design and its experimental characteristics are presented. The ultrasonic motor presented here has a special advantage in its thin construction.

The Effect of Aerodynamic Phase Lag on the Twin Vibration Mode Model of Aeroengine Fan Flutter

An earlier paper analyzed aeroengine fan flutter in terms of twin orthogonal vibration modes in the fan. This paper extends the analysis by incorporating variable aerodynamic phase lags between a blade motion and the resulting aerodynamic forces. The extended analysis predicts two independent kinds of flutter. If the total damping within each mode is negative, each mode develops a self-sustaining vibration at its own natural frequency. This was not predicted by the earlier twin mode analysis. Even when the damping in each mode is positive an interaction between the modes can cause flutter under some conditions. This behavior is basically of the form described in the earlier paper, but there are significant detailed changes when variable aerodynamic phase lags are introduced.

Measurement of Fan Vibration Using Double Pulse Holography

Supersonic unstalled flutter in gas turbine fans is a self-excited instability in which mechanical vibrations give rise to unsteady aerodynamic forces which drive the mechanical vibration. The phenomenon is very sensitive to the deflected shapes of the blades and to the spatial and temporal phases of the blades’ responses. This paper is concerned with the measurement of vibrational behavior on static fans and relating it to flutter. Accurate detailed data on the blade and disk vibration mode shapes of fans up to 2.2 m diameter has been measured using double pulse laser holography. Both axial and tangential components of the blade mode shape are obtained by taking holograms from two directions. The analysis of the holograms is performed with the aid of a computer linked television system which generates the required blade mode shapes directly from the photographs of the hologram reconstructions. The disk mode measurements on real fans have shown the existence of pairs of spatially orthogonal vibration modes which have similar shapes (e.g. both 4D) but slightly different natural frequencies. This frequency split between modes means that the flutter wave will experience a cyclic variation in amplitude and propagation speed as it travels round the fan. In addition, the temporal phase angle between twist and flap in a single blade, which is generally assumed to be 90 deg, will vary from blade to blade.