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An inertial linear ultrasonic motor with a novel double-stator structure is proposed for achieving higher performance and resolution in this paper. Utilizing a symmetrical structure and single sawtooth wave signal, the prototype is capable of outputting effective linear motion based on inertial movement. The validity and rationality of the prototype are investigated by conducting finite element analyses. The experimental setups are built up to acquire the output characteristics of the motor. The experimental results indicate that the motor can achieve a maximum output velocity of 8.746 mm/s and thrust force of 1.645 N, which is almost twice the output performance of a motor with a single stator. The displacement solution of the motor can be adjusted by changing the amplitude of the voltage, with a resolution of 27 nm. Simultaneously, the relationships between the output characteristics and the input parameters are measured and analyzed during the experiments. Compared to the actuators with complex structures and multi-signal drives, the proposed motor exhibits the merits of higher output performance with the double-stator structure, providing an alternative direction for the further development of the inertial linear ultrasonic motor. [ABSTRACT FROM AUTHOR]

The Oh-Park methodology was proposed to overcome the limitations of Steinberg's theory for evaluating the structural safety of space-borne electronics and has been experimentally verified at the printed circuit board (PCB) specimen level for various types of electronic packages, such as ball grid arrays (BGAs), column grid arrays (CGAs), and small-outline packages (SOPs). However, it is necessary to validate the design methodology because the PCB mounted on the housing is affected by the elastic mode of the mechanical housing. In addition, although the validity of the existing theory based on critical strain has been verified for horizontally mounted structures, there are cases where PCBs are mounted vertically. Therefore, it is essential to consider the dynamic influence of the boundary conditions of mounted electronics. In this study, electronics specimens with corresponding boundary conditions were fabricated, and a fatigue-life test was performed. In addition, a structural analysis using Steinberg's theory and the Oh-Park methodology was performed, and the results were compared with those of the fatigue-life test. The results showed that the analysis using the Oh-Park methodology accurately represented the test results, and the validity of the Oh-Park methodology for vertical electronics was verified experimentally. [ABSTRACT FROM AUTHOR]

An inertial linear ultrasonic motor with a novel double-stator structure is proposed for achieving higher performance and resolution in this paper. Utilizing a symmetrical structure and single sawtooth wave signal, the prototype is capable of outputting effective linear motion based on inertial movement. The validity and rationality of the prototype are investigated by conducting finite element analyses. The experimental setups are built up to acquire the output characteristics of the motor. The experimental results indicate that the motor can achieve a maximum output velocity of 8.746 mm/s and thrust force of 1.645 N, which is almost twice the output performance of a motor with a single stator. The displacement solution of the motor can be adjusted by changing the amplitude of the voltage, with a resolution of 27 nm. Simultaneously, the relationships between the output characteristics and the input parameters are measured and analyzed during the experiments. Compared to the actuators with complex structures and multi-signal drives, the proposed motor exhibits the merits of higher output performance with the double-stator structure, providing an alternative direction for the further development of the inertial linear ultrasonic motor.

The Oh-Park methodology was proposed to overcome the limitations of Steinberg’s theory for evaluating the structural safety of space-borne electronics and has been experimentally verified at the printed circuit board (PCB) specimen level for various types of electronic packages, such as ball grid arrays (BGAs), column grid arrays (CGAs), and small-outline packages (SOPs). However, it is necessary to validate the design methodology because the PCB mounted on the housing is affected by the elastic mode of the mechanical housing. In addition, although the validity of the existing theory based on critical strain has been verified for horizontally mounted structures, there are cases where PCBs are mounted vertically. Therefore, it is essential to consider the dynamic influence of the boundary conditions of mounted electronics. In this study, electronics specimens with corresponding boundary conditions were fabricated, and a fatigue-life test was performed. In addition, a structural analysis using Steinberg’s theory and the Oh-Park methodology was performed, and the results were compared with those of the fatigue-life test. The results showed that the analysis using the Oh-Park methodology accurately represented the test results, and the validity of the Oh-Park methodology for vertical electronics was verified experimentally.

High-speed rail vehicles are equipped with yaw dampers to avoid the arising of hunting motion when running at high-speed. Although these suspension components provide a stabilizing effect on the vehicles, they also influence the ride comfort performances by affecting the accelerations perceived by the passengers. In this context, this paper aims to correlate the installation angle on the vertical plane of such suspension components on the ride comfort performances of a generic high-speed train. The proposed methodology is based on multibody simulations of a model with deformable car body. The modal behavior of the model is aligned to the typical mode shapes and natural frequencies reported in literature. [ABSTRACT FROM AUTHOR]

Active optics is a key technology in ground-based large-aperture telescopes. The active correction of the surface shape of the primary mirror is used to reduce the surface shape error and improve the imaging quality. At present, the structure of the active optics support system is not standardized. Therefore, to ensure the imaging quality of a telescope using a 4m SiC (silicon carbide) primary mirror, this article designed an active support system for the primary mirror and comprehensively evaluated the performance of the system. The system used pneumatic actuators to correct the surface shape of the primary mirror and a six-hardpoint positioning mechanism to correct the pose of the primary mirror. A method for compensating for the force on the hardpoints that causes protrusions and dents on the primary mirror surface was proposed, which effectively improved the accuracy of the primary mirror surface. The bending-mode method was used to determine the correction force. To achieve better results in the surface shape correction based on the bending mode, the relationship between the order of the bending modes used in the correction and the correction effect was studied, enabling the system to achieve a higher surface shape accuracy with a smaller correction force. Finally, the performance of the system was evaluated under various conditions, such as under gravity, thermal load, and wind load. The results indicated that the system had good correction effects on the deformation of the primary mirror under various operating conditions and could meet the requirements of optical design for surface accuracy. In conclusion, this study not only verified the application of active optics technology based on the bending mode in large-aperture SiC mirrors, but also improved on the relevant theoretical research on active optics. [ABSTRACT FROM AUTHOR]

Active optics is a key technology in ground-based large-aperture telescopes. The active correction of the surface shape of the primary mirror is used to reduce the surface shape error and improve the imaging quality. At present, the structure of the active optics support system is not standardized. Therefore, to ensure the imaging quality of a telescope using a 4m SiC (silicon carbide) primary mirror, this article designed an active support system for the primary mirror and comprehensively evaluated the performance of the system. The system used pneumatic actuators to correct the surface shape of the primary mirror and a six-hardpoint positioning mechanism to correct the pose of the primary mirror. A method for compensating for the force on the hardpoints that causes protrusions and dents on the primary mirror surface was proposed, which effectively improved the accuracy of the primary mirror surface. The bending-mode method was used to determine the correction force. To achieve better results in the surface shape correction based on the bending mode, the relationship between the order of the bending modes used in the correction and the correction effect was studied, enabling the system to achieve a higher surface shape accuracy with a smaller correction force. Finally, the performance of the system was evaluated under various conditions, such as under gravity, thermal load, and wind load. The results indicated that the system had good correction effects on the deformation of the primary mirror under various operating conditions and could meet the requirements of optical design for surface accuracy. In conclusion, this study not only verified the application of active optics technology based on the bending mode in large-aperture SiC mirrors, but also improved on the relevant theoretical research on active optics.

In a flexoelectric sensing element using bending mode, estimation of the flexoelectric coefficient was investigated using 3-D stress/strain analysis and experiments. The proposed method uses the results (deformation and strain) from the finite element analysis (FEA). The estimated flexoelectric coefficients were compared with those obtained via the conventional method (Euler’s beam theory) under the assumption of the quasi 1-D stress field. The results show that the RMS value and standard deviation of the estimated flexoelectric coefficient for the 3-D stress field case of the sensing element are 31.51 µC/m and 0.24%, respectively. In addition, we found that the flexoelectric coefficient obtained from the results of the 3-D stress analysis is 1.8% smaller than that of the quasi-1-D stress analysis. Therefore, in order to obtain a more reliable flexoelectric coefficient in the sensing element, the results of the 3-D numerical stress analysis should be used for accurate estimation of the flexoelectric coefficient.

[Display omitted] • The transverse flexoelectric coefficient of porous PDMS is 2.9 times that of bulk. • A competitive mechanism between the strain gradient and permittivity is discovered. • An optimal porosity corresponding to the maximum polarization response is found. • The terminal of rehabilitation can collect and recognize the motions of patients. Owing to the flexibility, lightweight, long-life and low cost, polymers are promising candidates to realize electromechanical conversion in wearable electronics. The flexoelectric effect enables non-piezoelectric materials to achieve electromechanical coupling, thereby broadening application ranges of nonpolar polymers. In this work, the porous samples of polydimethylsiloxane (PDMS) with various pore sizes and porosities are fabricated by the sacrificial salt template method and the chemical gas foaming method. The flexoelectric polarization response can be tuned directly by the structural characters of the porous PDMS. The transverse flexoelectric coefficient of porous PDMS can reach approximately 2.9 times the counterpart of the bulk one. The competitive mechanism between strain gradient and permittivity is proposed on flexoelectricity of random porous media by dielectric impedance spectrums and finite element analyses. The present regulation of flexoelectricity provides an alternative to electromechanical conversion. With the deep learning technique based on one-dimensional convolution neural networks, actions of both sick and normal legs of various stroke patients can be well recognized by the designed device of rehabilitation. The present rehabilitation monitoring system, which is an innovative application of the flexoelectricity in the porous polymers, offers a new approach to support physical therapy for post-stroke patients. [ABSTRACT FROM AUTHOR]

In the flexoelectric sensing element using the bending mode, the estimation of the flexoelectric coefficient was investigated using 3-D stress/strain analysis and experiments. The proposed method uses the results (deformation and strain) from the finite element analysis (FEA). The estimated flexoelectric coefficients were compared with those obtained via the conventional method (Euler's beam theory) under the assumption of the quasi 1-D stress field. The results show that the RMS value and standard deviation of the estimated flexoelectric coefficient for the 3-D stress-field case of the sensing element are 31.51 µC/m and 0.24 %, respectively. In addition, it is found that the flexoelectric coefficient obtained from the results of the 3-D stress analysis is 1.8 % smaller than that of the quasi-1-D stress analysis. Therefore, in order to obtain a more reliable flexoelectric coefficient in the sensing element, the results of the 3-D numerical stress analysis should be used for accurate estimation of the flexoelectric coefficient. [ABSTRACT FROM AUTHOR]

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract In some active optics system, the influence function, which is the surface deformation ability of an actuator, is measured by directly detecting the mirror surface using an interferometer and the surface correction of the primary mirror is done using the Shack-Hartmann (S-H) sensor. However, if the wavefronts of the interferometer and the S-H sensor have an obvious rotation, a large error will be introduced to the correction force calculations. In this paper, bending modes are used to detect this wavefront rotation. Bending modes are a series of orthonormal stiffness-increasing modes calculated using the influence functions. Two methods, optimum search and top-line (a line passes through the surface center and the top of surface deformation peaks) detection, are developed and tested in simulation using the experimental data of a 620-mm active optics system. The detection errors of the two methods are 0.286° and 0.085° in the simulation, respectively. The rotation detection method is then tested on this 620-mm system. The simulation and experimental results show that top-line detection is a suitable method for the detection of wavefront rotation.

Polyatomic molecules have been identified as sensitive probes of charge-parity violating and parity violating physics beyond the Standard Model (BSM). For example, many linear triatomic molecules are both laser-coolable and have parity doublets in the ground electronic $\tilde{X} {}^2\Sigma^+ (010)$ state arising from the bending vibration, both features that can greatly aid BSM searches. Understanding the $\tilde{X} {}^2\Sigma^+ (010)$ state is a crucial prerequisite to precision measurements with linear polyatomic molecules. Here, we characterize the fundamental bending vibration of ${}^{174}$ YbOH using high-resolution optical spectroscopy on the nominally forbidden $\tilde{X} {}^2\Sigma^+ (010)$ ${}\rightarrow{}\tilde{A}{}^2\Pi_{1/2}(000)$ transition at 588 nm. We assign 39 transitions originating from the lowest rotational levels of the $\tilde{X} {}^2\Sigma^+ (010)$ state, and accurately model the state’s structure with an effective Hamiltonian using best-fit parameters. Additionally, we perform Stark and Zeeman spectroscopy on the $\tilde{X} {}^2\Sigma^+ (010)$ state and fit the molecule-frame dipole moment to $D_\mathrm{mol} = 2.16(1)$ D and the effective electron g -factor to $g_S = 2.07(2)$ . Further, we use an empirical model to explain observed anomalous line intensities in terms of interference from spin–orbit and vibronic perturbations in the excited $\tilde{A}{}^2\Pi_{1/2}(000)$ state. Our work is an essential step toward searches for BSM physics in YbOH and other linear polyatomic molecules.

In this article, to achieve high torque density and high power density of rotary ultrasonic motors (USMs), we develop a rod-shaped transducer operating in torsional/bending (T/B) modes and excite two elliptical motions on its bilateral ends to drive the rotor orthogonally pressed onto the transducer. Here, the torsional vibration, the driving structure, and the rod shape may enable the T/B motor to provide high driving force, large driving distance, and low weight, which facilitate the realization of high torque density and high power density. To assess the validity, first, we construct a transducer 43 and 110 mm in diameter and length, respectively. Then, we investigate the load characteristics of the T/B motor: When it works at the frequency of 21.64 kHz, the maximal torque and the maximal output power reach 10.1 N·m and 38.1 W, respectively. In the meantime, it yields the torque density and the power density of, respectively, 20.0 N·m/kg and 75.7 W/kg, which are, as predicted, relatively high compared to the values of most conventional rotary motors. This article not only validates the effectiveness of our proposal but also provides a new approach to design powerful rotary USMs. [ABSTRACT FROM AUTHOR]

The central theme of this work was to analyze high aspect ratio structure having structural nonlinearity in low subsonic flow and to model nonlinear stiffness by finite element-modal approach. Total stiffness of high aspect ratio wing can be decomposed to linear and nonlinear stiffnesses. Linear stiffness is modeled by its eigenvalues and eigenvectors, while nonlinear stiffness is calculated by the method of combined Finite Element-Modal approach. The nonlinear modal stiffness is calculated by defining nonlinear static load cases first. The nonlinear stiffness in the present work is modeled in two ways, i.e., based on bending modes only and based on bending and torsion modes both. Doublet lattice method (DLM) is used for dynamic analysis which accounts for the dependency of aerodynamic forces and moments on the frequency content of dynamic motion. Minimum state rational fraction approximation (RFA) of the aerodynamic influence coefficient (AIC) matrix is used to formulate full aeroelastic state-space time domain equation. Time domain dynamics analyses show that structure behavior becomes exponentially growing at speed above the flutter speed when linear stiffness is considered, however, Limit Cycle Oscillations (LCO) is observed when linear stiffness along with nonlinear stiffness, modeled by FE-Modal approach is considered. The amplitude of LCO increases with the increase in the speed. This method is based on cantilevered configuration. Nonlinear static tests are generated while wing root chord is fixed in all degrees of freedom and it needs modification if one requires considering full aircraft. It uses dedicated commercial finite element package in conjunction with commercial aeroelastic package making the method very attractive for quick nonlinear aeroelastic analysis. It is the extension of M.Y. Harmin and J.E. Cooper method in which they used the same equations of motion and modeled geometrical nonlinearity in bending modes only. In the current work, geometrical nonlinearities in bending and in torsion modes have been considered.

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In some active optics system, the influence function, which is the surface deformation ability of an actuator, is measured by directly detecting the mirror surface using an interferometer and the surface correction of the primary mirror is done using the Shack-Hartmann (S-H) sensor. However, if the wavefronts of the interferometer and the S-H sensor have an obvious rotation, a large error will be introduced to the correction force calculations. In this paper, bending modes are used to detect this wavefront rotation. Bending modes are a series of orthonormal stiffness-increasing modes calculated using the influence functions. Two methods, optimum search and top-line (a line passes through the surface center and the top of surface deformation peaks) detection, are developed and tested in simulation using the experimental data of a 620-mm active optics system. The detection errors of the two methods are 0.286° and 0.085° in the simulation, respectively. The rotation detection method is then tested on this 620-mm system. The simulation and experimental results show that top-line detection is a suitable method for the detection of wavefront rotation. [ABSTRACT FROM AUTHOR]

Considering high stiffness of the large SiC mirror, the orthogonal bending mode which is calculated from the mirror influence matrix is used to optimize active force and improve correction capability. First, a finite element model of a 1.23m SiC mirror and support system is employed to verify the algorithm's validity. Then, a 1.23m SiC mirror active support system is set up to correct surface using bending mode, and a further optimize of the algorithm is made based on this microscopy scale system. Finally, surface is corrected from 0.248λ RMS to 0.056λ RMS (λ=632.5nm). Result of the analysis and experiment shows that using bending mode can efficiently reduce active force range and improve correction capability. It is significant for active correction of high stiffness large SiC mirror. [ABSTRACT FROM AUTHOR]

These days, centrifugal compressors and other industrial turbomachines tend to be faster, downsized, and reduced in cost. If a technology can be established for operation of machines over higher critical speed using an active magnetic bearing, the number of impellers per casing can be increased, allowing downsizing and cost reduction of trains. In this study, experimental equipment of a flexible rotor supported by active magnetic bearings was developed to carry out experiments as a step toward developing the technology. The following results were obtained, (1) Mass distribution in designing flexible rotors allows adjustment of the critical speed by design. (2) With the modal balancing method under higher critical speed, the sixth critical speed was passed through, the world's first achievement of this.

Magnetoelectric resonators have been studied for the detection of small amplitude and low frequency magnetic fields via the delta-E effect, mainly in fundamental bending or bulk resonance modes. Here, we present an experimental and theoretical investigation of magnetoelectric thin-film cantilevers that can be operated in bending modes (BMs) and torsion modes (TMs) as a magnetic field sensor. A magnetoelastic macrospin model is combined with an electromechanical finite element model and a general description of the delta-E effect of all stiffness tensor components Cij is derived. Simulations confirm quantitatively that the delta-E effect of the C66 component has the promising potential of significantly increasing the magnetic sensitivity and the maximum normalized frequency change Δfr. However, the electrical excitation of TMs remains challenging and is found to significantly diminish the gain in sensitivity. Experiments reveal the dependency of the sensitivity and Δfr of TMs on the mode number, which differs fundamentally from BMs and is well explained by our model. Because the contribution of C11 to the TMs increases with the mode number, the first-order TM yields the highest magnetic sensitivity. Overall, general insights are gained for the design of high-sensitivity delta-E effect sensors, as well as for frequency tunable devices based on the delta-E effect.

• A linear motion stage driven by a bending hybrid ultrasonic motor is developed. • The vibration trajectories of the driving foot are simulated and analyzed. • The vibration trajectory is controlled by the voltage to achieve low speed. • Step responses of 5 mm/s, 10 mm/s, 20 mm/s, and 50 mm/s are achieved. • Maximum error of 3% and phase lag of 2.88° are achieved under sine speed control. The speed control tends to receive the restriction of dead-zone phenomenon when an ultrasonic motor (USM) works at the low speed range. A linear motion stage is designed and fabricated, in which a bending hybrid type USM using two separated bending modes is chosen for the low speed characteristic study. The shape and size of the vibration trajectory of the driving foot can be changed flexibly to realize the control of the output speed by controlling the vibration amplitudes of the driving foot in vertical and horizontal directions independently. The low speed characteristic experiment of the motion stage is accomplished based on a conventional PID controller, the speeds of 5 mm/s, 10 mm/s, 20 mm/s, 50 mm/s are achieved in the step control, respectively. In the sinusoidal speed control experiment, the reference speed varies sinusoidally with an amplitude of 20 mm/s, the maximum phase lag and amplitude error are lower than 3° and 3%, respectively. It is demonstrated that the low speed movement of the proposed linear motion stage can be realized by changing the vibration trajectory of the driving foot. [ABSTRACT FROM AUTHOR]

Highlights • Micromechanics of nonwoven materials with out-of-plane auxetic nature was analyzed. • A toolkit of analytical models of nonwoven materials has been presented. • A satisfactory agreement was observed between the theory and experiments. Abstract Needlepunched nonwovens represent a special class of three-dimensional (3D) fiber networks that successfully generated a host of applications but the rationale of their design involving the intricate microstructure and understanding of the mechanics of the relevant deformation is still lacking. Herein, the micromechanical behavior of needlepunched nonwoven materials possessing out-of-plane auxetic characteristics has been investigated by unraveling the anisotropic structure. The evolution of the 3D intricate architecture of anisotropic nonwoven materials under prescribed levels of tensile strain has been determined using a 3D optical profiler. Most importantly, the analytical models expressed in terms of the initial modulus and in-plane Poisson's ratio of the nonwoven materials are presented. A comparison between the theory and experiments revealed a satisfactory agreement for the modulus and in-plane Poisson's ratio. Further, a comparative analysis of well-known analytical models of in-plane Poisson's ratio with the experimental data clearly demonstrated that the plausible mechanism of deformation of fibers is bending and not stretching. [ABSTRACT FROM AUTHOR]

The central theme of this work was to analyze high aspect ratio structure having structural nonlinearity in low subsonic flow and to model nonlinear stiffness by finite element-modal approach. Total stiffness of high aspect ratio wing can be decomposed to linear and nonlinear stiffnesses. Linear stiffness is modeled by its eigenvalues and eigenvectors, while nonlinear stiffness is calculated by the method of combined Finite Element-Modal approach. The nonlinear modal stiffness is calculated by defining nonlinear static load cases first. The nonlinear stiffness in the present work is modeled in two ways, i.e., based on bending modes only and based on bending and torsion modes both. Doublet lattice method (DLM) is used for dynamic analysis which accounts for the dependency of aerodynamic forces and moments on the frequency content of dynamic motion. Minimum state rational fraction approximation (RFA) of the aerodynamic influence coefficient (AIC) matrix is used to formulate full aeroelastic state-space time domain equation. Time domain dynamics analyses show that structure behavior becomes exponentially growing at speed above the flutter speed when linear stiffness is considered, however, Limit Cycle Oscillations (LCO) is observed when linear stiffness along with nonlinear stiffness, modeled by FE-Modal approach is considered. The amplitude of LCO increases with the increase in the speed. This method is based on cantilevered configuration. Nonlinear static tests are generated while wing root chord is fixed in all degrees of freedom and it needs modification if one requires considering full aircraft. It uses dedicated commercial finite element package in conjunction with commercial aeroelastic package making the method very attractive for quick nonlinear aeroelastic analysis. It is the extension of M.Y. Harmin and J.E. Cooper method in which they used the same equations of motion and modeled geometrical nonlinearity in bending modes only. In the current work, geometrical nonlinearities in bending and in torsion modes have been considered. [ABSTRACT FROM AUTHOR]

A new non-resonant-type piezoelectric actuator with unlimited stroke was proposed, in which two transducers operated in hybrid bending modes were used to generate the desired displacements with micrometer scale. Compared with the PZT stack, both positive and negative dc voltages can be applied on the PZT elements to achieve large displacement. The vertical bending movement was used to control the contact state between the foot and the runner, whereas the runner was pushed by the horizontal bending movement. The operating principle of the stepping-wriggle driving was discussed. The motion planning of the bending transducers with eight steps was developed. The duty ratios and the phase difference of the two signals applied on the vertical PZT elements were 1/3 and 180°, respectively, which insured the reliable positioning of the runner. Excitation voltages with different rise times were applied on the PZT elements to discover its effects on the responses of the bending movements by a transient analysis. It was found that the transducer cost about 2 ms to reach the steady state, in spite of the difference of the rise times, but the rise time showed a significant effect on the oscillation amplitude of the bending motion. The motion trajectories of the driving tip were nearly rectangles with horizontal and vertical steady displacements of $\sim 6.10$ and 5.52 $\mu \text{m}$ , respectively. This paper can provide the guidance for the design of non-resonant-type piezoelectric actuator by bending modes.

Energy harvesting from mechanical vibration of buildings is usually realized by the use of devices, in which the main element is a prismatic beam with a rectangular cross-section. The beam has been the subject of scientific research; it is usually constructed with a carrying substrate that does not have piezoelectric characteristics and from piezoelectric material. In contrast, this investigation sought to create a beam structure with a piezoelectric composite only. The entire beam structure was made of a prototype piezoelectric particulate composite. Based on courses of voltage obtained in laboratory experiments and known geometry of the specimens, a series of finite element method (FEM) simulations was performed, aiming to estimate the piezoelectric coefficient d31 value at which the mentioned voltage could be achieved. In each specimen, sedimentation caused the formation of two distinct layers: top and bottom. The experiments revealed that the presented prototype piezoelectric particulate composite converts mechanical stress to electric energy in bending mode, which is used in energy harvesting from mechanical vibration. It is self-supporting and thus a carrying substrate is not required in the harvester structure.

In this paper, we propose a generator for piezoelectric energy harvesting from suspension structures. This device consists of a leaf spring and eight pairs of piezoelectric layers attached to inner and outer surfaces. We present a special type of leaf spring, which can magnify the force from the workload to allow the piezoelectric layers to achieve larger deformation. The generator is to solve the problem of vibration energy reutilization in a low-frequency vibration system. To verify the efficiency of the proposed configuration, a series of experiments are operated. The results indicate that the resonance frequency (25.2 Hz) obtained from the sweep experiment is close to the simulation result (26.1 Hz). Impedance-matching experiments show that the sum of the output power attains 1.7 mW, and the maximum single layer reaches 0.6 mW with an impedance matching of 610 KΩ, and the instantaneous peak-peak power density is 3.82 mW/cm3. The capacitor-charging performance of the generator is also excellent under the series condition. For a 4.7 μF capacitor, the voltage is charged to 25 V in 30 s and limited at 32 V in 80 s. These results demonstrate the exploitable potential of piezoelectric energy harvesting from suspension structures.

The main relations of a mathematical model for analyzing the stress-strain state and buckling of structurally-anisotropic panels made of composite materials are proposed. The mathematical model of a stiffening rib being in one-side contact with the skin is refined. One takes into account the influence of panel production technology, namely, residual thermal stresses and preliminary tension of reinforcing fibers. Exact analytical solutions for boundary value problems with the resolvent eight order equation are considered. The influence of the structure parameters on the level of stresses, displacements, buckling forces for bending and torsion modes has analyzed. [ABSTRACT FROM AUTHOR]

Torsion- and bending-dominant modes of a zigzag-shaped piezoelectric vibrational energy harvester were compared in terms of power generation using experimental and numerical methods. Output power measurements from 25 discrete mass loading configurations led to three major observations: (1) a torsion-dominant mode can produce a higher level of power compared to a bending-dominant mode, (2) generated power in the torsion-dominant mode displays a V-shape curve under certain mass loading, rather than continually increasing as a function of mass, and (3) generated power in the bending-dominant mode is largely independent of mass. These observations differ from the conventional wisdom that bending modes are better for energy harvesting and that power increases as a function of added mass. Numerical analysis is used to validate the variation of generated power and is found to be in agreement with the experimental results. Analysis of the displacement and gradation angle of equi-displacement measurements of the beam are used to provide understanding of the influence of dynamics of the energy harvester on power generation. [ABSTRACT FROM AUTHOR]

A three-DOF ultrasonic motor is presented in this paper. The proposed motor consists of four piezoelectric ceramic plates and a mental base with a flange that can fix the motor on a rack. The proposed motor takes advantage of a longitudinal mode and two bending modes, different hybrids of which can realize three-DOF actuation. Because of symmetric structure of the proposed motor, the resonance frequencies of the two bending modes are identical. And the resonance frequency of the longitudinal mode was tuned closed to the ones of the bending modes by adjusting the structural parameters in modal analysis. Then trajectories of nodes on the driving foot were obtained by the transient analysis to verify the feasibility of driving principle. Experiments including vibration shape test and output characteristic test were executed. The starting voltages of the rotation along horizontal axes are about 10 Vp-p. Under driving voltages of 200 Vp-p, the output velocities of three DOF can reach 280 rpm, 277 rpm and 327 rpm, respectively. The results of the experiments indicate that the proposed motor is characterized by low starting voltages and high output velocities. [ABSTRACT FROM AUTHOR]

A bonded-type linear ultrasonic motor via torsional/bending hybrid excitation was developed in this paper to not only enhance the actuating capability but also realize the lightweight. Here, the torsional vibration is excited by exciting out-of-phase longitudinal vibrations with diagonally arranged PZT plates rather than directly using the shear ones. Besides, four elliptic motions exist at the driving feet to drive the slider alternately. To examine the validity, first, the dynamic models capable of modelling the torsional vibration with the Mason circuits were constructed and a torsional/bending transducer was designed. Then, a prototype with the size of 35 mm × 10 mm × 5 mm was fabricated to test its vibration properties. Finally, the movement and load characteristics were measured and the results show that, at driving frequency of 34.68 kHz, the motor yielded the maximal thrust force of 2.175 N, no-load speed of 593 mm/s, and maximal output power of 179.8 mW. Moreover, the thrust force density and power density reach 265 N/kg and 21.9 W/kg, respectively, higher than those of some previously-reported linear USMs. This study validates the feasibility to achieve thrust force density and power density with torsional/bending motors and also paves a new way to design lightweight USMs. [Display omitted] • A bonded-type transducer with the torsional/bending modes is proposed to form a linear ultrasonic motor. • Four longitudinal PZT plates are bonded onto the vibrating body to excite torsional vibration. • The torsional/bending hybrid modes existing at the driving feet double the actuating time in one period. • The dynamic models for the torsional vibration with the Mason circuits are constructed to design the T/B transducer. • The T/B motor yields the thrust force density and power density of 265 N/kg and 21.9 W/kg, respectively. [ABSTRACT FROM AUTHOR]

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The resonance vibration control of active magnetic bearing (AMB) supported flexible rotors is a challenging topic in the industrial applications. This work addresses the two issues on the noncollocated AMB flexible rotor systems while passing through the critical speed. A modal separation scheme is established to enhance the observability of the bending mode, and a damping optimization procedure of the electromagnetic force is proposed to provide the maximum control efficiency. First, the rotor imbalance analysis is carried out, and several possible approaches to minimize the vibration of the flexible rotor are presented. Then, the detailed descriptions of the bending mode extraction scheme using notch filters and phase-lead compensators are discussed for a noncollocated flexible rotor system. The root locii of the closed-loop AMB-rotor system with and without additional phase-lead compensator are also performed. A solution to determining the phase angles between the measured rotor displacements to the bearing forces is established using the physical modeling and experimental identification. Finally, simulation and experimental results on a 10 kW magnetically suspended centrifugal compressor show the effectiveness of the proposed methods. [ABSTRACT FROM PUBLISHER]

[Display omitted] • Study highlights the possibility of practical implementation in real environment for powering low energy consuming devices. • Appropriately selected wake location manifolds the output power. • Shape change has tremendous impact on effective area of wake region for energy harvesting due to higher flow instability. • Increment of 3741% is obtained by introducing short stiff flag downstream to 120° opening cylinder compared to soft flag. Extensive wind tunnel experiments were performed to find the optimal and most influential parameters for energy harvesting from piezoelectric membranes (thin elastic cantilevered plates), herein called flags. Four different piezoelectric flags were tested in conjunction with the seven different bluff bodies at various wind speeds and streamwise gaps between the bluff body and flag. Stiffness of the flags was also varied along with its length to assess the impact on harvested power. Various flapping modes are observed for different flags which correspond to the amount of harnessed power. The results revealed that altering the stiffness of flag can produce an increase of 29 and 31 times in power generation for long and short flags, respectively. It was found that the 120-degree bluff body produced the largest power with the capability to generate a strong wake region. Further analysis of the best performing flag (short and stiff) for various bluff bodies shows a remarkable increase of 661.2 % in generated power. This membrane shows rhythmic periodic flapping with higher modes of deformation in comparison to its other flag counterparts. These alternate flags show out-of-plane and twisting motion which wastes strain energy and causes a cancelation effect, reducing total energy output. The results show that in designing an efficient and reliable energy harvester, the flag's stiffness and length as well as the shape of the bluff body play an important role. Furthermore, in comparison with the flutter phenomenon (i.e. a dynamic instability of the flag in the absence of a bluff body), the results with a bluff body demonstrate that higher energy generation can be achieved at a lower wind speed, thus paving the way for small and practical energy harvesting devices specifically in remote areas. [ABSTRACT FROM AUTHOR]

This paper presents the method to design a novel micro stirrer for high effective dissolution of cerebral thrombus or blood clot. The micro stirrer is a beam with supported one side and the other side is attached to an asymmetrical stirrer. The waves, which were excited by the transducer, propagate through the catheter and impinge to the inclined surface in the stirrer. The reflected waves generate bending mode in the stirrer to dissolve the thrombus. Tip trajectory results are investigated for the simultaneous estimation of all the mode shapes, due to obtain the best drive frequency. It seems that the expected motion is a mode shape which, despite has the bending at tip, there is no significant bending across the catheter. An important parameter has been developed to act as an indicator factor for mode shape detection in simulation analysis. The design algorithm is offered based on the stirrer length and full length of micro stirrer. The accuracy of the estimated design method is evaluated through the some other stirrer length.

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 735 mm/s and the maximal thrust is 1.1 N. [ABSTRACT FROM AUTHOR]

Bending-mode magnetostrictive-piezoelectric sensors clamped at its two extremities show promising results for an enhancement of its magnetic field sensitivity by using a phase modulation (PM) technique. In this operating mode, the sensor is excited by an external carrier at its bending resonant frequency. The results of such a magnetic field sensing by a magneto(elasto)electric bilayer when using a PM technique with a phase locked loop circuitry are presented. The aim of this method is to follow the phase shift at the bending resonant frequency of the sensor, which is proportional to the applied magnetic field for the small-signal regime. We obtained a magnetic sensitivity of ~1.5 kV/T and an equivalent magnetic noise level around 80 nT/ $\surd $ Hz at 2 Hz. These performances are presently limited by the noise from our electronics, suggesting that there is room for further improvements. [ABSTRACT FROM PUBLISHER]

Local perturbations observed in the 01 1 1 ( Π g ) → 01 1 0 ( Π u ) hot bands of 64 ZnH 2 , 66 ZnH 2 , 68 ZnH 2 , 64 ZnD 2 and 66 ZnD 2 have been analyzed. The 01 1 1 ( Π g ) state is perturbed by the nearby 040 vibrational level that contains 04 4 0 ( Γ g ), 04 2 0 ( Δ g ) and 04 0 0 ( Σ g + ) states. Appropriate Hamiltonian matrices were constructed in which the effects of rotational ℓ -type doubling, ℓ -type resonance and Coriolis interaction were taken into account, and nonlinear least squares fits were performed. Unperturbed constants were obtained for the 01 1 1 ( Π g ) states, along with vibrational energies of the 040 (perturbing) levels and the Coriolis interaction coefficients. Relative vibrational energies of the 040 and 030 levels were then used to estimate the origins of the bending mode fundamental bands, resulting in ν 2 vibrational wavenumbers of 634.45 cm −1 and 459.14 cm −1 , for 64 ZnH 2 and 64 ZnD 2 , respectively. [ABSTRACT FROM AUTHOR]

Complete similitude and distorted similitude are widely used in the experimental verification of large equipment structures. However, the existing similitude studies have only a single distorted factor and insufficient prediction accuracy. And the coupled shells cannot be scaled down for experimental verification due to the limitation of wall thickness. Aiming at solving the above problems, a new method of distorted similitude for coupling scaling laws is proposed. The coupling distorted scaling laws and the complete scaling laws of coupled cylindrical–conical shells are established to study the bending mode natural frequency. The predictive performance of different distorted factors on prototype characteristics is investigated. The simulation results show that the prediction errors of the coupling distorted scaling laws established by this method for the prototype natural frequency are less than 0.32%. Experimental results show the proposed method can predict the bending mode natural frequency of the prototype, and its error is within ± 1 %. The method proposed in this paper has less simulation calculation and high precision, and can be extended to more complex thin-walled structures. [Display omitted] • A new method for establishing the coupling scaling laws is proposed. • The coupling distorted scaling laws and the complete scaling laws of coupled cylindrical–conical shells are established for the first time. • The proposed method has very high prediction accuracy and less simulation calculation, compared with the existing method. • The predicted performance of different distorted factors is studied for the first time. [ABSTRACT FROM AUTHOR]

Structural optimization problems are normally formulated and solved in terms of mathematical programming. Unknown parameters of structure must satisfy the constraints of the problem and provide extreme value of objective function (for instance minimum weight or maximum load-bearing capacity of considering structure). It is known that in some cases the optimal systems have special properties. Knowledge of these properties allows investigator to develop methods for solving optimization problems and methods for creating systems with prescribed properties. [ABSTRACT FROM AUTHOR]

This article investigates the problem of robust stabilization for a flexible launch vehicle. Since the launch vehicle suffers from parametric uncertainties, bending modes, and external wind disturbances simultaneously, an observer-based methodology is provided to address these negative factors. The proposed method can guarantee the stability of the closed-loop system and minimize the H∞ performance index. Additional regional pole placement constraints are imposed on the feedback gain matrices to improve the transient performance of the system. A two-step strategy is proposed to solve the involving bilinear matrix inequality problem. Compared with existing methods, which mainly depend on introducing additional constraints to linearize the bilinear matrix inequality conditions, the proposed strategy can reduce the conservatism and is suitable for engineering practice. The simulation results for one operating point and nonlinear model illustrate the validity and effectiveness of the proposed control method. [ABSTRACT FROM PUBLISHER]

This study examines the influence of the most important parameters on delaying reflection cracking in geogrid reinforced overlay in bending mode, employing a large scale experimental set up. The objective was to investigate the effects of grid stiffness, tensile strength, coating type, amount of tack coat, overlay thickness, crack width and stiffnesses of asphalt overlay and existing asphalt concrete on reinforced asphalt overlay performance with geogrid interlayer. Results indicate that the cracked layer and overlay moduluses have strongest influence on reduction of reflective cracking. Also, two fatigue life estimation models for reflection cracking were developed, one based on initial strain (fatigue model) and the other by modifying Paris law for fracture mechanic model in mode I. It was found that the coefficient of determination of predicted fatigue lives and measured lives for the two developed models were sufficient. Therefore, both service life models can be used to estimate fatigue life of reflection cracking in bending mode (I). [ABSTRACT FROM AUTHOR]