Superposition Of Vibration Modes Research Articles

Differentiated tactile effects of vibration modal superposition considering the time course

Several theoretical studies on modal superposition methods to achieve tactile differentiation have been reported. However, there is still a lack of in-depth analysis and understanding of the regularity of the superposition of vibration modes and the resulting differences in tactile sensation. The touch beam vibrations are no longer in the form of standing waves after the modal superposition. The vibration points on the touch beam will present a periodic motion over time, instead of simply moving harmonically. The vibration response of the touch beam at high frequency, gave subjects a dramatically different tactile perception from that of a single inherent mode. Therefore, this paper reshapes the modal superposition theory of the haptic feedback technique to classify the vibration modes generated by the modal superposition of touch beams showing differences in tactile sensations considering the time course. The analysis and tactile texture prediction theories are improved compared to previous studies. The tactile sensation generated by the vibration patterns of left-right sway were found in the touch beam. Finally, the correctness of the tactile differentiation achieved by the modal superposition method was demonstrated by psychophysical assessment for different finger conditions.

Low-frequency sound absorbing metasurface using multilayer split resonators

Among the acoustic metasurfaces that can control the propagation of sound waves with the structure far thinner than the wavelength at the operating frequency, the split tube structure has shown its effectiveness in the lower frequency band. Here we focus on multiply layered split tubes to broaden the absorption spectrum. By numerical analysis, we show up-to six-layer structure possessing wideband (1–1000 Hz) sound absorption. The absorbing peaks in the frequency band below 1000 Hz are shown to be multiplexed not only by simple superposition of vibrational modes of each layer, but also by hybridization of the modes indicating collective motion of tubes.

The Preliminary Results of Crosstalk Analysis Under Vibration Stress

To assess the influence of vibration on the crosstalk between cables, the Finite Element Method is introduced to solve the cable displacement analysis under random vibration. Then the crosstalk model considering vibration is constructed by use of the Monte Carlo method. It is found that the superposition of vibration modes above three orders has little effect on the crosstalk analysis. Also, it is demonstrated that as the displacement induced by vibration increases, the distribution of crosstalk voltage becomes more dispersed, the worst-case crosstalk can occur.

Sub-cycle steering of the deprotonation of acetylene by intense few-cycle mid-infrared laser fields.

Directional breaking of the C-H/C-D molecular bond is manipulated in acetylene (C2H2) and deuterated acetylene (C2D2) by waveform controlled few-cycle mid-infrared laser pulses with a central wavelength around 1.6 μm at an intensity of about 8 × 1013 W/cm2. The directionality of the deprotonation of acetylene is controlled by changing the carrier-envelope phase (CEP). The CEP-control can be attributed to the laser-induced superposition of vibrational modes, which is sensitive to the sub-cycle evolution of the laser waveform. Our experiments and simulations indicate that near-resonant, intense mid-infrared pulses permit a higher degree of control of the directionality of the reaction compared to those obtained in near-infrared fields, in particular for the deuterated species.

The baffle influence on sound radiation characteristics of a plate

The acoustic radiation characteristics of the baffle plates and unbaffle plates are calculated and compared by single-layer potential and double-layer potential. Based on the boundary integral equation, the sound pressure integral equation of the baffle and the baffle are deduced respectively. According to the boundary compatibility condition, the sound pressure and the vibration velocity of the plates are obtained. Further, the dynamic equation of the structure is substituted into the vibration equation in the form of the baffle plate and the baffle plate. The sound pressure difference and the displacement of a plate surface are in the form of the vibration mode superposition and the acoustic radiation impedance of the double integral form is obtained, which determines vibration mode coefficient and sound radiation parameters. The effect of the baffle on the acoustic radiation characteristics of the thin plate is analyzed by comparing the acoustic radiation parameters with the simple and simple rectangular plate in water.

Dynamic analysis of thin-walled members using Generalised Beam Theory (GBT)

This paper presents the main steps and procedures involved in the development of a Generalised Beam Theory (GBT) formulation to perform dynamic analyses of thin-walled members subjected to initial perturbations or acting loads. It combines (i) the GBT modal discretisation of the cross-section deformation with (ii) the commonly adopted vibration mode superposition approach – this combination leads to an original “doubly modal” representation of the displacement field, which (i) provides deep insight into the mechanics involved in the dynamic response under consideration and, moreover, (ii) makes it possible to obtain accurate results with surprisingly low degree of freedom numbers. The application and potential of the formulation is illustrated by presenting and discussing numerical results concerning the dynamic responses of cold-formed steel lipped channel beam in several situations, namely (i) the damped oscillations following the release from a deformed configuration, (ii) the action of uniformly distributed loads with periodic (sinusoidal and square-wave) and impulsive (rectangular) time variations, and (iii) the effect of a point load moving along the span with constant speed. For validation purposes, the GBT-based results are compared with values yielded by Ansys shell finite element analyses – the total number of degrees of freedom involved in the GBT analyses was significantly lower.

Study on Optimization of Dynamic Characteristics of Turbo Generator Foundation

The dynamic characteristics of turbo generator foundation have an important impact on safe operation of power plant. The study first used the vibration mode superposition method to solve the structural vibration response and sensitivity through establishing the dynamic equations and optimization model of the foundation, and then determined the optimization variables, constraints and objectives according to the process conditions, and at last undertook multivariate optimization research on a 1000MW turbo-generator foundation. Finally, an optimization scheme which reduces both the linear displacement of foundation vibration and the amount of concrete used was obtained. The analysis results showed that the optimization method adopted in this study had higher efficiency and could achieve better technical and economic benefits.

The Cable-Stayed Bridge with the T - Structure Collaborative System Bridge Seismic Response Analysis

The main bridge of Guangdong jinma which is double cable planes concrete single tower cable-stayed bridge and T- rigid frame cooperative system,and causing great concern to the project owing to the practice successfully[1,2,3,4].This paper analysis Jinma Bridge with response spectrum method of seismic response in accordance with the objectives of the three standards of seismic resistance requirements .In order to ensure the calculation accuracy,before the previous 120 vibration mode superposition should be taken by adopting CQC（Complete Quadratic Combination）method in calculation of the response spectrum.

Vibration Analysis and Simulation of Siemens-Schottel Podded Propulsion

In order to study Siemens- Schottel- Propulsion (SSP) vibration for the marine electrical propulsion system, the SSP vibration analysis has been carried out in this paper. SSP suffers from harmonic vibration and torsional vibration of propeller and wave flow random disturbances. Vibration mode superposition method is applied to SSP vibration model. The SSP dynamic model has also been established based on SimMechanics. The simulation results show that the proposed way is important to forecast and prevent SSP vibration and to provide for the SSP management.

On the influence of vibrational modes and intramolecular isomerization processes on the NMR parameters of bullvalene: A Feynman path integral – ab initio investigation

The absolute isotropic shieldings and chemical shifts at the 13C and 1H nuclei of bullvalene have been theoretically studied under the conditions of thermal equilibrium. For temperatures T ⩽ 400 K the present Monte Carlo simulations predict a bare vibrational nuclear dynamics. T values > 400 K allow the superposition of vibrational modes and an intramolecular isomerization, i.e. the so-called Cope rearrangement. This result can be correlated with the “slow” and “fast” isomerization regime of bullvalene. In the slow regime nuclear magnetic resonance (NMR) measures four different 13C and 1H signals, a splitting that is in line with the molecular C 3v symmetry at the minimum of the potential energy surface (PES). In the fast regime only a single signal for the 13C and 1H nuclei is measured by NMR indicating that all bullvalene carbons and protons are equivalent in the NMR time-scale. To derive the NMR parameters of bullvalene we have combined the Feynman path integral quantum Monte Carlo (PIMC) formalism with a tight-binding (TB) Hamiltonian and the Gauge including atomic orbital (GIAO) approach in an ab initio Hartree–Fock formulation. The TB model has been used to calculate the ground state PES, the free energy barrier of the Cope rearrangement, the statistical weight of the nuclear configurations in thermal equilibrium as well as the radial distribution functions of the nuclei. The vibrational modes in a highly anharmonic potential cause an elongation of all bond lengths in thermal equilibrium. This leads to a topology dependent deshielding of the bullvalene nuclei. The T dependence of the deshielding is characteristic for dominating zero-point fluctuations for all temperatures studied. The GIAO based chemical shifts at the 13C and 1H nuclei are compared with experiment. The PIMC – ab initio approach leads to theoretical results of good quality. The T gradient of the 13C and 1H chemical shifts can be reproduced qualitatively by the present PIMC – ab initio approach.

Procedures for approximate eigenproblem reanalysis of structures

AbstractIn vibration mode superposition analysis, the main computational effort is spent in the solution of the eigenproblem. In reanalysis procedures this solution must be repeated for each change in the design. It is shown in this study how the combined approximations method can be used to improve the efficiency of some common iterative procedures. These procedures can then be used for efficient eigenproblem reanalysis. Solution of the reduced eigenproblem by the combined approximations method is first demonstrated. Procedures based on inverse iteration, inverse iteration with shifts, and subspace iteration are then considered. Some numerical examples show that high accuracy is achieved for very large changes in the design. In cases where higher accuracy is required, additional terms of the approximations may be considered. Copyright © 2004 John Wiley & Sons, Ltd.

Identification of Acoustic-Vibratory System by Acoustic Measurement

A new method for reducing ill-conditioning in a class of identification problems is proposed. The key point of the method is that the identified vibration of the sound source is expressed as a superposition of vibration modes. The mathematical property of the coefficient matrix, the practical error expanding ratio, and the stochastic error expanding ratio are investigated in a numerical example. The mode-superposition method is shown to be an effective tool for acoustic-vibratory inverse analysis. © 1996 John Wiley & Sons, Inc.

Identification of Acoustic-Vibratory System by Acoustic Measurement

A new method for reducing ill-conditioning in a class of identification problems is proposed. The key point of the method is that the identified vibration of the sound source is expressed as a superposition of vibration modes. The mathematical property of the coefficient matrix, the practical error expanding ratio, and the stochastic error expanding ratio are investigated in a numerical example. The mode-superposition method is shown to be an effective tool for acoustic-vibratory inverse analysis.

Damped vibration mode superposition method for dynamic response analysis

AbstractIn the dynamic response analysis of extremely complex structural systems in which the damping characteristics of each element are independent, the damping matrix is not always diagonalized by the use of undamped free vibration mode shapes. In the present paper, a mode‐superposition method by the use of damped free vibration mode shapes is developed for such structural systems. It is also shown that the Fast Fourier Transform (FFT) procedures, that are available for the dynamic response analysis of linear structural systems, are used effectively in this mode‐superposition method with good accuracy.