Vibrational Point Of View Research Articles

Vibration Analysis of an On-Board Charger Assembly for Electrical Mobility

This article deals with the vibration analysis of an On-Board Charger assembly to check the strength of its components with respect to vibrational load. On-Board Charger (OBC) is a system which is built for electrical vehicles to charge high-voltage battery packs by converting AC power from an external charging source into a DC voltage. The primary role of an onboard charger is to manage the flow of electricity from the grid to the battery. This means that the OBC should fit the necessities of the grid in locations wherever it will be used. Onboard chargers enable plug-in hybrid and battery electric vehicles (BEV) to charge anywhere, not just at designated charging locations, wherever there is AC power. The OBC which is studied in this article is used in three-wheeler vehicles and the weight of this assembly is quite more because of the heat sink and other electronic components; so it is important to check its strength through a vibrational point of view, as induced vibrational load in the vehicle is more while driving the vehicle. Here, the focus will be on all housing and its internal components such as PCB (Printed Circuit Board) and its electrical components. Electrical components connect with PCB with solder joints which provide mechanical and electrical connections between components and PCB. Simulation of an OBC assembly is done by using the ANSYS tool in which modal and harmonic analysis is carried out to check assembly’s strength. The main focus will be on the natural frequencies of the assembly; the aim is to increase the natural frequencies of the assembly above 150 Hz to avoid the resonating condition. The frequency response analysis was done for the range of 50-150 Hz for the acceleration of 15g and stresses and deformation of OBC assembly components are observed after frequency response analysis.
 Keywords: On-Board Charger; Solder joint; Frequency; Vibration, Harmonic analysis, Electrical Mobility, Materials, NVH, Simulation

Vibrational study of acrylonitrile dimer and acrylonitrile-water hydrogen-bonded complexes in solid neon supported by ab initio calculations

For the first time the experimental study of the complexation of acrylonitrile molecule (CH2=CHCN, noted AN) with water has been undertaken from a vibrational point of view as well as the homodimer (AN)2 in solid neon from 80 to 6000 cm−1 using Fourier transform infrared spectroscopy. From concentration effects and with the help of theoretical results we have identified several vibrational transitions for AN homodimer, AN-H2O, AN-(H2O)2, and (AN)2-H2O complexes. For the AN-H2O complex, in which the two submolecules interacting through hydrogen bonding, the infrared spectral changes (frequencies as well as intensities) indicate that the water plays the role of the proton donor. We highlight the presence of three and two isomers for the AN-H2O and AN-(H2O)2 complexes, respectively. Theoretical calculations at the second-order Møller-Plesset level have been performed to obtain their equilibrium geometries and vibrational spectra at the harmonic level and comparison with experimental data allows us to give structures of AN-H2O and AN-(H2O)2, complexes.

Vibrational study of hydrated methyl formate complexes in solid neon: Observation for the first time of three isomers for methyl formate-water complex

Methyl formate (MF) is an important interstellar medium molecule and it has been the subject of several theoretical and experimental studies in literature. The experimental study of the complexation of this molecule with water has never been undertaken from a vibrational point of view as well as the homodimer (MF)2. We highlight for the first time the presence of three isomers for the (MF)2, MF-H2O and MF-(H2O)2 complexes in solid neon. For the MF-H2O complex, we observe without ambiguity three isomers: two where the carbonyl oxygen served as the proton acceptor and one where the alkoxy oxygen was the proton acceptor. For the MF-(H2O)2 complex, we clearly observe three isomers especially by the observation of large frequency shifts of two MF modes. Theoretical calculations at the second-order Møller-Plesset level have been performed to obtain the equilibrium geometries and vibrational spectra at the harmonic level and comparison with experimental data allows us to give structures of observed complexes.

Filter algorithm based on cochlear mechanics and neuron filter mechanism and application on enhancement of audio signals

A filter algorithm based on cochlear mechanics and neuron filter mechanism is proposed from the view point of vibration. It helps to solve the problem that the non-linear amplification is rarely considered in studying the auditory filters. A cochlear mechanical transduction model is built to illustrate the audio signals processing procedure in cochlea, and then the neuron filter mechanism is modeled to indirectly obtain the outputs with the cochlear properties of frequency tuning and non-linear amplification. The mathematic description of the proposed algorithm is derived by the two models. The parameter space, the parameter selection rules and the error correction of the proposed algorithm are discussed. The unit impulse responses in the time domain and the frequency domain are simulated and compared to probe into the characteristics of the proposed algorithm. Then a 24-channel filter bank is built based on the proposed algorithm and applied to the enhancements of the audio signals. The experiments and comparisons verify that, the proposed algorithm can effectively divide the audio signals into different frequencies, significantly enhance the high frequency parts, and provide positive impacts on the performance of speech enhancement in different noise environments, especially for the babble noise and the volvo noise.

Analysis of vibration forces of magnetic origin acting on tank walls of power transformer

The aim of this paper is to present the impact of the leakage flux on magnetic shunts and tank walls of power transformers from vibrational point of view. The experimental studies of the large power transformers show that tank vibrations and the resulting acoustic emission at load condition are significantly higher than at no-load condition. The paper presents 3D finite elements model in electromagnetic domain used for the analysis of magnetic forces applied to shunts at rated short circuit state which are the origin of tank vibration. The main finding of the work is that forces equivalent to the magnetostriction deformation of the shunt interior are comparable with magnetic forces resulting from the stray field and applied to the shunts’ surface.

Blade synchronous vibration measurements of a new upgraded heavy duty gas turbine MGT-70(3) by using tip-timing method

The work described in this paper is part of a comprehensive prototype test conducted on a heavy duty power generation gas turbine recently upgraded by MAPNA Turbine Engineering and Manufacturing Company (TUGA). A Blade tip-Timing system is proposed to determine the synchronous vibration characteristics of the rotor blades and to validate the design calculations. The last three stages of turbine section are equipped with tip-timing sensors. Six probes are positioned along the circumferential direction for each stage. The locations of sensors are accurately chosen based on the values of the natural frequencies and the number of necessary modes needed to be captured. The vibration parameters of the blades are obtained by post-processing and analyzing of the acquired data. The resonance frequencies are plotted against rotating speed during transient acceleration of the machine and the damping and amplitude of vibration in resonance condition are also determined. The obtained results meet the designer expectations and confirm a safe operation from vibrational point of view.

Aeromechanical optimization of first row compressor test stand blades using a hybrid machine learning model of genetic algorithm, artificial neural networks and design of experiments

In this paper, optimization of the first blade of a new test rig is pursued using a hybrid model comprising the genetic algorithm, artificial neural networks and design of experiments. Blade tuning is conducted using three-dimensional geometric parameters. Taper and sweep angle play important roles in this optimization process. Compressor characteristics involving mass flow and efficiency, and stress and eigenfrequencies of the blades are the main objectives of the evaluation. Owing to the design of blade attachments and their dynamic isolation from the disk, the vibrational behavior of the one blade is tuned based on the self-excited and forced vibration phenomenon. Using a semi-analytical MATLAB code instability, the conditions are satisfied. The code uses Whitehead’s theory and force response theory to predict classical and stall flutter speeds. Forced vibrational instability is controlled using Campbell’s theory. The aerodynamics of the new blade geometry is determined using multistage computational fluid dynamics simulation. The numerical results show increasing performance near the surge line and improvement in the working interval along with a 4% increase in mass flow. From the vibrational point of view, the reduced frequency increases by at least 5% in both stall and classical regions, and force response constraints are satisfied.

Infrared spectroscopy of flavones and flavonols. Reexamination of the hydroxyl and carbonyl vibrations in relation to the interactions of flavonoids with membrane lipids

Detailed vibrational assignments for twelve flavonoids (seven flavones (flavone, 3- and 5-hydroxyflavone, chrysin, apigenin, fisetin and luteolin) and five flavonols (galangin, kaempferol, quercetin, morin and myricetin)) have been made based on own and reported experimental data and calculations at the B3LYP/6-31+G(d,p) level of theory. All the molecules are treated in a uniform way by using the same set of redundancy-free set of internal coordinates. A generalized harmonic mode mixing is used to corroborate the vibrational characteristics of this important class of molecules. Each flavonoid molecule can be treated from the vibrational point of view as made of relatively weakly coupled chromone and phenyl part. It has been shown that the strongest band around 1600cm−1 need not be attributable to the CO stretching. The way the vibrations of any of the hydroxyl groups are mixed with ring vibrations and vibrations of other neighboring hydroxyl groups is rather involved. This imposes severe limitations on any attempt to describe normal modes of a flavonol in terms of hydroxyl or carbonyl group vibrations. The role of water molecules in the appearance of flavonoid IR spectra is emphasized. Knowing for the great affinity of phosphate groups in lipids towards water, the immediate consequence is a reasonable assumption that flavonoid lipid interactions is mediated by water.

Static and dynamic analysis of bending–torsion coupling of a CFRP sandwich beam

The bending–torsion coupling for a sandwich beam is analysed from the static and vibrational point of view. Off-axis orientations in the skin and transverse graded core are proposed to perform the coupling. Solutions are first compared numerically from a static point of view using a complete beam theory. The natural frequencies and mode shapes are then studied experimentally and numerically. An experimental assembly test rig is presented, where a sandwich beam is embedded on the shaker and measurements are taken with a scanning vibrometer. These results are then compared to those calculated by a finite element model in order to verify the accuracy of the model and its ability to consider all the physical phenomena involved.

Approximate Analytical Methodology for the Restricted Three-Body and Four-Body Models Based on Polynomial Series

The restricted three-body problem (R3BP) and restricted four-body problem (R4BP) are modeled based on the rotating frame. The conservative autonomous system for the R3BP and nonautonomous system with period parametric resonance due to the fourth body are derived. From the vibrational point of view, the methodology of polynomial series is proposed to solve for these problems analytically. By introducing the polynomial series relations among the three directions of motion, the three-degree-of-freedom coupled equations are transferred into one degree-of-freedom containing the full dynamics of the original autonomous system for the R3BP. As for the R4BP case, the methodology of polynomial series combined with the iterative approach is proposed. During the iterative approach, the nonautonomous system can be treated as pseudoautonomous equation and the final polynomial series relations and one-degree-of-freedom system can be derived iteratively.

Natural vibration analysis of rectangular bottom plate structures in contact with fluid

A simple and effective procedure for the natural vibration analysis of rectangular bottom plate structures in contact with fluid is presented. Structural part of the coupled hydroelastic problem covers thin and thick rectangular plates and stiffened panels with different framing types. The eigenvalue problem is formulated using Lagrange׳s equation of motion and taking into account potential and kinetic energies of a plate structure and fluid kinetic energy, respectively. Natural frequencies and modes are obtained applying the assumed mode method using the characteristic polynomials of a Timoshenko beam. Potential flow theory assumptions are adopted for the fluid and the effect of free surface waves is ignored. From the boundary conditions for the fluid and structure the fluid velocity potential is derived and it is utilized for the calculation of added mass using the assumed modes. The developed theoretical model is verified with several numerical examples dealing with the natural vibration of bare plates and stiffened panels in contact with different fluid domains. A comparison of the results with those obtained by a general purpose FEA software showed very good agreement, especially for the lowest natural frequencies that are actually most relevant for the structural design from the viewpoint of vibration.

Characterization of emeralds by micro‐Raman spectroscopy

In recent years, the use of Raman spectroscopy as a gemological tool has largely increased, in particular in the conservation science field where a non‐destructive and contactless identification is required. In this work, we show the large amount of information which is possible to obtain with Raman analysis on one of the most important gems, emerald, the green variety of beryl. In particular, 14 not certified faceted emeralds have been studied by means of a standard micro‐Raman spectrometer, allowing also the identification of some fakes (garnet, glass, and quartz). All the emerald gems have been fully characterized from the vibrational point of view. In particular, the high frequency spectrum, in the OH region, has been exploited to estimate the amount of alkali ions present in the channels of the crystalline structure. In addition, solid and fluid inclusions have been identified and were useful to hypothesize the provenance of the mineral. The shape and position of the characteristic laser‐induced luminescence of chromium ions have helped to better define the origin of the gems. Copyright © 2014 John Wiley & Sons, Ltd.

Vibrational and Electronic Structure Analysis of a Carbon Dioxide Interaction with Functionalized Single-Walled Carbon Nanotubes

Electronic and vibrational properties of different single-walled carbon nanotubes (SWNTs) interacting with a CO2 molecule are investigated through the use of density functional theory (DFT) calculations and the discrete variable representation (DVR) method, respectively. We observed a considerable geometry difference between pristine and doped nanotubes. Consequently, a greater binding energy between the former type of nanotubes and the adsorbing molecule is achieved, a fact that finds experimental support and leads us to consider cobalt-doped nanotubes as promising candidates for chemical sensors. From the vibrational point of view, we note that the zigzag chirality tends to present higher values of vibrational frequencies for most of the states considered regardless of the nanotubes being doped or not. The potential energy curves (PECs) for the interactions between CO2 and all of the considered nanotubes together with spectroscopic constants are provided, and the reliability of the performed calculations makes the data a useful source of comparison for future works.

Physical properties of thermoelectric zinc antimonide using first-principles calculations

We report first principles calculations of the structural, electronic, elastic and vibrational properties of the semiconducting orthorhombic ZnSb compound. We study also the intrinsic point defects in order to eventually improve the thermoelectric properties of this already very promising thermoelectric material. Concerning the electronic properties, in addition to the band structure, we show that the Zn (Sb) crystallographically equivalent atoms are not exactly equivalent from the electronic point of view. Lattice dynamics, elastic and thermodynamic properties are found to be in good agreement with experiments and they confirm the non equivalency of the zinc and antimony atoms from the vibrational point of view. The calculated elastic properties show a relatively weak anisotropy and the hardest direction is the y direction. We observe the presence of low energy modes involving both Zn and Sb atoms at about 5-6 meV, similarly to what has been found in Zn4Sb3 and we suggest that the interactions of these modes with acoustic phonons could explain the relatively low thermal conductivity of ZnSb. Zinc vacancies are the most stable defects and this explains the intrinsic p-type conductivity of ZnSb.

Hydrogen bonds determine the structures of the ternary heterocyclic complexes C2H4O···2HF, C2H5N···2HF and C2H4S···2HF: density functional theory and topological calculations

A theoretical study of structural, electronic, topological and vibrational parameters of the ternary hydrogen-bonded complexes C(2)H(4)O···2HF, C(2)H(5)N···2HF and C(2)H(4)S···2HF is presented here. Different from binary systems with a single proton donor, the tricomplexes have the property of forming multiple hydrogen bonds, which are analyzed from a structural and vibrational point of view, but verified only by means of the quantum theory of atoms in molecules (QTAIM). As traditionally done in the hydrogen bond theory, the charge transfer between proton donors and acceptors was computed using the CHELPG calculations, which also revealed agreement with dipole moment variation and a cooperative effect on the tricomplexes. Furthermore, redshift events on proton donor bonds were satisfactorily identified, although, in this case, an absence of experimental data led to the use of a theoretical argument to interpret these spectroscopic shifts. It was therefore the use of the QTAIM parameters that enabled all intermolecular vibrational modes to be validated. The most stable tricomplex in terms of energy was identified via the strength of the hydrogen bonds, which were modeled as directional and bifurcated.

Modelling and vibration of a non-classical tilt-rotor wing system

AbstractProblems related with the mathematical modelling and eigenvibration of a tiltrotor aircraft-wing system built up of anisotropic composite materials are investigated. The wing-mounted rotor that can tilt from the vertical position to a horizontal one is modelled and analysed from the vibrational point of view. In this sense, its behaviour is analysed as a function of the mass size, mass moment of inertia, tilt angle and spin speed of the spinning rotor and of its location along the wing span. While the rotor is considered to be rigid, the aircraft wing is modelled as a thin-walled beam that features a doubly-symmetric cross-section contour and incorporates the elastic coupling between flap-lag-transverse shear, on one hand, and between extension-twist, on the other hand. Numerical simulations are provided and pertinent conclusions are outlined.

Conformation study of HA(306–318) antigenic peptide of the haemagglutinin influenza virus protein

Several HLA-DR alleles present the immunodominant HA(306–318) peptide of haemagglutinin of the influenza virus to T cells. NMR data of the peptide in various water solutions exclude any α-helix or turn conformations. Circular dichroism and Fourier transform infrared spectroscopies indicate an estimated β-extended structure in water of 31% and 28%, respectively, with spectra shape similar to the ones observed for β-sheet containing proteins. The H/D amide exchange suggests a stable length-dependent interchain hydrogen-bonding. The partially β-extended conformation of HA(306–318) in solution might be close to the one found in HA(306–318)–HLA-DR1 complex. These results suggest different interconverting extended conformations of HA(306–318), depending on the microenvironment of the solution medium. This flexibility emphasizes the ability of some peptides to fit more easily the binding site of several HLA-DR molecules. Similar results were obtained on the HIV P25(263–277) peptide which has been previously shown to be a good DR1 binder.From a vibrational point of view, infrared Amide I frequencies of secondary structures in peptides were ascertained.As previously demonstrated for proteins in solution, Fourier transform infrared and circular dichroism spectroscopies appear to be valuable tools for conformational properties of peptides. Their use may contribute to the detection of peptide conformation-binding relationship which has to be further tested by biochemical and biological studies.

Vibroacoustic optimization of skin damped structures for noise reduction

Most of the time the widely used passive treatments are designed to obtain the highest achievable damping. Although this might be satisfactory from a vibrational point of view the approach is not optimal for noise reduction. The idea is illustrated in the case study of a plate on which polymer/aluminum thin patches have been bonded. The system acoustic pressure and structure displacement equations are transformed into a single integro differential one governing the plate displacement. The solution is then expanded into a series of resonance modes. These modes are estimated using a perturbation expansion with respect to the fluid/solid density ratio. Numerically, in vacuo resonance modes are firstly computed using a viscoelastic incompressible 3D FE program together with a Newton-type iterative method and a sparse complex matrix solver implementing ARPACK. Radiation modal impedances are then computed to ponderate the in vacuo solution. The numerical model has been experimentally validated. Its specificity lies in the separate computation of three damping components: thermoelastic, skin and acoustic damping, this last one being caused by the fluid/structure coupling. Finally an optimization process determines an optimal system configuration to achieve the lowest acoustic damping while obtaining the highest viscoelastic damping.

FLUIDELASTIC ANALYSIS OF TUBE BUNDLE VIBRATION IN CROSS-FLOW

Tube bundles in cross-flow vibrate in response to motion-induced fluid-dynamic forces; hence, the resultant motions are considered to be a fluidelastic vibration. The characteristics of the vibration depend greatly on the features of the fluid-dynamic forces and the structure of the tube bundle. Therefore, in this study, the equations of motion of the tube bundle are derived. From the viewpoint of vibration, each tube is not independent of the surrounding tubes because its vibration is affected by fluid-dynamic coupling with the neighboring tubes. Thus, the equations are a set of coupled equations and the solution is obtained as an eigenvalue problem. The fluid-dynamic forces, which are indispensable in the calculation, have been obtained by experiments using a vibrating tube in the bundle; it was found that the forces depend strongly on the reduced velocity. Using these equations and the fluid forces, critical velocities of the tube bundle vibration are calculated, and it is found that the critical velocity is strongly dependent on the fluid-dynamic force characteristics, as they vary with the reduced velocity. Vibration tests of the tube bundle have also been conducted, and the critical velocities obtained in the tests are compared with the calculated values; agreement with the calculated values is good, demonstrating that the method of calculation is useful. The effects of mass ratio, frequency deviation and damping deviation of tubes in the bundle on the critical velocity are also examined theoretically. It is found that it is better to treat the mass ratio and the logarithmic decrement separately when the mass ratio is less than 10. Differences in natural frequencies make the critical velocity large. Similarly, differences in logarithmic decrement may distribute the vibration energy to other tubes and make the critical velocity large.

キャスターに発生する振動がキャスター上の人に及ぼす影響の観点からみた床凹凸の相対的評価方法の提示 : キャスターに発生する振動の観点からみた床凹凸の相対的評価方法に関する研究(その2)

キャスターに発生する振動がキャスター上の人に及ぼす影響の観点からみた床凹凸の相対的評価方法の提示 : キャスターに発生する振動の観点からみた床凹凸の相対的評価方法に関する研究(その2)