Vibrational Point Of View Research Articles

発生する振動からみたキャスターと床凹凸の関係についての基礎的検討 : 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1)

This study is a fundamental examination about the relationship between running casters and unevenness of floors. The purpose of this study is to present relative evaluation method of unevenness from a viewpoint of vibration on casters. Concretely, we examined correlation between the grades or types of unevenness from a viewpoint of vertical acceleration on casters which had various specifications (weight, diameter of wheel, running rate and solidness of wheel). As a result, we showed the possibility of ranking unevenness by the acceleration and the necessity of considering not only unevenness but also solidness of floors when we evaluate unevenness of floors.

Calculation of internal valence force constants for XY 4 ( Td) tetrahedral molecules

Valence force constants have been calculated in terms of simple dependent rectilinear internal coordinates for a series of XY 4 tetrahedral molecules that have been studied from a vibrational point of view. These molecules include the tetrahydrides of carbon, silicon, germanium and tin, and the tetrafluorides of carbon, silicon and germanium. Using the most recent and reliable force constants in symmetry coordinates, the pure vibrational force field has been arrived at by applying Kuczera's treatment. The results show that the seven F R dependent constants are reduced to five F * R independent constants; the same occurs for the F 0 S independent force constants. The relationships f * rα = − f *′ rα and f *′ αα = − f * α − 4 f * αα are obtained from the sum rule in Kuczera's treatment. On the basis of Wilson's S vectors and from the interactions between the displacement coordinates, a method is proposed here to obtain the above relationships. This allows individual values to be assigned to the bending, bending—bending and bending—stretching force constants for the above-mentioned molecules, without the need for recourse to any model whatsoever. Likewise, in each case we have attempted to obtain an empirical function to fit the force constant values dependent on the bond lengths. This method allows us to some extent to predict the values of the force constants for some tetrahydride molecules of this group, which has not yet been studied experimentally.

Basis set superposition error effects on electronic and νFX, νF⋅⋅⋅N stretching modes of hydrogen bonded systems FX⋅⋅⋅NCX (X=H,D)

The FH⋅⋅⋅NCH hydrogen-bonded complex, which is a reference structure, has been reviewed from an electronic and vibrational point of view. Ab initio calculations have been made, using a large basis set and thus providing first structural and electrical properties on the subunits when the electronic correlation effects are taken into account in very close agreement with the experimental data. The structure and dipole moment of the complex are well represented. The νFH and νF⋅⋅⋅N stretching modes are calculated by means of the variational method, taking into account the mechanical anharmonicity and anharmonic coupling between both vibrations. It is shown that the νF⋅⋅⋅N stretching frequency, which is larger than the experimental value at the self-consistent-field level and especially when electronic correlation effects are taken into account, is strongly decreased, and so approaches the experimental value, when corrected for basis set superposition error.

EXPERIMENTAL INVESTIGATION OF VIBRATION CHARACTERISTICS OF TAPERED ROLLER BEARINGS.

This paper deals with the rib—roller end contact of taper roller hearings from the vibrational point of view in order to diagnose its failure when running under different operating conditions of axial loads, speeds, lubrication, and mounting fits. The dynamic response of an axially loaded tapered roller bearing is obtained experimentally. A test rig is built to investigate the vibrational response of the tapered roller bearings when running under different operating conditions.The results show that the vibrational response of the tapered roller bearings increases with the axial loading, unbalance, rotational speed, lack of lubrication, grade of fit, and wear of bearing elements.

Small Vibrations of Nonlinear Dynamic Systems Containing Non-Rigid Bodies Excited by Stationary Stochastic Processes

Abstract From a vibrational point of view, real vehicles form dynamic systems containing non-rigid bodies and nonlinear two-force elements, often excited by stationary random processes. Their theoretical investigation in a broader frequency range is practically possible in the frequency domain only. In the treatment of nonlinearities second-order stochastical linearization methods can be used advantageously. The amount of necessary computations can be vastly reduced by using known receptance matrices of all bodies in the system in its equations of motion after Fourier transformation. The article describes the receptance properties of non-rigid bodies, their use for the determination of the dynamic system's transfer functions and the determination of the output processes' spectral density matrix under stationary random external excitation using stochastical second-order linearization of the nonlinearities.

Calculation of internal valence force constants for XY 6( Oh) octahedral molecules

The valence force constants have been calculated in terms of simple dependent rectilinear internal co-ordinates for a series of XY 6 octahedral molecules that have been amply studied from a vibrational point of view, i.e. the hexafluorides of sulphur, selenium, molybdenum, tungsten and uranium. The calculations have been carried out using the most recent force constants in symmetry co-ordinates to appear in the literature and following Kuczera's treatment, according to which the indetermination of the internal valence force constants involved in redundancies can be solved by using the transformation F* R= W T WF R W T W, which he calls the pure vibrational force field. The results show that the eleven F R dependent constants are reduced to seven F* R independent constants, the same number as the F S independent force constants. This is because of the zero value of the ƒ′* dα constants and the relationships ƒ* dα= −ƒ″* dα ƒ* αα = −ƒ″* αα ƒ* α=−2ƒ′* αα−ƒ′″* αα that are obtained from the combination of the above mentioned F* R transformation and the sum rule in Kuczera's treatment. These latter relationships can be obtained from the interactions between the displacement coordinates with which they are associated. This has allowed individual values to be assigned to the bending, bending—bending and stretching—bending constants for the above mentioned molecules without the need for recourse to any model whatsoever.

Vibrational spectra of N,N-dimethyl/diethylaniline, N,N,N′,N′-tetramethyl/tetraethyl-p-phenylenediamine and N,N,N′,N′-tetramethyl/tetraethylbenzidine derivatives

Abstract The ground state and protonated state (quaternized salt) vibrational spectra (200–1800 cm −1 ) of the title amines are reported for various ring and/or methyl deuterated derivatives. Complete assignments are proposed and compared to those established for the parent hydrocarbons, benzene and biphenyl, and for the parent primary amines, aniline, p -phenylenediamine and benzidine. The electronic distribution, N( n )→ring(π) charge-transfer character and inductive effects are characterized from a vibrational point of view. Finally changes in the vibrational and electronic conformation upon protonation of the nitrogen atom are discussed. These results provide a fundamental basis for the vibrational investigation of excited states and reactive transients of aromatic amines.