The RANDAP-11, which was developed by JSME RC-SC 30 in 1976 for correlation and spectral analysis of a multiple input system, has the function of power contribution analysis. Although this function was originally intended for analysis of a feedback control system, the author has tried to use this function for separation of correlated power conponents which are present in general multiple input vibration system. Since the power contribution analysis has been proved to be useful for this purpose as the result of numerical simulation analyses of various types of systems, the author went on to analyze how stresses in an exhaust pipe of a truck are dependent on the vibrations.
The externally-pressurized gas journal bearings with circular slot restrictors are investigated theoretically and experimentally to determine the dynamic properties. The theoretical analyses are presented for a single-row admission bearing and a double-row admission one, respectively, by using Reynolds equations in which inertia forces of a gas-films are considered into. The accuracy of the theoretical method is demonstrated by comparison with experimental results. Good agreement between the theoretical and experimental results are obtained, and it is consequently shown that the present theoretical method can accurately predict the dynamic properties of a journal bearing with a circular slot restrictor.
A system program of curve-fitting for general purpose is made to analysis the modal parameters from a transfer function obtained by a vibration test and to reconstruct the frequency curve of the transfer function. Both the frequency domain and the time domain curve-fitting is possible under assumption of three kinds of dampings, namely the proportional viscous, general viscous and the hysteretic dampings. A transfer function of a mass-spring system of three degrees of freedom is fitted by six methods with this program, and calculated results of modal parameters are compared with the rigorous solution. Next, a transfer function of a steel plate obtained by the vibration test is fitted with this program, and the result is compared with the experimental one.
Generation method of the appropriate pulse trains which should be utilized as alternative excitation inputs for the structural response analysis in terms of various types of random excitation is presented. Criteria for getting optimum pulse trains are established based on the evaluation of the structural response spectra. Fundamental considerations are briefly made concerning about the comparison of the response properties through random motions with those through pulse trains taking a single-degree-of-freedom system as a structure model. Results obtained fairly well correspond to the experimental results using shaking test. Shape and number of the pulse trains can be optimally determined by the calculation of the difference of the response spectra among both input cases within the periods including main natural periods of structures. Optimization can be successfully carried out by taking the artificially simulated narrow-band excitations and also the nonstationary broad-band excitations like seismic motions as inputs for numerical examples.
For the purpose of reducing the detrimental vibration which may cause a labour hazard such as a white finger disease, this paper proposes a new vibration isolation type handle device for hand-operated vibration tools in which a handle member is substantially rigidly connected to a vibration body and which, nevertheless, is capable of effectively isolating detrimental vibration. Moreover, it can be made to have a light weight. The handle device is designed by the principle based on making a vibration node on the handle at the desired frequency range. To demonstrate the effect of vibration isolation by application of the handle device, the experiment using the hand-operated electro motive grinder has been carried out, and then the acceleration transmitted to the handle in the region of 5400 rpm ∼6600 rpm has been reduced under 1/3, especially that at 6000 rpm near zero.