This paper shows a method of reducing the resonant frequency of a transversely vibrating bar and gives a guiding principle of design of a miniature virator with low frequency. The resonant frequency of a vibrator can be reduced without changing the length of the vibrator by means of following two methods; the one is to load mass at the end of a bar whereas another is to cut off a part at the root (clamped end) of the bar. Thus the vibrator can be made smaller in size. As far as design of tunning bar loaded with additional mass is concerned, an analysis of the bar carried out by regarding the additional mass as a concentrated mass has already been reported; whilst, in this paper, the process and the results of examination of the bar in case where the additional mass was considered as distributed are described. In other wards, stepped-cantilevers were used and general analysis was conducted by way of "electro-mechanical analogy". And for providing convenience for design, the several cases of reduction of frequency were calculated, and then a few experiments were conducted with the view of comparing with theoretical values.
In this paper, we treat a model in which a spring is inserted between the vessel A and the body B with the view of preventing the vibration of B, and the driving force is applied on the vessel A. In this model, the vibration of B can be largely supressed by decreasing the resonance frequency of the system composed of A, B and the spring inserted between them. But the relative displacement between A and B becomes larger as the softer spring is used, and in an extreme case, B may come into collision with A. If B would come into collision with A, B might be broken as the result of the too high acceleration of B. There are possibilities of the collision, if the driving force contains a large quantity of low frequency components. In a method generally used for preventing the collision, a vibrational loss (resistance) is added to the spring; however, the effectiveness of suppression of the vibration is decreased by increasing the resistance. It is desirable to use soft spring when the relative displacement is larger than a limited value, if there are few chances where large driving force is applied on the system. In such systems, the body B may be scarcely vibrated cases, and even if it may have fairly large acceleration in a few cases, the body B may be saved from damage as the body B does not come into collision with the vessel A. The impulse response of the system is analyzed in the first part of this paper. By the use of the preceding results, analysis was made with the view of finding the change of the distribution of the response of the system caused by the distribution of the driving force. The maximum values of the relative displacement between the vessel A and the body B and the acceleration of B are taken up as the responses. The acceleration of the body B refering to the vessel A becomes somewhat larger when the amplitude limiter is set on, though the possibility of the collision between A and B and the danger of very large acceleration resulted from the collision can be largely decreased. Consequently, a proper design may be necessary for making such systems effective.