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The authors have been developing magnetic rubber dampers with a constraining layer (MRDC). MRDC are generally installed on vibrating steel plates by the magnetic attractive force of the magnetic rubber layer. The damping performance of these MRDC depends mainly on the frictional loss due to the relative slip motion arising between the magnetic rubber layer and the vibrating steel plate. In the previous papers, the flexural vibration of a beam with a sheet of MRDC was theoretically analyzed by taking the frictional loss due to the relative slip motion into account and the equation to calculate the loss factor of the beam with a sheet of MRDC was derived. In this paper the flexural vibration of a plate partially or fully covered with MRDC has been theoretically analyzed based on Rayleigh-Ritz method with the eigenfunction of flexural vibration of a beam with MRDC as trial functions and the equations to calculate the loss factor of the plate partially or fully covered with MRDC have been derived.

The authors have been developing magnetic rubber dampers with a constraining layer (MRDC). They are generally installed on vibrating steel plates with the magnetic attractive force of the magnetic rubber layer. The damping performance of these MRDC depends mainly on the frictional loss due to the relative slip motion arising between the magnetic rubber layer and the vibrating steel plate. In the previous paper, the flexural vibration of a beam with a sheet of MRDC was theoretically analyzed by taking the frictional loss due to the relative slip motion into account and the equation to calculate the loss factor of the beam with a sheet of MRDC was derived. In this paper, the modal loss factors of the beam with a sheet of MRDC were calculated based on the derived equation, and those calculated values were compared with the data obtained experimentally using the method of resonance. Also, the relationship between the loss factor of the beam with a sheet of MRDC and material properties-magnetic attractive force, the content of ferrite powder, the thicknesses of constraining-, magnetic rubber-, and base-layers has been discussed.

This paper deals with the quenching of self-excited vibrations of a rotating circular plate subjected to a concentrated frictional force as a function of relative slip velocity exerted on its outer circumference by dynamic absorbers. Results obtained with the method of multiple scales and the shooting method showed that (1) dynamic absorbers tuned to the natural frequency of the vibration mode to be controlled and arranged at a certain angle relating to the vibration mode are the most effective, (2) such mountings of not one but several dynamic absorbers for every possible occurring mode, enable us to quench self-excited vibrations perfectly, and (3) thus, the effective masses of the dynamic absorbers are 10-3 in the order of mass of the circular plate. The analytical results are confirmed by the experiment concentrating on the perfect quenching of frictional vibrations of the rotating disk.

To examine the effects of contact pressure and relative slip displacement on smoothing conditions of surface asperities acommpanied with no bulk plastic deformation of a workmetal, disk specimens were compressed by a punch in a closed die and rotated with the die. A little amount of the relative slip displacement under the contact pressure accelerated remarkably the smoothing of the surface asperities and thereby the workmetal surfaces were smoothed completely to the same surface roughness as the tool. The surface roughness change of the workmetal were approximated by the experimental equations which were expressed as a function of the contact pressure and relative slip displacement. On the basis of these results, smoothing conditions of surface asperities accompanied with bulk plastic deformation of a workmetal were investigated by a free upsetting of disk specimen and an upsetting of ring specimen in a closed die. Consequently, the smoothing conditions of the workmetal surface in these forming processes also could be approximated by the same equations as the above experimental equations.

This paper deals with the self-excited vibration of a Mindlin circular plate subjected to distributed frictional forces as a function of relative slip velocity in two regions on its outer circumference. However, the effect of the internal resonances is not considered here. It is derived from the averaging method that there exist two stable steady-state solutions of single mode with different spatial location with respect to two frictional regions. The stable solutions become, in general, unstable as the distributed regions widen, but, on the other hand, the stable self-excited vibrations due to the distributed frictions occur anew. However, within a certain length of the distributed regions, the self-excited vibration characteristic has the same tendency as the one due to the concentrated frictional forces at two points, which was dealt with in the previous paper.

This paper theoretically deals with the self-excited vibrations of a rotating Mindlin circular plate subjected to a concentrated frictional force as a function of relative slip velocity exerted on its outer circumference, when the circular plate has some imperfections .As typical of the imperfections, the authors considered the additional masses for the circular plate without imperfection. It turned out from the method of multiple scales that (1) only single modes are stable, (2) the imperfection has a tendency to suppress the occurrence of the self-excited vibrations in the same manner as the rotating speed and the optimal arrangement of the additional masses to control the self-excited vibrations is obtained for each mode, and (3) the resulting vibration shows the waveforms with beats.

新たに押出し形摩擦試験機を試作し,工業用純アルミニウム材料を用いて無潤滑・低すべり速度条件における焼付き発生機構の解明を試みた.ダイス出口の新生面露出位置で相対すべりも生じ焼付き発生の第1因となる.種々の面圧下で相対すべりを強制した摩擦試験と比較した結果,高面圧範囲では高摩擦拘束のため相対すべりが抑制され,また高静水圧のため素材表面相のせん断破壊が抑制され,焼付き発生が遅れることが明らかになった.

This paper deals with the self-excited vibrations of a rotating Mindlin circular plate subjected to a concentrated frictional force as a function of relative slip velocity exerted on its outer circumference. It turns out from the averaging method and a direct numerical integral method that only single modes are stable, the generating modes are fixed in space even if the circular plate rotates and the resulting modes deviate from those generated in a stationary circular plate in the rotating direction due to rotation. Furthermore, the self-excited vibration becomes unstable or the steady-state solutions cease to exist, as the rotating speed is increased. The analytical results are confirmed by the experiment.