STUDY ON PATTERN FORMATION PHENOMENA IN MECHANICAL ENGINEERING

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1.In order to make clear the generation mechanism of the polygonal wear which is one of the abnormal wears of automobile tire, the modeling and the analysis were performed, and a very good agreement between the experimental and the theoretical results were confirmed. The results obtained are summarized as follows :(1) The generation mechanism of the pattern formation phenomenon caused by the first natural vibration mode of tire itself in the vertical direction was made clear by modeling a system with time lag in which the wear quantity of the generated in the rolling contact surface is fed back to the contact surface after one rotation of tire as a forced displacement for the vibration in the vertical direction.(2) Almost regular polygonal pattern is formed on the tire tread in the circumferential direction when the polygonal wear is generated. The generation regions are in some limited ones satisfying the relation of (natural frequency of tire) * (polygonal number of tire) * (rotation … More al frequency of tire).(3) The difference in modeling of wear quantity of tire and wear resistance give almost no effect upon the width of generation regions of polygonal wear. However, it gives a significant influence upon the generation rate (the degree of instability) of the polygonal wear.2.The pettern formation of a work piece in centerless grinding machines was dynamically analyzed, and the experimental and the theoretical results were compared. The pattern formation means the polygonal deformation of the work piece. The surface of the work piece is deformed into a certain convex polygon during the grinding process, and these work pieces become consequently useless. The modeling of the system was described, regarding this phenomenon as an unstable vibration in grinding due to the time lag. As the results, it was made clear that (1) the unstable vibration tends to occur at nearly the natural frequencies of the grinder system and of the work piece itself, (2) the locations of the unstable regions in which mainy the work piece vibrates, vary periodically among even and odd polygonal numbers, and (3) the effect of the center height angle upon the polygonal deformation agrees well with the results of actual machines.3.The unstable vibration generated in multiple stage super calender including rolls covering rubber in the paper making machine was analyzed, taking the viscoelastic characteristics of rubber into account. The experimental results of the polygonal deformation of the roll-covering rubber due to the natural mode of order 10 agreed well with the analytical results.4.The flash over phenomenon of DC motor was researched, and the analytical model was constructes. The experimental and the analytical results will be compared. Less