Papers by Keyword: Local Mode

Abstract: Coherency is used to characterize the degree of confusion between generators which oscillate against each other, so it can judge the process which generators oscillate from local mode to inter-area mode. The coherency is the value of the direction cosine by using angle of the generators. when the direction cosines of two generator is 1 that indicates the oscillation direction between the two generators is inter-area oscillation mode; when the direction cosines of two generator is-1 that indicates the oscillation direction between the two generators is local oscillation mode. Coherency is affected by speed governing system and excitation system of generator.Using two area systems verifies the theoretical analysis is correct.

Abstract: with the speed rising of railway train and the weight lightening of car-body, the frequency range of car-body is widened and the natural frequency is decreased. Especially, the local modes of car-body are caused by suspension device under the car-body bottom, which lead to large vibration response, influence the ride comfort and fatigue failure of structure. In this paper, the whole mode of car-body was analyzed through finite element software. The local mode of car-body bottom and side wall were computed by method of equivalent stiffness constrain. The results show that the local mode of car-body is mainly caused by asymmetry suspension device. The modal analysis method and local modal analysis method adopted in this essay provide the reference and guide the dynamic structural design.

Abstract: A dynamic model of the spindle-cutter coupling system is established including the gyroscopic effects and shear deformation. Dynamic characteristic of the system is analyzed by utilizing the whole transfer matrix method (WTMM) based on the Riccati transformation, and strain energy distribution of the system is estimated. Dynamic characteristic of the system is optimized by univariate search technique. And optimal path in the system optimization is provided. According to the optimal path, a method of local mode elimination by decreasing stickout length of the milling cutter is proposed. The calculation results indicate that preload level of front bearing and rear bearing is the key factor of dynamic optimization after local mode elimination.