Characteristics of Nonlinear sloshing

The oscillation of free surface in a tank grows when the frequency of excitation is near its natural frequencies. This phenomenon is called the sloshing. It is important to understand the characteristics of sloshing in safety design and reliability assessment of the liquid storage tanks Nonlinear liquid motion in various type of tanks partially filled with liquid (i.e. a circular cylindrical tank, a rectangular tank, a annular cylindrical tank , etc.) is investigated. The liquid surface oscillation has the nonlinearity in nature. The nonlinearity of the liquid surface oscillation is taken into account in the response analysis.


Liquid surface oscillation: photograph
Liquid surface oscillation: photograph


Frequency response: deepFrequency response: shallow
   Frequency response: deep     Frequency response: shallow

Vibration characteristics of mistuned bladed disk

When calculating a response of bladed disk system, it is usually assumed that the characteristics of all blades are identical (called by tuned bladed disk system). But it is known that, if the characteristics of blades differ slightly (called by mistuned bladed disk system), amplitude of vibration of some blades in mistuned bladed disk system become large compared to the perfectly tuned system. These phenomena are called localization. The dynamic characteristics of mistuned bladed disk system are investigated.


Bladed-disk system
Bladed-disk system


Frequency response:LocalizedFrequency response:Not localized
    Frequency response:Localized  Frequency response:Not localized

Estimation of Stochastic Response Distribution of a Non-linear System Using Lattice Boltzmann Method

The lattice Boltzmann method has been applied to calculate the probability density function of a nonlinear system subjected to white noise excitation, because of its advantage that the algorithm of the lattice Boltzmann method easily satisfies the both conditions that probability is non-negative and total probability equal to one. The probability density function is governed by partial differential equation known as the Fokker-Planck equation. The local rule of the lattice Boltzmann method is obtained by assuming Fokker-Planck equation as a kind of diffusion-drift partial differential equation.

Countermeasure against Regenerative Chatter in End Milling Operations with Vibration Absorbers

Chatter can result in the poor machined surface, tool wear and reduced product quality. Chatter is classified into the forced vibration and the self-excited vibration in perspective of the generation mechanism. It often happens that the self-excited chatter becomes problem practically because this causes heavy vibration. Regenerative chatter due to regenerative effect is one of the self-excited chatter and generated in the most cutting operations. Therefore, it is very important to quench or avoid regenerative chatter. It is well known that chatter can be avoided by selecting the optimal cutting conditions which are determined by using the stability lobe of chatter. However, it is difficult to predict the stability lobe of chatter perfectly because the prediction accuracy of it depends on the tool geometry, the vibration characteristics of the tool system and the machine tool and the material behavior of the workpiece. In contrast, it is made clear that the stability lobe of chatter has been elevated in the wide range of spindle speed by the vibration absorber in the turning operations. In this work, the relationship between the suppression effect of the vibration absorbers and the tuning parameters of them are investigated by the stability analysis and the cutting test.

Countermeasure against disk brake squeal

Disk brake squeal is a problem that makes drivers uncomfortable. In a luxury car, it might cause recall problem. For many years, the investigation into the generation mechanisms of squeal and the countermeasures against it have been developed. Some effective countermeasures have been developed to reduce squeal in disk brakes. However, these are empirical methods and quantitative parameters to suppress squeal have not yet been considered. In this paper, a dither control is applied to a pad to suppress disk brake squeal. It is made clear the design methods and the characteristics of a dither control to suppress the self-excited vibration caused by Coulomb friction.

Experimental apparatus
Disk brake

Mainly Paper

[2012]

Characteristics of Random Vibration of Mistuned Bladed Disk
Journal of System Design and Dynamics, The Japan Society of Mechanical Engineers, Vol. 6, No. 1, pp. 120-130.
Hiroki TAKAHARA, Takayuki SUGIYAMA, Yutaka NAKANO

[2011]

Free Vibration Analysis of Multi-Surface Liquid Motion in a Rectangular Tank with Different Surface Areas
Journal of Environment and Engineering, Vol. 6, No. 2, 2011, pp. 340-351.
Hiroki TAKAHARA, Shinji TAMURA, Jun FUKUDA, Yoichi HIKITA, Koji KIMURA

Squeal and chatter phenomena generated in a mountain bike disc brake
Journal of Sound and Vibration, Vol. 330, No. 10, pp. 2138-2149.
Takashi Nakae, Takahiro Ryu, Atsuo Sueoka, Yutaka Nakano, Takumi Inoue

Investigation into Vibration Absorbers Attached to Tool Holder against Chatter in End Milling Operations
The 14th Asia Pacific Vibration Conference, Proceedings of the 14th Asia Pacific Vibration Conference, Vol. 3, pp. 1503-1512.
Yutaka NAKANO, Hiroki TAKAHARA, Hirotaka MATSUMOTO

[2010]

COUNTERMEASURE AGAINST REGENERATIVE CHATTER IN END MILLING OPERATIONS WITH VIBRATION ABSORBERS
ASME 2010 International Mechanical Engineering Congress & Exposition, 2010.
Yutaka Nakano, Hiroki Takahara

Experimental and Analytical Chatter Prediction Method in End-Milling Process
2nd INTERNATIONAL CONFERENCE ON VIBRO-IMPACT SYSTEMS, No.37.
Yutaka Nakano, Hiroki Takahara

Tokyo Institute of Technology

Copyright (C) Takahara & Nakano Laboratory, Tokyo Institute of Technology All Rights Reserved.