Concentrated Mass Model Research Articles

集中系モデルを用いた2次元音響空間の能動騒音制御

集中系モデルを用いた2次元音響空間の能動騒音制御

Sloshing Phenomenon Analysis by Using Concentrated Mass Model

Sloshing Phenomenon Analysis by Using Concentrated Mass Model

集中系モデルを用いた閉空間の能動騒音制御

集中系モデルを用いた閉空間の能動騒音制御

Analysis of nonlinear shallow water waves in a tank by concentrated mass model

The sloshing of liquid in a tank is an important engineering problem. For example, liquid storage tanks in industrial facilities can be damaged by earthquakes, and conversely liquid tanks, called tuned liquid damper, are often used as passive mechanical dampers. The water depth is less often than the horizontal length of the tank. In this case, shallow water wave theory can be applied, and the results indicate that the surface waveform in a shallow excited tank exhibits complex behavior caused by nonlinearity and dispersion of the liquid. This study aims to establish a practical analytical model for this phenomenon. A model is proposed that consists of masses, connecting nonlinear springs, connecting dampers, base support dampers, and base support springs. The characteristics of the connecting nonlinear springs are derived from the static and dynamic pressures. The advantages of the proposed model are that nonlinear dispersion is considered and that the problem of non-uniform water depth can be addressed. To confirm the validity of the model, numerical results obtained from the model are compared with theoretical values of the natural frequencies of rectangular and triangular tanks. Numerical results are also compared with experimental results for a rectangular tank. All computational results agree well with the theoretical and experimental results. Therefore, it is concluded that the proposed model is valid for the numerical analysis of nonlinear shallow water wave problems.

集中系モデルを用いた音声生成解析

Speech is produced by self-excited oscillation of vocal cords. In previous works, the vocal cords were modeled to perform by time history analysis of self-excited oscillation in various ways. However, eigenvalue analysis of coupled acoustic and vocal cords vibration has been not performed. In this paper, we propose a concentrated mass model to analyze a speech production and a self-excited oscillation in the vocal cords, this model can be applied to eigenvalue analysis. This model consists of mass points, connecting springs and dampers. And, we simulate a speech production by the concentrated mass model. Then, we conduct an experiment by using model of vocal organ. We confirm the validity of the concentrated mass model by comparing numerical results and measurement results. According to these result, it is concluded that proposed model is valid.

集中系モデルによるスロッシング現象の解析（第1報 微小振幅時に対する線形モデルの提案および自由振動解析）

集中系モデルによるスロッシング現象の解析（第1報 微小振幅時に対する線形モデルの提案および自由振動解析）

集中系モデルを用いた 2 次元音響空間の能動騒音制御

集中系モデルを用いた 2 次元音響空間の能動騒音制御

ロータ質量付加による面内鳴きへの影響

Squeal often generates in car disc brakes. Brake squeal gives discomfort for driver. Also, it is misled abnormality of the system, therefore car maker has many troubles with claims from customers. Disc brake squeal is classified in terms of its generation mechanism. It has been found in previous studies that two types of squeal exist in disc brakes. One is called out-of-plane squeal, and the other is called in-plane squeal. There are many reports that treat the out-of-plane squeal caused by Coulomb friction. Recently, the occurrence of in-plane squeal has been increasing, and the mechanism of in-plane squeal is not yet fully understood. This paper clarifies the characteristic of the in-plane squeal by using an actual machine experimentally. The vibration mode of in-plane squeal is investigated. Additionally, the effect of brake pad thickness on squeal and the frictional characteristics of disc brakes are investigated. From these experiments, the generation mechanism of in-plane squeal is confirmed. A simple analytical model is also set up. The analysis model was consisted of disc and brake pads which are expressed as beams with a concentrated mass model. It is confirm that the characteristics of the unstable vibration agree well with those of the in-plane squeal generated in the floating type of car disc brake. And influence on in-plane squeal by additional mass to rotor using this linear analysis model is investigated.

集中系モデルによる2次元音響－膜振動連成解析

集中系モデルによる2次元音響－膜振動連成解析

集中系モデルによるスロッシング現象の解析

Sloshing phenomena in containers under earthquakes often cause serious accidents. In case of an oil tank with floating roof, the sloshing phenomenon and the structural vibration should be treated as the coupled problem. Lagrangian fluid finite element model has been used for the analysis of the coupled problem because the compatibility and the equilibrium condition are automatically satisfied at the boundary between the fluid and the structure. However, the degree of freedom of the Lagrangian model becomes large because the fluid particles in the Lagrangian model move vertically and horizontally. In addition, the Lagrangian model has physically-meaningless spurious modes caused by the redundancy of the degree of freedom. In this paper, to establish the efficient and accurate analytical model for the coupled problem, liquid in a rectangular container is modeled as the nonlinear concentrated mass model. The model consists of masses, non-linear connecting springs and connecting dumpers. Some masses move horizontally, the others move vertically. The horizontally movable masses are governed by the equations of motion. The vertical displacements of masses are determined from the displacements of the horizontally movable masses based on the incompressibility of the liquid. The characteristics of the connecting springs are derived from the static and dynamic pressures of the liquid. The degree of freedom of the proposed model is smaller than that of Lagrangian model and the spurious modes does not occur in the proposed model. To confirm the validity of the proposed model, the time history response of the model is compared with experimental result.

702 Coupled Analysis of Two-Dimensional Acoustic and Vibration by Concentrated Mass Model

702 Coupled Analysis of Two-Dimensional Acoustic and Vibration by Concentrated Mass Model

集中系モデルを用いた状態フィードバックに基づく能動騒音制御（音響機器を含む1次元音響空間のモデルベース制御）

集中系モデルを用いた状態フィードバックに基づく能動騒音制御（音響機器を含む1次元音響空間のモデルベース制御）

集中系モデルを用いた押込試験による生体柔軟性計測技術の開発

集中系モデルを用いた押込試験による生体柔軟性計測技術の開発

703 Two-dimensional Acoustic Analysis by Concentrated Mass Model

703 Two-dimensional Acoustic Analysis by Concentrated Mass Model

109 集中系モデルを用いた2次元音響-振動連成解析 : スプリアス除去モデルを用いた連成解析(騒音・振動の解析技術(1))

We have proposed a concentrated mass model to perform a two-dimensional acoustic analysis. This model consists of masses, connecting springs, connecting dampers and based support dampers. In our previous report, we proposed a concentrated mass model for a coupled system which consists of acoustic space and a membrane and verified the validity of the model. However, the result of eigenvalue analysis by this model includes some modes which are physically inappropriate, such as spurious modes or zero frequencies. In this paper, a spurious mode removal model for a coupled system is proposed. The result of eigenvalue analysis agrees with modes calculated by FEM model and doesn't contain those inappropriate modes. Furthermore, the degree of freedom of this model can be reduced keeping its matrix symmetrical and its calculation time is faster than FEM's which has asymmetrical matrices. Therefore, it is concluded that the proposed model is valid for the coupled analysis of acoustic and vibration.

Analysis of pressure wave in gas-liquid two-phase flows by concentrated mass model

A pressure wave generated by a compressor propagates in an air-conditioner piping system and causes a noise problem. The flow condition in the air-conditioner piping system becomes often a one-component two-phase flow, and attenuation of the pressure wave in the one-component two-phase flow is larger than the two-component two-phase flow because of the effect of the mass transfer. It is also important for the safety of nuclear reactors to understand the characteristic of pressure wave problems in the one-component two-phase flow. In this paper, we propose a concentrated mass model to analyze the pressure wave problems in the one-component two-phase flow. This model consists of masses, connecting springs, connecting dampers, and nonlinear base support dampers. The connecting spring and the connecting damper are derived from the compressibility of the gas phase and the effect of the mass transfer when the phase-change occurs. And the nonlinear base support damper is derived from the pipe friction. Additionally, an experiment on an air-conditioner piping system is performed, and the experimental results are compared with the numerical result in order to confirm the validity of the model. The numerical computational results agree very well with the experimental results. Especially, the attenuation of the pressure wave generated by the phase-change is numerically reproduced. Therefore, it is concluded that the proposed model is valid for the numerical analysis of the pressure wave problem in the two-phase flow.

221 集中系モデルによる2次元音響解析 : 三角形要素の検討

221 集中系モデルによる2次元音響解析 : 三角形要素の検討

923 集中系モデルを用いた状態フィードバックに基づく能動騒音制御

923 集中系モデルを用いた状態フィードバックに基づく能動騒音制御

222 集中系モデルによる2次元音響解析 : 解析と実験の比較

222 集中系モデルによる2次元音響解析 : 解析と実験の比較

105 集中系モデルによる2次元音響解析(音響・構造の連成解析)

We have proposed a concentrated mass model to perform a two-dimensional acoustic analysis. This model consists of masses, connecting springs, connecting dampers, and based support dampers. In the previous report, the result of eigenvalue analysis by this model includes some spurious values and zero natural frequencies. In this paper, a spurious mode removal model which is changed the distribution of masses is proposed to analyze natural frequencies without spurious values. Furthermore, this model can be reduced order to remove zero natural frequencies. To confirm the validity of proposed model, the numerical results by this model are compared with the theoretical values in time domain and frequency domain. All results agree with theoretical values. Furthermore, spurious values and zero natural frequencies are removed in eigenvalue analysis. Therefore, it is concluded that the proposed model is valid for two-dimensional acoustic analysis.