Passengers boarding on a railway vehicle are usually treated as additional mass in designing carbody and the natural frequencies of carbody flexural vibrations are considered to decrease as the number of passenger increases. However, some previous studies indicate that on-board passengers behave not as additional mass but as damping. This paper examines the damping effect due to passengers by using actual railway vehicles and compares the measurement results to the cases that iron blocks or water tanks are loaded. A stationary excitation test in the rolling stock testing plant for a commuter-type vehicle and a running test on a commercial line for a Shinkansen-train were conducted. From both tests, relatively large vibration reduction effects upon different natural modes of flexural vibration of the carbodies and little change of their natural frequencies were observed when passengers were aboard. On the other hand, natural frequencies were decreased when iron blocks or water tanks were loaded. The authors also tried to develop a numerical model to express the flexural vibration of carbody with passengers. It was found that a simple 1-DOF mass-spring-damper system with low natural frequency and high damping ratio can simulate a passenger well. According to those measurement results, it is expected that a new and valuable damping device against carbody flexural vibrations can be realized if we can simulate or mimic the effect of passengers correctly. Some basic directions or policies to develop such damping devices were discussed.

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A simplified analytical method is applied to vibration analysis of a commuter railway vehicle. Vibrationmeasurement test results for a real commuter vehicle show that the vibration characteristic of the vehicle is verycomplex; therefore, usual beam model cannot be applied. In the proposed method, the carbody is modeled as abox-type structure; this enables to express three-dimensional elastic vibration of carbody. A numerical model forthe commuter vehicle is established by using the method. Numerical results are compared with the experimentalresults. Good agreement is observed for natural vibration mode properties and frequency response functions.Some vibration suppression measures are examined by using the numerical model, and it is found that to increasebending rigidity of the floor is more effective than increasing vertical bending rigidity of the side lengthwisemember.

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Under the existing method based on a detailed equation for evaluating the wind speed that can cause a vehicle to overturn, it is assumed that the crosswind blows the vehicle at the same wind speed uniformly over the entire length of the vehicle body along the track. However, taking into consideration the actual wind state, there is a wind speed distribution over the length of the vehicle body and there is a high possibility that the crosswind does not blow at the same wind speed over the entire length of the vehicle body. Therefore, if the wind speed distribution is considered, it becomes possible to evaluate the critical wind speed in more detail. In previous research, an evaluation formula of aerodynamic force in consideration of the wind speed distribution has been proposed with the natural wind direction assumed to be 90 degrees. On the other hand, the calculation of the wind speed that can cause a vehicle to overturn requires extending the evaluation formula so as to be applicable to the other natural wind directions. In this study we proposed, extending the existing evaluation formula, a method of calculating the critical wind speed in consideration of the spatial fluctuation of wind speed. We also evaluated the critical wind speed for the combination of the vehicle and the track constructions with the proposed method. In addition, we also evaluated the critical wind speed in accordance with changes in the height of the center of the car body from the ground and the roughness length. As a result of the evaluation, we confirmed that the critical wind speed increases by up to 1.4m/s, provided that the vehicles and railway structures are those assumed in this study.

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The effect of passengers boarding on a railway vehicle is usually considered as additional mass in designing carbody. This means that natural frequencies of flexural vibrations of a carbody are decreased as the number of passenger increases. However, previous researches, in which some stationary excitation tests were carried out for actual railway vehicles, indicate that on-board passengers behave not as additional mass but as damping. In this report, the authors examine the damping effect by passengers in running condition. A series of running test using a Shinkansen-train was conducted, and relatively large reduction of flexural vibration of carbody was observed when passengers were on-board. We also tried to imitate or simulate the damping effect by passengers using flexible polyethylene tanks filled with water. As a result of excitation test for a commuter-type test vehicle, at least two-different modes of flexural vibration were reduced when water tanks (total 630-1050 kg) were loaded.

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It has been reported by the authors that recent actual lightweight railway vehicle car bodies have complex flexural vibration shapes. The mode shapes of commuter vehicles are complex in particular, with the roof and floor moving out of phase from each other. Such complicated vibration often worsens the riding comfort. In order to reduce such vibrations, especially those with large relative deformation between roof and floor, a new vibration reduction device has been developed. The new vibration reduction device, which is called SPD (stanchion pole damper), looks similar to ordinary stanchion pole, but it connects the main structure of roof and floor and it has built-in viscous damper. Four SPDs are applied to actual commuter vehicle car body and stationary vibration test is carried out to confirm the validity of SPDs. From the test results, it is shown that the SPD can reduce the flexural vibration of the car body successfully.

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This paper presents an analytical method to investigate the three-dimensional elastic vibration problems on a railway carbody. The carbody is modeled as a simply-supported non-circular cylindrical shell without end plates. Transfer matrix method is applied to the analysis model. The model has an advantage of the matrix size for calculation. Therefore we have applied this model to simulate the effect of the rigidity of the connecting part between roof and side panel. As a result, it is found that amplitude ratio of floor to roof can be reduced when we set the rigidity of the connecting part between roof and side panels to higher value. And it is also found that the natural frequencies become higher at the same parameter changing.

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Passengers boarding on a railway vehicle are usually treated as additional mass in designing carbody and natural frequencies of carbody flexural vibrations are considered to decrease as the number of passenger increases. However, some previous studies indicate that on-board passengers behave not as additional mass but as damping. This report examines the damping effect by passengers using actual railway vehicles and compares the measurement results to the cases that iron blocks or water tanks are loaded. A stationary excitation test in the rolling stock testing plant for a commuter-type vehicle and a running test on a commercial line for a Shinkansen-train were conducted. From both measurement tests, relatively large vibration reduction effects upon different natural modes and little change of their natural frequencies were observed when passengers were boarding. On the other hand, natural frequencies were decreased when iron blocks or water tanks were loaded. The authors also tried to develop a numerical model to express the flexural vibration of carbody with passengers. It was found that a simple 1DOF mass-spring-damper system with low natural frequency and high damping ratio can simulate the passenger well. A new and valuable damping device against carbody flexural vibrations can be realized if we can simulate or mimic the effect of passengers correctly. Some basic directions or policies to develop such damping devices were discussed finally.

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軽量化が進んだ最近の車両では車体質量に対する乗客質量の割合が増加している.例えば軽量ステンレス製のではモータのない中間付随車の場合,車体質量が13〜15トン程度であるので,定員乗車(約160名)の際には乗客の質量は車体質量の70%程度となる.車両の快適性に対する要求が高まるなかで,振動乗り心地の向上,とくに上下方向の車体弾性振動低減が重要となっているが,車体の設計や振動解析において乗客質量の影響は単純な質量増として扱われることが多かった.これに対し著者らはこれまでに,高速車両の実車体に人と鉄塊を載せて車体を定置加振する試験を行い,人員乗車による影響は単純な質量増とは異なり,車体の減衰能増大の傾向が強いことを明らかにしている.本報告では,車体が単純な「はり」に類似した形状で弾性振動する特性をもつ高速車両とは異なり,車体の屋根と床が独立に変形する傾向が強いを対象に加振試験を行い,人員乗車による車体床面の振動特性の変化を調べるとともに,それを表現する車体弾性振動と乗客の連成振動解析モデルの構築に関する検討を行った.今回得られた結果をまとめると以下のようになる. (1)今回対象とした試験車両の車体は,入力に対する加速度評価点(車体の長手方向中央で左右方向は側寄り腰掛直下の床面)の加速度周波数応答(FRF)は, 8Hzおよび13Hz付近に弾性振動による卓越したピークを持つ.人員乗車により,そのいずれのピークについても周波数の変化は少ないが高さが低下すること(図A1),乗車人数増大に伴ってピーク高さ低下量も大きくなること,乗車時の姿勢によりピーク高さ低下量が異なる場合があることなどがわかった. (2)今回は2名から14名乗車という比較的少人数の乗車条件であったが,車体弾性振動に対する減衰付与効果は大きく,損失係数は空車時に比べて3倍から7倍程度の増大(14名乗車時,振動モードや乗車姿勢により異なる)になることがわかった(図A2). (3)上記の試験結果を表現する解析モデルの構築についても検討した。そして,車体は平板とはりの接続系としてモデル化する簡易解析モデルで表し,乗客一人をばね,粘性減衰の並列系で支持された1質量とするモデルを付与することで,試験結果を良く再現できることを数値計算により示した.

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Under the existing method based on a detailed equation for evaluating the wind speed that can cause a vehicle to overturn, the instantaneous wind velocity at one point is taken into consideration. In this study, we evaluated the results of the calculations of the critical wind speed which were conducted in consideration of the spatial fluctuation of wind speed. In addition, we also evaluated the critical wind speed in accordance with changes in the height of the center of the car body from the ground and the roughness length. As a result of the evaluation, we confirmed that the critical wind speed increases by up to 1.4m/s, provided that the vehicles and railway structures are those assumed in this study.

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The critical wind speed of overturning obtained by the RTRI detailed equation, which is used in the static analysis of railway vehicle overturning under cross wind, tends to be lower than that intuitively estimated because it assumes the superposition of the worst conditions. In order to improve the accuracy of the evaluation, the previous research focused on the aerodynamic coefficients that have the greatest influence on the calculation results, but few studies on the lateral vibrational inertia force have been conducted. Therefore, in order to evaluate the critical wind speed of overturning reflecting the actual conditions, we examined an evaluation method based on the measured value of the lateral vibrational acceleration.

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It’s generally known that tangential force of wheel/rail interface which depends on a change of coefficient of friction between wheel and rail has a big influence on a steady lateral force of railway vehicle. According to our past researches, regardless of an attack angle, tangential force coefficient becomes smaller in the case with fine unevenness than in the case without fine unevenness on the surface by means of a two-disk rolling contact machine. In particular, a tangential force coefficient is more affected by the situation of with /without fine unevenness under low relative humidity condition. The conditions under low relative humidity are almost the same as the conditions that a coefficient of friction of wheel/rail is high. In this paper, in order to reduce steady lateral force during a railway vehicle passing curve, we proposed a new wheel tread profile with providing one streak of fine unevenness, called ‘Micro-ribbed wheel tread profile’ on a wheel tread away from a flange. We verified a validity of this wheel tread profile by applying a numerical analysis and a running test in RTRI. As a result, we confirmed that the Micro-ribbed wheel tread profile is effective to reduce the steady lateral force of the outside wheel/rail interface when the railway vehicle is passing curve under high coefficient of friction between wheel and rail.

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This paper describes a study of bending vibration of a railway vehicle carbody by FEM. Railway vehicles with lightweight carbody have some natural modes of bending vibration in the high sensitivity frequency region for humans. Therefore, suppressing the bending vibration is necessary to improve the riding comfort. However, their vibration shapes are complicated, so it's difficult to calculate the effect at design process. The authors have developed the FEM model that is composed of whole carbody supported by air springs, and the simulation is carried out to calculate natural frequencies, mode shapes and frequency response function. The results show that it is able to evaluate the vibration mode characteristics of actual railway vehicle using the FEM model.

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The vertical elastic vibrations of railway vehicle carbodies are needed to reduce from the viewpoint of riding quality. The first bending mode and diagonal distortion mode are commonly observed almost all railway vehicle carbodies. The natural frequencies of the two modes exist around 10Hz which is known to be a sensitive frequency for human. In this paper, a vibration reduction method about the two modes by using active mass dampers is suggested. A stationary excitation test for an actual railway vehicle is conducted to confirm the feasibility of this method. As a result of the excitation test, two modes of above mentioned elastic vibration of the carbody are reduced successfully.

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近年の車両は,高速化,ランニングコストの低減等への期待から積極的に軽量化が行われている.一方で車体の軽量化は,車体剛性を低下させ車体の上下弾性振動の増加を招くという問題がある.この上下弾性振動の1次の固有振動数は人が不快と感じる周波数帯域に近いため,乗り心地の観点から新幹線だけでなく在来線車両でも問題とされており,軽量化車両に対する弾性振動の制御手法の提案・検討が必要となっている.また,近年スマート構造という考え方が注目され,宇宙構造物の分野等で研究がなされている.このスマート構造とは,構造部材に小型アクチュエータやセンサを組み込み人間における筋肉や神経の機能を持たせたものであり,制御装置の小型化,軽量化につながるといった利点がある.本研究では,軽量ステンレス製の試験用車両に積層型ピエゾアクチュエータを用いたスマート構造技術を適用し,人の乗り心地に最も影響する車体の弾性1次振動を低減させることを目的とする.制御器の設計にはH_∞制御理論を用い,車体の曲げモーメントをアクティブに制御することで車体の弾性振動の低減を図った.実験で使用した車両を図A1に示す.この実験車両は総研が保有する軽量ステンレス製の試験用車両である.主な諸元は長さ19.5[m],幅2.95[m],高さ2.60[m],質量10,600[kg]となっており,最近のと同様の車体構造を持っている.この試験車両の左右側梁に,冶具を介して12ケ所に計24個のヒ.エゾアクチュエータを取り付けた。H_∞制御理論を用いて設計した制御器の制振性能を確認するため,制振試験を行った.外乱としての入力波を動電型加振器より入力し,その時の車体中央部加速度を測定する.これをフィードバック信号として用い,制御器からピエゾアクチュエータへ制御電圧が出力され制御が行われる仕組みとなっている.制振試験における車体中央部の加速度のボード線図を図A2に示す.ここで外乱入力には0.1〜20Hzのスイープ波を用いた.この図の固有振動数のピークを比較すると33%振動を低減出来ている事がわかり,これより積層型ピエゾアクチュエータを用いて車体の弾性1次振動が低減可能であることを確認した.

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To prevent bogie hunting motion and reduce carbody vibration in railway vehicles, a new mounting structure for yaw dampers has been proposed in this report. The new mounting structure enable to reduce the excitation force transmitted from a bogie frame to a carbody through yaw dampers. The prototype device was installed in a full-scale test vehicle and bogie hunting test was carried out at the Railway Technical Research Institute’s rolling stock testing plant to examine the running safety. Moreover, we performed vehicle dynamics simulation using versatile multibody dynamics analysis software SIMPACK. In this paper, the outline of the new mounting structure for yaw damper is presented and results of the bogie hunting test and the vehicle dynamics simulation are also described.

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It is pointed out that the yaw dampers, which are often installed in between carbody and bogie frame of a high-speed railway vehicle, have such unfavorable points that the damping force is generated not only in the yawing direction but also in other direction. As a result the damping force is generated also to the longitudinal or pitching vibration of a bogie, and the excitation force acts in the longitudinal direction of the carbody resulting in the increase of the carbody vibration of the longitudinal or vertical direction. In this research, to enable the reduction of the excitation of the carbody vibration while maintaining the original function of yaw dampers to prevent bogie hunting motion, a new mounting structure of yaw dampers on railway vehicles has been developed. The new mounting structure enables to reduce the excitation force transmitted from a bogie frame to a carbody through yaw dampers. In this paper, the effect of yaw dampers on the carbody vertical vibration is firstly shown based on the results of an excitation test of a full-scale vehicle, then the outline of the new mounting structure for yaw dampers and the design and manufacture of the prototype device are presented. The vehicle dynamics model based on multi body dynamics was constructed and the suppression effect of the yaw damper force generated to movement in the direction other than the yawing direction of a bogie was verified by the numerical simulation. Moreover, the prototype device was installed on a full-scale test vehicle and a bogie hunting motion test was carried out to verify the running stability.

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The authors are developing a vibration simulator, which consists of field-portable exciters (actuators) and data processing software, to estimate vertical vibration and riding quality of railway vehicles. One of the main characteristics of the vibration simulator is that the acceleration power spectral density (PSD) at arbitrary point on the carbody while running is synthesized numerically from measured data obtained when each axle box or each wheelset is excited individually. This report focuses upon the data processing technique of the simulator. A series of excitation tests for a commuter vehicle was carried out to confirm the basic concept to synthesize (estimate) the PSD by using the rolling stock testing plant as exciters. Several excitation methodologies and data processing formulae are compared among each other in this report. It is shown that the estimated PSDs well agree with actual PSDs. It is found out that the estimation gives high accurate results when each wheelset is excited individually and acceleration values at excited axle boxes are used in estimation analysis.

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