著者

バチスタ レアンドロ 酒井 康徳 朱 彊 吉岡 勇人

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会関東支部総会講演会講演論文集

巻号頁・発行日

vol.2016, pp._OS0601-1_-_OS0601-2_, 2016

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Silicon carbide (SiC) is a promising wide-bandgap semiconductor for future power electronics and system applications. However, high-efficient and ultra-precise dicing of SiC remains a challenge due to its extremely high hardness and brittleness. Investigation of the influence of laser processing parameters on cut quality of laser diced SiC wafer can improve efficiency and precision. In this work, 4H-SiC wafers were processed with multi-passes of a CO_2 continuous laser source. The influence of the laser power and scanning speed on the cut quality was evaluated. The experimental results showed that it was possible to obtain a smooth surface, with average arithmetic roughness as small as 0.56μm at effective speed as fast as 1.25mm/s.

著者

尾越 翔大 吉田 優貴 伊賀 龍斗 村上 由祐 谷本 隆一

出版者

一般社団法人 日本機械学会

雑誌

東海支部総会講演会講演論文集

巻号頁・発行日

vol.2015, pp._200-1_-_200-2_, 2015

著者

下田 将太朗 平野 敦也 近藤 拓馬 谷本 隆一

出版者

一般社団法人 日本機械学会

雑誌

東海支部総会講演会講演論文集

巻号頁・発行日

vol.2016, pp._503-1_-_503-2_, 2016

著者

川副 嘉彦

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 C編 (ISSN:03875024)

巻号頁・発行日

vol.58, no.552, pp.2467-2474, 1992-08-25 (Released:2008-02-26)

参考文献数

3

被引用文献数

2 4

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There are a number of unclarified points regarding the impact phenomena and the optimum design of tennis rackets. The present study is based on the idea that the dynamics of a racket consists of the dynamics of a rigid body with an arm swing given at a grip as a boundary condition, an impact between a ball and strings with racket frame as an input force, and the structural vibration of the racket. In this paper, impact force and impact duration are investigated, considering the strong nonlinearity of the restoring force of ball and strings. Furthermore, the coefficient of restitution of the tennis racket is estimated using a personal computer on the basis of the impact phenomena and the experimental modal analysis. In order to predict the contact duration, which has an influence on the racket vibration, a simple impact model has been proposed, i.e., that the contact duration is determined by the natural period of a whole system composed of the mass of the ball, the stiffness of the ball and strings, and the reduced mass of the racket at the impact point on the racket face. The calculated results agree fairly well with the experimental results.

著者

見邨 康平 小池 関也

出版者

一般社団法人 日本機械学会

雑誌

シンポジウム: スポーツ・アンド・ヒューマン・ダイナミクス講演論文集 2016 (ISSN:24329509)

巻号頁・発行日

pp.A-34, 2016 (Released:2017-06-19)

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Motion-dependent term (MDT), which consists of centrifugal force, Coriolis force and gyroscopic effect moment expressed in the equation of motion for a multi-link system, plays significant roles in the generation of bat head speed through not instantaneous effect but cumulative effect of the exerting joint torques in baseball batting. According to our previous studies that calculate dynamics contributions of the whole-body joint torques considering generating factor of the MDT, the forward/backward rotational torque (FBR torque) at torso joint plays a significant role in the generation of bat head speed. These studies, however, show that the lower limb joint torques do not contribute directly to the bat head speed. Therefore, the purpose of this study was to make clear the functional roles of the lower limb joint torques considering the cumulative effect of exerting joint torques. The whole-body with bat was modelled as a system of sixteen-rigid linked segments. The contributions of the lower limb joint torques to the exerting FBR torque at torso joint were quantified through dynamic contribution equation, which relates lower limb joint torques to the torso FBR torque, derived from both dynamics joint force contribution equation of whole-body system and equilibrium balance equation with respect to rotational movement of the lower trunk segment. The results obtained in this study show 1) lower limb joint torque, especially flexion/extension torque at both hip joints, is a large contributor to the generation of the torso FBR torque, and 2) lower trunk inertial force term and other terms are small contributors to the FBR torque. The development of this analytical method would enable us to quantify the contribution of the lower limb joint torques.

著者

小池 関也 見邨 康平

出版者

一般社団法人 日本機械学会

雑誌

Dynamics & Design Conference 2016 (ISSN:24242993)

巻号頁・発行日

pp.506, 2016 (Released:2017-06-19)

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Previous studies, which calculate dynamic contributions of the whole-body joint torques to the generation of bat head speed by using the equation of motion for whole-body with bat system, showed that the motion-dependent term is the largest contributor to the generation of the bat head speed at the ball impact, and also showed that joint torques of the upper limb joints and the torso joint are the main contributors to the head speed with consideration of the generating factors of the motion-dependent term. These results do not tell us the roles of the lower limb joints in the bat head speed generating mechanism. So in order to quantify the roles of the lower limb joints in the mechanism, we quantify the dynamic contributions of the whole-body joint torques to the generation of forward/backward rotational motion of the lower trunk segment during baseball batting motion. Five collegiate baseball players participated in this experiment. They performed hitting a teed ball as strong as possible. Kinetic data of each hand and each foot were obtained by using an instrumented bat equipped with 28 strain gauges and 3 force platforms, respectively. From the results, the flexion/extension torque of both hip joints showed the largest contribution to the forward angular velocity of the lower trunk segment against the large negative contribution due to the torso joint torque. This result indicates that these hip joint torques play an important role to exert large rotational torque at the torso joint, and these hip joint torques show indirect contributions to the bat head speed.

著者

斉藤 一哉

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会誌 (ISSN:24242675)

巻号頁・発行日

vol.119, no.1175, pp.556-557, 2016-10-05 (Released:2017-09-15)

著者

川副 嘉彦 沖本 賢次 沖本 啓子

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 C編 (ISSN:03875024)

巻号頁・発行日

vol.72, no.718, pp.1900-1907, 2006-06-25 (Released:2011-08-16)

参考文献数

15

被引用文献数

1 2

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Players often say that some strings provide a better grip and more spin than others, but ball spin did not depend on string type, gauge or tension in the past laboratory experiment. There was no research work on the spin to uncover what is really happening during actual tennis impact owing to difficult experiment. This paper made clear the mechanism of top spin and its improvement by lubrication of strings according to the high speed video analysis. It also provided the more detailed explanations of spin behavior by comparison between a lubricant string racket and a famous 'Spaghetti strings racket' which was banned in 1978 by the International Tennis Federation since it used plastic spaghetti tubing over the strings to reduce friction resulting in the excessive spin on the ball. As the main strings stretch and slide side ways more, the ball is given more spin due to restoring force parallel to the string face when the main strings spring back and the ball is released from the strings. Furthermore, it showed that the more spin results in the reduction of shock vibrations of the wrist joint during impact.

著者

澤田 純平 吉野 正人 鈴木 康祐

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.84, no.861, pp.18-00023-18-00023, 2018 (Released:2018-05-25)

参考文献数

22

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Dynamic behavior of binary water droplets approaching each other in cloud is simulated by the improved two-phase lattice Boltzmann method with the Continuum Surface Force (CSF) model. This method does not need to solve the pressure Poisson equation and enables us to calculate two-phase flows with high density ratio accurately and efficiently. In this study, we investigate the effects of the Reynolds number Re, the Weber number We, the impact parameter B (the relative distance between the centers of two droplets), and the droplet size ratio on the behavior of the binary droplets for liquid-gas density ratio of 800. We first simulate a stationary liquid droplet in a gas to confirm the validity of the present method. We next simulate off-center approach of two equal-size droplets and investigate the effects of the Reynolds number and the Weber number. It is seen that at low Weber numbers of We ~ O(10-2), there are two types of behavior during approach of two equal-size droplets, namely coalescence and deviation. In this Weber number region, it is found that they can deviate from each other at low Reynolds numbers of Re ≲ O(1) in spite of B ≤ 1.0, whereas collision and subsequent coalescence occur at higher Reynolds numbers of Re ≳ O(10). We finally simulate approach of two unequalsize droplets with various size ratios. It is found that the behavior of the droplets is different from that in the case of the equal-size droplets owing to asymmetric velocity field and droplet deformation. In addition, the smaller droplet tends to deviate from its original path more significantly than the larger droplet.

著者

潮見 俊輔 押味 良和 沼田 紘司

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.84, no.861, pp.17-00568-17-00568, 2018 (Released:2018-05-25)

参考文献数

8

被引用文献数

2

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Object detection function of turnout and switch mechanism is one of an important function for safety of railway system. An object between a tongue rail and a stock rail on a turnout is detected by a lock mechanism of a switching machine and circuit controllers, which are applied on high-speed railway. Designer of switch mechanism has checks his detecting function design by experiments, which were sole way to check it, using real turnout and switch mechanism. In this paper, we described an equation of motion of the switch mechanism and the turnout using multi-body dynamics and flexible multi-body. Moreover, we described a method, which calculate shape of tongue rails inserted an object between rails. By results of calculations, we confirmed that the proposed method could simulates the shape of rails, which is affected by object. Computing time is 40% shorter than an experiment, however, the result includes an error which causes that the model was assumed deformation of tongue rails as 2-d deformation.

著者

谷口 文彦 中川 智皓 新谷 篤彦 伊藤 智博

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.84, no.861, pp.17-00534-17-00534, 2018 (Released:2018-05-25)

参考文献数

11

被引用文献数

1

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Inverted pendulum vehicles controlled by movement of driver's center of gravity (COG), such as Winglet or Segway are the examples of Personal Mobility Vehicles (PMV). PMV is sometimes expected to be used in pedestrian spaces. When a driver brakes an inverted pendulum vehicle suddenly, the driver has to move his/her COG backward largely and has the risk to lose his/her balance due to the characteristics of vehicle control. Therefore, we aim to achieve a vehicle control system that is friendly to drivers in emergency. In the previous study, the coupling model of a vehicle and a human had been built on Multibody Dynamics and the technique to brake an inverted pendulum vehicle automatically had been proposed using that model. In this study, we carried out two experiments to decide the timing of the automatic braking system defined as Time To Collision (TTC). We carried out two experiments about stopping distance when a driver brakes an inverted pendulum vehicle suddenly and when the automatic braking system is operated, and we compared those results. Then, it was shown that stopping distance operated by the automatic braking system is shorter than by human driver's sudden braking operations. In addition, we derived TTC1 ( 0.7 s ) of inverted pendulum vehicles from these experiments about stopping distance by human drivers' sudden braking. Then, we derived reaction time ( 0.4 s ). Finally, we proposed a safety system using TTC1 and the reaction time. When TTC reaches 1.1[s], the alarm makes a human brake an inverted pendulum vehicle suddenly. Then if a human doesn't brake an inverted pendulum vehicle suddenly and TTC reaches 0.7[s], the automatic braking is operated.

著者

瀧上 唯夫 秋山 裕喜 朝比奈 峰之 山本 克也

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.84, no.861, pp.17-00531-17-00531, 2018 (Released:2018-05-25)

参考文献数

13

被引用文献数

1

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It is one of the important issues to investigate the vibration behavior of railway bogies, since the vibration of the bogies may result in loosening bolts which fix the parts to the bogie frames or/and fatigue fracture of the parts themselves. A technique for predicting the vibration of bogie parts is proposed by which the acceleration power spectral densities (PSDs) at evaluated points are predicted with the use of frequency response functions (FRFs) between the axle boxes and the evaluated points, together with the use of measured accelerations of axle boxes. Stationary excitation tests are conducted to identify the FRFs, and the axle boxes or rails were hit with impulse hammers to excite the bogies. Alternatively, the new approach without the stationary tests is also proposed in this study. In this case, the FRFs are identified with the accelerations acquired in the preliminary running tests in car depots. The proposed technique is applied to the vibration prediction of the bogies for several types of railway vehicles including electric cars and a diesel car, and the differences or ratio between the predicted and actually measured PSDs are evaluated. It is confirmed that the preliminary running tests are preferable to stationary excitation tests for improving the prediction accuracy. It is also verified that the prediction error can be reduced in the case where not only the vertical but the lateral and longitudinal accelerations of axle boxes are considered as the excitation inputs under the conditions that the principal component regression is applied to identify the FRFs.

著者

成澤 慶宜 水野 毅 高崎 正也 石野 裕二 原 正之 山口 大介

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.84, no.861, pp.17-00523-17-00523, 2018 (Released:2018-05-25)

参考文献数

17

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A basic single-degree-of-freedom magnetic suspension system consists of one floator, one electromagnet and one amplifier. For multi-degrees-of-freedom control, multiple electromagnets and multiple amplifiers are necessary, which increases the cost of total system. As a means of overcoming this problem, parallel magnetic suspension has been proposed which controls multiple floators or multi-degree-of-freedom motions with a single power amplifier. In this system, all of the suspended points move simultaneously even when a disturbance acts on one of the suspended points solely because all electromagnet's coils are connected. This paper studies the moving direction of each suspended point with respect to a step disturbance in double parallel magnetic suspension system. The analytical study shows that the response direction is determined by the system parameter that relates the response speed of each subsystem. In the slower subsystem, the suspended point moves in the same direction as the applied force while in the faster subsystem, the suspended point moves in the opposite direction. In other words, the slower subsystem has positive stiffness while the faster system has negative stiffness. To confirm this prediction, step responses are measured in the experimental apparatus.

著者

高田 宗一朗 井上 裕文 篠田 茂樹

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.84, no.861, pp.17-00522-17-00522, 2018 (Released:2018-05-25)

参考文献数

20

被引用文献数

2

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In this paper, deterioration diagnosis for distribution main pipe was studied using the uniform cylindrical shell approximation and in-plane bending mode. The in-plane bending mode is expected to have high accuracy in detection of deterioration, because the eigen frecuency of the mode is proportional to pipe thickness. First, using the finite element method, the characteristics of in-plane bending mode are investigated. It is confirmed that in-plane bending mode has little small dependence on the pipe length and the boundary conditions at the pipe ends, it appears in the audio frequency bands, and it has linear dependence on the pipe thickness. In addition, formula with two dimensional ring approximation is derived. Moreover, the average thickness and the uniform-cylindrical shell approximation are introduced for deal with the deteriorated pipe. Using the thinning pipe thickness of previous study, validity of the average thickness and the uniform-cylindrical shell approximation were confirmed. On the other hand, actual pipeline has the sub-structure, for example, valve, hydrant, and so on. In order to deal with the coupled vibration between the cylindrical shell and the sub-structure, eigenvalue analysis are conducted using the Semi-Analytical Receptance Method (SARM). The experimental consideration were conducted in case of that the sub-structure non-attached case. The in-plane bending mode is observed experimentally on the actual pipe system and its resonant frequency shows good match with the theoretical values.

著者

上道 茜 金築 一平 金子 成彦

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.84, no.861, pp.17-00514-17-00514, 2018 (Released:2018-05-25)

参考文献数

15

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Hydrogen combustion is attracting attentions because of zero CO2 emission. Recently, a gas turbine which uses hydrogen-rich fuel is being developed. In our previous study, we examined the influence of hydrogen-containing ratio on combustion oscillation for fuel mixtures of hydrogen and town gas (13A) experimentally. In the experiment, pressure oscillations were measured by a sensor which is installed at the bottom of the combustor. It is found that two oscillation frequencies near 200 Hz and 400 Hz were simultaneously detected in the case of hydrogen-containing fuels, whereas single oscillation frequency around 350 Hz was observed in the case of only 13A fuel. To understand this difference of oscillating frequencies, we conducted acoustic analysis using one-dimensional different diameter acoustic model. However, this simplest model could not reproduce three types of oscillating frequencies obtained by the experiment. Besides, we used an acoustic impedance of the bottom of the combustion chamber as an acoustic boundary condition. The acoustic impedance is measured experimentally under the noncombustion (cold) condition and corrected by combustion temperature obtained by equilibrium calculation. As a result of applying the corrected acoustic impedance, the three types of oscillating frequencies could be reproduced by acoustic analysis. Furthermore, to express the difference among fuel mixtures, delay times, flame positions, and the mean temperature in the chamber were calculated by the CFD simulation. Consequently, it is found that the acoustic analysis result could reproduced the difference among fuel mixtures; hydrogen makes the oscillating frequencies a little higher, because temperature becomes higher and delay time becomes shorter.

著者

CHALERMPONG Kolawach 山浦 弘 原 謙介

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.84, no.861, pp.17-00512-17-00512, 2018 (Released:2018-05-25)

参考文献数

15

被引用文献数

1

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This research studied an influence of the inertia of the hoisting rope on the dynamics of a mobile crane system. Two dynamics models of the mobile crane were formulated with the inertia included rope model and the massless rope model, and their dynamics response were compared. The floating frame of reference formulation was used in formulating the model of the deformable components. In the simulations, we variated the length of the rope and the mass of the hoisted load then applied the slewing motion to the boom for 10 seconds and let the system underwent free vibration for another 10 seconds while the boom angle was fixed. The deformation of the rope and the comparison of the hoisted load motion between two models were considered. The results illustrated that the rope model with included inertia was able to illustrated its bending during the crane operation and this deformation increased with the length of rope. It appeared that the deformation of the boom tip had influences on the deformation of the rope. In the motion of the hoisted load, the time - history data illustrated that the inertia included rope model had slightly higher frequency than the massless rope model during the free motion, and the trajectory also showed the slightly larger sway. In addition, the total calculation time of the inertia included rope model was around 13 times longer. The difference in the motion of the hoisted load from both models increased with the length of rope but decreased when the mass of load increased. In conclusion, the model with included inertia of rope showed different response to the massless rope model at long rope and light load condition, and this difference was decreased at short rope and heavy load condition.

著者

眞田 明 辻 善夫 岩田 和大 川野 道則 岩蕗 仁 下山 安彦

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.84, no.861, pp.17-00511-17-00511, 2018 (Released:2018-05-25)

参考文献数

6

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Hydraulic breakers, which are used to demolish concrete structures or rocks etc., make a loud noise. It is considered that one of the major noise sources of the breaker is the longitudinal vibration resonance of the breaker's chisel. Hence, in order to suppress the noise, a chisel in which a dynamic damper is integrated is proposed in this paper. The proposed dynamic damper consists of ring-shaped weight and ring-shaped plastic spacers. To install it on the chisel, a portion of the chisel must be made slender because the diameter of the chisel is limited by size of the chisel holder of the breaker. Because of this structure, the resonance frequencies of longitudinal vibration modes of the chisel are changed with parameters of the dynamic damper, such as the sizes and the position, etc. Therefore, it is difficult to design the dynamic damper with conventional ways. First, vibration response of the proposed chisel is derived with the transfer matrix method theoretically. Second, experimental results of the frequency response are shown and confirm the validity of the theoretical model. Then, effects of the parameters of the dynamic damper are investigated with the model. Finally, the experimental results of the impact noise during demolishing work are shown. These results show that the proposed chisel is valid and feasible for reducing the noise from hydraulic breakers.

著者

安田 正志 佐藤 栄児 山田 学 梶原 浩一 早津 昌樹

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.84, no.861, pp.17-00509-17-00509, 2018 (Released:2018-05-25)

参考文献数

10

被引用文献数

2

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Research on seismic isolation technology was also a question of how much restoring force can be reduced. The seismic isolation rubber with thin film like rubber and metal plates stacked in multiple stages to reduce the restoring force has achieved great success. However, there still exists restoring power, measures against long-period earthquakes are not perfect and vertically unprotected. This research is an effort to make three-dimensional seismic isolation more realistic with higher performance by further minimizing resilience in all directions. The developed three-dimensional seismic isolation mechanism consists of an air levitation mechanism that isolates horizontal vibration and a spring link mechanism that isolates vertical vibration. Excitation experiments of the prototype were carried out using real-scale three-dimensional seismic waves by the E-defense shaking table. As a result, excellent characteristics of horizontal periodicity and vertical natural period of 5 s were confirmed. The vibration isolation performance at 1 Hz was about 20 dB in all three directions, and the high isolation performance not found in conventional equipment was verified. They were also supported by analytical models.

著者

松田 吉平 田中 謙一郎 今井 秀幸 五井 龍彦 佐藤 恭一 田中 裕久

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.84, no.861, pp.17-00472-17-00472, 2018 (Released:2018-05-25)

参考文献数

4

被引用文献数

2

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The traction drive - integrated drive generator (T-IDG®) has been developed since 1999 to replace current hydrostatic transmission drive generators. The T-IDG® consists of a generator and a half-toroidal traction-drive continuously variable transmission (CVT), which maintains a constant output speed of 24,000 rpm. In terms of coping with recent trends of high-power electric drive aircraft (MEA) and the need for weight reduction, a high-speed traction-drive CVT is advantageous over current hydro-static drive transmissions. To control a speed ratio of the high-speed CVT accurately, it is essential to know the speed-changing response. In conventional study, the speed-changing response is approximately proportional to a rotational speed; however, in the high speed CVT, a minute deformation during the speed change affects its response. This paper describes the analysis and a developed theory of the speed-changing response of a toroidal CVT, with showing test results which verify the response of the high speed CVT, whose input speed is 20,000 rpm at maximum with a peripheral speed of traction contact of 70 m/s.

著者

上村 祥平 今西 悦二郎

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.84, no.861, pp.17-00468-17-00468, 2018 (Released:2018-05-25)

参考文献数

13

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This paper presents a dynamic simulation technique for the rigid body system coupled with the hydraulic system considering the digging behavior of the soil. The rigid body system and hydraulic system is modeled based on the Newton-Euler formulation, while the soil is modeled by the discrete element method (DEM) using the cohesive model proposed by Utili and Nova(2008). The co-simulation is carried out for the rigid body/hydraulic coupling system and the soil. Firstly, the digging simulation of the soil for the bucket of the hydraulic excavator is carried out for the cohesive soil and the sandy soil. The digging behavior of the soil and the digging force are discussed. Secondly, the co-simulation technique for the rigid body/hydraulic coupling system and the soil is presented. Finally, the dynamic simulation of the hydraulic excavator is carried out for the digging operation, the behavior of the hydraulic system and the soil is discussed for the cohesive soil and the sandy soil. It is shown that the digging power of the arm driving system for the sandy soil can be reduced by considering the cohesive force. It is clarified that the present technique can evaluate the hydraulic system of the hydraulic excavator for any characteristics of the soil.