Spatial behavior of the curved pipe conveying fluid is examined theoretically and experimentally under the condition that fluid velocity has a small pulsating component. First-order ordinary differential equations, which govern the amplitudes and phases of the non-planar pipe vibration, are derived from the nonlinear nonself-adjoint partial differential equations by the liapnov-schmidt reduction.The forced vibration of the in plane motion and the parametric excitation of the out-of-plane vibration exist depending on the value of the pulsating frequency. Furthermore the experiments were conducted with the silicon rubber pipe conveying water. The spatial displacement of the pipe was measured by the image processing system which was based on the images from two CCD cameras. The typical feature of the pipe vibration, which has been predicted in the theory, was confirmed qualitatively.

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In our research, we have analyzed a propagation of pulse inside a collapsible tube, which could be seen inside an artery of human body. Flow inside collapsible tube is basically analyzed using continuity equation, NS equation and equilibrium of force on tube walls. In the process of analytical solution with perturbation method, these equations could be transferred into a KdV equation, which is known for producing solitary wave. Analytic solution and its form are derived.

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In the engine exhaust system, the sine pressure wave changes to the shock wave because of nonlinear effect. Numerical simulation of this phenomenon was conducted by using finite difference method, but the computation speed was slow.This paper proposes a practical nonlinear wave analysis model, which uses a concentrated model. This model consists of masses and nonlinear springs and connecting dampers and base support danpers. By using this model, the simurations are carried out for a sound tube problem and a progressive wave problem in order to confilm the validness of this model. Numerical results agree well with experimental results.

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The stability was investigated for a safety valve mounted to a vessel through an inlet pipe by experiments and analysis. It was found that interaction between the pressure wave propagation through the inlet pipe and valve disc motion causes the instability. Longer inlet pipe could be stable due to the longer period of the propagation of the pressure wave and the attenuation effect of the mechanical friction of the safety valve. Stability analysis can explain the instability phenomena, however it cannot explain the stable condition with longer inlet pipe. Numerical simulation is effective to predict the stability for the longer inlet pipe.

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The characteristics of the pressure pulsations in the drum connected to piping system excited by centrifugal compressors or blowers at blade-passing frequency were investigated. In this study, the equivalent resistance of a compressor and that of piping systems were introduced to the three dimensional calculation model, so that the non-linear damping proportional to velocity squared in the system is properly incorporated. As a result, the pressure response in the drum as well as pipe can be well evaluated by this model. Furthermore, the effect of the acoustic dynamic absorber on the pressure pulsations in the pipe and drum is evaluated.

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Vibration amplitudes of a control valve in a cavitating flow were measured varying opening rate from 20% to 40%. Moreover, pressure on the valve sheet was measured synchronously to examine the correlation between the fluctuating fluid force and the response of the valve. As a result, the amplitude in the drag direction was increased drastically when the cavitation coefficient K_m exceeded 0.8. It was expected that this phenomenon was the coupling problem with cavitating flow and a structure from the correlation between the fluid force and the response.

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The stability of Ann-wrapping (wrapping Ann with "Konashi") motion of Kyogasi-sweets making hasn't been reported. The purpose of this study was to examine stability of fingers motion(39trials) in Phase 1 (Building): Wrapping from the bottom to the middle position of sweets. Coefficient of variance (CV) of the maximum flexion angle, the maximum extension angle, the time of flexion movement, and the time of extension movement were calculated. The CV values of maximum flexion angle and the time of extension movement were small. According to these results, it was considered that the fingers motion was stabile.

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"Temae" of Japanese Tea Ceremony is a technique to prepare beverage of Tea, and the body motion is valued for beauty. However the cause of beauty is unclear, and it has not been formal knowledge. In this study, motion analysis of "Temae" was performed to reveal the cause of beauty in an expert. As the results, characteristics of motion in "chadou temae" included that 1). motion of whole body is stopped when formal behavior is shown to the guest. 2). to carry out "temae" exactly and smoothly, a device is looked carefully when it is picked up, 3). in order to show motion continuously and smoothly, either right or left hand is in motion moving at all times, 4). A basic posture of setting is one broken to pick up a device, then immediately return to pre posture.

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Soldering process of metal fittings of flag is not well known generally. For this reason, the process involves a special skill at making flags with hands. The purpose of this study was to investigate the process of soldering and the characteristics of human movement during soldering process. Three-dimensional upper extremity kinematics and eye movement data were collected. The resulting data show that the process divided into eleven stages, and the movement of arm interacted with the movement of eye.

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NAWA is strung by twisted bundles of straw. The process of crafting NAWA is not well known generally. For this reason, the process involves a special skill at crafting NAWA with hands. The purpose of this study was to investigate the relationship between skill level and the physical characteristics of NAWA. Tensile test was carried out, and cross sectional photographs were obtained. Also, three-dimensional upper body kinematics data was collected. The resulting data show that the movement of arm related with strength and structure of NAWA.

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"Interval" which was recognized in Japan has not examined scientifically. In this study, "Interval" was related to short break of fingers motion in making "Kanaami". The purpose of this study was to examine "Interval" from the point of view of acceleration value in fingers motion. The duration of "Interval" defined as -0.9〜0.9m/sec^2. As a result, there was "Interval" in around 15〜40% time after main task started. According to this result, it was considered that there was "Interval" in the working time.

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There are several approaches for the jump mechanism of the robot. Compressed air and coiled spring are usually utilized for the power source of the jump robot. In this paper, we proposed the jump mechanism for the robot using the flat spring actuator system. This system can be applied to the smooth motion and the jump motion. The proposed mechanism was verified by computer simulations and experiments.

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This paper proposes SSM (Sensor Steering Mechanism) for lateral guided vehicle with rear wheel steer mechanism. Author demonstrated the geometry of SSM for the front wheel steer type and the reverse phase four-wheel steer type one. SSM presents a stable lateral guiding performance for automated vehicle which follows a straight and curved path created by guideway. The other hand, SSM is not established for a rear wheel steer type vehicle. Rear wheel steer vehicles are forklifts and backward moving of the conventional motor vehicles of which steering wheels are located at the front. SSM for the rear wheel steer vehicles enables a forklift to automated moving on every spaces, if the control method by SSM is established. This paper leads SSM relation for a rear wheel steer vehicle and constructs an experimental robotic vehicle with proposed SSM. Simulated and experimental data show the advantages of proposed SSM.

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The biped robot produces a problem of a rollover and home range reduction by external force and step and an obstacle. Presently, ASIMO has overcome this problem. But it is expensive, it is difficult to be moved by familiarly. The sensor and degree of freedom are added to robot for ROBO-ONE which it is easy to get. Judging with the sensor whether it gets over the obstacle, the biped walking robot enables to evade. When the robot rises at stairs, the range of the leg lifting which is necessary to step over is judged by oneself, the obstacle is passed by robot.

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This paper discusses controllability of three dimensional orientation of a freely rotating rigid body under conservation of angular momentum by means of changing the moment of inertia. The analysis model for rotating body consists of three pairs of particles symmetrically located around the center of mass. Analysis based on symbolic manipulation shows that the three dimensional attitude is locally reachable by moving one pair of particles along its coordinate axis. Numerical simulation shows that the reachable set under input limit is different from theoretical prediction.

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Recently, research has concentrated on pneumatic robot hand. Here, we develop a pneumatic actuator driven by low pressure. We develop a five-fingered robot hand by using the pneumatic actuator, and we construct a master-slave system to enable the robot hand to perform the same operations as a human hand. Next, a 1-link arm is made, which has one degree of freedom using the pneumatic actuators, and the models of actuator and 1-link arm is constructed. We construct a control system for the 1-link arm and verify its control performance.

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In recent years, the industrial articulated robot is asked for improvement in operating accuracy, and application to new work. Then, in this study, we aplly the hybrid position, posture, force and moment control proposed by us until now to the grinding work robot. Firstly, a hybrid position, posture, force and moment control with compensation of gravity and inertia using a computed torque method was proposed. Moreover, the effectiveness of the technique of this study was confirmed from the Analysis result of grinding work by using generalized mechanism analysis software.

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Multi-axis force/moment sensor can measure force and moment is helpful for robotic force control. But the smallest multi-axis force/moment sensor has oversized height and worsens the stability of tasks. So it is expected to develop thin type multi-axis force/moment sensor enables robot hand to grasp object as if it were human. Therefore, we aim to develop thin type four-axis force/moment sensor can be mounted to finger cushion direction in this study. We obtained sufficient sensitivities concerning each axial direction as a result of sensitivity evaluation being based on finite element analysis and characteristic test applied determined positions putting strain gauges.

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The physiological mechanism of coupling between neuronal activity, metabolism and cerebral blood flow (CBF) is not clarified enough. This study shows an analytical model and the governing equations of oxygen transport from arteriole to tissue, and added the adjusting function of CBF in response to the change in the oxygen partial pressure (pO_2). The authors have examined activity-dependent changes in pO_2 and CBF response in an arteriole by numerical simulation with the mathematical model. The results of changes in pO_2 in the arteriole depend on the location. CBF response changes with change in pO_2 in vessel wall.

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Meanings of signals measured by NIRS have many unclear points. In this study, we evaluate NIRS data based upon numerical simulation of oxygen transport to cerebral tissue. With a cylindrical coordinate system of oxygen transport from an arteriole to its surrounding tissue, we simulate the activity-dependent oxygenation changes. On the basis of calculated data, we derive quantities of two kinds of hemoglobin in the arteriole by using the oxygen dissociation curve, and theoretically decompose each hemoglobin change into its factors. As a result, we showed that the deoxy-Hb reply during nervous activity might relate closely with nervous activity.

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Vascular endothelial cells covering the inner surface of capillaries transport various macro molecules by movement of membrane pits called "caveolae". A recent paper indicates that there exists diaphragm around the neck of the caveolae. The purpose of this study is to clarify the influence of the diaphragm on vesicular transports. First, a system of nonlinear differential equations is derived according to the variational principle. Then the solution is given by shooting method. Next by using the 3-D model of the caveolae, CFD software PHOENICS solves equation of continuity and Navier-Stokes equation, and it provides blood flow over the caveolae with or without diaphragm.

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In recent years, NIRS has been widely utilized for monitoring oxygen metabolism of human brain. Though NIRS can measure two kinds of hemoglobin, only oxy-Hb has received attention as a criterion for judgment of a brain function. Therefore, implications of changes in deoxy-Hb have not been revealed enough and have to be investigated from a physical viewpoint. In this study, numerical simulation of oxygen transport to cerebral tissue is conducted to obtain transient hemoglobin changes with different blood flow rate to short stimulations. Our numerical results suggest that increase in deoxy-Hb during stimuli shows physiological signals coming from capillaries.

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In this study, a new sensor system is developed to detect compliance of cultured cells by using dynamic response of a piezoelectric vibrator. The sensor was integrally controlled by a micromanipulator system, while dimensions and morphologies of the cells were measured by an inverted phase contrast microscope system. Experimental studies have been carried out using normal human osteoblast. The studies have shown the sensor's capability to detect changes of mechanical properties of the cultured cells. Also, the method has shown the relationship between compliance and repolymerization time of the stress fiber.

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Neural stem cells have been studied to promote neurogenesis in regenerative therapy. It is important to investigate not only chemical factors but also mechanical factors such as hydrostatic pressure in. In this study, we investigated effects of mechanical vibration on cell proliferation and differentiation by in-vitro cell culture. It is shown that mechanical vibration promotes the proliferation and its cause is likely the suppression of apoptosis, and that the mechanical vibration at the experimental condition does not affect the differentiation of neural stem cells to nerve cells or glia cells.

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The healing of articular cartilage that possesses little capacity for self-repair after having been damaged is still a clinical problem. This paper describes the effects of vibration stimulation on chondrocytes in three-dimensional culture that imitates actual articular cartilage in relation to the production of regenerative cartilage tissue, using collagen gel and artificial skin as a carrier. The obtained results are that the mechanical vibration advances the matrix production and the proliferation of chondrocytes.

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In this study, a three-dimensional micro vibration stage is developed, in which a doubly steric L-shaped clamped-free beam type vibrator is utilized. The device has very simple structure and is quite easily sterilized, is extended to control system of cell culture. Experimental studies have been carried out by using normal human osteoblast. Dynamic stimulation is applied to the cell utilizing the device. In order to estimate effect of dynamic stimulation, we define parameters of projected area and slenderness ratio of the cell. The studies have shown that the cell has capability to detect dynamic stimulations and to change its own figure.

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The method for real time measurement of the dynamic stiffness in subcutaneous tissues was developed by the authors. The dynamic stiffness is estimated by using the self-excited vibration generated by the positive feedback of velocity. In this report, we show the response and the accuracy of frequency estimation are improved by using Kalman filter as an adaptive filter. And the internal damping of the apparatus measurement is reduced. As a result, the time-varying dynamic stiffness on human body by muscular contraction can be measured rapidly and stability. And the dynamic stiffness on parts of the human body are measured, their characteristics are compared.

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Reduction of seismic response of house is an important problem for aseismic design. In this paper, spherical damper, cylindrical damper and rectangular parallelepiped damper with silicon oil is developed for reduction of seismic response of two-story house. For reduction of seismic response of two-story house, an oil damper is connected to the ceiling of the first floor and the foundation. Resonance curves are obtained for various coefficient of kinematic viscosity of silicon oil. Peak responses in resonance curves are focused on. Damping ratio and peak amplitude ratio for the first vibration mode are obtained for various forms of damper. It is found that the peak responses are reduced when dampers are used.

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The vibrations such as earthquake and traffic vibration give us danger or unpleasantness. Vibration control devices have been developed to protect the structures from these vibrations, and some of these devices have been applied. However, the deflection of detached houses is small, and the performance of damper isn't obtained against small vibrations. In this study, the new type of damper which has displacement amplification mechanism has been developed to solve the above problem. This paper reports on the vibration control performance of damper which was examined by traffic vibration test.

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To suppress vibration on a long-span floor, caused by traffic and walking, Tuned Mass Damper (TMD) is usually set up. However, TMD can not adapt to vibration caused by an earthquake because of limitation of stroke of TMD. Therefore a new TMD that is adaptable to both traffic vibration and earthquake vibration is required. Then this paper aims at research and development of the vibration control device that adapts to tboth traffic and earthquake vibration. The vibration control performance for earthquake depends on the parameter of the buffer material. The displacement after impact is decreased by an increase of stiffness of buffer material. However, vibration control performance decreases because the impact force grows.

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Recently, isolation and vibration control technology have been attracted as technology that can reduce seismic damage. Especially, a vibration control device is more easy to install in an existing building compared with an isolation device. However, to spread it to the detached house widely, a further improvement on the economy and the performance is demanded. This paper focuses attention on a brace type damper that uses high damping rubber. The purpose of this paper is to develop the damper for detached house.

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This paper proposes a new method for utilization of variable damping in a vibration system. The coefficient of variable damping can be changed as that in the case of a sine wave, i.e. parametric excitation whose frequency can be arbitrarily selected. As a results of the parametric excitation, the vibration amplitude of the system increases because of the resonance at arbitrary frequency of the external input. We have confirmed the resonance of the damping parametric excitation by simulation and experiment. In this paper, we propose a method of frequency response analysis of the vibration system with the parametric excitation of damping coefficient and the external harmonic excitation. Finally, we consider about the SDOF vibration model with the external input that includes two frequency contents, and we propose a new vibration control method that the outputs interfere with each other by the parametric excitation.

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In the previous paper, a friction damper using two sets of V-shaped links, viscoelastic blocks and brake shoes, which has resisting force characteristic of hardening type and returning characteristic to the original position, is proposed. In this paper, the authors confirm that this hardening type friction damper is effective for suppressing the vibration of a single-degree-of-freedom system caused by long-period seismic ground motions as well as by common seismic ground motions. Numerical seismic response analyses were carried out for a single-degree-of-freedom system supported with the hardening type damper. The calculated results were compared with those for a viscous damper and a friction damper with constant friction force, and the effectiveness of the hardening type friction damper was confirmed. The validity of the calculations was substantiated experimentally.

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Colloidal damper is a dynamic damper which uses a principle difference of surface extensor force, which is occurred by the direction of movement of surface. Some characteristics of the colloidal damper was investigated by our group. So this paper presents a damping characteristics of colloidal damper for the amount ratio of silica gel and water, volume of cylinder and pre-pressure of the cylinder by changing exciting frequency and displacement of a piston. As the results it is known that optimum amount of ratio of silica gel and water exist for cross section of cylinder, damping characteristics increases as increase of pre-pressure of the cylinder and the optimum volume of the cylinder is exist for a given damping force or capacity.

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Dynamic performances of the rear suspension of a mountain bike (bicycle) equipped with colloidal damper are experimentally investigated. A novel design of the colloidal damper is proposed: colloid is introduced inside of a tank that is separated by a filter from the main cylinder in which a controlled quantity of water is supplied. A three degree of freedom vibration model is used to estimate the transfer function. All the components of the bicycle were weighted and all the mass elements introduced in the model were evaluated. After computation of the spring constants of all elastic elements, the values obtained were confirmed through impulse tests. Relation between the tire spring constant and the air pressure was found by compression tests. Method of the logarithmic decrement was used to evaluate the damping coefficient of the saddle. Actual suspension (compression helical spring mounted in parallel with an air damper) and the trial colloidal suspension were dynamically tested on a classical fatigue machine and the damping coefficient was determined. Then, during travel tests of the mountain bike on joy-steps and half-sinusoidal steps, the performances of the actual and colloidal rear suspensions were evaluated. Concretely, from vibrations measured on the frame and saddle, the ride-comfort factor and the transmissibility factor of vibrations from the rough pavement to the bicycle's frame were evaluated.

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Dynamic performances of the frontal suspension of an automobile equipped with colloidal dampers are experimentally investigated. A compact design of the colloidal damper, that provides also adequate durability, is achieved by introducing the colloid inside of a tank that is separated by a filter from the main cylinder in which only water is supplied. Three types of absorbers are considered: used oil damper (after 100,000km travel distance), unused oil damper (0km travel distance) and unused colloidal damper. First, all these absorbers were dynamically tested on a classical fatigue machine and the damping coefficient was determined. Then, they were mounted on the real suspension and travel tests of the automobile on joy-steps and half-sinusoidal steps were performed. From vibrations measured at suspension extremities and driver seat, ride-comfort factor and the transmissibility factor of vibrations from the rough pavement to the car's drive-shaft were evaluated.

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This paper deals with dynamic vibration absorber with silicone oil damper. Although silicone oil is used for torsional viscous damper, the dynamic properties of the silicone oil are unknown to be exact. Dynamic tests are conducted under condition of some temperatures, and the results are reduced to master curves of the dynamic properties. Next, the model for the dynamic properties is considered, frequency response analysis of the main system added the dynamic vibration absorber with silicone oil damper are represented. The maximum of the frequency response is control by the shape factor of the silicone oil damper, the natural frequency of the main system and mass ratio.

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Effect of base shape on damping characteristics of rocking of rigid body is presented. We pay attention to the fact that free vibration amplitude of rigid body decrease rapidly without dampers or damping materials. We consider rocking of rigid body is very attractive as a low cost dynamic vibration absorber. At first, damping characteristics of rocking of typical rigid body with flat base shape is discussed theoretically. Next, we propose new type rigid body which base shape is polygon in order to design damping characteristics of rigid body in wide range. Theoretical analysis method for damping characteristics of rigid body is derived. By calculating damping ratio of proposed rigid body using derived equations, it can be seen polygon base shape is very useful to design dynamic characteristics of rigid body.

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Recently, dynamic vibration absorber with viscoelastic material was studied. In the study, the given dynamic property of viscoelastic materials is described by fractional derivative model, and dynamic vibration absorber is optimized on the shape factor of the viscoelastic material. And good results are obtained within some region of natural frequency of the primary system. But, the analytical method taking account of frequency and temperature dependence of the viscoelastic material for the dynamic absorber is not proved experimentally. In this paper, the analytical method of dynamic vibration absorber with viscoelastic material is verified experimentally employing chloroprene rubber.

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Dynamic property of polyurethane foam is investigated experimentally. Polyurethane foam is loaded periodically with various amplitudes and various frequencies, and load, deflection and velocity of the polyurethane foam are measured. Using non-parametric identification technique in time domain, dynamic property of polyurethane foam is modelized as a function of velocity and deflection of polyurethane foam. Experiments are conducted with various condition of size of test piece and mount of compression, the dependence of the dynamic property on these parameters is investigated.

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An identification method of vibrational damping parameters for roll core materials of sandwich panels is presented by using the finite element eigenvalue analysis. The vibrational damping model proposed by Adams et al. is used to calculate damping ratios for identification problems. The identification problem of vibrational damping parameters can be converged as a nonlinear optimization problem. Vibrational damping parameters are identified by using the quasi-Newton method, so that damping ratios calculated by the finite element analysis may be agree with those measured by the vibration test. As numerical examples, equivalent vibrational damping parameters of roll core sandwich panels are identified and compared with the experimental results.

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This research is concerned with the development of new method of acoustic transmission loss (TL) of panels. The conventional TL estimation method needs a big facility which includes a pair of acoustic reverberation rooms. This method has some problems as follows; (1) These kind of experimental facility is very rare so one cannot keep enough time for experiments. (2) Panel size is limited. (3) Measured results are affected by the panel size, panel setting method, so on. (4) The conditions under which panels are used are different from the conditions in the experiments and this difference sometimes makes large discrepancies. Considering these subjects, the new method are studied which does not need the acoustic rooms and reflect the conditions under which panels are used. This method uses the experimental modal analysis which needs the impact hammering data. At first, theoretical research was executed based on statistical vibration analysis with the modeling of acoustic defuse field. Numerical studies were done and results of this method showed nice coincidence with the conventional method based on the plane wave modeling of acoustic field. In the next step, experimental validation was conducted; proposed method was applied to the simply supported aluminum panel. In the frequency range below 1KHz, the results showed good coincidence with the data on the literature. Based on these results it was achieved that the proposed method is accurate and practical.

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In this paper the authors proposed a new type of vibration control device that has variable inertial mechanism using half toroidal wheels, in order to get a function of vibration cut-off when vibration frequency equals to anti resonance frequency of inertial mass. The device consists of a piston cylinder, a ball screw, a ball nut, bearings, variable inertial force mechanism composed of half toroidal wheels and power transmission wheels. The device has a small inertial force when the power transmission is located in small ratio of contact radius between two half toroidal wheels by a servo motor, and a large inertial force in case of large ratio of contact radius, so the controlled inertial force can be derived continuously. Test device is made, and the resisting force characteristics are measured by using a shaking actuator. Next, simulations of frequency responses and seismic responses using a one-degree-of-freedom system with the device under proportional controlled are carried out. The effects of vibration suppression are confirmed numerically.

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This paper describes vibration analysis using finite element method for elastic block connected by nonlinear concentrated springs with nonlinear hysterisis. The restoring force of the spring has cubic nonlinearity and nonlinear hysterisis damping. Finite element for the nonlinear spring having complex coefficients is expressed and is connected to the elastic block modeled by linear solid finite elements in consideration of complex modulus of elasticity. Further, the discredited equations in physical coordinate are transformed into the nonlinear ordinary coupled equations using normal coordinate corresponding to linear natural modes. This transformation yields computation efficiency.

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The purpose of this work is to identify the characteristics of a nonlinear vibration system subjected to a random input. In a general, a statistical technique of a higher order spectra (HOS) could be used for non-gaussian data analysis. Here, exiperimental model (Magnetic model) analysis was executed for an asymmetrical and symmetrical nonlinear vibration system, and showed nonlinear mappinng.

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In this report, a new magnetic damper based on Lent's law is introduced. This magnetic damper is different from a magnetic damper based on Lorentz force. It utilizes magnetic attractive force or repulsive force caused by eddy-currents induced on the conducting plate. First, the principle of the new magnetic damper is described, and then the experimental setup to demonstrate the principle is fabricated and tested. The experimental setup, next, is modeled in detail and magnetic damping forces are calculated. As the result, the analytical results agree well with the experimental results.

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Pattern formation phenomena often occur in contact rotating systems. A prevention method using dynamic absorbers was suggested and a design method of the effective dynamic absorbers was formulated in the previous reports. The dynamic absorbers are individually designed one by one for each mode. However, before and after the dynamic absorbers are installed, the relativity between unstable vibrations can not be clarified exactly. In order to overcome this difficulty, the authors introduce a method using complex eigenvectors at minimum points, which means regions where unstable vibrations may occur. The effectiveness of the present method is verified from the results of numerical computations for a 5-DOF system as an example.

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This work deals analytically and experimentally with the stability chart of the regenerative chatter vibration in end milling process. Dynamic milling model was considered to have two orthogonal degrees of freedom. By solving the eigenvalue problem of this model, we investigate stability of this dynamic milling system. As a result the agreement between the analytical and experimental results on the stability chart in up cut milling and down cut milling was confirmed. Furthermore, we investigate the effect of the vibration characteristics of tool and the instantaneous angular immersion of tool on stability chart.

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This paper deals with a countermeasure against pattern formation phenomena of roll covering-rubber. The pattern formation phenomena sometimes occur in paper making machines, winder systems of elastic yarn and thin sheet winders. In these systems, the pattern formation phenomena are mainly caused by the viscoelastic characteristics of the roll covering rubber, the elastic yarn and the thin sheet. These pattern formation phenomena lead to a fatal damage on products. The authors conducted experiment to clarify the suppressive effect of the damping, the variation of rotating speed and the dynamic absorber on the pattern formation. It was found that the pattern formation phenomena were suppressed by these three countermeasures.

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This paper deals with the experimental result of polygonal deformation phenomena in contact rotating system. Using an experimental device on the model of hot leveler of the steel making machine, growth process of the polygonal deformation was observed in the driving upper roll by laser displacement meter. The experimental result was compared with analysis, and the countermeasure by dynamic absorbers was examined.

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