Vibration analysis of the viscoelastic damped sandwich disk is studied. Analytical results are as follows. (1) Analytical method of natural frequency coupled with loss factor for the sandwich disk is presented. (2) Loss factor of the sandwich disk is the function of parameters which arc elasticity, damping and thickness of the viscoelastic layer. And, maximum loss factor is obtained using suitable value of these parameters. (3) Natural frequencies coupled with loss factor are higher than the case of without loss factor. Especially, this tendency is remarkable at maximum loss factor.
This paper deals with evaluation of nonlinear vibration specific characteristic of a continuous body with a gap under stationary random input waves by experiments. The experimental model is a fixed beam with both ends which has mass on the center and a thin plate fixed with both ends with a gap between the mass and the plate. It was found that the form of a transfer function when the mass is colliding with the plate is the form with one large peak. If the collision is begun, the dominant frequency become larger than the eigen-frequency. Furthermore if the input acceleration becomes large, the dominant frequency changes to the larger one. If the collision is begun, equivalent damping ratio becomes large. When the input acceleration becomes large, the equivalent damping ratio becomes large and becomes to vary around a constant value. The probability density for peak magnitude of displacement (PDPMD) is expressed as the Rayleigh distribution, when not colliding. It was found that PDPMD is expressed in a sum of the Rayleigh distribution and the normal distribution approximately, when colliding.
In order to analyze the vibration of a structure whose elements are connected with bolts, it is necessary to estimate the flexural rigidity of the bolted connections. One of the authors has proposed a calculation method for obtaining the flexural rigidity of bolted annular flange connections. For verification of the calculation method, bending tests have been performed. This paper deals with the resonant frequencies of some models for verification of the calculation method. FEM analysis, considering the flexural rigidity, and vibration tests are performed. Calculated resonant frequencies are in fairly good agreement with experimental ones.
A CFRP sandwich composite beam containing electro-rheological (ER) fluids as a variable damper is prepared. The vibration strain responses of the composite beam supported under the cantilevered condition are measured by an Extrinsic Fabry Perot Interferometric (EFPI) optical fiber strain sensor. The experiment is conducted under external sinusoidal excitations. The timing of a sinusoidal electric field supplied to the ER fluids is adjusted by observing vibration strain responses with the EFPI optical fiber strain sensor. It is shown that damping properties of CFRP laminates are changed by controlling phase differences of the sinusoidal electric field from the strain response of the composite beam. The sinusoidal electric field having phase lead difference of 90° from the vibration response is most effective for suppressing the vibration of the composite beam. These experimental results are also explained by using a simplified equation of motion for the composite beam with a variable damping factor considering the strain dependency of ER fluids.
We propose to apply cubic curves to express damping force characteristics of dampers using electrorheological (ER) fluid having apparent viscosity that can be modified by an electric field. The cubic curves can express damping forces decreasing with increasing in the piston speed of the damper. In conventional dampers, their damping forces usually increase with increasing in its piston speed. In this paper, we obtained the cubic curves minimizing the maximum acceleration of the mass of a vehicle model with ER dampers using an optimization method.
This paper treats nonlinear control of a hydraulic servo system to suppress micro stick-slip vibrations. The system consists of a hydraulic cylinder, a servo-valve and a personal computer. Self-excited vibrations of two different types occur in the conventional feedback control system. Discontinuous control signal generated through a D/A converter causes a stick-slip vibration of micron order over the wide range of the feedback gain. Increasing the feedback gain results in the other type of stick-slip vibration of nearly ten times larger amplitude due to the locally increased flow gain in the underlap region of the servo-valve. The feedback linearization technique is applied to compensate the nonlinearity of the valve. Numerical simulation and experiment were performed for both the present nonlinear control system and the ordinary linear control system to confirm the validity of the former one in suppressing the micro stick-slip vibration. The other type of micro stick-slip vibration due to the D/A converter was effectively suppressed by improving the resolution of the input signal.
The difficulty in controlling a distributed-parameter structure lies in the infinite number of structural modes, causing spillover destabilization of the control system. This paper proposes an active vibration control method for such a structure using cluster control. It is the purpose here to propose a novel active vibration methodology called cluster control, which makes it possible to suppress all vibration modes of the cluster of interest. First, it is mathematically verified that every eigenfunction of a planar structure can be expressed in terms of modal indices (m, n), thereby dubbed as the (m, n) modes. Then, a cluster filtering method is introduced, whereby all eigenfunctions are clustered into a finite number of groups, each member of a group having common characteristics. By verifying the reciprocity between sensing and actuation of a structure, the cluster actuation method is then introduced, enabling excitation of the eigenfunctions of a targeted cluster. Moreover the cluster control method consisting of both cluster filtering and actuation is presented, allowing suppression of all structural modes of the targeted cluster without causing instability of the control system. Finally, an experiment demonstrates the validity of the method for suppressing all vibration modes of a cluster.
This paper considers the newly proposed cluster control of a distributed-parameter structure, which falls into a category of MAC (Middle Authority Control) in-between conventionally used LAC and HAC, thereby it possessing both the benefits of simple control structure by LAC and high control performance by HAC. First, from a viewpoint of feedback control, this paper clarifies the structure of a cluster control system, showing that it is possible to control a cluster independently without causing any influence onto other clusters. Experimental results show that cluster control is performed with sufficient control effect for suppressing targeted cluster of a distributed-parameter structure. With the aim of suppressing all structural modes of a structure, equivalent to suppressing all clusters, a design procedure for the cluster control system is proposed. Comparing with DVFB (Direct Velocity Feedback) widely used for active control of distributed-parameter structure, DVFB is found to be a special case of the cluster control.
In order to reduce the longitudinal vibration of a pipe string for mining manganese nodules from deep sea floors, the pipe string was assumed to be supported by a linear or nonlinear spring at its upper part. The analyses of the longitudinal vibration and stress produced in the pipe string show that the linear-spring support itself tends to increase the resonance frequency of the pipe string as well as the resonance amplitude of buffer at the lower end of the string, while reducing the maximum axial stress of the pipe in case of the small spring constant. The hard-spring support strengthens this tendency and the soft-spring support tends to act reversely.
Antagonized bellows damper filled with an electrorheological (ER) suspension containing sulfonated polymer particles in silicone oil, has been developed, which consists of two metal bellows and an ER valve with several cylindrical electrodes. The damping characteristics and the vibration isolation control have been investigated experimentally and numerically. It was confirmed by experiments that the ER damper under constant applied voltage behaved like a coulomb friction damper, and the active damper could be constructed, by electrically varying the friction like forces proportional to the damper speed, to be a viscous damper with electrically controlable damping proportinal to the feedback gain. Two control strategies were applied to a single-degree-of-freedom vibration isolation system consisting of a mass, a spring, and the ER damper. A proposed new conceptual nonlinear feedback control strategy using the ER active damper was found to be most effective to reduce the vibration transmissibility of the system, and to lead the vibration isolation results almost similar to that of a full active vibration control case using an actuator. These experimental results of vibration isolation performances have been simulated very well by a numerical analysis based on a proposed analytical model of the ER damper.
Equations of motion for multi-layer piezoelectric cylindrical shells and the equations of integrated piezoelectric sensors are derived. The state equation is obtained by solving the equations of motion with modal expansion method. The feedback control method, feedforward control method, and their combination as a hybrid control method are applied in the control of forced vibration of the piezoelectric cylindrical shell with integrated sensors and actuators. The simulation and experimental results show that good control effectiveness can be obtained by using the integrated piezoelectric sensors and actuators in conjunction with the hybrid control method.
We experienced much damage to travelling type cranes in the 1995 Hyogoken-Nanbu earthquakes such as derailment, bending failure of legs and collapse by the rocking motion. This paper presents a method of evaluating the strength of the structural part of the travelling crane against earthquakes taking the rocking motion into consideration. Formulas proposed for the evaluation are derived from a study of the behavior of a simple model based on its deformation and response periods of the rocking motion of the rigid body. Numerical calculation results from these formulas are found to coincide satisfactorily with that from a nonlinear transient response by FEM analysis.
This report deals with the experimental and analytical study of seismic response behavior of piping systems in industrial facilities such as petro-chemical, oil refinery and nuclear power plants. Piping is generally put on the supporting structures. Therefore, frictional vibration occurs between piping and supporting system during seismic excitation. Special attention is focused on this nonlinear frictional dynamic responses of piping systems due to frictional vibration appearing among piping and supporting devices. Two mock-up piping structure models are excited by large scale shaking table. FEM models are made from the mock-up piping of shaking test, and modal parameters of linear system are calculated. The time history responses are calculated by nonlinear response analysis using calculated modal parameters. Friction response spectrum are proposed to calculate the maximum responses having frictional behavior. The maximum responses calculated by friction response spectrum are compared with the maximum responses obtained by experiment.
The anisotropic property of Fiber Reinforced Plastics (FRP) greatly influences the vibration characteristics. In this paper, a natural frequency of FRP considered its anisotropic property by the rule of mixture is calculated by using the real eigenvalue analysis of the FEM model. It is assumed that the dissipation model of vibration energy is presented by the mass-spring model. This model expresses shear springs of fiber and matrix resin which connect in series. The spring coefficients are identified by the sensitivity analysis. In this analysis, the elastic modulus of matrix resin is chosen as the design parameter. Then matrix resin is viscoelastic, the shear spring is presented by km(1 + iηm). Therefore, the loss factor of FRP is calculated by dividing imaginary part of the total shear spring coefficient by real one. This method is sufficiently reliable to predict the vibration characteristics of FRP.
The purpose of this paper is to decompose a global stiffness matrix with overlapping matrices on finite element method. Generally a efficiency of computational on finite element method depend upon solving of the global stiffness equation. If the global stiffness matrix is composed to band matrix, we can regard it as interconnected matrices composed of overlapping matrices. The decomposed algorithm is to removed interconnected element in overlapping matrices. Thus the global stiffness equation can decompose decoupled linear algebraic equation with low order. The decomposed equations are independently each other the reduced order equations can be solved by using parallel processing. In order to demonstrate the effectiveness of the proposed algorithm, a brief example is shown.
The purpose of this paper is to solve a class of a global stiffness equations for Finite-Element Method (FEM). Recursive algorithm is derived that the global stiffness equation is decomposed to decoupled linear algebraic equations with low order. Solutions are constructed by sum of a zero-order solution and an error solution. The solution can be approximated to exact solution with an error solution by repeating calculation of reduced-order error equation. For structural analysis of FEM, there exist difficult cases for calculating by a computational error since the global stiffness matrix contains elements of different order. By using recursive approach, however, it can be solved the global stiffness equation to avoid the computational error. Since the decomposed equation are independently each other the reduced-order equation can be solved by using parallel processing. In order to demonstrate the effectiveness of the recursive approach, a simple numerical example will be shown. The results show that the recursive approach converge with the rate of convergence of accuracy O(ε).
Hydrostatic transmission technologies applied to a variety of modern power control systems such as in industrial and marine machinery and mobiles should not be aimed at productivity only but increased human and environmental friendliness also. Vibration of hydraulic piston pumps excited by delivery pressure pulsation has raised acute noise problems. For clarification of mechanism of pulsation generation, the delivery flow fluctuation of a pump combined with the dynamic response of a delivery circuit consisting of arbitrary elements including pipes and chokes is analyzed in this work. The motion equations expressing the pump-and fluid-structure systems are formulated. The results of numerical dynamic response analyses performed using the Newmark-β method agree satisfactorily with the experimental results. Moreover, the influence of a filtering circuit on the reduction of the delivery flow fluctuation is clarified. It is confirmed that the circuit markedly reduces the dynamic response of the pump.
This paper is concerned with the estimation of the ODSs (Operating Deflection Shapes) of a system with unsteady state. It is usually difficult to identify the ODSs, because the responses under operating condition are not always in steady state. Therefore, the adaptive identification scheme of the ODSs for non-stationary signal has several needs. This paper present a new type of subspace method which can identify well-excited frequencies and the ODSs corresponding to those frequencies. In order to prove the adaptability of this scheme for time-varying signals, we demonstrate its performance on artificially generated responses. Then we use the responses of an actual structure and show the effectiveness of this scheme with real data. These results are in good agreement with analytical ones and lead us to believe that the proposed scheme can be successfully used for the identification of time-varying signals.
This paper discusses control of a crane mounted on a tower-like flexible structure. Although a fast transfer of the load suspended from the edge of the boom of the crane causes not only the sway of the load itself but also the vibration of the flexible structure, the objective of this study is to control both the sway of the load and the vibration of the flexible structure by the up-and down positioning control torque to the boom. At first a mathematical model for the experimental model of the tower crane and a reduced order model for a controller design are introduced. Next, we design an H∞ compensator for the reduced order model so that the compensator simultaneously controls the position of the boom, the sway of the load and the vibration of the flexible structure, and suppresses the spillover phenomenon due to the model reduction. By simulations and experiments it is verified that the designed compensator has superior vibration control performances to those the conventional angular velocity control for the boom has.
The jerk (the time rate of change of acceleration) is one of the most important kinds of bodily sensitive information. In driving situation, when a vehicle accelerates or decelerates rapidly, skilled drivers can adaptively control the vehicle by perceiving wheel spin or wheel lock from subtle vehicle jerk information, rather than from wheel-speed information. This suggests that the performance of vehicle motion control systems, including the extent of "natural" feeling for drivers, can be improved by enabling the systems to detect jerk and/or acceleration information, and emulate responses of a skilled driver. We have developed a sensor for deriving the values of both acceleration and jerk by using the law of electromagnetic induction. This sensor performs well and has several potential applications. This paper introduces the principle and performance of jerk sensor, and also proposes other possibility of motion control systems using jerk information.
This paper presents a new design method of servo control system based on resonance/antiresonance characteristics. The system frequency characteristics at resonance/antiresonance frequency are derived and used to analyze the system dynamic behavior, and the relationship between the gain characteristic at the antiresonance frequency and the disturbance rejection characteristic is also discussed. By frequency shaping design, a simple design principle is presented. It is shown that the proposed design method has advantages of clear high-frequency characteristic and better disturbance rejection over the traditional design method based on stiffness model. The validity of the proposed method is also examined by experiments on a flexible joint arm.
This paper deals with the design of a deadbeat servo system for a single-input, single-output linear digital system. The optimal deadbeat servo system with the output feedback in the z-domain is induced from the fixed endpoint optimal servo system in the time-domain. This servo system has a finite-time settling property (deadbeat property) and a ripple-free property, and the transient responses are improved over those of the minimum-time deadbeat control. Furthermore, by using the two-degrees-of-freedom configuration, more robust parameterizations are provided for the optimal deadbeat servo system.
In this paper, we propose a design scheme with δ-operator of the direct-method model reference adaptive control systems(MRACS) for the pneumatic servo system. In this design scheme, the discrete-time model of the plant is described using δ-operator and the sampling-time is chosen very small. The direct-method MRACS is constructed for the minimumphase model of the plant which is gained by neglecting the small coefficients of the above mentioned discrete-time model. The effectiveness of this design scheme is confirmed by the experiment using the existent pneumatic servo system.
This paper deals with a design method of decentralized PID control systems based on parameter tuning using partial model matching on frequency domain. Stability of the control system is also considered. It is shown that the diagonal dominance, which is necessary to realize a stable decentralized control system, can be relaxed by introducing a parallel feedforward compensator even if the plant has an unmodelled dynamics. Effectiveness of the method is confirmed through the numerical simulation.
In this study, we propose two methods for the sensorless positioning control of a robot arm. First, we propose using adaptive observer directly in order to estimate the state of the system. Adaptive observer is a state estimator which contains the parameter identification in addition to the state estimation. This method is applicable to the robot arm with direct drive system. In the actual system, the nonlinear characteristics often exists at the drive system because of the speed reducer. However it is very difficult to design adaptive observer in consideration of the nonlinear characteristics. Then, secondly, we propose identifying the parameter using adaptive identifier and estimating the state of the system using sliding mode observer. This method is useful for the robot arm which contains the nonlinear characteristics at the drive system. In two methods mentioned above, sliding mode controller is used, Moreover, concerning the second method, we proved the usefulness by experiments.
This paper is concerned with the positioning control of single link flexible arm using sliding mode control theory. We designed for the control system using output feedback method. But the high gain sliding mode controller often causes the control system unstable based on spillover phenomena in higher frequency region. Therefore, we also design for the switching hyperplane using H∞ control theory. But H∞ controller has a problem which is a big overshoot. Then we apply to Q parametrization which has a performance of H∞ controller. In a word, nominal controller is the H∞ controller. Q parametrization can satisfy some constraints, for example norm, overshoot, settling time and so on. Q controller has a good performance. However, it becomes a high-order compensator. In this study, it becomes from 6th to 25th-order.
Tuning of the control parameters of a fuzzy controller depends on trial and error. How this can be accomplished efficiently is an important subject that should be investigated in fuzzy control. We propose a method in which the membership functions of a fuzzy controller can be simply set up by utilizing the knowledge of tuning parameters in a conventional PID controller. In this method, fuzzy control is realized as follows: the piecewise linear membership functions that are determined from the knowledge of tuning parameters in a PID controller are set up in the antecedent parts of the four fuzzy control rules of a simple structure. Then, the simplified inference method that enables high-speed inference is applied to the fuzzy control rules.
In the robust motor control system which consists of a conventional servo amplifier or a disturbance observer, the motion of the motor has a robust anti-interference controlling function against the disturbances. When this kind of robust anti-interference servo system is used to drive the load, the reactive force of the load is treated as a disturbance. The motor resists the disturbance and will revolve continuously, thus the robust motor system will easily generate a vibration of load. In this research, we have studied a driving method that reduces the reactive force of load by identifying the reactive force of load. By reducing the driving reactive force generated when the motor drives, the system degrades the rapid acceleration and deceleration and thus the vibration of the load is decreased. As a result of this driving method, a gentle drive of the mechanical system can be achieved.
This paper presents an algorithm for estimating the 3-D position of objects from monocular gray images. This algorithm has an advantageous property that needs no point-to-point correspondences. There are four steps in the algorithm. At the first, the 3-D shapes of object before and after rotation motion are recovered from image brightnesses. Then, moments of various order of the shape of the object are computed. Two vectors that are transformed according to rotation matrix under 3 D rotation, are constructed for the shape of the object before and after the rotation motion, respectively. At the third step, the rotation matrix is estimated using these vectors with SVD (Singular Value Decomposition). At the last, the rotation axis and the rotation angles are computed from the rotation matrix.
Generally, in the self-localization method based on positions of landmarks, it is necessary for robots to manage the maps of the landmarks. In multiple robot systems, it is, however, difficult to keep the consistency among all the maps carried by the robots when the maps are updated frequently and dynamically. In this paper, we introduce Intelligent Data Carriers (IDCs) to realize map-free self-localization in multiple robot systems. The IDC is a portable data management device developed at RIKEN. By putting an IDC in the work area and storing its own position data in itself, robots can acquire the position of the IDC using local communication without refering to any maps. Detalied procedures to acquire and integrate various information are presented. The efficiency of the proposed method are discussed based on the results of the experiments. It is confirmed that this method is available for the robot to localize its own position in multiple robot environment.
ODV9 is a newly designed nonholonomic omni-directional vehicle. ODV9 is proposed for an indoor mobile platform. An indoor mobile platform is required to move in narrow spaces freely and to travel bumpy road surfaces in some measure. ODV9 has four wheel modules, with each wheel module incorporating one motor, one brake, and one wheel. The coupling of steering and driving, that results in errors and tire slippage, does not occur ODV9 intrinsically because each wheel module has only one motor. Compared with other ODVs, the advantages of ODV9 are not limited to the simplicity of its mechanism. Benefiting from using a normal type wheel equipped with a tire, ODV9 is capable of moving in various environments. In this paper the mechanism and the various running modes of ODV9 are discussed, and some experimental results are shown.
In order to detect human characteristics of avoidance motion and construct avoidance motion algorithm, we conducted two experiments. In these experiments, passing behavior was employed as avoidance motion. In the first experiment, we recorded human passing behaviors using VTR on the road under natural settings. The analysis of the VTR recordings revealed that human avoidance motions in passing were categorized as three types. In the second experiment, we conducted human passing experiments in the laboratory. Subjects passed an experimenter who is stood, walked, and ran with short steps. The results of these experiments indicated that human avoidance motion has mainly following two characteristics: (1)the locus agrees well with the catenary, and (2)the walking velocity is costant in passing. The avoidance motion algorithm was constructed based on these characteristics. We will apply these characteristics and the algorithm in the field of mechatronics and robotics, especially to the avoidance motion of a mobile robot.
This paper aims to give an analytical view on what kind of inter-robot communication to use for cooperation in distributed mobile robotic systems. The efficiency of local and global communication is compared based on the analysis of information transmission time to multiple robots. Using local communication, the information about a specific task is diffused between robots gradually. We analyze this diffusion and derive the transmission time required for necessary robots to obtain the information. Global communication by time-division access is also analyzed to compare the transmission time. The analysis concludes that local communication is more effective than global one in environments where cooperative tasks are executed by multiple mobile robots in a distributed manner.
Optical novelty filter based on the two-wave mixing in a photorefractive BaTiO3 crystal is applied to motion detection for the purpose of its application to the robot vision. A simple method is proposed to realize the reflex vision system that a human being possesses. Our method uses a photo detector array to detect the output from the optical novelty filter and the detector element that obtains the highest signal is selected. By simulations using a simple animations, it is showed that the larger or the faster object can be detected in higher probability. Tracking a moving object is demonstrated with a 2×2 photo-transistor array and the selective circuit including the exclusive gate circuit.
A wide angie high distortion lens system has been developed to realize a foveated visual information optically. The lens system has several advantages in the application of the central vision and the peripheral vision, and it enables multi-purpose use based on the image from a single camera. This paper introduces a new concept of Virtual Cylindrical Screen to detect objects in the front scene, and proposes a method of monocular motion vision, based on the optical flow between the sequential images, to detect stationary objects existing inside the Virtual Cylindrical Screen. For a moving robot it is important to recognize quickly the object in the front. The comparisons between the special lens system and a pinhole camera are carried out with respect to the characteristics of the proposed method. The basic experimental results also prove that the proposed method is effective.
This paper deals with the development of a new method for detecting the number of cloth. It is necessary to detect one or plural number of sheets to avoid mishandling. This detecting sensor utilizes the variation of the phase of transfer function within entire acoustic system. The impedance of sheets varies with the number of sheets. Characteristic acoustic impedance and complex wave number define the material peculiar and the most fundamental characteristic. It is useful for the detection of the number of cloth to know characteristic impedance of cloth. So that, we tried to measure characteristic impedance and wave number. The measured impedance of sheets by transfer function method was introduced into theoretical analysis. The results of experiments and theoretical analysis show fairly good coincidence.
Measurement of unsteady or pulsating flowrate in hydraulic pipelines is very important. In general, an air chamber is inserted to a pipeline as an accumulator in order to reduce the pulsation of flow. In this paper, we proposed a new method for the measurement of unsteady flowrate in a pipeline using the change in pneumatic pressure and temperature in the air chamber. In this method, it was assumed that the temperature was determined by change of state and heat transfer. Because the measurement of the chamber temperature is difficult, we estimate the temperature by numerically solving the heat transfer equation. In order to evaluate the method, a simple experimental model was employed, and measured flowrate profile was compared to the estimated one. Good agreement was achieved between the measured and estimated flowrates, and then the validity of this method was demonstrated.
A robot has its original error of link length and angular offsets. Consequently, it has low adsolute positioning accuracy, although the robot has good repeatability. For this reason, calibration of manipulator is required. This paper proposes the calibration method using information obtained through a vision sensor, which is installed on the hand. First, the robot makes a series of movements with a vision sensor. Next, the sensor projects laser into an onject and takes an image at each position, and then 3D position of the spot on the sensor coordinates is obtained. Finally, parameters are calibrated using error of 3D position by the Newton method. Additionally, this paper shows the calibration results by the proposed method.
This paper describes a new method for KANSEI-based satisfactory design of artifacts. Taking subjective evaluation for handling and stability of vehicle as a typical example, each process is explained as follows: (1) Numerous valuables are measured through driving tests of various vehicles. A part of those are vehicle responses. The subjective evaluation for three items is performed by professional evaluators. (2) The multi-dimensional and nonlinear relations among KANSEI values, i.e. the subjective scores, and measurable vehicle responses, are implicitly formulated within a multilayer neural network. (3) Some vehicle responses which are most sensitive as well as most strongly correlated to each KANSEI value are selected among all vehicle responses by means of a sensitivity analysis using the well trained network in step (2), and linear correlation factors among each KANSEI value and each vehicle response. (4) The multi dimensional relation among each subjective score and its corresponding selected items are then implicitly formulated within a smaller size neural network. (5) Using the well trained network in step (4) together with whole area search method, we can easily draw a multi-dimensional design window (DW). An actual model of the DW is also manufactured by a rapid prototyping technique. Such an actual model of the DW in KANSEI-based design of artifacts may strongly support collaborative design environments through KANSEI information among designers.
The present paper examines the optimal laminate configuration to maximize the flutter boundary for simply-supported symmetrically laminated plates with bending-twisting coupling. The Rayleigh-Ritz method is used to solve the natural vibration, and modal analysis using several lowest natural modes is applied to obtain the supersonic panel flutter boundary. First, the flutter characteristics are clarified with use of lamination parameters. Next, the optimal laminate configuration to maximize the flutter boundary is obtained using mathematical programming method where the lamination parameters are adopted as intermediate design variables.
Economic feasibility of cogeneration systems with a fuel cell is investigated in consideration of its failures. An optimal unit sizing method is extended to this case so that it enables to consider probability of the failures. Equipment capacities and maximum contract demands of utilities are determined so as to minimize an expectation value of the annual total cost by taking account of the system's operational strategy to satisfy hourly changing energy demands even if fuel cell's failures happen. Parametric studies are carried out to investigate the influence on economy of the length of down time due to the failures, the repair cost of the fuel cell or annual average frequency of failures. Through the studies, it is found that the failures of the fuel cell greatly influence system's economy, and that the aforementioned parameters greatly change equipment capacities and economy of the fuel cell cogeneration system.
This study investigates a computer support system applying functional modeling techniques for the conceptual design phase of engineering systems. This paper describes a systematic representation of design information, where a design is represented by the four models of goal, function-goal, function-structure, and structure in a systematic and organized form. A graphical interface system is developed to support the efficient representation of the design information. The design information of a waste process plant is expressed to demonstrate the representation capability of the design models.
This paper deals with the temperature dependency of the photovoltaic effect in PLZT element which plays an important role of the characteristics of the optical actuator using PLZT element. Firstly, it is shown by the experiment that the photovoltaic effect is greatly affected by the temperature of the PLZT element. Then, it is clarified that its temperature dependency ascribes to the reduction of the electric resistance in PLZT element with the increase of the temperature. Finally, the validity of the simulation of the photovoltaic effect including the temperature dependency is shown by the experiment.
A wear resisting steel was developed in the expectation that it may supersede high phosphorus gray cast iron for improving the strength of sliding elements of a marine diesel engine. In order to investigate the influence of the surface hardness and the surface modification treatment on the scuffing capacity of the wear resisting steel, the two cylinder test was carried out under oil lubrication. The test rollers had two kinds of hardnesses; one was 860 HV for bearings, and the other was 370 HV for sliding materials of cylinders. The electroless Ni-P alloy plating and sulfurizing treatments were employed. The scuffing capacity of the wear resisting steel was larger than that of the high chromium bearing steel SUJ 2. The scuffing capacity of the harder wear resisting steel was smaller than that of the softer one. The electroless Ni-P plating treatment slightly increased the scuffing capacity, while the sulfurizing treatment had no effect on the scuffing capacity of the wear resisting steel.
The optimum design on hydrostatic spherical bearings in fluid film lubrication is studied theoretically. The analytical solutions for load-carrying capacity, recess pressure, flow rate, frictional torque, power loss and stiffness are derived for both the fitted and clearance type bearings with a capillary or an orifice restrictor. Their power loss and stiffness as a function of the equivalent radius of loads and the size of restrictors are illustrated. The optimum size of their restrictors is obtained. The effects of the seat angles, clearance-ratio and operating conditions on the bearing characteristics and the optimum size based on the minimum power loss are clarified.
Feeding under-cutting of Lorentz wheel cutting method of Hindley hourglass worm gearing is analyzed at first. And the shape of the wheel tooth surface is made clear by the analysis and the measuring method of the wheel by 3-dimensional coordinate measuring machine is proposed. Statical and dynamical tooth contact are analyzed to control the accuracy of manufacturing a pair of Hindley hourglass worm gearing.
A method using the finite element simulation for determining coiling conditions of intermediate plates in a coilbox installed between roughing and finishing stands of hot strip rolling is proposed. The coilbox has the function of preventing the drop in temperature due to the radiation from the surface of the plate in the waiting between the roughing and finishing stands, because the surface area is considerably reduced by coiling the plate. In the present method, non-steady-state deformation of the plate in the coilbox is simulated by the finite element method, and the rolls are appropriately moved in accordance with the simulated results to bend the plate circular. Since the formation of the coil is influenced by the formed shape near the front end of the plate, the deformation behavior near the front end is monitored during the finite element simulation, and the positions of the rolls for coiling the plate are determined from the monitored shape. In addition, the coiling of plates becomes stable due to the control of the rotation of the roll for forming the front end.
Precision truing and dressing techniques using an electrophoretic phenomenon was newly developed for spherical diamond wheels with fine grains. Truing was carried out by rolling loose abrasives within a contact surface between the wheel and anode, that was reversely preformed against the spherical shape. Also, soft dressing was carried out by bringing the wheel into contact with a gelled film on the anode. An electrophoretic phenomenon was employed to generate a gelled film on the anode by attracting loose abrasives and high-molecular weight electrolyte in the polishing fluid. The truing test clearly indicated that both surface roughness and sphericity of under 1 μm could be achieved within 5 minutes, in the case where surface roughness of under 5 μm was preliminarily created by pretruing using a metal bonded wheel. It was also established by the dressing test that the gelled film on the anode behaved like a soft polisher, so that a sufficient chip pocket, without any residual damage on the bond surface, could be derived.
Future flexible manufacturing systems require intelligent machine tools equipped with effective in-process monitoring systems for machining environment. To meet this specification, the sensor which has properties such as multifunctionality, reliability, sensitiveness and compactness, is urgently required. Therefore, we developed a multifunctional compact sensor based on a new concept. The output of the proposed sensor contains the information concerning both thermal and mechanical behavior in a machining environment consisting of machining status, tool status, workpiece status and swarf status. Consequently, the proposed sensor can simultaneously detect the cutting force and temperature which are useful to monitor chatter vibration, tool wear, swarf flow pattern, and so on. In this paper, the static and dynamic performances of the proposed multifunctional sensor have been verified through a series of actual cutting experiments.
Theoretically defined Boolean operations of topology-based two-dimensional cell decomposition solid models (geometric cell complex chains, not subsets of an Euclidean space) are applied to a modeler. These Boolean operation processes are constructed by common subdivision operation (subdivision and union-compatible operation) processes and traditional set operation (union, difference, intersection) processes of cell decomposition solid models. In this modeler, Boolean operations of two cell decomposition solid models which have boundary elements in contact are carried out. The difference between Boolean operation processes of these cell decomposition solid models and those of solid shape models (closed regular sets, subsets of an Euclidean space) is discussed.