A human stands on a one degrees-of-freedom mechanical vibration stage is considered. The human body and the mechanical vibration stage is modeled as a linear two-degrees-of-freedom vibration system. The experimental frequency response verifies the assumption of the two degrees-of-freedom system. The mass, the viscocity, and the stifness parameters are identified by the freqeucny domain least squares method. In the experiment, some postural, visual, or psychological load conditions are examined for some human subjects. The relation between the experimental conditions and the identified parameters are discussed.

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To evaluate a ride comfort, vibration characteristics of passengers are important. It's necessary to construct a model which represents vibration characteristics of the passenger seated on a vehicle seat with high accuracy. Therefore, passenger-seat modeling is been conducted by combining the passenger model with the seat model that are separately constructed by using a multi-body approach. In this paper, the passenger model is tried to be constructed for high accuracy based on the response of the passenger seated on a urethane seat whose boundary conditions with the passenger is similar to ones of actual seat. The process and results of this modeling are presented.

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Recently, an improvement of ride comfort is essential for vehicle designs to add commodity value. A technique to well estimate the ride comfort for vehicle passengers is strongly required from the above viewpoint. This paper investigates the modeling of a passenger with consideration of a postural control system of human body. Firstly, a passenger model on a rigid seat is constructed by multi-body approach, where only the passive property is taken into account. Secondly, the postural control system of human body is introduced into the multi-body model. The frequency range of interest is up to 3Hz, and the input vibration direction is in lateral direction.

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This paper describes the image recognition using chaotic search. As a nonlinear dynamical system, BVP model with the edge of chaos is treated, which shows the behavior of neuron in biological system. In this research, the chaotic search is applied to image recognition using the edge of chaos. First, the occurrence of chaos in BVP model is examined using the Lyapunov exponent. Second, in order to perform image recognition, a method of chaotic search is proposed. Finally, through simulation studies, it is verified that chaotic search is possible both for fixed and moving targets.

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In neurosurgery brain shift throughout the surgical procedure has been a major issue affecting the spatial accuracy of conventional neuronavigation system. This study aims at adequacy evaluation of the developed anatomically detailed three-dimensional finite element brain model and improving the model for CPU time reduction. The computation of the gravity-induced brain shift was conducted using ABAQUS/Explicit. Deformation of the brain surface due to gravity after dura opening was demonstrated in 3D view under the anatomical constraint of the brain substructures. The illustrative results indicated the valid of the developed model and successfully demonstrated the prediction capability of brain shift using it. Additionally we succeeded in reduction of CPU time by improved model.

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A new optimal control model of human arms has been developed to simulate two-point reaching movement characteristics for the human three-joint arm system. This model optimizes its evaluation function in which three kinds of energy are incorporated into the evaluation function of the previous modified minimum-torque change model with a wrist joint's freezing mechanism. Consequently, the following results were clarified: (1) the new model reproduces two-point reaching movement characteristics for the human three-joint arm system; (2) this new model's function is not dependent on target positions. These suggest that the new model is more effective as a model of the human three-joint arm control system and that energy optimization can involve the trajectory planning of two-point reaching movements.

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This research focuses on formulating a three-link (an upper body, two thighs, and two lower legs) and three-joint optimal control model that reproduces rising movements from a chair and considering optimization factors indispensable for realizing the same rising movements as humans. Consequently, it was clarified that the experimentally measured rising movements are reproduced by the optimal control model minimizing a new evaluation function in which the energy consumed by muscle viscosity and the displacement of the center of mass are incorporated into the modified minimum torque-change criterion. This result suggests that the three kinds of optimization factors can be strongly involved in realizing rising movements.

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A human's gait rhythm changes from one's natural gait rhythm into the frequency of the ground vibration. This phenomenon is called as "pull-in effect". It is known that London Millennium Bridge was closed because the pull-in-effect induced large lateral bridge vibration. Most of studies about pull-in-effect have addressed qualitative property about pull-in effect. In this research, conventional dynamic model was improved to carry out quantitative analysis. Damping while landing and power to maintain walking were introduced in the analytical model. Simulation results of phase difference between a bridge and a human corresponds to that of experimental ones. In order to evaluate horizontal oscillation of the Millenniums Bridge caused by pull-in effect, simulation of walking on the free platform was carried out. In conclusion, a quantitative analysis of the pull-in effect became possible with the use of the improved passive walking model.

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The purpose of this study was to investigate individual differences in contributions of muscle forces of support leg to the acceleration of the whole body's CG in running. The method which we have proposed in previous study was used to quantify the contribution by using a musculoskeletal model consisting of 35 Hill-type muscles and of 5 DOF with SIMM software (MusculoGraphics Inc.). Six male subjects participated in experiment, and the results showed that individual differences of the muscle force contributions are observed in Vastus and Soleus muscles, and those muscles show large contribution to the acceleration ofthe CG.

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Kyoto Bow is a Japanese traditional bamboo bow which is made from 100% natural materials. The bamboo bow is made by sandwiching maple, wax tree and burned bamboo planks between two strips of bamboo. This configuration is similar to a hybrid composite. The perfection of the bow very much depends on the skills and sensibility of the craftsman. Therefore, it is desirable that his implicit knowledge is quantified. There are some special procedures, which are considered to be implicit knowledge, during the making of the bamboo bow that provides the bow with some interesting characteristics. The purpose of this research is to quantify this implicit knowledge in bamboo bow fabrication by using scientific procedure. In order to understand the implicit knowledge, experiments were performed in two different areas corresponding to the strength of materials and motion analysis. In the case of strength of materials, the mechanical properties of each material were characterized. FEM analysis revealed the effect of the asymmetrical core structure (Nakauchi) of the bow on the rotation moment. Motion analysis confirms that Kyoto bow is more user friendly as compared to modem composite bows. As the result, it was clarified that bamboo bow has some excellent properties come from hybrid structure.

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Motion analysis in the producing process was performed in an artisan of woodwork using hammer and chisel to shave a zelkova. The joint angle of right elbow having hummer repeated flexion and extension within a certain angle. Furthermore, duration time and velocity of the first hitting were longer and slower than those of other hitting, respectively. These results suggest that an artisan carefully performed for the first hitting to shave a zelkova with taking a longer time.

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This study proposes a dynamic elasto-plastic analysis method which can accurately simulate buckling behavior of cylindrical water storage tanks during earthquake. This proposed method takes into account the behavior of oval-type vibration as well as beam-type vibration. In the proposed method, water in the tanks is modeled and coupled analysis between fluid and structure is adopted in addition to consideration of large deformation of the tank walls. The analytical results by the proposed method have been in good agreement with those of experiment in the matter of occurrence of oval-type vibration, mode of buckling and buckling load.

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The response of the structure subjected to nonstationary random vibration such as earthquake excitation is nonstationary random vibration. Calculating method for statistical characteristics of such a response is complicated. The secondary system such as piping systems, tanks and other mechanical equipment is installed on the primary system such as buildings and supporting structures. Calculation method for statistical characteristics of the response of the secondary system is more difficult. Then, practical and simplified method to obtain theoretical statistical value is required. Mean square value of the response is usually used to evaluate random response. Integral of mean square value of the response corresponds to total energy of the response. In this paper, a simplified calculation method to obtain integral of mean square value of the response of the secondary system is proposed. It is found that the proposed method gives exact value of sum of mean square value of the response

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An elevator rope for a high-rise building is excited forcibly by the displacement of the building caused by earthquakes and wind forces. In this paper, simplified calculation methods, single degree of freedom (SDOF) system and finite element method (FEM), for estimating rope deflection during earthquake are presented by using buildings acceleration. Finite difference analyses of rope vibration are also performed to verify the validity of these simplified calculation methods. The calculated results of these simplified calculation methods are in fairly good agreement with that of the finite deference analyses.

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Some steel materials for pipes exhibit cyclic hardening behavior under cyclic loads. This behavior leads to higher stiffness and resonant frequencies of piping systems. It is important to consider these effects in order to predict seismic responses of piping systems. We studied modeling procedure of piping material to simulate such inelastic behavior. The procedure flow was illustrated to suggest appropriate stress-strain relationship and hardening rule. Material models in the flow were applied to the simulation of the seismic test of piping system made of stainless steel. These results were compared with the test result, and the applicability of each model was discussed.

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Generally, Mechanical structures installed in nuclear power plants are designed statically in elastic region. But from the viewpoint of cost, this method includes a lot of margin and it isn't an efficient method. Recently, Energy Balance Method is watched as a new design and evaluation method. In this report, piping models, which are generally used in the nuclear power plant, are made and input oscillation disturbance. According to the experiment, the relation between energy balance equation and fatigue of materials appeared a piping model.

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This paper deals with vibration response caused by pulses in an earthquake from the viewpoint of the energy balance equation. Recently seismic waves including pulses have been measured in various earthquakes. It was reported that these pulses wave induce severe damage to relatively long period structures such as detached houses. However investigations regarding influences of pulses are not sufficient. Therefore this paper investigates influences of pulses from the viewpoint of energy balance. The investigation is implemented by analysis of an actual seismic wave including pulses, a vibration experiment and a simulation.

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The regulatory guide for seismic design of nuclear power plant has been vastly revised at several fields. Main items under revision are observed such as the requirement of making appropriate concern for the dynamic coupling effects of horizontal and vertical components of earthquake, and the consideration of probabilistic risk assessment against the uncertainty of earthquake. The purpose of this paper, therefore, is to estimate the stochastic peak responses of multi-degree-of-freedom structure with closely spaced natural frequencies under the consideration of the correlations between multi components of earthquake, also aiming at reliability of SRSS method. For this target, one mathematical model is developed in order to analytically evaluate the effects of correlation between components of input, and the stochastic vibration analysis is executed based on FEM-based eigen mode analysis and transition matrix method. The analytical results are compared with those by Monte Carlo simulation.

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The spent fuels from nuclear power stations are stored in a canister which is put in a cask until reprocessed. The cask is freely standing on a horizontal floor in general. Thus, it is very important to evaluate the rocking motion of a cask-canister system due to seismic excitation. In an analytical model, the canister and the cask are treated as rigid bodies which are connected by a spring. The equations of motion are derived for rocking motion when the floor is subjected to the horizontal earthquake excitation. The rocking angle of the cask and the relative displacement of the canister against the cask are evaluated by numerical simulation, and the effects of the canister vibration on the cask motion are discussed.

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This paper investigates the parametric instability in a straight bellows subjected to unsteady oscillating internal fluid pressure by the earthquake experimentally. It is observed that the lateral vibration in the bellows increases rapidly when the dynamic pressure in the piping system due to the seismic excitation in the bellows becomes larger. Then the parametric instability is caused in the bellows. The critical dynamic pressure for exciting the parametric instability obtained by experiment is compared with simulation results obtained by numerical simulation.

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The development of informational technology (IT) in recent years has been great. Therefore the IT infrastructure has become one of important social infrastructures. The earthquake-proof performance of the trunk line route is great,but that of edge systems is not enough.Then, JIS/EIA 19 inch Rack systems was selected as one of the equipment in the edge systems, and the earthquake-proof performance tests was applied.

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Earthquake-proof measures in order to continue the function of medical facilities during and after an earthquake has been studied. The earthquake-proof performance of equipment in the medical facilities is not fully understood. Furthermore, practical methods of seismic countermeasures are not established. First of all, in order to verify the earthquake-proof performance of the medical equipment, the seismic experiments of the medical equipment by a medium-size shaking table were conducted. The seismic experiments clarified the earthquake-proof performance of the medical equipment and its behavior during earthquakes. Moreover, numerical models of the medical equipment were constructed based on the experimental results, and numerical analyses of its behavior were conducted.

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intensity analysis and damage experiments of a universal joint. The Kashiwazaki Kariwa nuclear power plant suffered damage from the Niigata Chuetsu offing earthquake. The earthquake motion damaged an overhead traveling crane of the No.6 nuclear reactor building. The damaged portion consisted of the universal joint. As a cause of the damage it is thought that the universal joint was loaded from the torque of the earthquake motion. In the experiment, the miniature model of the universal joint is loaded with the torque and damaged. Similarly, in the analysis by 3DCAD and CAE, the miniature model is loaded with the torque and damaged. The experimental result is compared with the analysis result and the validity of the analysis is examined.

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A new device for reduction of seismic response of mechanical system is developed. The device is friction bearing which consists of upper and lower plates with spherical holes and sandwiched spherical metals. Seismic response is reduced by friction between plates and metals. A computer rack is put on the device and shaken by the shaking table. Acceleration responses on friction bearing and rack are measured. The maximum values and standard deviations of the response and the excitation are obtained. It is concluded that the repose is reduced by the proposed device.

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In this paper, the authors propose a three-dimensional seismic isolation table which is composed of a vertical isolation system using V-shaped link mechanism and a horizontal isolation table using X-Y rails. The vertical isolation system has an approximate bilinear-type spring force characteristic. The three-dimensional seismic responses of a mass installed on the table board were measured using a vibration machine. The experimental results were compared with the calculated results, and the effects of vibration isolation in three-dimensional directions and the validity of the calculations were substantiated.

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In this paper, the authors propose a three-dimensional seismic isolation table consisting of a vertical seismic isolation system using a Λ-shaped link mechanism and a horizontal seismic isolation table using semicircular springs. The vertical isolation system has an approximate bilinear spring force characteristic. The seismic responses of a mass installed on the table boards of the vertical and three-dimensional isolation tables were measured using a three-dimensional vibration machine. These experimental results were compared with the calculated results, and the effects of vibration isolation in three-dimensional directions and the validity of the calculations were substantiated.

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This paper investigates the vibration characteristics of the seismic isolator system for the tower crane on the building. The presented isolator is composed of set of parallel links which provides spherical bearing, springs and dampers. The natural period and the damping coefficient of the tower crane can be tuned by these springs and dampers. As the results of experiment and numerical simulations, the presented seismic isolator is effective for the tower crane on the buildings.

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This study aims at research and development of the intelligent seismic isolation system using air-bearings as isolation device and earthquake early earning as trigger. A superstructure is supported by air-bearings installed at the foundation. Compressed air generated by compressor is gushed from the air-bearings and the air film is generated between the air-bearings and the ground surface. Then structure floats from ground and no seismic motion is transferred to superstructure. In this paper, principle of isolation performance that is investigated by numerical analysis and vibration experiment is described.

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This paper deals with an isolation device by using friction force. An isolation device decreases response acceleration and external force. Therefore, earthquake damage is reduced. However, an isolation device has a demerit for large relative displacement. The purpose of this research is to decrease the relative displacement by using the friction force. Then, an analytical model in consideration of the friction force is proposed, and a simulation is analyzed with actual earthquake waves. Consequently, it is thought that effective friction force exists, and this force decreases both the response acceleration and the relative displacement. This is considered to change with the properties of earthquake waves. Then, the model to which friction power is changed in linear was proposed from the relation with the compression spring attached in the lower part by changing the angle of a friction surface. An experimental device is made under the same conditions as the proposed analytical model. The experimental results are compared with the analytical results.

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A base-isolation and vibration control technique has been applied positively to architectural and civil structures after Kobe earthquake, and now the techniques are adopted as general vibration reduction technique for many structures. In such situation, an application of the vibration attenuation device to the small-scale structure has been carried out actively in recent years. Especially, in the important institution of the cities such as a refuge place, a hospital, a school, an information and a communication institution where function maintenance is needed, it is important to maintain its performance of the machinery and equipment in the facility with an upgrade of structural seismic safety. Moreover, in the future, upgrading of seismic safety of the particular equipments is urgent business. This study has been examined a low cost and compact damping device for base-isolation system of light weight mechanical structures like computer server racks. In this paper, the experimental and analytical results on basic performances of the damping device using damping effect caused by eddy current.

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To strengthen the competitiveness of machine products, it is indispensable in the initial stages of development to create and run on computer virtual prototypes with which mechanical performance, functioning and reliability can be confirmed. This paper introduces the basic theory of automating modeling process of complex mechanical systems on computer. The main modeling strategy is that the energic primitive systems defined by Lagrangian should be interconnected through interconnection multiport systems which can be obtained by employing principle of interconnections. The virtual prototypes are visualized and differential algebraic equations are hierarchically derived via bond graph. Simple virtual prototypes are introduced using modeling of mechanical system and analysis examples.

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To analyze thrust force of Tripod Constant Velocity Joint, we construct a detailed model based on Multibody Dynamics approach. This model includes all main parts of the joint as rigid bodies and considers all force elements with respect to contact and friction acting among these parts. By comparing the computational results of the thrust force with the experimental ones, we verify this model. Moreover, we show the influence of the skew of needle rollers on the thrust force and evaluate the contribution of frictional forces at each contact region to the thrust force.

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This paper presents a formulation for dynamics of unicycle systems with nonholonomic constraints using principle of interconnection. It is shown that Planck-Okada-Arsove's logic enables to derive kinematical and dynamical constraints for unicycle systems and also that a mathematical model of unicyle systems can be obtained by incorporating those kinematical and dynamical constraints into the Lagrange-d'Alembert principle in the context of the constrained Lagrangian system. Finally, an example of unicycle systems is shown with a bond graph model as well as with numerical simulations.

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Recent reports imply that railway vehicles could derail solely by the ground motions of earthquakes. Thus, we should further study the derailment mechanism of these cases, to pursue to minimize the risk of railway system. We developed our original vehicle dynamics simulation and employed it for numerical analyses. We obtained the following outcomes. (1) Most of derailments are brought as the result of the rocking motion of a vehicle by track excitations underneath. The derailing motions are observed similarly regardless of vehicle speed. (2) The excitation amplitudes for derailment are influenced by vehicle speed particularly in lower input frequencies.

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In this investigation, the on-line and off-line hybrid contact algorithm for modeling wheel/rail contact problems is developed based on the elastic contact formulation. In the tabular contact search used in existing specialized railroad vehicle dynamics codes, contact points are predicted using an assumption of rigid contacts. For this reason, the contact points can be different from those predicted by the on-line based contact search used in elastic contact formulation. The difference in the contact point becomes significant when flange contacts that have large contact angles are considered. In the hybrid algorithm developed in this investigation, the off-line search that can be effectively used for the tread contact is switched to the on-line search when the contact point is jumped to the flange region. By so doing, a computationally efficient procedure is achieved while keeping accurate predictions of contact points on the wheel flange. Furthermore, the use of the proposed hybrid algorithm can eliminate the use of time-consuming on-line search procedures for the second points of contact as well. Since the location of second points of contact is pre-computed in the contact geometry analysis, the occurrence of two-point contact can be predicted using the look-up table in a straightforward manner. It is demonstrated by several numerical examples that the proposed hybrid contact search algorithm can be effectively used for modeling wheel/rail contacts in the analysis of general multibody railroad vehicle systems.

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There are several formulations for beam element in the large deformation and displacement problem. Recently, the absolute nodal coordinate formulations are studied for such problems. In this paper, the authors propose a formulation and an assembling method of the beam element for which the shape function is expressed in terms of the quadratic function in the absolute nodal coordinate approach. The usefulness of the proposed method is verified by the numerical simulations.

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The paper proposes a modeling method of flexible multibody systems based on principle of interconnection, especially, for the case in which flexible bodies are given by flexible beams that undergo large overall motions by mechanical joints. First, it is shown how flexible beams can be modeled as multiport systems using the principle of interconnection and also how geometric nonlinearities appeared in couplings between flexible deformations and large overall motions can be incorporated into the FEM model. It is further shown how kinematical and dynamical relations associated with large deformations of the beam can be formulated by employing moving frames and also be systematically represented by a dual set of connection matrices. Lastly, the present model is examined by numerical simulations.

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A simulation model of a hybrid excavator has been developed for the estimation of the fuel consumption and the optimum design of the hybrid system dynamics in the practical operation of the hybrid excavator. The hybrid excavator consists of a hybrid power train system with power electronics devices such as converter, an actuator system driven by electro-hydraulic system, and linkage system of a front attachment with the boom, the arm, and bucket. The simulation model enables us to analyze these systems totally. In this paper, the power electronics system is modeled to second order differential equations of motion, and the total system equations are established with considering the coupling with the power electronic system, the hydraulic system, and linkage system. The boom system is picked up for the operability design for the residual vibration, and the energy saving effect is estimated for the practical operations.

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To analyze the pressure distribution on engine main bearings, we developed a flexible multibody dynamics (FMBD) solver with a built-in elasto hydrodynamically lubrication (EHL) solver of engine main bearings. Furthermore, for the reduction of computational cost, we use the efficient component mode synthesis method that can consider both the entire deformation modes of cylinderblock and local deformation modes of the main bearings by several hundreds modes. It was applied to FMBD analysis of an in-line 4 cylinder engine under runnning conditions. Then, we confirm the availability and the advantage of the FMBD with EHL analysis of engine main bearings.

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A 3-D Full Scale Earthquake Testing Facility (E-Defense) was built in Miki Hyogo in January 2005 by National Research Institute for Earth Science and Disaster Prevent (NIED). The E-Defense makes it possible to do full-scale 6 DOF shaking tests. The E-Defense reproduces the earthquake wave which was actually observed. The test body for the E-Defense is assumed about 1200 tons while the shaking table mass is about 750 tons. The mass ratio becomes substantially large, and greatly influences shaking performance. Therefore simulation tools are needed which allow us to understand shaking performance in advance. In this research, we identify the component of E-Defense, and we make simulation tools. And it aims at the development of simulation tools that can verify the performance.

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In the next generation baby carriage, the comfort for the infant and the parent will be required in addition to the safety. In order to develop the comfortable baby carriage, basic data on the vibration which an infant prefers or does not feel unpleasantly are required. In this study, a shaking table is designed and the control system is developed for shaking the table under the front and right wheel of the baby carriage according to the desired waveform. The control system is the proportional controller with the outer feedback loop based on the discrete time sliding mode control technique. Then, the performance is confirmed by the numerical simulation and the experiment. And, it is clarified that the robustness for the disturbance can be improved by shaping the input waveform in the outer feedback loop.

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When a shaking-table of an earthquake simulator is driven for the seismic experiment of a specimen, its motion is affected by a reaction force caused by the specimen on the table. This paper presents a reaction force compensation methodology of shaking tables for earthquake simulators. The methodology is designed by using the DMM (Dual Model Matching ) based on the model matching method. And we adjusted feedforward control and feedback control. The effectiveness of the proposed technique is verified by experiments.

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This paper describes the separation and transportation of works using elliptical vibration in the condition to exceed the jumping limit. When the vertical vibration is 1.2G-1.8G, gappy works jump and the characteristics of transportation change considerably. On the other hand, flat works don't jump and the characteristics change little. This phenomenon allows us to separate gappy works from flat one at high speed, because the relative velocity of them is widened. By measuring the pressure fluctuation between table and flat work, we made clear the cause that flat works don't jump in the condition to exceed the jumping limit.

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This paper describes open loop control that imitates velocity FB control promptly grows up, attenuates the displacement of the transportation table, and the high-speed fixed quantity supply can be done. Open loop control focus on control force of velocity feed back control. It was clarified that the control power becomes equal with the output that the power instruction was passed through the notch filter. In addition, when the power instruction is a sine wave, the control power can be shown by the addition to driving frequency component and natural frequency component.

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This paper verifies the expressions for power input and subsystem energy by modal density of subsystem in Statistical Energy Analysis (SEA) by means of FEM calculation. First, vibration response in the modal form is used to derive their expressions. It is shown that the employment of average in space and frequency for the power input and subsystem energy of the subsystem can be expressed mainly by the modal density. Coupling loss factor between plate subsystems is also analytically estimated by using the wave theory and is determined mainly by the modal density. In order to verify their modal density descriptions, FEM calculations are performed to compare subsystem energies, power inputs and coupling loss factors on three kinds of structures with different subsystem shapes with the same modal densities. The analytical SEA predictions are also compared with the FEM calculation results.

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Frequency domain analysis by Finite Element Method and Boundary Element Method are used in vibration and acoustic problems. But recently, not only demand for quiet sound design but also comfortable sound designs arise. Therefore it is necessary to predict radiation sound in time domain at a design stage. In this paper, we apply CIP method for time domain analysis of vibration and acoustic problems to examine the transient analysis and the process of excitation of the vibration or acoustic mode. And we realize the prediction of sound radiation from the vibrating structure in time domain by using vibration and acoustic CIP analysis together.

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We introduce a technique for estimating damped analysis of automotive body panels with sound absorption structure. It calculates damping properties for sound-proof structures involving panel(elastic body), resin sheet (viscoelastic body) and felt(porous media). For elastic and viscoelastic body displacement are modeled using conventional finite elements using complex modulus of volume elasticity. In the porous media, both effective density and volume elasticity have complex module to represent damped sound fields. Particle displacement in the porous media is discretized using finite element method. Displacement vectors as common unknown variables are solved under coupled condition between elastic body, viscoelastic body and porous media and gas. Further, explicit expressions of modal loss factor for the mixed structures are derived using asymptotic method. Using this technique, eigenvalue analysis and frequency responded were calculated for some automotive body panels with sound absorption structure. We showed that phenomena of sound absorption with viscoelastic body.

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This paper deals with analysis for positioning of sound absorbing materials in a muffler having expansion chamber. Elements of absorber are modeled by 3D finite element, which having complex density and complex volume elasticity. By expanding the solution of complex eigenvalue problem with small parameter, equations of motion are derived using first order of asymptotic components. From the equations, contribution of damping elements on modal damping is derived in consideration of multiple modes. The sound absorber is arranged in muffler according to this contribution. It proposed a positioning method of sound absorbers within the limits of design feasible region and it applied to the expansion type muffler and availability of this method is verified.

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In the research of the tone quality of a classic guitar, the control of the vibration modes on the surface board is important. The couple bending modes on the front and rear face cause the "glottal sound " which is unsuitable for the guitar sound. The glottal sound has the rapid damping wave shape by the diffusion of the vibration energy with creating the sound strongly. It is occasioned by the dynamic change of the guitar acoustical room volume. We can find the higher sound pressure level on the sound hole of the guitar.. In the main case, there are the opposite phase vibration modes between the front face and the rear face.

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