Hysteresis Damping Research Articles

Mplicit Identification of Contact Parameters in a Continuous Chain Model

Accurate contact modeling is of great importance in the eld of dynamic chain simulations. In this paper emphasis is on contact dynamics for a time-domain simulation model of large chains guided in a closed loop track. The chain model is based on theory for unconstrained rigid multibody dynamics where contact within the chain and with the track is dened through continuous point contacts using the contact indentation and rate as means. This paper presents an implicit method to determine contact parameters of the chain model through the use of none gradient optimization methods. The set of model parameters are estimated by minimizing the residual between simulated and measured results. The parameter identication is tested on four dierent formulations of the Hunt-Crossly hysteresis damping factor with the aim of recognizing a superior model.

Frequency Response Analysis of Diaphragm for Small Earphone Supported by Nonlinear Springs with Hysteresis Using Finite Element Method

For small earphones, this paper describes vibration analysis using three-dimensional finite element method for elastic diaphragm supported by multiple nonlinear concentrated springs with linear hysteresis damping. The restoring forces of the springs have cubic nonlinearity. Finite element for the nonlinear springs with hysteresis are expressed and are connected to the elastic diaphragm modeled by linear solid finite elements in consideration of complex modulus of elasticity. Further, the discretized equations in physical coordinate are transformed into the nonlinear ordinary coupled equations using normal coordinate corresponding to linear natural modes. Harmonic balance method is applied to the equations to obtain nonlinear resonance responses. This transformation yields computation efficiency. The calculated resonance responses by the proposed method are verified by experimental responses. In the experiment, the earphone's diaphragm displacement and the envelope response are measured using a laser displacement meter.

312 非線形集中ばねで支持された吸音二重壁構造の高速非線形減衰応答解析

This paper describes vibration analysis using finite element method for automotive sound proof structures with automotive body frames supported by nonlinear concentrated springs. The restoring force of the spring has cubic nonlinearity and linear hysteresis damping. To calculate damping properties for automotive sound proof structures including elastic body, viscoelastic body and porous body, displacement vectors as common unknown variable are solved under coupled condition. Further, the discretized 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. Influences of the nonlinear springs and sound proof structures are clarified on the nonlinear frequency responses.

DYNAMIC CENTRIFUGE MODEL TEST OF PILE-SUPPORTED BUILDING WITH SEMI-RIGID PILE HEAD CONNECTIONS IN LIQUEFIABLE SOIL

Dynamic centrifuge tests are conducted using soil-pile-structure models in order to investigate the seismic behavior of a building with semi-rigid pile head connections in liquefiable soil. The dynamic test results show that: (1) The semi-rigid pile head connection is effective for reducing the bending moment of a pile in liquefied soil; (2) The natural period of the soil-pile-structure system with semi-rigid pile head connections becomes longer than that of the system with rigid pile head connections during liquefaction; and (3) The hysteresis damping induced by the dynamic interaction between liquefied soil and piles in the system with semi-rigid pile head connections is larger than that in the system with rigid pile head connections.

Compliant contact force approach for forward dynamic modeling and analysis of biomechanical systems

This work deals with the problem of contact modeling and analysis of biomechanical systems involving contact events between soft materials, such as in the case of natural and artificial joints. Modeling contacts with high degree of energy dissipation plays a crucial role in the analysis, design and control of many biomechanical systems in the measure that soft materials are characterized by low or medium values of the coefficient of restitution. The contact force model presented in this work is developed with basis on the foundation of the Hertz law together with a hysteresis damping parameter that accounts for the energy dissipation during the contact process. This approach is based on the analysis of dissipated energy related to the coefficient of restitution, stored elastic energy and the dissipated energy associated with the internal damping of the contacting bodies. A demonstrative application example is used to provide the results that support the analysis and discussion of procedures, methodologies and assumptions adopted throughout this work.

On the continuous contact force models for soft materials in multibody dynamics

A general and comprehensive analysis on the continuous contact force models for soft materials in multibody dynamics is presented throughout this work. The force models are developed based on the foundation of the Hertz law together with a hysteresis damping parameter that accounts for the energy dissipation during the contact process. In a simple way, these contact force models are based on the analysis and development of three main issues: (i) the dissipated energy associated with the coefficient of restitution that includes the balance of kinetic energy and the conservation of the linear momentum between the initial and final instant of contact; (ii) the stored elastic energy, representing part of initial kinetic energy, which is evaluated as the work done by the contact force developed during the contact process; (iii) the dissipated energy due to internal damping, which is evaluated by modeling the contact process as a single degree-of- freedom system to obtain a hysteresis damping factor. This factor takes into account the geometrical and material properties, as well as the kinematic characteristics of the contacting bodies. This approach has the great merit that can be used for contact problems involving materials with low or moderate values of coefficient of restitution and, therefore, accommodate high amount of energy dissipation. In addition, the resulting contact force model is suitable to be included into the equations of motion of a multibody system and contributes to their stable numerical resolution. A demonstrative example of application is used to provide the results that support the analysis and discussion of procedures and methodologies described in this work.

에너지흐름해석법을 이용한 중고주파수 대역 자동차 도어 진동예측

In this paper, the energy flow analysis(EFA) of the body-in-white door of a real automotive was performed using the energy flow finite element method(EFFEM) to effectively predict the vibrational responses of built-up structures in the medium to high frequency range. To increase the validity of EFA results, the structural hysteresis damping loss factor was measured by the experiment using the concept of statistical energy analysis(SEA). As the excitation frequency increases, the predicted results simulated with EFFEM generally agree with the experimental results.

A new model for dry and lubricated cylindrical joints with clearance in spatial flexible multibody systems

A new approach to model and analyze flexible spatial multibody systems with clearance of cylindrical joints is presented in this work. The flexible parts are modeled by using absolute nodal coordinate formulation (ANCF)-based elements, while the rigid parts are described by employing the natural coordinate formulation (NCF), which can lead to a constant system mass matrix for the derived system equations of motion. In a simple way, a cylindrical joint with clearance is composed of two main elements, that is, a journal inside a bearing. Additionally, a lubricant fluid can exist between these two mechanical elements to reduce the friction and wear and increase the system’s life. For the case in which the joint is modeled as a dry contact pair, a technique using a continuous approach for the evaluation of the contact force is applied, where the energy dissipation in the form of hysteresis damping is considered. Furthermore, the frictional forces developed in those contacts are evaluated by using a modified Coulomb’s friction law. For the lubricated case, the hydrodynamic theory for dynamically loaded journal bearings is used to compute the forces generated by lubrication actions. The lubricated model is based on the Reynolds equation developed for the case of journal bearings with length-to-diameter ratios up to 1. Using this approach, the misalignment of the journal inside the bearing can be studied. Finally, two demonstrative examples of application are used to provide results that support the discussion and show the validity of the proposed methodologies.

Numerical Simulation of Impact Responses for an Elastic Structure with a Viscoelastic Spring Including Nonlinear Hysteresis Damping

To compute dynamic characteristics of nonlinear viscoelastic springs with elastic structures having huge degree-of-freedom, Yamaguchi proposed a new fast numerical method using finite element method. In this method, restoring forces of the springs are expressed using power series of their elongation. In the expression, nonlinear hysterisis damping is introduced. Finite element for the nonlinear spring having complex coefficients is expressed and is connected to the elastic structures modeled by linear solid finite element. Further, to save computational time, the discrete equations in physical coordinate are transformed into the nonlinear ordinary coupled equations using normal coordinate corresponding to linear natural modes. In this report, the proposed method is applied to simulation for impact responses of a silicone block with an elastic structure (a S-shaped structure) by colliding with a concentrated mass. The concentrated mass has initial velocities and collides with the silicon block. Accelerations of the elastic structure and the concentrated mass are measured using Levitation Mass Method proposed by Fujii. The calculated accelerations from the proposed FEM, corresponds to the experimental ones.

Comparison Between Elastic Foundation and Contact Force Models in Wear Analysis of Planar Multibody System

In this paper, two procedures to analyze planar multibody systems experiencing wear at a revolute joint are compared. In both procedures, the revolute joint of interest includes a clearance whose shape and size are dictated by wear. The procedures consist of coupled iterative analyses between a dynamic system analysis with nonideal joints and a wear prediction to determine the evolution of the joint clearance. In the first procedure, joint forces and contact pressures are estimated using the elastic foundation model with hysteresis damping via the dynamic analysis. In the second procedure, a contact force model with hysteresis damping is used to estimate the joint forces. In the latter case, however, the contact pressure is estimated using a finite element method (FEM). A comparison in performance of the two models is facilitated through the use of an experimental slider-crank mechanism in which wear is permitted to occur at one of the joints. It is observed that the two procedures provide similar estimates for the dynamic response and wear volumes but substantially different predictions on the wear profiles. Additionally, experimental results show that while predictions on the wear volume from both models are reasonably accurate, the FEM-based model produced more accurate predictions on the wear profile.

A STUDY ON THE EARTHQUAKE RESPONSE CHARACTERISTIC OF HYSTERESIS DAMPER USING SLY120 AND SS400

To examine earthquake response characteristics of hysteresis damper using SLY120 and SS400 steel panel damper, earthquake response test were performed. In this paper, restoring force characteristic of hysteresis damper which is obtained by loading test are assessed using numerical analysis model. A skeleton shift model, which has been used frequently in conventional analysis, is applied. Using a hybrid earthquake response test system, various characteristics of structural components that are difficult to model and to express mathematically are detected by test and incorporated into the computer system to promote numerical analysis of the whole system. In this research, hybrid earthquake response simulation of the linked vibration suppression structure is carried out, whereas hysteresis damper at the linked vibration control structure are selected as the actual loading test part and the peripheral frame is considered to be the virtual structure part.

Response Behavior of Steel Latticed Cylindrical Shell Structures with Hysteresis Dampers in the Substructure

Response Behavior of Steel Latticed Cylindrical Shell Structures with Hysteresis Dampers in the Substructure

A Study to Improve Earthquake Resistant Capacity of Steel Gable Truss Structures by Applying Hysteresis Dampers to the Column Bases

A Study to Improve Earthquake Resistant Capacity of Steel Gable Truss Structures by Applying Hysteresis Dampers to the Column Bases

Rate dependency of depth in nanoindentation of polycrystalline NiTi

The recent increased use of shape memory alloys (SMAs) for engineering applications manifests the need of checking the aspect of rate in NiTi. The ability of models and experiments to accurately predict the rate dependency of function–rate relationship is important. This paper concentrates on the rate dependency of depth in nanoindentation of NiTi where different tips have been used. To explain the phenomena, hysteresis damping areas are investigated. The results show decreasing depth at higher rates is due to the amount of latent heat generated from phase transition and relaxation time for heat release.

Analysis of Damped Vibration for Viscoelastic Blocks Connected by a Nonlinear Spring with Linear Hysteresis Using FEM Described by Normal Coordinate

This paper describes a vibration analysis study using the finite element method (FEM) for two viscoelastic blocks connected by a nonlinear concentrated spring. One of these blocks is supported by a linear concentrated spring. The restoring force of the spring is expressed as a power series of the relative displacement between the blocks. This restoring force includes linear hysteresis damping. Therefore, a complex spring constant is introduced for the linear component of the restoring force. The finite elements for the spring are expressed and they are attached to the viscoelastic structures, which are modeled as linear solid finite elements. The discrete equations in terms of physical coordinates are transformed into nonlinear ordinary coupled equations using normal coordinates corresponding to the linear natural modes. These transformed equations are then computed to obtain the nonlinear frequency responses with a fairly small degree of freedom. The effectiveness of this analysis is checked using a basic mass-spring model. Moreover, the influences of the storage modulus of the blocks on the nonlinear responses are clarified. Further, the influences of the dissipated energy on the nonlinear frequency responses of the viscoelastic blocks are investigated.

MECHANICAL CHARACTERISTICS OF REINFORCEMENT SOIL BY BAGS

The soil-bag has the large bearing capacity to the external force, because the materials inside soil-bags are wrapped and confined completely by the bag. In this study, the compression tests and cyclic shear tests were performed to evaluate the mechanical characteristics of the soil-bags for the design of the reinforcement soil by bags. As the results, the experimental compression baring loads almost agree with the theoretical values and the characteristics of the high performance hysteresis damping of the piled up soil-bags were found out.

Simulation of planar flexible multibody systems with clearance and lubricated revolute joints

Modeling of clearance joints plays an important role in the analysis and design of multibody mechanical systems. Based on the absolute nodal coordinate formulation (ANCF), a new computational methodology for modeling and analysis of planar flexible multibody systems with clearance and lubricated revolute joints is presented. A planar absolute nodal coordinate formulation based on the locking-free shear deformable beam element is implemented to discretize the flexible bodies. A continuous contact-impact model is used to evaluate the contact force, in which energy dissipation in the form of hysteresis damping is considered. A force transition model from hydrodynamic lubrication forces to dry contact forces is introduced to ensure continuity in the joint reaction force. A comprehensive study with different lubrication force models has also been carried out. The generalized-α method is used to solve the equations of motion and several efficient methods are incorporated in the proposed model. Finally, the methodology is validated by two numerical examples.

Pseudo-elastic hysteresis damping characteristics of SMA hybrid composite lamina

The longitudinal mechanical behavior of shape memory alloy (SMA) composite lamina subjected to longitudinally strain or stress controlled cyclic loading is investigated. The SMA is under pseudo- elastic condition and the fibers are embedded (bonded) to the host material. The influences of temperature, volume fraction of SMA and longitudinal modulus of the host material on the stress-strain relation and energy dissipation of the SMA hybrid composite lamina are discussed. The results indicate that the stress-strain curve of the lamina per cycle shows a hysteresis loop. The hysteresis damping decreases with increasing temperature and with decreasing volume fractions of SMA. In addition, the hysteresis damping is nearly independent of the longitudinal modulus of the host material under strain controlled loading. However, it depends dramatically on the longitudinal modulus of the host material under stress controlled loading, which shows the SMA composite lamina has high pseudo-elastic hysteresis damping when the longitudinal modulus of the host material is low.

PREDICTION OF ENERGY ABSORPTION CAPACITY OF HYSTERESIS DAMPERS INSTALLED IN DAMAGE CONTROL STRUCTURES

In this paper, the energy absorption capacity of a hysteresis damper installed in a damage control structure was investigated. The performance of a hysteresis damper is limited by its fracture. The method predicting the metal fatigue life is extended to apply to the evaluation of the life of dampers. However, the method based on the energy absorption is necessary for the earthquake-resistant design. The conclusions obtained from this paper can be summarized as follows. (1) The energy-based method to evaluate the ultimate performance of a hysteresis damper was proposed based on the results of the cyclic loading tests. (2) The characteristic of the distribution of the energy response of the damage control structure is clarified based on the results of the earthquake response analyses. (3) By using these results, the simple method to predict the energy absorption capacity of the damper was proposed.

Characteristic Equation-Based Dynamics Analysis of Vibratory Bowl Feeders With Three Spatial Compliant Legs

In automatic assembly, a vibratory bowl feeder plays a crucial role for reorienting the parts and feeding them into an assembly process. Taking the bowl as a platform and three prismatic flat-spring supports as spatial compliant legs and based on the continuum dynamics, this paper examines the bowl feeder from the point-of-view of a compliant platform device by applying von Mises' compliance study to each of the flat-spring legs and establishes a screw system of each leg. The compliance and Jacobian matrix of the bowl feeder are presented, the potential and kinetic energies are analyzed, and the dynamics models are established, leading to the characteristic equations of the compliant platform device. This generates for the first time the shape function integrated stiffness matrix and inertia matrix. This paper further analyzes the two characteristic equations of both a simplified system and a generalized system, implements the comparative study of the system natural frequencies between the two system models, and presents the stability analysis involving the system hysteresis damping. The effect of platform design parameters on the natural frequencies of the system under damping is identified and modal analysis of the system is carried out according to different forms of the excitation force. This paper presents a comprehensive study of the dynamics of this kind of compliant devices.