Friction Damper Research Articles

Enhancing seismic performance of brace frame using self-centering friction damper with variable slip stiffness

A novel self-centering friction damper with variable slip stiffness (VSFD) is proposed to achieve ideal self-centering capability and limit the responses of the brace frame structure under the extremely rarely occurring earthquake (EROE), and its critical difference from the self-centering friction damper with constant slip stiffness (CSFD) is the hardening post-yielding stiffness. Through mechanical analysis, the VSFD exhibits ideal flag-shaped hysteretic behavior with the desired self-centering and energy dissipation capacity. The experimental study confirms that the hysteretic behavior of the VSFD is affected by friction coefficient, slope angle and transverse compressive force. The combination of disc spring stacks with various stiffness can provide variable compressive stiffness for the VSFD. The ratio of the residual sliding load to the initial sliding load increases with pre-compressive force, and so does the self-centering capacity. The hardening post-yielding stiffness ratio is proportional to the ratio of strong to weak stacks of the disc springs. The displacement corresponding to the hardening point decreases as the preloading weak stacks’ deformation capacity decreases. The VSFD can dissipate energy even if the deformation is small, and the damping ratio drops with increasing deformation, pre-compressive force and compressive stiffness. The updated displacement-based design procedure is proposed and the comparative dynamic time history analysis is conducted for the brace frames with different kinds of braces. The results show that the seismic responses of brace frames with the CSFDs and VSFDs are comparable under the rarely occurring earthquake (ROE), which meet the performance objectives, while the latter has smaller displacement response and larger floor acceleration than the former owing to its hardening post-yielding stiffness. Due to the considerable residual deformation under the ROE and EROE, the response of brace frame with the conventional friction dampers (CFDs) differs dramatically.

Machine learning-based design of a seismic retrofit frame with spring-rotational friction dampers

In this study a machine learning-based design procedure for a new seismic retrofit system is presented and its seismic retrofit capability is validated by intensive seismic analyses. The retrofit system consists of a steel frame with rotational friction dampers (RFD) at beam-column joints and linear springs at the corners providing both energy dissipation and self-centering capabilities to existing structures. The performance-based seismic design procedure of the spring-rotational friction damper (SRFD) retrofit system is developed using a genetic algorithm (GA) and an artificial neural network (ANN). The performance of the presented retrofit system and its optimum design procedure is evaluated using case study models for multi-limit states by investigating seismic fragilities, life-cycle cost (LCC), and seismic Resilience Index (RI) before and after the retrofit. According to the analysis results, the SRFD retrofit system proved to be effective in decreasing story drifts, seismic fragility, and LCC of the retrofitted structures significantly. The retrofitted models turn out to be more resilient and recover better than the un-retrofitted models after earthquakes. The developed performance based design procedure is proved to be effective in seismic retrofit of case study structures to satisfy multi-level design objectives.

A novel self-centering friction damper with elastic post-buckling plates to retrofit bridge bents

The self-centering energy dissipation dampers (SCEDs) have been demonstrated in mitigating the residual deformation of structures under strong ground motions. However, existing researches show that the damping force demand of SCEDs is higher than conventional dampers such as viscous dampers, BRBs or friction dampers for same design displacement of self-centering retrofitted structures, which could lead to higher base shear and acceleration responses of structures. In order to alleviate the problem, a novel self-centering damper composed of elastic post-buckling plates and adjustable friction devices (PBSCFD) was proposed. Compared with conventional SCEDs, the proposed PBSCFD has low secondary stiffness and adjustable energy dissipation capacity, which is beneficial to control the additional internal force of members adjacent to the damper in self-centering retrofitted structures. Based on the configuration and working principle of the PBSCFD, the theoretical force-displacement relationship of the damper was derived. Subsequently, a scaled PBSCFD was manufactured and tested under quasi-static loading to investigate its mechanical properties and to verify the theoretical constitutive model. In order to demonstrate the seismic performance of PBSCFDs, the double-column bridge bent retrofitted with PBSCFDs was designed by direct displacement-based seismic design method (DDBD), and its seismic performance was examined by elastic-plastic time-history analysis. Finally, effects of secondary stiffness ratio of self-centering dampers on seismic mitigation of self-centering retrofitted bridge bent were investigated. The results show that PBSCFDs have certain advantages in controlling the base shear and acceleration of the retrofitted bridge bent compared to conventional SCEDs with significant secondary stiffness.

Sensitivity Analysis of Dry Friction Damper in Stay Cables

The aim of this study is to provide an overview of damper sensitivity with dry friction mechanism in relation to its positioning and force to control cable vibrations in cable-stayed bridges. Finite element method is used to implement the cable model. Decay tangent evaluation takes into account the damper position varying in the first 5% of cable total length. To numerically solve the second-order nonlinear ordinary differential equation, the Newmark method with average acceleration is used. The results indicate the appearance of higher vibration modes with the application of dry friction damping, which can influence the interaction between two dampers. With the application of two dry friction dampers to the same cable using the equivalent viscous damping theory and the Newmark method, it is possible to perceive different results, where dry friction presents a considerable gain when not adapted to the linear viscous damping theory.

Oscillation decay of a pendulum by an air jet

A heavy pendulum oscillating in a vertical air jet is studied in this short communication. Different jet Reynolds number and initial inclination angle of the pendulum are considered. As the jet Reynolds number increases, it is always observed that the time taken by the pendulum to reach the final equilibrium vertical state reduces. The suction pressure induced by the streamlines of the air jet deflected by the pendulum aids the gravitational restoring force. The subsequent increase in the frictional damping force from the pivot of the pendulum is shown to be responsible for this behavior. A theoretical model along with numerical results corroborate this conclusion.

Modeling of disc springs based on energy method considering asymmetric frictional boundary

Disc springs have excellent ability to absorb and dissipate energy, and are widely used as basic vibration isolation units in the design of vibration isolators for naval power systems. Focusing on the effect of friction on disc springs, a mechanical model of disc springs considering asymmetric frictional boundary is developed. The additional load to overcome the Coulomb friction damping is derived analytically by the energy method. Finite element analysis of disc springs is carried out and the results for large and small frictional conditions are compared with the theoretical results. Quasi-static experiments on disc springs are carried out and the proposed method is further validated. The results show that the analytical model based on energy method can describe the load–displacement characteristics of disc springs and their combinations under symmetric and asymmetric frictional boundaries accurately. Based on the analytical solution, the influence of the structural parameters of the disc springs on the damping effect is investigated. The stiffness and damping of disc springs are linearly related to the friction coefficient. In addition, the magnitude of the effect of asymmetry of the boundary friction on the mechanical properties of the disc springs varies with the structural parameters.

Longitudinal displacement control of a long-span suspension bridge under random traffic loads using a polyimide friction damper

This paper proposes a novel method to control the cumulative displacement of the girder end of a long-span suspension bridge caused by traffic loads using friction dampers. Friction dampers have Coulomb damping characteristics and high initial stiffness, providing a significant damping force at low speed to suppress the longitudinal deformation of the girder end. The working mechanism of the friction damper is explained, and the performance of the proposed polyimide (PI) friction damper is tested. A random traffic load model of a long-span suspension bridge is established, and the longitudinal displacement, reaction force time history, longitudinal peak displacement, and cumulative longitudinal displacement (CLD) under different yield forces of the PI friction damper are analyzed. We propose the excess ratio δ of the yield displacement to determine the optimum yield force. The influences of different vehicle speeds and traffic flows on the performance of the PI friction damper are discussed. The results show that the PI friction damper substantially reduces the longitudinal displacement, longitudinal peak displacement, and CLD of the girder end; the reduction rate of the CLD exceeds 57% when the yield force of the PI friction damper is 1000 kN. The vehicle speed and traffic flow have negligible influences on the CLD of the long-span suspension bridges equipped with PI friction dampers in the normal working range.

Investigation of the effect of longitudinal creepage on wheel squeal

Wheel squeal is generally attributed to the lateral wheel vibration induced by lateral creepage. It should be noted, however, longitudinal creepage also exists at wheel/rail interface. Given the significance of longitudinal creepage in vehicle dynamics, a test rig that can introduce various longitudinal creepages by changing the teeth number of synchronous pulley is developed in this research, and measurement results show that squeal spectrum has three dominant peaks, whose sound pressure levels decrease with longitudinal creepage. In order to investigate the reason why longitudinal creepage can mitigate wheel squeal, a model of a wheel/rail system is developed in this research to analyse this phenomenon using complex eigenvalue method, and the results show the inner wheel tends to generate unstable vibration at three different vibration modes, correlating well with the dominant peaks of sound spectrum. Further analyses can illustrate the reason why longitudinal creepage can mitigate wheel squeal: the absolute value of effective damping ratio of each mode decreases with longitudinal creepage, so structural damping and frictional damping are less likely to be overcome by negative damping.

Development of hybrid rubber damper-restrainer (HRDR) system for structures under sever dynamic excitation

Nowadays, high damping rubber materials are extensively implementing in various types of structure to mitigate harmful effect of imposed vibration and dynamic force to the structure. Although, the rubbers exhibit noticeable damping in the shear action, however, de-bounding, shear rupture and delamination of rubber layers under cyclic loads, undermine the load-bearing capacity of the rubber dampers and increase their maintenance costs. Hence, the action of the rubbers is considerably high under applied compression to generate resistant force to restrain the deformation.For this reason, in this research, a new hybrid rubber damper-restrainer (HRDR) system is proposed. The system comprises a high-damping rubber component designed to dissipate applied vibrations, along with a pair of hyper-elastic rubbers intended to restrain displacement. Therefore, the developed HRDR device is capable of dissipating vibrations while restraining large movements to prevent any damage and debounding of the rubber layers and also, protect the structure from excessive displacements.To examine the performance of the proposed device, the numerical model of a HRDR was developed using the finite element simulation and subsequently, nonlinear dynamic analyses were conducted for the 6 storey prototype steel structure furnished with HRDR device. The findings revealed that the structure equipped with the HRDR device exhibited outstanding response against applied earthquake excitation which is proving high efficiency of HRDR device to diminish vibration effect on structure and prevent any excessive deformations. The HRDR device is applicable to any types of framed structures through installing via chevron brace system in steel structures or short wall in reinforced concrete structures. Furthermore, the developed HRDR device can be implemented in bridge structures, between the deck and pier of bridge to effectively dissipate vibrations and restrain the movement of the bridge span under traffic loads.

Seismic Upgrading of Existing Steel Buildings Built on Soft Soil Using Passive Damping Systems

In regions prone to seismic activity, buildings constructed on soft soil pose a significant concern due to their inferior seismic performance. This situation often results in considerable structural damage, substantial economic loss, and increased risk to human life. To address this problem, this study focuses on the seismic retrofitting of steel moment-resisting frames using friction and metal-yielding dampers, taking into account the soil-structure interaction. The effectiveness of these retrofit methods was examined through a comprehensive non-linear time history analysis of three prototype structures subjected to a series of intense seismic events. The soil behavior was simulated using a non-linear Bouc-Wen hysteresis model. Various parameters, including lateral displacement, maximum drift ratio, the pattern of plastic hinge formation, base shear distribution, and dissipated hysteretic energy, were used to compare the performance of the two retrofit strategies. The findings from the non-linear analyses revealed that both retrofit methods markedly enhanced the safety and serviceability of the deficient buildings. The retrofitted structures exhibited notable reductions in residual displacements and inter-story drift compared to the original frame structures. In the original frame, primary structural elements absorbed a significant amount of the seismic input energy through deformation. However, in the retrofitted frames, dampers dissipated up to 90% of the total input energy. Additionally, integrating dampers into the original frames effectively transferred the non-linear response of the structural elements to the dampers.

좁은 주파수 대역의 랜덤 가진을 받는 블레이드 어셈블리에서 인위적인 미스튜닝에 의한 마찰 댐퍼의 성능 변화

좁은 주파수 대역의 랜덤 가진을 받는 블레이드 어셈블리에서 인위적인 미스튜닝에 의한 마찰 댐퍼의 성능 변화

Theoretical Decay Results of a Swelling Soils System with Frictional Damping Versus Viscoelastic Damping

Theoretical Decay Results of a Swelling Soils System with Frictional Damping Versus Viscoelastic Damping

Optimal energy decay for a viscoelastic Kirchhoff equation with distributed delay acting on nonlinear frictional damping

In this paper, we have analysed the influence of viscoelastic and frictional damping on the decay rate of solutions for a Kirchhoff-type viscoelastic wave equation with a distributed delay acting on nonlinear internal damping. Taking the relaxation function of a fairly large class and using the method of energy in which we introduce an adapted Lyapunov functional and by exploiting certain properties of convex functions, under certain assumptions on the constants of system, we obtain the optimal decay rate of energy in the sense that it is compatible with the decay rate of the relaxation function.

Cyclic behavior and seismic control performance of SMA friction damper

Using superelastic shape memory alloy (SMA) bars and non-asbestos organic friction material, this study developed an innovative self-centering friction damper (SCFD). This hybrid passive control device consists of the self-centering device using SMA bars and the friction energy dissipation device which can provide excellent self-centering ability and energy-absorbing ability to meet the requirements of civil engineering applications. To explore the feasibility and hysteretic properties of the SCFD, experimental tests under cyclic loading were conducted. According to the experimental results, the proposed SCFD exhibited a stable and repeatable flag-shaped hysteretic response, which can achieve the recovered displacement of 76.07% and dissipated energy of 6.04 kJ at 42 mm. The finite element model of the SCFD using ABAQUS software was established and validated by experimental results. And a series of numerical simulations with different parameters were performed, which enables a more in-depth interpretation of the SCFD. Additionally, a system-level nonlinear time-history analysis was performed on a three-story steel frame equipped with and without SCFDs. The dynamic analysis results indicated that the SCFDs could effectively reduce structural damage and enhance post-earthquake recoverability under rare earthquakes.

Nonlinear dynamics of turbine bladed disk with friction dampers: Experiment and simulation

Accurately predicting the nonlinear dynamic response of aero-engine components is critical, as excessive vibration amplitudes can considerably reduce the operational lifespan. This paper compares experimental and numerical nonlinear dynamic responses of an industrial aero-engine, specifically focusing on the first stage turbine bladed disk with under-platform dampers (UPDs). The friction forces between UPDs and blades result in a strongly nonlinear dynamic response, influenced by stick, slip and separation contact states at the interfaces. These contact states, and the resulting global dynamic responses, are predicted with an advanced industrial modelling approach for nonlinear dynamics. The predictions are compared, updated and validated against measurement data from an operational engine test. Results highlight the importance to validate models against industrial data and show that realistic contact pressure distributions are required for increased prediction reliability. The novelty of this work includes (1) the use of unique industrial experimental data from a fully operational aero-engine, (2) the observation, at the end of engine testing, of real contact conditions in blade/UPD interfaces, (3) detailed modelling of these contact conditions with high-fidelity finite element representations in nonlinear dynamic solvers. Based on this unique industrial validation work, guidelines are proposed to improve the state-of-the-art modelling of nonlinear dynamics in structures with friction contacts.

Scaled Shaking Table Tests Simulating the Damage of the School Gymnasium in the 2016 Kumamoto Earthquake

The transverse out-of-plane response of the RC moment frame on the arena floor damaged a school gymnasium that was expected to function as a natural disaster shelter. It was composed of heavy RC substructure and a light steel roof, which partially collapsed, resulting in the facility's permanent destruction in the 2016 Kumamoto earthquake. This study describes scaled shaking table tests that simulate out-of-plane response-induced damage to the RC moment frame of the school gymnasium during the 2016 Kumamoto earthquake and verifies the damage mechanism proposed by the previous numerical simulation and the efficiency of a response control by the friction damper support. Furthermore, the study validates two methods for evaluating the response of the RC moment frame and the overall buckling strength of the roof truss member with semi-rigid joints.

Tradeoff between mass sensitivity and performance in quasi-zero stiffness vibration isolators

Quasi-zero stiffness isolators are a promising technology to reduce vibration transmission over a large frequency range while maintaining passive operation and low cost. Many different types of QZS isolators have been demonstrated utilizing a variety of mechanical, pneumatic, and magnetic components. While some of these types have their own unique challenges, other challenges are more general. Two of these challenges are mass sensitivity and hysteresis in the load-deflection curve caused by snap-through buckling, friction, or structural damping. This work investigates the impact of force-deflection hysteresis on isolation performance through experimental techniques. Results show that increasing hysteresis reduces the mass sensitivity but worsens the isolation performance at low frequencies. A tradeoff must be made between these two aspects but can be overcome by shifting the QZS region to difference forces. A simple method to achieve this adaptability exists for certain types of QZS structures, therefore enabling a variety of practical applications within a certain design window.

Stabilization of a thermoelastic diffusion system of type II damped and delayed

ABSTRACT The present paper is devoted to the study of exponential stabilization of a one-dimensional thermoelastic diffusion problem of type II for isotropic and homogeneous materials with frictional damping and time delay. The system of equations under consideration is a coupling of three hyperbolic equations involving three variables considering frictional damping and time delay on each variable. Using semigroup theory, we prove the well-posedness by the Lumer–Phillips theorem and the exponential stability by exploring the dissipative properties of the linear operator associated with the model through the Gearhart–Huang–Pruss theorem.

Review on self-centering damper for seismic resilient building structures

In recent years, major earthquakes in China, Chile, New Zealand and Japan caused many building structures severely damaged, which must be overhauled or rebuilt. Therefore, how to improve the seismic resilience of building structures has been widely concerned. The energy dissipation dampers are proposted to install in some parts of the structure to produce large damping and dissipate much seismic energy input. While, the disadvantage of these traditional dampers is that they cannot automatically restored to the original position after the earthquake, and the residual deformation may result in huge economic losses. In recent years, researchers proposed to combine self-centering devices with traditional dampers to obtain self-centering capacity in addition to energy dissipation capacity, and the self-centering dampers can effectively avoid post-earthquake damage of the structure. This paper first reviews the mechanical characteristics and development of traditional dampers, including metal yield dampers, friction dampers, viscoelastic dampers, viscous fluid dampers, etc. Then, the research of self-centering dampers is summarized according to the types of self-centering devices, including shape memory alloy (SMA) type, steel tendon and strand type, and mechanical spring type. Further, the experimental research and seismic design methods of structures with self-centering dampers are reviewed, as well as the classic engineering applications of different dampers. Finally, the future directions need to be concerned in the further research are mentioned, which is benefical to the future engineering popularization and applicaition of self-centering dampers.

A numerical model for non-linear shear behavior of high damping rubber bearings

The dynamic behavior of isolated structures is strongly controlled by the force–deformation constitutive behavior of the isolators. Among the different types of existing isolation devices, High Damping Rubber Bearings (HDRBs) are commonly used in practice, which behavior is highly non-linear and difficult to model analytically. Consequently, this article proposes a simple, but sufficiently accurate, mathematical model for simulating the non-linear shear behavior of HDRBs under large deformations, and an estimation procedure for its parameter values using the geometrical features and mechanical characteristics of the device. First, we briefly describe the phenomena observed in the experimental test data, as well as other phenomena not observed within the range of experimental deformations. Then, the mathematical formulation is presented, which is based on the consideration of two components connected in parallel, a hyperelastic spring and a dissipative component. The governing equation for the former is derived from the expanded formulation of the Mooney–Rivlin model for isotropic hyperelastic materials, and the latter from a Bouc-Wen model with hardening. A novel model is included to account for stiffness degradation, including scragging and Mullins effects, which is developed from experimental data of 924 tested devices. The proposed model fits well the experimental test results of HDRBs with different geometric features and material properties. Based on the evolution laws for the different variables, the model can be successfully used in structural dynamic analysis. To facilitate model calibration, a statistical estimation procedure is proposed to reduce the 17 force–deformation constitutive model parameters of the isolator to 9 unknown parameters, which are computed from the geometric features of the device and mechanical characteristics of the rubber material. This makes the calibration of the force–deformation constitutive model parameters feasible. The estimation procedure successfully predicts the behavior of an average device within a batch of HDRBs, showing good agreement with two different experimental datasets.