Friction Damper Research Articles

Seismic performance of glulam frame with friction damper and column shoe: Experimental investigation and simplified numerical model

Resilient timber structure is a new branch of structure design. To reduce seismic damage of timber structures, an innovative resilient glulam frame (IRF) with friction dampers and column shoes was proposed in this paper. The IRF was connected by use of beam-to-column joints with friction dampers and column-base joints with column shoes. An IRF specimen and a conventional glulam frame (CF) specimen, with a scale ratio of 1:2, were tested under reversed cyclic load. The failure modes, hysteretic curves, stiffness degradation, and energy dissipation capacity of the specimens were obtained. Results indicated that the IRF was low-damage except replaceable Shape Memory Alloy (SMA) strips tensile failure. The load-carrying capacity of IRF did not significantly change compared to the CF specimen, but the energy dissipation capacity was enhanced by approximately 100%. A simplified numerical model of timber frames was developed and validated, and then the time-history analysis of multi-story IRF structure was performed. It was further demonstrated that the adoption of IRF significantly reduced the maximum story drift and residual drift of structures, especially during severe earthquakes.

Effects of the Seal Wire on the Nonlinear Dynamics of the Aircraft Engine Turbine Blades

Abstract Complicated systems made of multiple components are known to be difficult to model, considering their solutions can change dramatically even with the slightest variations in conditions. Aircraft engines contain such complicated systems, and some components in aircraft engines' turbines can cause significant changes in the system's overall response. Hence, this study is focused on investigating the behavior of a turbine blade of an aircraft engine and the effects of the contact between the blade and the seal wire on the dynamics of the blade-disk system. The investigation is performed via various numerical simulations in time and frequency domains. One sector of the bladed disk is modeled using the finite element method with the lock plate and the seal wire imposing cyclic symmetry boundary conditions in the static, modal, and frequency domain forced response analyses. In time domain analyses, the cyclic symmetry is replaced with simplified displacement restricting boundary conditions. The time domain analysis contains steady-state forced responses of the system. The results show that contact with the seal wire is not a major source of nonlinearity and damping. The contacts with the lock plate contribute more to the vibration damping than the seal wire. However, compared to the contacts at the root of the blade, both components remain less significant with regard to frictional damping and nonlinearity.

Damping investigation for multi-Layered riveted cantilever beams

The damping of a vibrating structure is prominent to avoid its catastrophic failure due to resonance. Layered and riveted structures are introduced to provide dry frictional damping. Optimization of different parameters of a dynamic structure that will damp out the amplitude to the maximum extent is required. This article investigates the damping mechanism of the multi-layered riveted cantilever beams for the variation of its different parameters using response surface methodology (RSM). Initially, experiments were done on riveted cantilever beams using a frequency response function (FRF) analyzer. Later, the parameters that affect the damping ratio together with the corresponding damping ratio values were utilized in the full factorial design to obtain the possible runs using Minitab-19.0 software. Next, RSM was executed on these runs. The significant parameters and their interactions that affect the damping ratio were discussed. Keeping significant parameters only, the reduced mathematical model for determining the damping ratio was also obtained. Moreover, the interaction, main effects plots, and the optimum values of parameters for minimizing and maximizing the damping ratio were obtained. Finally, validation of damping ratios from full, reduced mathematical regression models obtained using RSM, and the predicted damping ratios using artificial neural networks (ANN) was done using that from FRF analyzer, and ANN is proved as a more accurate prediction technique when compared with the RSM technique in the prediction of damping ratios of multi-layered riveted cantilever beams.

Damping in stay cable with damper: Practical universal damping curve and full-scale measurement

This paper includes two main parts which are the development of a universal damping curve for cables of cable-stayed bridges with dampers and a full-scale measurement of cable damping. In the first part, the universal damping curve is derived for cables with viscous dampers or High Damping Rubber (HDR) dampers. The proposed damping curve is a single curve which incorporates several cable-damper parameters like cable bending stiffness, boundary conditions at cable ends (hinged, fixed or restraint ends), damper stiffness, damper support stiffness and added negative stiffness. A numerical approach by a finite difference method (FDM) is also developed to verify the proposed universal damping curve. In addition to FDM, the accuracy of the proposed curve was confirmed with damping formulations in literature over ten different damper types. The results showed a good agreement of estimated damping between proposed damping curve and others. Additionally, a significant improvement in estimating cable damping was observed through two available full-scale tests, which compared the results between proposed curve and current curve. The second part in this study presents a full-scale measurement of cable vibration and a real application of the proposed damping curve for the identification of damping in cables of Shinminato Bridge (cable lengths from 100 to 200 m). Both HDR and viscous dampers were used for the cable vibration control of the bridge. The results of damping analysis indicated that the HDR damper effectiveness was higher than 0.7 whereas this effectiveness was smaller than 0.4 for the viscous damper.

Experimental testing of GCr15 bearing steel with different surface treatments as passive friction energy-dissipative shims

The seismic performance of buildings can be improved by adding supplemental damping using friction dampers. The friction behavior of the metallic shims becomes more stable with increasing surface hardness ratio between the friction pair. However, as hardness increases, metallic materials tend to become more brittle, which increases the risk of accidental failure. This study investigated the performance of a friction energy dissipator using bearing steel (GCr15) treated by a grinding-strengthening process, a special manufacturing technology for bearings steel commonly used in mechanical engineering. Two base materials, Q355 and B450, were additionally compared with GCr15. Each base material used three different surface treatments, i.e., cleaned surface (CS), sand-blasting (SB), and grinding-strengthen (GS) treatments. The surface hardness of Q355-GS, B455-GS, and GCr15-GS increased by 13.62 %, 17.38 %, and 19.71% compared to their base materials, while sand-blasting didn’t have an increased effect on surface hardness. The nine specimens were quasi-statically tested to investigate the effect of surface treatment on the friction behavior of the metallic shims. For the three Q355-like and three B450-like specimens, the wear mechanism mixed abrasive and adhesive wear. The GCr15-CS experienced contact fatigue failure, while the GCr15-SB and GCr15-GS exhibited abrasive wear resulting in standard rectangular hysteretic loops with a high degree of coincidence. The friction performance of GCr15-GS was the best among the nine friction shims, because it has less loss in friction coefficient and strength during fatigue loading, the least fluctuation in bolt force, and the smallest degradation and coefficient of variation in friction strength.

Wood for guitars II : How the material properties of a spruce guitar top influence the tonal quality of the guitar

Pacific Rim Tonewoods is the world’s largest supplier of spruce tonewood for the soundboard and bracing of the acoustic guitar. A previous study from our research group (JASA 2019) has demonstrated the importance of (1) longitudinal Young’s Modulus and (2) density of the spruce soundboard on the tonal quality of steel string guitars. This study used pairwise comparisons of listener preference to rank a particular guitar model (the Taylor 814ce). The present study updates this previous work, adding a third material property: internal friction (damping) of the soundboard, as measured by the logarithmic decrement of the resonating spruce billet. In addition, objective data on tonal quality were measured on guitars recorded in an anechoic chamber at the Technical University of Dresden, Germany. Spectral sequence analysis, transfer function, and tone decay were measured, and are correlated with the perceptual data. With these data, we can demonstrate the relative importance of the three material properties on the “performance factors” of guitar quality, such as volume, responsiveness, timbre, attack, and sustain. In doing so, we hope to provide the lutherie community with a predictable means of integrating tonewood material properties into their designs, in order to consistently produce their desired tonal outcomes.

Vibration Analysis and Suppression Methods of the Wing of an Underwater Glider

Vibration analysis and suppression methods are widely studied in mechanical systems. In this study, rubber damping materials were employed to enhance the vibration suppression performance of the wing of an underwater glider. A finite element model was established to analyze the vibration characteristics of the wing. The excitation characteristics of the actuator were determined by experimental methods. The wet mode shapes and corresponding frequencies of the wing of the underwater glider were investigated. The vibration suppression performance of rubber damping materials with different thickness and hardness was discussed. The optimal parameters of the rubber pads on various positions were provided to minimize the excitations from the actuator. This paper provides valuable insights for developing vibration suppression techniques for the wings of an underwater glider.

Seismic performance of self-centering braced rocking frame with novel self-centering friction dampers characterized by low-secondary stiffness

Research has demonstrated that self-centering energy dissipation dampers (SCEDs) are effective devices for reducing the residual deformation of structures after a strong earthquake. However, the equivalent damping ratio of SCEDs is relatively lower than that of conventional dampers such as viscous dampers, BRBs, or friction dampers. According to displacement spectrums, the lower damping ratio could result in a lower natural period and higher equivalent stiffness of structures for a given displacement target, and thus the structures could attract more earthquake action to the structures. To alleviate the problem, a novel self-centering damper composed of elastic post-buckling plates and adjustable friction devices (PBSCFD) was proposed and used as the self-centering braces for a self-centering braced rocking frame (SBRF) structure for example. First, the theoretical force-displacement relationship of the PBSCFD was derived based on its configuration and work principle, and then a scaled PBSCFD was manufactured and tested to investigate its mechanical properties and verify the theoretical constitutive model. Subsequently, the SBRF structure with PBSCFDs was designed by the direct displacement-based seismic design method (DDBD), and its seismic performance was examined by elastic–plastic time-history analysis. Finally, the effects of the secondary stiffness ratio of the self-centering braces on seismic mitigation of the SBRF structure were investigated. The results show that PBSCFDs is characterized by classic self-centering behavior with low secondary stiffness, which can be designed to obtain significant control effects on the base/interstorey shear and interstorey drift ratio of the SBRF structure under rare and extremely rare earthquake compared to the conventional SCEDs with significant secondary stiffness.

Numerical and Theoretical Analyses of Friction-Oval Section Mild Steel Rod Composite Dampers

In order to improve the seismic and energy dissipation capacity of the whole structure, a friction-oval section mild steel rod composite damper (FOSRCD) was proposed, and its working principle was clarified. The finite element analysis of FOSRCD was carried out, and the effects of friction, frequency and displacement on the damper performance were studied. Considering the structural characteristics of FOSRCD and the mechanical models of friction dampers and mild steel rod dampers, the restoring force model of the composite dampers was proposed and compared with the numerical simulation results. The results showed that the FOSRCDs had good performance and could provide stable energy dissipation capacities in both directions, with the energy dissipation coefficient exceeding 2.3 and the equivalent damping ratio exceeding 0.37. The theoretical analysis results were in good agreement with the numerical simulation results, which verified the theoretical restoring force model; the FOSRCDs make full use of the friction energy dissipation and the shear and bending energy dissipations of the mild steel rod. It enables the two dampers to work together to achieve the purpose of multi-stage energy dissipation. FOSRCD’s structure allows it to dissipate energy in both the X- and Y-directions. The composite dampers have a variety of restoring force models and can be utilized in a wide range of practical applications.

Global attractors for porous elastic system with memory and nonlinear frictional damping

This paper is concerned with the long‐time behavior of a porous‐elastic system with infinite memory and nonlinear frictional damping. We prove that the dynamical system generated by the solutions of the equations is dissipative, only under the basic conditions (for the well‐posedness) on the memory kernel and the frictional damping . Further, we come up with a condition on , being more general than the usual one (with a positive constant ), under which we prove the asymptotic smoothness and quasi‐stability (the latter needs some stronger condition on ) of the dynamical system. Accordingly, we obtain the existence of a global attractor and show the finite dimensionality of the attractor.

On the vibration control of semi-active friction dampers with piecewise defined contact geometries

Suppressing unwanted vibrations has been a major challenge for more than a century. Semi-active dampers offer a compromise between the high energy costs of active solutions and their increased flexibility. A nonlinear system that utilizes dry friction and piecewise defined contact geometries is used as the basis for a semi-active damper. Furthermore, a slow frequency-based control that does not solely rely on dissipation is considered and compared to the conventional Skyhook Control. Simulations show that the strategy is an effective approach for vibration reduction.

Experimental and Numerical Study on Hysteretic Behavior of Frictional Energy Dissipation Steel Truss.

In this study, the hysteretic behavior of a novel frictional energy dissipation steel truss (FED-ST) is examined. The proposed FED-ST incorporates a friction damper with brass as the friction material into the top chord of traditional truss to improve the seismic performance of the staggered truss framing systems. A FED-ST specimen with a scale of 1:2.5 was subjected to a hysteresis test. The hysteretic behavior, ductility, and energy dissipation capability were analyzed considering the test findings. It is demonstrated that the FED-ST specimen has favorable ductility and an energy dissipation capacity that is 7.3 times more than that of a conventional truss specimen. The test findings were then used to compare and validate a finite element (FE) model. The FE analysis results are in strong agreement with the test results, demonstrating the validity of the modeling approach. To further investigate the impact of the cover plate width on the behavior of the FED-ST, preliminary parametric research was also carried out.

On the energy decay of a viscoelastic piezoelectric beam model with nonlinear internal forcing terms and a nonlinear feedback

In this paper, we consider a piezoelectric beam model with nonlinear source terms and investigate the interaction between a viscoelastic damping and a nonlinear frictional damping. Under general assumptions on the relaxation function and the nonlinear feedback, we establish explicit formulae for the energy decay rates of this system and prove that the energy decays at a rate dictated by the weaker damping. Our results substantially improve some earlier related results in the literature.

Seismic design and evaluation of controlled rocking outrigger core wall (CROCW) system using equivalent energy design procedure (EEDP)

In this paper, a novel earthquake resilient reinforced concrete core wall system named the controlled rocking outrigger core wall (CROCW) system is proposed. The CROCW consists of two high-performance seismic force resisting systems along its two principal axes. Along one principal axis is the controlled outriggered rocking wall (CORW), where an outrigger is situated at the roof and controlled rocking at the base. Dampers are incorporated within the outrigger and the rocking base to allow CORW to provide stable energy dissipation during earthquake excitation. Along the other principal axis is the self-centering coupled wall (SCCW). In the SCCW system, the self-centering friction dampers are incorporated within the coupling beams to dissipate the earthquake energy, while the base is designed to rock. The proposed CROCW system can be designed using the novel equivalent energy design procedure (EEDP). Four prototype buildings (two different building heights and two different building sites) were designed using the EEDP presented in this paper. The detailed nonlinear time history analysis was conducted to assess the performance of CROCW system. The results demonstrate that the CROCW system can be efficiently designed using the EEDP procedure to achieve a superior performance and low damage response at multiple levels of earthquake shaking intensities.

Investigation on vibration mitigation methodology with synergistic friction and electromagnetic damping energy dissipation

Investigation on vibration mitigation methodology with synergistic friction and electromagnetic damping energy dissipation

Improvement of the Analytical Model of an Energy Dissipator and Validation with Experimental Tests of a Prototype

An improved numerical formulation for a self-centering frictional damper is presented. This was experimentally validated through quasi-static tests carried out on a steel-made prototype of the damper. Its design is ad hoc for implementation in the seismic protection of industrial storage racks. The conceptual model of the device was adjusted to the prototype built. The formulation of the analytical model, a parametric analysis of it, and the validation with experimental results are presented. The improvement of the model presented here explicitly considers elements included in the prototype, such as a system of load transmission rings and the friction between all of the components that slide or rotate relatively. In the experimental validation, the parameters of the improved model were determined. The numerical predictions for the improved model were contrasted with those obtained with the original one and with the experimental results. This demonstrates that the improvement leads to a better adjustment of the numerical predictions concerning the experimental measurements, which is useful for nonlinear analysis. The device withstood forces of considerable magnitude in addition to dissipating enough energy per load–unload cycle to be effective in the seismic protection of industrial storage racks.

Sliding-mode observer-based fault diagnosis and fault-tolerant control of the main drive system of rolling mill

In order to address the problem that the main drive system of rolling mill is easily affected by the impact of biting steel, and considering the nonlinear friction damping and the external perturbations of the main drive system of rolling mill during the rolling process, a fault model of the main drive system of rolling mill is established, and a fault diagnosis and fault tolerance control method of the main drive system of rolling mill based on the nonlinear sliding-mode observer is proposed. In order to suppress the influence of external perturbations on fault diagnosis, a nonlinear sliding-mode observer is constructed for fault diagnosis and fault reconfiguration of the system, and the robustness of the observer to fault reconfiguration is improved by using the sliding-mode control rate [Formula: see text], and the stability of the designed nonlinear sliding-mode observer is proved using Lyapunov’s stability theorem. In order to ensure that the system can operate normally even after a fault occurs, a reference model is designed, and a new controller is redesigned for fault-tolerant control of the system by adding a fault compensation term to the original control scheme using fault estimation information. Through the simulation study of the main drive system of stand F4 of 2030 mm cold rolling mill, it is verified that the observer can accurately track the system state with an angular velocity error of 2.45% and detect and estimate the main drive system failure of rolling mill with an estimation error of no more than 0.04% after a fault occurs; the fault-tolerant control of the main drive system of rolling mill is carried out by using the fault information to restore the system to its normal state, and the angular velocity error is 1.89%.

The Vibration Attenuation Characteristics of Dynamic Vibration Absorbers Array for Tuned and Mistuned Bladed Disk

Abstract Dynamic vibration absorbers array (DVAA) is a newly developed and promising technique for vibration attenuation of integrally bladed disk (blisk) by mounting underneath the disk. In this paper, the vibration attenuation characteristics and energy dissipation mechanism of DVAA for tuned and mistuned blisk are parametrically studied, where the viscous and frictional damping are both considered. The lumped parameter model of a blisk is employed for the convenience of parametrical study. Analytical power flow formulas within the blisk–DVAA system are derived to characterize the dynamic interaction between blisk and DVAA. Four typical modes of a blisk with different nodal diameters and deformation characteristics are selected to evaluate the performance of DVAA. Then, the effects of the mass ratio, the frequency ratio and the damping ratio of DVAA on the vibration of tuned and mistuned blisk are addressed. Numerical results show that a light DVAA can significantly mitigate the resonant amplitudes of the tuned and mistuned blisk. Such damper is effective for the modes with different modal characteristics and can provide robust vibration attenuation performance against random mistuning.

An Analytical Study on Using Maxwell-Coulomb Friction Damper to Mitigate Quasi-Static Response of SDOF Systems

Excessive cumulative stroke in the longitudinal movement of long-span suspension bridge can led to premature fatigue damage in the bridge's connecting components. However, existing control devices, like viscous damper, remain suboptimal. This paper aims to reveal the underlying mechanism of cumulative stroke control and find an effective control method to address this issue. Firstly, the statistical and frequency characteristics of longitudinal displacement were analyzed based on a 24-hour field measured data set. Secondly, the cumulative stroke control performance of nonlinear viscous damper was evaluated with a SDOF system, uncovering the reasons for their low efficiency in controlling cumulative stroke. Thirdly, the Maxwell-Coulomb friction damper was introduced to control the excessive cumulative stroke, and its effective control performance was validated. Finally, a novel parallel model combining viscous dampers and friction dampers was proposed to leverage the superior performance of friction damper in controlling the cumulative stroke under daily operation condition, while also harnessing the seismic response mitigation capacity of the viscous damper. This research enhances the understanding of cumulative stroke control in long-span suspension bridges and presents an innovative control method by introducing the Maxwell-Coulomb friction damper, highlighting its potential for practical application in bridge engineering.

Modelling and experimental identification of spring-damping properties of the off-road vehicle rubber tracks, rubber belts, and rubber-bushed tracks subjected to flexural vibrations

In the article, a model for predicting the energy losses caused by the flexural vibrations of rubber tracks, rubber belts, and rubber-bushed metal link-tracks for off-road vehicles is proposed, and a test stand and an experimental procedure are developed to identify the mechanical parameters of this model. The track or belt is represented by a chain of discrete rigid links connected by revolute joints, and a discrete spring-element is placed in parallel with multiple Maxwell-elements in each joint to capture the flexural rigidity and damping of the real track or belt. The mechanical parameters of the joint are found by testing real tracks or belts under cyclic bending. The models consisting of three, four, or five Maxwell-elements per joint are the most successful in predicting the response of a sample rubber track to cyclic bending. The spring-damping properties of tracks and belts identified with the method discussed herein can be applied in simulation studies on the interaction of tracked vehicles and soil. Furthermore, vehicle elements such as rubber bushings for suspension systems, rubber torsion springs, and oil-filled and rubber torsion dampers can be tested with this method to find their spring-damping properties required by vehicle dynamics simulations.