Design Of Damper Research Articles

Nonlinear dynamics and stability of the supercritical tail rotor drive shaft with dry friction damper

Due to its high power-weight ratio and low maintenance cost, the supercritical tail rotor drive shaft has attracted more and more attention in helicopter design. The dry friction damper is specifically designed to suppress the excessive vibration of the supercritical shaft when passing through the critical speed. The stability of the shaft/damper system and the vibration damping efficiency are affected by the nonlinear rub-impact process between the shaft and the damper. In order to reveal the damping mechanism and the stability of the shaft/damper system, and to guide the design of the damper, a nonlinear dynamic model of the system is established. Typical responses for systems with different rub-impact stiffness, clearance, rub-impact friction coefficients and critical dry friction forces are obtained by numerically solving the nonlinear governing Equations. The dynamic characteristics and stability of the system are investigated by drawing the bifurcation diagrams, whirling orbits and time history diagrams. It is demonstrated that there exists three forms of rub-impact between the shaft and the friction damper, namely, the forward full annular rub-impact, forward local annular rub-impact and backward local annular rub-impact. The unstable backward full annular rub-impact is not present. With an increasing critical dry friction force and rub-impact friction coefficient, the rub-impact system will easily evolve into the backward local annular rub-impact region which decreases the system's stability. A decreasing clearance or an increasing rub-impact stiffness will induce a similar effect, but the influence of rub-impact friction coefficient and critical dry friction force is more obvious. Moreover, the effects of these four device parameters on the transcritical vibration amplitude are also derived, which will give a useful guidance for the design of the dry friction damper.

Design and simulation of linear transverse flux eddy current damper for vehicle suspension

An eddy current damper, which partially converts vibration energy to heat one in order to reduce vibration, is studied and applied in fields of mechanism, vehicle etc. This paper presents a novel Linear Transverse Flux Eddy Current Damper(LTFECD), which is used in vehicle suspension system. The transverse flux, which means the direction of up-and-down movement of plunger is vertical relatively to the plane of magnetic field, is a highlight of the design. It facilitates the mechanical structure, and the volume space is used effectively and sufficiently. The copper winding is applied, which provides an enhanced force combined with eddy current damping force. The copper winding can also adjust the damping force accordingly. A three-dimensional model is designed and electromagnetic simulation with finite element software is performed. The model of a single wheel vehicle suspension is built and simulated with the LTFECD. The result of design and simulation shows that the LTFECD characteristics can meet the requirement of vehicle suspension, and the suspension with LTFECD can reduce the vertical acceleration of sprung mass body. The improvement of design is discussed for engineering application.

Study on test of oil gap and damping of diesel reel spring-type torsional vibration damper

Torsional vibration damper plays an important role in reducing torsional vibration of diesel crankshaft. Reel spring-type torsional vibration damper is widely used in high-power diesel with medium-high speed. By using this kind of damper, shaft natural frequency can be greatly adjusted, and the torsional amplitude of crankshaft free end can be reduced. Crankshaft stress can be decreased as well. The inertia, stiffness, and damping are the characteristic parameters on reel spring-type damper design. Especially, damping is a significant parameter closely related to structure dimension to reducing torsional vibration. In this paper, a free modal test of reel spring-type damper is carried out, and it is concluded that the damping of reel spring-type damper decreases with the increase of the side plate oil gap. By establishing the damping calculation model of the damper, using fluid theory and CFD simulation analysis method, the accuracy of the test results is proved. This conclusion provides a basis for the design and optimization of reel spring-type torsional vibration damper.

A design of magnetorheological-fluid elastomer damper for engine mount

A design of magnetorheological-fluid elastomer damper for engine mount

Optimal design of dampers in seismic applications utilizing the MOPSO algorithm

New technological developments in engineering present an opportunity for improved efficiency in structural design through optimization. High-performance computing resources reduce the time needed for computational calculations. Concurrently, optimization algorithms have greatly evolved to provide the opportunity to solve complicated nonlinear engineering problems that typically include several interrelated, and often conflicting, objectives under a set of constraints. This research proposes a method for the optimal design of viscous dampers in seismic applications utilizing the multi-objective particle swarm optimization (MOPSO) algorithm. The MOPSO, with its inherent metaheuristic approach and geographically-based adaptive grids, effectively discovers global and diverse non-convex solutions. To further improve the efficiency and quality of the search in the milieu of an engineering application, we have extended MOPSO by introducing constraints on objective functions and implementing parallel computing. Additionally, this research provides recommendations on how to efficiently generate reliable solution sets by proper selection of objective (cost) functions and adequate set-up of MOPSO input parameters. These recommendations are derived from a series of sensitivity studies. The proposed method is verified by utilizing an engineered solution of a viscously damped moment frame. It was found that under the same set of constraints and performance objectives, MOPSO produces a solution set that contains outcomes that are superior to the engineered solutions. For example, the MOPSO solution set contains outcomes that reduce demands on dampers (force and stroke) while maintaining engineering demand parameters, generating construction savings as a result of the reduced manufacturing costs of dampers.

Eddy current loss estimation for direct drive wind turbine generators with superconducting excitation winding by numerical and analytical models

AbstractDirect drive wind turbine generators with superconducting excitation winding are studied with focus on the electromagnetic damper design. A semi‐analytical eddy current model is built for parametric design studies based on a vector potential approach. The considered generators employ open stator slots and exhibit strong saturation effects, so that an analytical expression for the source terms is not adequate. Whilst the field equations are solved analytically, an equivalent current loading, accounting for slotting effects and saturation, is obtained by magnetostatic models applying the 2D finite element method (FEM). The proposed framework for the extraction of the current loading is universal and may also be applied to other machine types (e.g., permanent magnet synchronous machines, [PMSM]). In relation to transient FEM models, a considerable time‐saving can be achieved, which is particularly beneficial in case of large models, for example, in case of fractional slot windings or intermittent feeding schemes. The eddy current loss in warm and cold rotor parts in a direct drive generator in the 7 MW power class are computed with the semi‐analytical and transient 2D FEM models under variation of the damper geometry and the stator winding configuration. Minimum damper dimensions as well as constraints regarding applicable stator windings are derived.

Optimization Analysis of Hysteretic Dampers Design Parameters on Seismic Performance of a Novel Self-Centering Prefabricated Concrete Frame

ABSTRACT To study the effect of the design parameters of dampers on seismic behaviors of the novel self-centering prefabricated concrete (SCPC) frame joint, eight pseudo-static loading tests with five sizes of dampers were conducted. Furthermore, three sizes parameters of dampers are applied on the seven-story prefabricated frames which are designed by the displacement-based method. Elastoplastic time-history analyses of three buildings are conducted at the DBE and MCE levels, respectively. Finally, the displacement-based seismic design method of the novel frame is implied to be effective, and the optimal design parameters of the proposed hysteretic damper for the novel SCPC frame are obtained.

Optimization design of multiple tuned mass dampers for semi-submersible floating wind turbine

Compared with spar-buoy and tension-leg platform floating offshore wind turbines (FOWTs), the flexibilities in operating water depth promote generalized applications of semi-submersible FOWT. In this study, a passive structural control strategy of a tuned mass damper (TMD) design method for a semi-submersible FOWT was implemented to mitigate FOWT responses under combined winds and waves. A reduced coupled model of a semi-submersible FOWT with TMDs mounted in the nacelle and platform was established based on D'Alembert's principle. Sequentially, the parameters of the reduced coupled model were estimated using the Leven-Marquardt (LM) algorithm, and the simulation accuracy was validated by comparison with the related fully coupled model in OpenFAST. To minimize the standard deviation of tower-top displacement, the design of the TMD was optimized by genetic algorithm (GA) based on the reduced coupled model, and three different TMD configurations were proposed. Furthermore, the effectiveness of the optimized TMDs was evaluated based on a fully coupled model in OpenFAST under typical sea states. The optimized nacelle and platform TMDs could effectively suppress the tower fundamental and platform pitch frequencies, respectively. Moreover, improved mitigation effects were observed using the optimized multiple TMDs, which comprise local dampers installed in the nacelle and platform.

Ultra-high mechanical damping during superelastic bending of micro pillars and micro beams in Cu-Al-Ni shape memory alloys

Mechanical spectroscopy techniques and internal friction measurements have historically offered a key contribution to the understanding of fundamental mechanisms of defects mobility and phase transformations in many kinds of materials. Nowadays, at the beginning of the millennium, the apparition of the new paradigm of nanotechnology reveals new unforeseen properties of the materials at the nano-scale. Nevertheless, instrumented nanoindentation appears as a new mechanical spectroscopy technique to approach the measure of internal friction at the nano-scale through the direct evaluation of the loss factor η. Indeed, nano compression tests on micro and nano pillars recently measured ultra-high mechanical damping in several Cu-based shape memory alloys (SMA). A step forward is given in the present work, approaching the design of potential micro dampers of SMA working in bending and torsion modes. Several micro devices were milled by focused ion beam (FIB) technique, on [001] oriented single crystals of a Cu-Al-Ni SMA. Ultra-high mechanical damping is demonstrated during superelastic bending of square section micro pillars by in-situ testing inside the scanning electron microscope, using a flat apex 60º-conical indenter in off-axis mode. Then, a series of micro beams and micro cantilevers were designed and milled by FIB, and tested using instrumented nanoindentation equipment by applying the load in bending mode as well as in a mixed bending-torsion mode during off-axis tests. In all cases, the internal friction, or mechanical damping per cycle and per unit of volume, was calculated from the measured load-displacement curve. Superelastic cycling during bending of micro pillars, micro beams and micro cantilevers, exhibits stable and reproducible ultra-high mechanical damping with a loss factor η > 0.1. These results paved the road for designing micro-dampers of Cu-based SMA, able to work in different mechanical modes of compression, bending and torsion, opening the way for many applications of mechanical damping at the nano-scale.

Transient Temperature Field Simulation Analysis of Magnetorheological Grease Torsional Vibration Damper

To reveal the transient temperature distribution pattern inside the magnetorheological grease (MRG) torsional vibration damper and explore the relationship between the current and the internal temperature of the device, the transient temperature simulation analysis of the MRG device was conducted in this paper. Firstly, a theoretical heat transfer model of MRG torsional vibration damper with dual heat source structural feature was established based on the Bingham constitutive model and the temperature-dependent viscosity characteristic of MRG. Then, the transient temperature field model of the MRG torsional vibration damper was developed by the finite element method, and the temperature field distribution and temperature-time variation characteristics of the MRG torsional vibration damper were analyzed. The simulation results show that the temperature rise of MRG in the working domain is the fastest, and the temperature rise rate slows down after the device works for 5.4s. The simulation results reveal the internal temperature distribution and temperature rise characteristics of the torsional vibration damper, which provides a theoretical basis for the structural optimization and control strategy design of MRG torsional vibration damper considering temperature factor.

Multiobjective Optimization Design for a MR Damper Based on EBFNN and MOPSO

The structural parameters of the magnetorheological (MR) damper significantly affect the output damping force and dynamic range. This paper presents a design optimization method to improve the damping performance of a novel MR damper with a bended magnetic circuit and folded flow gap. The multiobjective optimization of the structural parameters of this MR damper was carried out based on the optimal Latin hypercube design (Opt LHD), ellipsoidal basis function neural network (EBFNN), and multiobjective particle swarm optimization (MOPSO). By using the Opt LHD and EBFNN, determination of the optimization variables on the structural parameters was conducted, and a prediction model was proposed for further optimization. Then, the MOPSO algorithm was adopted to obtain the optimal structure of the MR damper. The simulation and experimental results demonstrate that the damping performance indicators of the optimal MR damper were greatly improved. The simulation results show that the damping force increased from 4585 to 6917 N, and the gain was optimized by 50.8%. The dynamic range increased from 12.4 to 13.2, which was optimized by 6.4%. The experimental results show that the damping force and dynamic range of the optimal MR damper were increased to 7247 N and 13.8, respectively.

Design and modelling methodology for a new magnetorheological damper featuring a multi-stage circumferential flow mode

Design and modelling methodology for a new magnetorheological damper featuring a multi-stage circumferential flow mode

Optimal Design of MR Dampers by Considering Design Criteria and Dampers Distribution Effect

Optimal Design of MR Dampers by Considering Design Criteria and Dampers Distribution Effect

Optimal Design of a Passive SMA Damper to Control Multi-modal Stay Cable Vibrations

Optimal Design of a Passive SMA Damper to Control Multi-modal Stay Cable Vibrations

Design and testing of a steering damper for motorcycles based on a shear-thickening fluid

This work is intended to show the feasibility of the utilisation of a shear-thickening fluid as working fluid in a steering damper for motorcycles. To that end, a prototype of a steering damper has been designed and then tested under different working conditions. Unlike conventional models, this new steering damper bases its performance on the combination of very simple rod geometries and a shear-thickening fluid of different concentrations. The experiments carried out with a test machine demonstrate that, despite its simplicity and reduced cost of manufacturing, the prototype shows similar behaviour to a conventional high-performance racing steering damper. The Bouc–Wen model has been used to reproduce the behaviour of the shear-thickening fluid-based damper prototype. The parameters of the model have been obtained following an optimization process to fit the model’s response to the experimental data when exciting the damper at different speeds. Results show that the damper’s behaviour can be properly modelled with a single combination of parameters.

엔진 마운트 최적 댐핑 제어와 MR 마운트에의 적용

Passenger ride comfort is an integral component of any road vehicle. Ride comport is impacted by vibration resulting from road roughness of low frequency, and also engine vibration of high frequency. The engine mount is an essential component, which acts as a vibration isolator from unwanted vibration. However, vibration isolation requires conflicting design criterion, such as high damping in low frequency range, and low damping in high frequency range. The purpose of this study was to develop a new optimal damping design method for engine mounts based on minimizing HSUB∞/SUB-norm. The damping minimizes HSUB∞/SUB-norm of displacement and force transmissibilities in the wide-frequency vehicle operating range. The proposed optimal damping control was applied to a Magnetorheological (MR) engine mount, to investigate the vibration isolation performance. The feasibility of the proposed method is verified, with some numerical simulation examples.

Optimal Tracking and Resonance Damping Design of Cascaded Modular Model Predictive Control for a Common-Mode Stabilized Grid-Tied $LCL$ Inverter

A cascaded modular model predictive control (MMPC) method is designed for a modified nonisolated <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$LCL$</tex-math></inline-formula> grid-connected inverters to provide resonance damping, improved dynamic performance, and leakage current attenuation capabilities. The continuous control set model predictive control strategy is applied for the proposed method. The active damping function of the inner loop MMPC is analyzed in detail to illustrate the mechanism of improving the system dynamic performance. The cascaded MMPC method is compared with the conventional proportional-integral (PI) control methods with/without a notch filter to show the merits in resonance damping and dynamic response. The optimal control parameters design procedure is elucidated with the tuning mechanism of the MMPC weighing factor and PI gain. With the proposed optimal MMPC design method, the dynamic performance of rising time and overshoot are improved compared to the conventional PI control methods with/without the notch filter. The simulation and experimental results verified the proposed control design method.

Bi-objective optimal design of an electromagnetic shunt damper for energy harvesting and vibration control

Owing to the electromechanical energy conversion capacity, electromagnetic shunt dampers (EMSDs) are widely applied to vibration suppression or energy harvesting from vibrating structures. Either one of the two functions can be optimized in the designs of EMSD found in the literature. In this paper, a bi-objective optimization methodology of EMSD is proposed for the simultaneous maximization of energy harvesting from the damper and the suppression of resonant vibration of a dynamic structure. An EMSD with opposing magnet pairs configuration is designed to achieve the two design objectives simultaneously in a single-degree-of-freedom (SDOF) system and a dynamic vibration absorber (DVA). It is proved analytically and experimentally that maximum energy can be harvested by the EMSD when its internal impedance equals to the external electrical resistance of the electrical circuit. Minimum resonant vibration amplitude of the primary mass can be achieved at the same resistance ratio in the DVA system by selecting the suitable number of opposing magnet pairs of the EMSD without affecting the internal resistance. An EMSD with opposing magnet pairs configuration is designed and tested in a single-degree-of-freedom (SDOF) system and a dynamic vibration absorber. Following a proper procedure, the electromechanical transduction factor of the proposed EMSD can be tuned to achieve both objectives simultaneously. The harvested energy is higher when the EMSD is deployed in the SDOF system than in the DVA system, but the frequency bandwidth for energy harvesting is much wider in the DVA system. Analyses lead to a design guideline of the EMSD for achieving the bi-objective optimization.

Multiphysics Design of an Automotive Regenerative Eddy Current Damper

This research presents a finite element multi-physics design methodology that can be used to develop and optimise the inherent functions and geometry of an innovative regenerative eddy current (REC) damper for the suspension of B class vehicles. This methodology was inspired by a previous work which has been applied successfully for the development of an eddy current (EC) damper used for the same type of applications. It is based on a multifield finite element coupled model that can be used to fulfil the electromagnetic, thermal, and fluid dynamic field properties and boundary conditions of a REC damper, as well as its non-linear material properties and boundary conditions, while also analysing its damping performance. The proposed REC damper features a variable fail-safe damping force, while electric power is advantageously regenerated at high suspension frequencies. Its damping performance has been benchmarked against that of a regular hydraulic shock absorber (selected as a reference) by analysing the dynamic behaviour of both systems using a quarter car suspension model. The results are expressed in terms of damping force, harvested power, thermal field, comfort and handling, with reference to ISO-class roads. The optimisation analysis of the REC damper has suggested useful guidelines for the harmonisation of damping and regenerative power performances during service operation at different piston speeds.

Multi-Condition Temperature Field Simulation Analysis of Magnetorheological Grease Torsional Vibration Damper

To reveal the transient temperature distribution pattern inside the magnetorheological grease (MRG) torsional vibration damper and explore the relationship between the current and internal temperature of the device, the transient temperature simulation analysis of the MRG device was conducted in this study. Firstly, a theoretical heat transfer model of MRG torsional vibration damper with dual heat source structural feature was established based on the Bingham constitutive model and the temperature-dependent viscosity characteristic of MRG. Then, the transient temperature field model of the MRG torsional vibration damper was developed by the finite element method, the temperature field distribution and temperature–time variation characteristics of the MRG torsional vibration damper at 0A, 1A, and 2A working conditions were analyzed, and the effects of viscosity and slip factors on the temperature rise of the device were investigated. The simulation results show that the temperature rise of MRG in the working domain is the fastest, but a gradual slowing of the temperature rise rate. The magnitude and rate of temperature rise are maximum when the 1A current is applied to the torsional vibration damper. Finally, the current–temperature curve is obtained by fitting the simulation results. The results of the analysis reveal the internal temperature distribution and temperature rise characteristics of the torsional vibration damper, which provide a theoretical basis for the structural optimization and control strategy design of the MRG torsional vibration damper considering temperature as a factor.