Academic literature on the topic 'Underplatform damper'
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Journal articles on the topic "Underplatform damper"
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Gastaldi, Chiara, Teresa M. Berruti, and Muzio M. Gola. "Best practices for underplatform damper designers." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 232, no. 7 (February 1, 2018): 1221–35. http://dx.doi.org/10.1177/0954406217753654.
Full textAbstract:
The purpose of this paper is to offer a practical demonstration of how essential preoptimization is in the design of underplatform dampers for turbine blades. Preoptimization can be thought of as a “prescreening” which allows excluding, since the early design stages, a high number of poorly performing damper–platform configurations. This concept, previously presented by the authors, is here extended and its generality for all blade bending modes is rigorously demonstrated. The paper addresses a test case where the introduction of curved-flat underplatform dampers is necessary to avoid a dangerous resonance crossing in the operating rotational speed range of a real turbine disk. It is shown how preoptimized dampers are the only ones that manage to satisfy all functional requirements, including those in the nonlinear operating regime. The same set of dampers may have been identified by exploring, through hundreds of computationally intensive nonlinear calculations, the performance of all possible damper configurations. The latter approach, i.e. iterative design, is unpractical and has to be repeated for each new set of blades since it is based on a test case-specific trial-and-error procedure. Preoptimization substitutes iterations with knowledge of the damper behavior and can therefore be considered as “informed design”: viable damper configurations are instantly singled out through simple but insightful considerations on the damper equilibrium of forces and moments.
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Berruti, Teresa, Christian M. Firrone, M. Pizzolante, and Muzio M. Gola. "Fatigue Damage Prevention on Turbine Blades: Study of Underplatform Damper Shape." Key Engineering Materials 347 (September 2007): 159–64. http://dx.doi.org/10.4028/www.scientific.net/kem.347.159.
Full textAbstract:
Forced vibrations can lead to an irreparable damage of a blade array. Devices called “underplatform damper” that dissipate the vibration energy are employed in order to reduce blade vibration amplitude. The present paper deals with the design of the underplatform damper. A numerical code to calculate the forced response of a blade array with dampers has been previously purposely developed. A method is here proposed for the estimation of the unknown contact parameters demanded by the code. The computation results are here validated by means of comparison with experimental results on a static test rig. Three dampers with different shape are tested.
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Sanliturk, K. Y., D. J. Ewins, and A. B. Stanbridge. "Underplatform Dampers for Turbine Blades: Theoretical Modeling, Analysis, and Comparison With Experimental Data." Journal of Engineering for Gas Turbines and Power 123, no. 4 (October 1, 1998): 919–29. http://dx.doi.org/10.1115/1.1385830.
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This paper describes a theoretical model for analyzing the dynamic characteristics of wedge-shaped underplatform dampers for turbine blades, with the objective that this model can be used to minimize the need for conducting expensive experiments for optimizing such dampers. The theoretical model presented in the paper has several distinct features to achieve this objective including: (i) it makes use of experimentally measured contact characteristics (hysteresis loops) for description of the basic contact behavior of a given material combination with representative surface finish, (ii) the damper motion between the blade platform locations is determined according to the motion of the platforms, (iii) three-dimensional damper motion is included in the model, and (iv) normal load variation across the contact surfaces during vibration is included, thereby accommodating contact opening and closing during vibration. A dedicated nonlinear vibration analysis program has been developed for this study and predictions have been verified against experimental data obtained from two test rigs. Two cantilever beams were used to simulate turbine blades with real underplatform dampers in the first experiment. The second experiment comprised real turbine blades with real underplatform damper. Correlation of the predictions and the experimental results revealed that the analysis can predict (i) the optimum damping condition, (ii) the amount of response reduction, and (iii) the natural frequency shift caused by friction dampers, all with acceptable accuracy. It has also been shown that the most commonly used underplatform dampers in practice are prone to rolling motion, an effect which reduces the damping in certain modes of vibration usually described as the lower nodal diameter bladed-disk modes.
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Panning, Lars, Walter Sextro, and Karl Popp. "Spatial Dynamics of Tuned and Mistuned Bladed Disks with Cylindrical and Wedge-Shaped Friction Dampers." International Journal of Rotating Machinery 9, no. 3 (2003): 219–28. http://dx.doi.org/10.1155/s1023621x03000198.
Full textAbstract:
One of the main tasks in the design of turbomachines like turbines, compressors, and fans is to increase the reliability and efficiency of the arrangement. Failures due to blade cracks are still a problem and have to be minimized with respect to costs and safety aspects. To reduce the maximum stresses, the blades can be coupled via friction damping devices such as underplatform dampers that are pressed onto the blade platforms by centrifugal forces. In this work, a method will be presented to optimize two different types of underplatform dampers in bladed disk applications with respect to a maximum damping effect.In practice, underplatform dampers with various geometric properties—cylindrical and wedge-shaped—are commonly used and lead to different contact conditions. A discretization of the contact areas between the blade platforms and the dampers is applied to be able to investigate nearly arbitrary contact geometries and spatial blade vibrations. The functionality of the two mentioned damper types has been studied in detail under different working conditions of the assembly. The advantages and disadvantages of both damper types are pointed out and strategies are presented to improve the damper design. In this context, the influence of mistuning effects is discussed in terms of statistical mistuning of the blades' natural frequencies due to manufacturing tolerances as well as systematical mistuning due to a deliberate slight variation of the blade masses or geometries.
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Pesaresi, L., L. Salles, R. Elliott, A. Jones, J. S. Green, and C. W. Schwingshackl. "Numerical and Experimental Investigation of an Underplatform Damper Test Rig." Applied Mechanics and Materials 849 (August 2016): 1–12. http://dx.doi.org/10.4028/www.scientific.net/amm.849.1.
Full textAbstract:
During operation mechanical structures can experience large vibration amplitudes. One of the challenges encountered in gas-turbine blade design is avoiding high-cycle fatigue failure usually caused by large resonance stresses driven by aeroelastic excitation. A common approach to control the amplitude levels relies on increasing friction damping by incorporating underplatform dampers (UPD). An accurate prediction of the dynamics of a blade-damper system is quite challenging, due to the highly nonlinear nature of the friction interfaces and detailed validation is required to ensure that a good modelling approach is selected. To support the validation process, a newly developed experimental damper rig will be presented, based on a set of newly introduced non-dimensional parameters that ensure a similar dynamic behaviour of the test rig to a real turbine blade-damper system. An ini- tial experimental investigation highlighted the sensitivity of the measured response with regards to settling and running in of the damper, and further measurements identified a strong dependence of the nonlinear behaviour to localised damper motion. Numerical simulations of the damper rig with a simple macroslip damper model were performed during the preliminary design, and a comparison to the measured data highlighted the ability of the basic implicit model to capture the resonance frequencies of the system accuratelyю
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Petrov, E. P., and D. J. Ewins. "Advanced Modeling of Underplatform Friction Dampers for Analysis of Bladed Disk Vibration." Journal of Turbomachinery 129, no. 1 (February 1, 2006): 143–50. http://dx.doi.org/10.1115/1.2372775.
Full textAbstract:
Advanced structural dynamic models for both wedge and split underplatform dampers have been developed. The new damper models take into account inertia forces and the effects of normal load variation on stick-slip transitions at the contact interfaces. The damper models are formulated for the general case of multiharmonic forced response analysis. An approach for using the new damper models in the dynamic analysis of large-scale finite element models of bladed disks is proposed and realized. Numerical investigations of bladed disks are performed to demonstrate the capabilities of the new models and an analysis of the influence of the damper parameters on the forced response of bladed disks is made.
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Gola, M. M., and C. Gastaldi. "Latest investigations on underplatform damper inner mechanics." VESTNIK of the Samara State Aerospace University, no. 5-1(47) (June 15, 2015): 215. http://dx.doi.org/10.18287/1998-6629-2014-0-5-1(47)-215-226.
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Szwedowicz, Jaroslaw. "30-Year Anniversary of Friction Damper Technolgy in Turbine Blades." Mechanical Engineering 132, no. 04 (April 1, 2010): 54–55. http://dx.doi.org/10.1115/1.2010-apr-8.
Full textAbstract:
This article discusses the use of friction damper technology in turbine blades. In 1980, Jerry Griffin published an integrated approach for the underplatform friction damper design, utilizing centrifugal loading. The idea was to apply an individual metal piece, which is pressed by the centrifugal load against the platforms of vibrating turbine blades. The dissipation energy is then produced by friction sliding between the vibrating platforms and the pressed damper. Griffin’s findings have opened up friction damping technology, which is now commonly utilized by many Original Equipment Manufacturers in gas and steam turbines. Every year, new publications show the development of sophisticated interdisciplinary knowledge for predicting the nonlinear blade dynamic behavior in the most reliable manner. Friction dampers reduce resonance amplitudes several times with respect to that for sticking contact condition. But they only act efficiently in a narrow frequency range for the resonance of interest. Therefore, other technologies are continuously being developed, based for instance on piezomaterials, which can extend the allowable limits of High Cyclic Fatigue for the conventional blade alloys.
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Afzal, Mohammad, Leif Kari, and Ines Lopez Arteaga. "Adaptive control of normal load at the friction interface of bladed disks using giant magnetostrictive material." Journal of Intelligent Material Systems and Structures 31, no. 8 (March 13, 2020): 1111–25. http://dx.doi.org/10.1177/1045389x20910269.
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A novel application of magnetostrictive actuators in underplatform dampers of bladed disks is proposed for adaptive control of the normal load at the friction interface to achieve the desired friction damping in the structure. Friction damping in a bladed disk depends on operating parameters, such as rotational speed, engine excitation order, nodal diameter normal contact load, and contact interface parameters, such as contact stiffness and friction coefficient. The operating parameters have a fixed value, whereas the contact interface parameters vary in an unpredictable way at an operating point. However, the ability to vary some of these parameters such as the normal contact load in a controlled manner is desirable to attain an optimum damping in the bladed disk at different operating conditions. Under the influence of an external magnetic field, magnetostrictive materials develop an internal strain that can be exploited to vary the normal contact load at the friction interface, which makes them a potentially good candidate for this application. A commercially available magnetostrictive alloy, Terfenol-D is considered in this analysis that is capable of providing magnetostrain up to 2 × 10-3 under prestress and a blocked force over 1500 N. A linearized model of the magnetostrictive material, which is accurate enough for a direct current application, is employed to compute the output force of the actuator. A nonlinear finite element contact analysis is performed to compute the normal contact load between the blade platform and the underplatform damper as a result of magnetostrictive actuation. The nonlinear contact analysis is performed for different actuator mounting configurations and the obtained results are discussed. The proposed solution is potentially applicable to adaptively control vibratory stresses in bladed disks and consequently to reduce failure due to high-cycle fatigue. Finally, the practical challenges in employing magnetostrictive actuators in underplatform dampers are discussed.
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Firrone, Christian M., and Stefano Zucca. "Underplatform dampers for turbine blades: The effect of damper static balance on the blade dynamics." Mechanics Research Communications 36, no. 4 (June 2009): 515–22. http://dx.doi.org/10.1016/j.mechrescom.2009.01.002.
Full textDissertations / Theses on the topic "Underplatform damper"
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Cigeroglu, Ender. "Development of microslip friction models and forced response prediction methods for frictionally constrained turbine blades." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1181856489.
Full textBook chapters on the topic "Underplatform damper"
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Berruti, Teresa, Christian M. Firrone, M. Pizzolante, and Muzio M. Gola. "Fatigue Damage Prevention on Turbine Blades: Study of Underplatform Damper Shape." In Damage Assessment of Structures VII, 159–64. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-444-8.159.
Full textConference papers on the topic "Underplatform damper"
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Gola, Muzio M., and Chiara Gastaldi. "Understanding Complexities in Underplatform Damper Mechanics." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-25240.
Full textAbstract:
All numerical models of friction damped bladed arrays require knowledge or information of contact-friction parameters, which are established either through direct frictional measurements, done with the help of single contact test arrangements, or by fine tuning the parameters in the numerical model and comparing the experimental response of damped blade against its computed response. Some critical assumptions are necessary to the purpose, such as the position and extension of the real contact areas and the values of local friction coefficients. In the light of recent results from direct measurements on under-platform dampers [1–3] it became evident that a dedicated routine for the damper mechanics is a much more effective tool to capture those finer details which are essential to an appropriate description of damper behaviour. This was made possible by the successful effort of the present authors to accurately measure the forces transmitted between the platforms through the damper and to relate them with the relative platform movement [2]. Simulations, and the matching experiments which are here not described, are performed under so called out-of-phase (O-O-P) and in-phase (I-P) condition simulating the two basically important motion types. Damper forces and damper kinematics are discussed for two highly representative cases in the low frequency range. Diagrams are then used to show the sensitivity to contact parameters, input motion and initial conditions on damper behaviour, casting heavy doubts on the validity of oversimplified practices.
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Panning, Lars, Karl Popp, Walter Sextro, Florian Go¨tting, Andreas Kayser, and Ivo Wolter. "Asymmetrical Underplatform Dampers in Gas Turbine Bladings: Theory and Application." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53316.
Full textAbstract:
During operation, the rotating blades of a gas turbine are subjected to centrifugal forces as well as fluctuating gas forces, resulting in blade vibrations. In addition to material damping, aerodynamical and blade root damping, underplatform dampers are widely used to increase the amount of damping and to decrease blade vibration amplitudes. The friction forces generated by the relative displacements between the underplatform damper and the blade platforms provide a significant amount of energy dissipation. In practice, a number of different underplatform damper designs are applied. Basically, these are wedge dampers with flat contact areas, cylindrical dampers with curved surfaces or asymmetrical dampers with both flat contact surfaces on one side and curved contact surfaces on the other. The latter damper type combines the advantages of both the wedge and the cylindrical damper by preventing the damper from pure rolling on the one hand as it has been observed for cylindrical dampers and on the other hand, avoiding a diverged plane area contact in case of a wedge damper, causing a damper lift-off. This paper will focus on the investigation of cylindrical and asymmetrical underplatform dampers. A comparison between measurements of rotating assemblies in Siemens PG gas turbines (V84.2, V64.3A and V94.3A(2)) under test and real operating conditions with cylindrical and asymmetrical underplatform dampers and the predictions of the developed theoretical model are presented. Special attention is paid to the frequency shift due to the application of an underplatform damper, since in particular for stationary gas turbines, in addition to the amplitude reduction, the accurate prediction of the resonance frequency is of major interest.
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Gastaldi, Chiara, and Muzio M. Gola. "Pre-Optimization of Asymmetrical Underplatform Dampers." In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-57359.
Full textAbstract:
The numerical coupled optimization of an underplatform damper is the exploration of its dynamics through a finite element model which includes both the damper and the blades. This is an effective approach if the initial damper mass and geometry have been previously selected in such a way that those parameter combinations leading to undesirable damper behavior (i.e. contact point lift-off, jamming, excessive contact forces) are ruled out a priori. This can be obtained through a pre-optimization where, after choosing the damper type the following main steps are followed: 1. ensure that damper jamming is avoided through an appropriate choice of platform angles, in function of the friction coefficients; 2. ensure that damper lift-off is avoided through an appropriate choice of the shape and position of the damper-platform flat contact surface and the position of the damper mass center; 3. set upper and lower limits to the value of damper-platform contact forces (as a multiple of the damper centrifugal force), the first being related to friction and wear problems, the second to the very existence of bilateral contacts; 4. check the model, and in particular the values of friction coefficients and contact stiffness, against experimental results. Once the above knowledge concerning the most desirable damper shape has been gathered an effective coupled-optimization can safely be performed. This is done by finding the most effective match between the damper size/mass and the bladed disk through a non-linear dynamic calculation (not examined in this paper). The outcome of both the pre-optimization and the coupled optimization are strongly dependent on the assumed values of friction coefficients, which depend on the contact surface type (then, different for the left and right side of the damper) and the contact pressure. The paper capitalizes on already developed tools, presented in previous ASME papers, such as the test rig developed by the AERMEC lab to draw the appropriate values of contact parameters, the numerical model representing the stand-alone dynamics of the damper between the platforms and the automatic random sampling tuning procedure. The purpose of the paper is to illustrate the procedure through the analysis of a family of rigid bar dampers with a curved-flat cross section.
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Zucca, Stefano, Juan Borrajo, and Muzio M. Gola. "Forced Response of Bladed Disks in Cyclic Symmetry With Underplatform Dampers." In ASME Turbo Expo 2006: Power for Land, Sea, and Air. ASMEDC, 2006. http://dx.doi.org/10.1115/gt2006-90785.
Full textAbstract:
In this paper a methodology for forced response calculation of bladed disks with underplatform dampers is described. The FE disk model, supposed to be cyclically symmetric, is reduced by means of Component Mode Synthesis and then DOFs lying at interfaces are further reduced by means of interface modes. Underplatform dampers are modeled as rigid bodies translating both in the radial and in the tangential direction of the engine. Contacts between blade platforms and damper are simulated by means of contact elements characterized by both tangential and normal contact stiffness, allowing partial separation of contact surfaces. Differential equilibrium equations are turned in non-linear algebraic equations by means of the Harmonic Balance Method (HBM). The methodology is implemented in a numerical code for forced response calculation of frictionally damped bladed disks. Numerical calculations are performed to evaluate the effectiveness of both the reduced order model and the underplatform model in simulating the dynamic behavior of bladed disks in presence of underplatform dampers.
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Zucca, Stefano, Christian M. Firrone, and Muzio Gola. "Coupled Static/Dynamic Modeling of Wedge Dampers for Turbine Blades." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-23466.
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Friction damping is one of the most exploited systems of passive control of vibration of mechanical systems. A common type of blade-to-blade friction dampers are the so-called underplatform dampers (UPDs); they are metal devices placed under the blade platforms and held in contact with them by the centrifugal force acting during rotation. The effectiveness of underplatform dampers to dissipate energy by friction and reduce vibration amplitude depend mostly on the damper geometry and material and on the static pre-loads pressing the damper against the blade platforms. The common procedure used to estimate the static pre-loads acting on underplatform dampers consists in decoupling the static and the dynamic balance of the damper. A preliminary static analysis of the contact is performed in order to compute the static pressure distribution over the damper/blade interfaces, assuming that it does not change when vibration occurs. In this paper a coupled approach is proposed. The static and the dynamic displacements of blade and underplatform damper are coupled together during the forced response calculation. Both the primary structure (the bladed disk) and the secondary structure (the damper) are modelled by finite elements and linked together by contact elements, allowing for stick, slip and lift off states, placed between each pair of contact nodes, by using a refined version of the state-of-the-art friction contact model. In order to model accurately the blade/damper contact with a large number of contact nodes without increasing proportionally the size of the set of non-linear equations to be solved, damper and blade dynamics are modelled by linear superposition of a truncated series of normal modes. The proposed method is applied to a bladed disk under cyclic symmetric boundary conditions in order to show the capabilities of the method compared to the classical decoupled approaches.
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Gao, Shimin, Yanrong Wang, and Zhiwei Sun. "An Energy Method for Assessing the Damping of Turbine Blade Underplatform Damper and Forced Response Verification." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-14532.
Full textAbstract:
Abstract Rotating turbine blades in aircraft gas turbines are subject to high loads which can result in high cycle fatigue (HCF) failure. In order to reduce the vibration of blades, underplatform dampers are widely used to increase the damping by dry friction dissipating the vibration energy. This paper proposes an energy method (EM) for assessing the damping effect of underplatform dampers with the contacts of one cylinder and one flat without calculating the forced response. In this method the characteristic curve of the damping ratio of the damper on the vibration stress of the blade is used to design the damper. The design objective is that the damper can provide an optimal damping ratio on a given range of vibration stress if resonance occurs. This paper proposes a method for calculating the response and the performance plot based on the above characteristic curve to compare with Direct Time Integration (DTI). The effects of parameters such as contact stiffness, modal data and rotation speed, friction coefficient, damper mass on the damping ratio characteristics are analyzed. Based on the allowable vibration stress of the blade, the design process of the underplatform dampers using damping ratio characteristic curve is given. The proposed method is suitable and efficient for situations where the presence of the damper does not greatly affect the mode shape of the blade.
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Gola, Muzio M., Marcelo Braga dos Santos, and Tong Liu. "Measurement of the Scatter of Underplatform Damper Hysteresis Cycle: Experimental Approach." In ASME 2012 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/detc2012-70269.
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This work presents the design and the calibration of a test rig specially developed to measure the in-plane forces transferred between the blade platforms through the under-platform damper and their relative displacement. This device is composed of two distinct parts each one representing a platform. One is static and accommodates the load cells which measure the forces in two perpendicular directions; the other produces the in-plane motion, actuated by two piezoelectric stacks. The device reproduces any in-plane relative displacement between two adjacent platforms and measures both the relative motion between platforms and the forces they reciprocally transmit. The damper, placed between the two platform simulators, is loaded by thin wires pulled by dead weights, a way to apply the equivalent of the centrifugal force. The mechanical features of the rig are described and discussed with their influence on the measurements. An example application is given. Tests aim at assessing the role of “outer” measured parameters (such as frequency and amplitude of platform-to-platform relative displacement, damper external load (simulating the in-service centrifugal load), damper geometry) on the shape and area of the hysteresis cycle and therefore the damper real and imaginary stiffness components. It is found that equal values for the supposedly governing “outer” parameters may lead to a multiplicity of markedly different hysteresis cycles. The same happens if platform-to-platform force is considered rather than displacement. It is shown how the system evolves through the many possible equilibrium conditions. It is also shown how the forces between damper and underplatforms are calculated. It is suggested that the measurement of platform-to-platform hysteresis cycles is an effective way to synthetically approach the problem of elastic coupling and energy dissipation between adjacent blades, while detailed knowledge of forces exchanged between the underplatform and damper contact surfaces will be a valuable tool toward the better knowledge of damper micromechanics, perhaps opening a better way to finding damper geometries capable of reducing the scatter of hysteresis cycle shape and area. Two dampers are investigated, at this stage, in order to assess the dependence of the above said behavior on the damper geometry. Results show that dampers exhibit multiple behaviors under the same input conditions. They may be alarming because they show that the damper-platforms system always converges to the solution with the lowest hysteresis area, a fact which deserves of course deeper investigations.
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Bessone, Andrea, Federico Toso, and Teresa Berruti. "Investigation on the Dynamic Response of Blades With Asymmetric Under Platform Dampers." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-42597.
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The paper presents the experimental activity about the dynamic response of the blades of a gas turbine for power generation carrying underplatform dampers. The final aim of the activity is to provide an experimental data base to validate the results of a numerical tool which calculates the response of the blades with underplatform dampers. The blades have fir tree attachments and an asymmetric damper is fitted between the blade platforms. The dynamic behavior of the blades is detected by an experimental campaign on two blades mounted in a test rig. Stepped sine measurements are performed with a closed-loop control system on the excitation amplitude. Different levels of excitation amplitude and centrifugal force on the damper are tested. The test campaign pointed out the presence of damping due both to the underplatform damper and to the blade attachment. The contribution of the different damping sources are discussed and analyzed. A method is suggested to identify the root damping which is not constant but proved to depend on the excitation force on the blades.
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Petrov, E. P., and D. J. Ewins. "Advanced Modelling of Underplatform Friction Dampers for Analysis of Bladed Disc Vibration." In ASME Turbo Expo 2006: Power for Land, Sea, and Air. ASMEDC, 2006. http://dx.doi.org/10.1115/gt2006-90146.
Full textAbstract:
Advanced structural dynamic models for both wedge and split underplatform dampers have been developed. The new damper models take into account inertia forces and the effects of normal load variation on stick-slip transitions at the contact interfaces. The damper models are formulated for the general case of multiharmonic forced response analysis. An approach for using the new damper models in the dynamic analysis of large-scale finite element models of bladed discs is proposed and realised. Numerical investigations of bladed discs are performed to demonstrate the capabilities of the new models and an analysis of the influence of the damper parameters on the forced response of bladed discs is made.
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Firrone, Christian M., Stefano Zucca, and Muzio Gola. "Effect of Static/Dynamic Coupling on the Forced Response of Turbine Bladed Disks With Underplatform Dampers." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59905.
Full textAbstract:
Friction contacts are often used in turbomachinery design as passive damping systems. In particular underplatform dampers are mechanical devices used to decrease the vibration amplitudes of bladed disks. Numerical codes are used to optimize during design the underplatform damper parameters in order to limit the resonant stress level of the blades. In such codes the contact model plays the most relevant role in the calculation of the dissipated energy at friction interfaces. One of the most important contact parameters is the static normal load acting at the contact, since its value strongly affects the area of the hysteresis loop of the tangential force and therefore the amount of dissipation. A common procedure to estimate the static normal loads acting on underplatform dampers consists in decoupling the static and the dynamic balance of the damper. A preliminary static analysis of the contact is performed in order to get the static contact/gap status to use in the calculation, assuming that it does not change when vibration occurs. In this paper a novel approach is proposed. The static and the dynamic displacements of the system (bladed disk + underplatform dampers) are coupled together during the forced response calculation. Static loads acting at the contacts follow from static displacements and no preliminary static analysis of the system is necessary. The proposed method is applied to a numerical test case representing a simplified bladed disk with underplatform dampers. Results are compared with those obtained with the classical approach.