On the relevance of a microslip contact model for under-platform dampers

Gastaldi, Chiara; Gola, Muzio

doi:10.1016/j.ijmecsci.2016.06.015

Cited by 48 publications

(23 citation statements)

References 29 publications

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“…In detail, the tripod and the structure hosting the force sensors have been redesigned to increase the overall stiffness of the rig [18]. This had a positive impact over the frequency operating range which increased from [≈5-80] Hz to [≈5-160 Hz].…”

Section: The Test Rig Evolutionmentioning

confidence: 99%

“…This choice allows to account for the presence of "microslip", first theorized by Cattaneo in 1938 [16], and later explored by Mindlin [17]. Modeling microslip is particularly relevant in those cases where high normal loads prevent actual slipping of the complete interface: in that case the gradual loss of stiffness that forecomes gross slip and the consequent dissipation does have an impact on the system response, while it becomes negligible if the gross slip regime is reached [18].…”

mentioning

confidence: 99%

“…Recently, a novel contact element, fit to take into account microslip as well as the nonlinearity in the normal direction typical of nonconforming contacts, has been proposed [18]. 1 Furthermore, Herzog et al [7] have shown that Dynamic Lagrangians may incur in convergence problems for penalty parameters lower than 107 N/m, thus highlighting a possible limitation of their use in case of "softer" contact interfaces.…”

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confidence: 99%

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Modeling Friction for Turbomachinery Applications: Tuning Techniques and Adequacy Assessment of Heuristic Contact Models

Gastaldi¹

2018

Contact and Fracture Mechanics

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Friction dampers are commonly included into turbine designs to limit the turbine blades resonant vibrations and thus avoid high cycle fatigue failures. In order to effectively predict the effect of friction dampers on the turbine dynamics, friction is included into the simulation through specific mesoscale contact models. These models require knowledge of contact parameters to offer meaningful predictions. Standard single-contact test arrangements may fail to capture the true contact conditions and kinematics of friction dampers, especially for complex multi-interface contacts interested by variable normal loads. Several methodologies have been proposed in the literature: the lack of a "shared" approach in the field pinpoints a true "gap" in the research. Overcoming this difficulty is of primary importance, as it is the one feature that separates a state-of-the-art numerical code from a true design tool. Purpose of this chapter is to illustrate the experimental/ numerical tools and methods developed to fill this gap for a common family of friction dampers, called "underplatform dampers" with a curved-flat cross section. Both cylinder-on-flat and flat-on-flat interfaces are addressed. The adequacy of the state-of-theart contact model is discussed on the basis of a large data set obtained performing an extended experimental campaign on multiple damper samples.

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Section: The Test Rig Evolutionmentioning

confidence: 99%

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Modeling Friction for Turbomachinery Applications: Tuning Techniques and Adequacy Assessment of Heuristic Contact Models

Gastaldi¹

2018

Contact and Fracture Mechanics

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“…He and Ren [18] studied the reducing vibrational characteristics of the blade by the two-dimensional friction model and finite element model. A purposely developed contact model was tuned on a single-contact test and then included in the numerical model of a curved-flat damper to simulate its cylindrical interface [19]. A microslip model was developed for analyzing the damping effect of under-platform dampers for turbine blades, but the inertia and rotating effects of the damper were ignored for simplicity [20].…”

Section: Introductionmentioning

confidence: 99%

Dynamics of a Turbine Blade with an Under-Platform Damper Considering the Bladed Disc’s Rotation

Jia

Yang

et al. 2019

Applied Sciences

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“…A carefully designed and constructed rotating test rig was used to make precise measurements of the forced vibration response of a bladed disk with fitted under-platform "cottage-roof" friction dampers, the corresponding numerical predictions were carried out too, and then a comparison between the measured and predicted response curves was made and the degree of correlation was discussed [15]. To what extent microslip due to the combined nonlinearities along the normal and the tangent of non-conforming contact surfaces influenced the damper behavior was investigated [16]. Ostachowicz [17] established a harmonic balance method (HBM) for forced vibration analysis of dynamic systems damped by dry friction forces.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Response of a Simplified Turbine Blade Model with Under-Platform Dry Friction Dampers Considering Normal Load Variation

Ouyang

Ren

et al. 2017

Applied Sciences

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Dry friction dampers are widely used to reduce vibration. The forced vibration response of a simplified turbine blade with a new kind of under-platform dry friction dampers is studied in this paper. The model consists of a clamped blade as two rigidly connected beams and two dampers in the form of masses which are allowed to slide along the blade platform in the horizontal direction and vibrate with the blade platform in the vertical direction. The horizontal and vertical vibrations of the two dampers, and the horizontal and transverse platform vibrations are coupled by friction at the contact interfaces which is assumed to follow the classical discontinuous Coulomb's law of friction. The vertical motion of the dampers leads to time-varying contact forces and can cause horizontal stick-slip motion between the contact surfaces. Due to the relative horizontal motion between the dampers and the blade platform, the vertical contact forces and the resultant friction forces act as moving loads. The Finite Element (FE) method and Modal Superposition (MS) method are applied to solve the dynamic response, together with an algorithm that can capture nonsmooth transitions from stick to slip and slip to stick. Quasi-periodic vibration is found even under harmonic excitation.

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On the relevance of a microslip contact model for under-platform dampers

Cited by 48 publications

References 29 publications

Modeling Friction for Turbomachinery Applications: Tuning Techniques and Adequacy Assessment of Heuristic Contact Models

Modeling Friction for Turbomachinery Applications: Tuning Techniques and Adequacy Assessment of Heuristic Contact Models

Dynamics of a Turbine Blade with an Under-Platform Damper Considering the Bladed Disc’s Rotation

Dynamic Response of a Simplified Turbine Blade Model with Under-Platform Dry Friction Dampers Considering Normal Load Variation

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