The influence of microslip on vibratory response, Part II: A comparison with experimental results
TL;DR: In this article, the influence of microslip on the resonant response of structures that are restrained by a friction contact is discussed, and a new model of micro-slip described in the companion paper is used in simulating the vibratory response of three sets of experiments.
About: This article is published in Journal of Sound and Vibration.The article was published on 1986-06-08. It has received 110 citations till now.
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TL;DR: It is clear that multi-scale effects can dominate performance of friction contacts, and as a result more research is needed into computational tools and approaches capable of resolving the diverse length scales present in many practical problems.
Abstract: Friction is a very complicated phenomenon arising at the contact of surfaces. Experiments indicate a functional dependence upon a large variety of parameters, including sliding speed, acceleration, critical sliding distance, temperature, normal load, humidity, surface preparation, and, of course, material combination. In many engineering applications, the success of models in predicting experimental results remains strongly sensitive to the friction model. Furthermore, a broad cross section of engineering and science disciplines have developed interesting ways of representing friction, with models originating from the fundamental mechanics areas, the system dynamics and controls fields, as well as many others. A fundamental unresolved question in system simulation remains: what is the most appropriate way to include friction in an analytical or numerical model, and what are the implications of friction model choice? This review article draws upon the vast body of literature from many diverse engineering fields and critically examines the use of various friction models under different circumstances. Special focus is given to specific topics: lumped-parameter system models !usually of low order"—use of various types of parameter dependence of friction; continuum system models—continuous interface models and their discretization; self-excited system response—steady-sliding stability, stick/slip, and friction model requirements; and forced system response—stick/slip, partial slip, and friction model requirements. The conclusion from this broad survey is that the system model and friction model are fundamentally coupled, and they cannot be chosen independently. Furthermore, the usefulness of friction model and the success of the system dynamic model rely strongly on each other. Across disciplines, it is clear that multi-scale effects can dominate performance of friction contacts, and as a result more research is needed into computational tools and approaches capable of resolving the diverse length scales present in many practical problems. There are 196 references cited in this review-article. #DOI: 10.1115/1.1501080$
395 citations
TL;DR: In this paper, an adjusted Iwan beam element (AIBE) is proposed for dynamic response analysis of beam structures containing joints, which consists of a combination of springs and frictional sliders that exhibits nonlinear behavior due to the stick-slip characteristic of the latter.
201 citations
TL;DR: In this paper, a physically motivated, continuous microslip model of friction is developed for analyzing the dynamic response of frictionally damped structures in which the friction interface is subjected to high normal loads.
185 citations
TL;DR: In this paper, a theoretical model for analyzing the dynamic characteristics of wedge-shaped under-platform dampers for turbine blades is presented, with the objective to minimize the need for conducting expensive experiments for optimizing such dampers.
Abstract: 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.
127 citations
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TL;DR: In this paper, the dynamic Lagrangian mixed frequency-time method (DLFT) is proposed to calculate the non-linear steady state response to periodic excitation of structural systems subject to dry friction damping.
125 citations
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241 citations
TL;DR: In this paper, a physically motivated, continuous microslip model of friction is developed for analyzing the dynamic response of frictionally damped structures in which the friction interface is subjected to high normal loads.
185 citations
TL;DR: In this article, a nouvelle methode for le calcul de la reponse en regime stationnaire des structures amorties par frottement, which est compatible avec les codes par element fini existants, is presented.
Abstract: Developpement d'une nouvelle methode pour le calcul de la reponse en regime stationnaire des structures amorties par frottement, qui est compatible avec les codes par element fini existants. Resultats montrant, par simulation d'une poutre d'essai, que la precision de la methode est acceptable dans le cas d'un amortisseur essentiellement rigide et amelioree quand la flexibilite de l'amortisseur devient plus comparable a celle de la poutre d'essai
86 citations
TL;DR: In this article, the feasibility of using blade-to-ground friction dampers to stabilize flutter in blades was investigated and the range of amplitudes over which friction damping can stabilize the response, the maximum negative aerodynamic damping that can be stabilized in such a manner, and the effect of simultaneous resonant excitation on these stability limits.
Abstract: This paper investigates the feasibility of using blade-to-ground friction dampers to stabilize flutter in blades. The response of an equivalent one mode model in which the aerodynamic force is represented as negative viscous damping is examined to investigate the following issues: the range of amplitudes over which friction damping can stabilize the response, the maximum negative aerodynamic damping that can be stabilized in such a manner, the effect of simultaneous resonant excitation on these stability limits, and the determination of those damper parameters which will be the best for flutter control.
72 citations
TL;DR: In this article, l'etude de l'impact d'une mauvaise concordance sur le comportement and la conception d'amortisseurs de frottement entre aubes du type utilise pour controler la reponse de resonance des aubes de turbines dans les moteurs a turbine a gaz.
Abstract: Resultats de l'etude de l'impact d'une mauvaise concordance sur le comportement et la conception d'amortisseurs de frottement entre aubes du type utilise pour controler la reponse de resonance des aubes de turbines dans les moteurs a turbine a gaz. Discussion sur l'importance des variations de la force de frottement lors de glissements, sur la reponse dynamique des roues a aubes a bandage
67 citations