Laboratory experiments to study ice-induced vibrations of scaled model structures during their interaction with level ice at different ice velocities

Nord, Torodd Skjerve; Lourens, Eliz-Mari; Määttänen, Mauri; Øiseth, Ole; Høyland, Knut V.

doi:10.1016/j.coldregions.2015.06.017

Cited by 13 publications

(22 citation statements)

References 21 publications

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“…9b, oscillator displacement comparisons are presented in the intermittent crushing regime at a 0.02 ms −1 speed. In this case, the displacement amplitude as calculated by using the proposed model is in good agreement with that presented in [27]. In Fig.…”

Section: Discussionsupporting

confidence: 85%

“…In Fig. 9a, Curve 1 depicts the oscillator displacements in the lock-in regime at 0.18 ms −1 as obtained by the model presented in this paper; Curve 2 and Curve 3 give the model results and experimental data from [27], respectively. For the lock-in regime presented in Fig.…”

Section: Discussionmentioning

confidence: 97%

“…We investigate this system in the next section. To simplify the formulas, we will use the notation (27) for the averaged quantities.…”

Section: Asymptotic Solutions Of the Oscillator Equationmentioning

confidence: 99%

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On a simple oscillator problem describing ice-induced vibrations of an offshore structure

2019

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In this paper, a new simple oscillator model is considered describing ice-induced vibrations of upstanding, water-surrounded, and bottom-founded offshore structures. Existing models are extended by taking into account deformations of an ice floe and a moving contact interaction between an ice rod, which is cut out from the floe, and the oscillator which represents the offshore structure. Special attention is paid to a type of ice-induced vibrations of structures, known as frequency lock-in, and characterized by having the dominant frequency of the ice forces near a natural frequency of the structure. A new asymptotical approach is proposed that allows one to include ice floe deformations and to obtain a nonlinear equation for the simple oscillator vibrations. The instability onset, induced by resonance effects for the oscillator and generated by the ice rod structure interaction, is studied in detail.

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Section: Discussionsupporting

confidence: 85%

Section: Discussionmentioning

confidence: 97%

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On a simple oscillator problem describing ice-induced vibrations of an offshore structure

2019

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“…Moreover, in the railway transportation, the estimation of the wheel–rail contact forces is crucial to assess rolling contact fatigue and damage detection on the track as well as to certify the vehicle design safety . In addition to the input identification, the state estimation has also received very much attention in the structural dynamics to predict stress and fatigue life, to identify damage, and to determine the response in inaccessible points …”

Section: Introductionmentioning

confidence: 99%

“…[10][11][12] In addition to the input identification, the state estimation has also received very much attention in the structural dynamics to predict stress and fatigue life, to identify damage, and to determine the response in inaccessible points. [13][14][15][16][17][18][19][20][21][22] As a matter of fact, it is not feasible directly to measure the exposed load by transducers when we have not access to the location and sometimes when economic factors are important; however, the transient response at some points are captured utilizing various sensors (strain gauge, accelerometer, and displacement transducer). Therefore, majority of engineers and researchers prefer to employ one of indirect methods to identify dynamic loads in such cases.…”

Section: Introductionmentioning

confidence: 99%

Bayesian framework for simultaneous input/state estimation in structural and mechanical systems

Valikhani

Younesian

2019

Struct Control Health Monit

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Summary Real‐time input/state estimation by means of the observed response has drawn considerable attention in the structural, dynamic, and control systems. In this line, a minimum‐variance unbiased (MVU) estimator has been utilized to develop three‐step filters that sometimes experience instability and divergence, especially for the input estimation in structural dynamics. To solve this challenge, this study is aimed at to estimate both the input and state simultaneously for a linear system. A Bayesian framework is developed, in which the prior information of the unknown input in terms of the a priori probability density function is incorporated in estimation process. Formulation of the estimation is presented in the state‐space representation in presence and absence of the direct feedthrough. Three‐step filters including input estimation, state prediction, and the updating are developed for the system having model uncertainty and noisy observed data. In addition to the estimation, another novel feature of this study is to predict the steady states of the filters in the closed‐form representation. We also establish sufficient conditions for convergence and stability of the proposed filters. At the end, the efficiency, robustness, and advantage of the approach is verified through numerical studies for different systems. Results for the input and state estimation are compared with real values according to the MVU estimator for the observed noisy data sets.

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General Conditions for Full-Field Response Monitoring in Structural Systems Driven by a Set of Identified Equivalent Forces

Lourens

Fallais

2017

Lecture Notes in Civil Engineering

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Laboratory experiments to study ice-induced vibrations of scaled model structures during their interaction with level ice at different ice velocities

Cited by 13 publications

References 21 publications

On a simple oscillator problem describing ice-induced vibrations of an offshore structure

On a simple oscillator problem describing ice-induced vibrations of an offshore structure

Bayesian framework for simultaneous input/state estimation in structural and mechanical systems

General Conditions for Full-Field Response Monitoring in Structural Systems Driven by a Set of Identified Equivalent Forces

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