References of "Delhez, Elise"
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See detailComparative Study of Reduced Order Modeling Techniques Applied to Geometrically Nonlinear Structures
Delhez, Elise ULiege; Nyssen, Florence; Batailly, Alain et al

Poster (2019, June)

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See detailExperimental and numerical study of the second order moment of the first passage time of a steel strip subjected to forced and parametric excitations
Delhez, Elise ULiege; Vanvinckenroye, Hélène ULiege; Denoël, Vincent ULiege et al

in Proceedings of the International Modal Analysis Conference (IMAC) XXXVII (2019, January)

The first passage time is the time required for a stochastic process to leave a subdomain of the state space for the first time when starting from a given initial state in this subdomain. Analytical ... [more ▼]

The first passage time is the time required for a stochastic process to leave a subdomain of the state space for the first time when starting from a given initial state in this subdomain. Analytical studies of the first passage time of a linear Mathieu oscillator subjected to forced and parametric excitations defined as δ-correlated Brownian noises highlighted the existence of three behavioral regimes for the average first passage time. The current work describes the design and outcomes of an experimental study demonstrating the practical existence of these regimes for the second order moment of the first passage time. On the one hand, tests are carried out on an experimental set-up consisting in a pre-stressed strip subjected to forced and parametric stochastic excitations. On the other hand, a finite element model of the structure is built, updated and used to address the same problem using a numerical approach. Both the experimental tests and the numerical simulations produce mean square first passage time maps that provide evidence for the existence of the three foreseen behavioral regimes. The good match of the first passage time maps confirms the accuracy of the finite element model updating as well as the relevance of the theoretical model for this type of problem. [less ▲]

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See detailNumerical and experimental study of first passage time of a steel strip subjected to forced and parametric excitations
Delhez, Elise ULiege; Vanvinckenroye, Hélène ULiege; Golinval, Jean-Claude ULiege et al

in Proceedings of the 28th International Conference on Noise and Vibration Engineering (2018, September)

The first passage time refers to the time required for a dynamical system to reach a target energy level for the first time, departing from a known initial state. Analytical studies of the first passage ... [more ▼]

The first passage time refers to the time required for a dynamical system to reach a target energy level for the first time, departing from a known initial state. Analytical studies of the first passage time of a linear Mathieu oscillator under stochastic forced and parametric excitations defined as Brownian white noises identified three behavioral regimes for the first passage time. The current work describes the design and use of an experimental set-up in order to validate the existence of the regimes. This paper successively describes the design and the finite element modeling of the set-up consisting in a pre-stressed steel strip, the reduction of the system to a single-degree-of-freedom system to match the framework of the theory, numerical studies on the influence of the frequency bands of the excitations on the first passage time and the experimental tests. Qualitatively, two of the three regimes are successfully observed in the experiment. Quantitatively, a good match is observed between the experimental and model results. [less ▲]

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See detailExperimental and numerical study of first passage time
Delhez, Elise ULiege

Master's dissertation (2018)

The first passage time refers to the time required for a dynamical system to reach a target energy level for the first time, departing from a known initial state. Analytical studies of single-degree-of ... [more ▼]

The first passage time refers to the time required for a dynamical system to reach a target energy level for the first time, departing from a known initial state. Analytical studies of single-degree-of-freedom systems governed by the linear Mathieu equation and subjected to broadband forced and parametric excitations have revealed the existence of different regimes for the first passage time. This Master thesis aims at the experimental validation of the existence of these regimes for a real structure consisting in a strip pre-stressed by a mass. The complete process, from the structure design to the experimental validation, is conducted in this work. A finite element model of the structure is built in Matlab and updated with various state-of-the-art techniques from the field of experimental modal analysis. A model reduction of the full multi-degree-of-freedom system is introduced to match the conditions of the analytical results. It is shown that the dynamics of the structure can be approached by a single-degree-of-freedom reduced model only when both the forced and parametric excitations are narrow-band processes. The influence of narrow-band excitations on the first passage time is therefore studied numerically. The results of this numerical preparatory study are used to define the conditions of the experimental tests. First passage time maps are reproduced experimentally in the framework of the linear single-degree-of-freedom Mathieu equation. This work provides the first physical evidence that the first passage time of real multi-degree-of-freedom systems can be characterized with the physical properties of the structure. It also addresses for the first time the influence of narrow-band excitations. Therefore, it opens the way to broadening the scope of the first passage time theory beyond the context of one-degree-of-freedom linear systems subjected to broadband excitations considered so far. [less ▲]

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See detailExperimental and numerical modal analyses of a pre-stressed steel strip
Delhez, Elise ULiege

Report (2017)

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