Damage localization in offshore structures using shaped inputs

Ulriksen, Martin Dalgaard; Bernal, Dionisio; Nielsen, Morten Eggert; Damkilde, Lars

doi:10.1016/j.proeng.2017.09.273

Cited by 3 publications

(3 citation statements)

References 9 publications

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“…Input shaping is a simple yet effective technique to reduce residual vibration in point-to-point movement of flexible systems. Its applications are expanding from crane [15,19,22,24,40], hard disk drive [28], industrial robot manipulator [20,21,35], liquid sloshing [1], flexible spacecraft [27,42], X-Y platform [33,39,41], elevator [14], quadrotor and drone [5,12,18], DC motor, car wiper [28], offshore structure [36], to micro and nano systems like nano positioner and MEMS actuator [2].…”

Section: Introductionmentioning

confidence: 99%

Input Shaping for Flexible Systems with Non-Zero Initial Conditions

Moonmangmee,

Juyploy,

Chatlatanagulchai

2023

Trends Sci

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Input shaping is a finite-impulse response (FIR) filter whose coefficients are designed to produce a shaped input that avoids exciting lightly-damped modes. As a result, flexible systems can be commanded to move quickly from point to point with minimum residual vibration. However, traditional input shaping techniques assume zero initial conditions, limiting their usability for systems with non-zero initial conditions, such as, emergency stops of cranes. Besides, in practice, movement of flexible systems is often initiated when the systems are not completely stationary. In these situations, the performance of the input shaping technique deteriorates. In this paper, a modification of shaper’s impulse sequence at the beginning of the move is proposed to bring the moving flexible system to a stop before commencing movement. The modification utilizes the work and energy method to determine the distance and time as functions of the initial states for base excitation of flexible systems, rendering its application to nonlinear systems. By concatenating this modification with the existing input shapers, a novel shaper called the non-zero initial conditions zero-vibration-derivative (NI-ZVDk) input shaper is introduced. The NI-ZVDk input shaper effectively prevents the movement of flexible systems from their initial states. To demonstrate the effectiveness of the approach, a 2-mass system is utilized as a benchmark for general flexible systems with 2 degrees of freedom. Various types of motion, including pure translation, pure rotation, and combined translation-rotation, are considered. Extensive simulation results showed that, using the proposed NI-ZVDk input shaper, the flexible systems can move from non-zero initial conditions to their desired destinations with less time and less residual vibration. HIGHLIGHTS The Input Shaping (IS) technique is used to suppress residual vibrations by creating destructive interference in impulse responses This method presents a novel design modification for IS when initial conditions are non-zero This technique can be extended for use in various nonlinear vibratory systems For example, it can be used when a crane needs to stop abruptly from non-zero initial conditions without residual vibrations GRAPHICAL ABSTRACT

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Section: Introductionmentioning

confidence: 99%

Input Shaping for Flexible Systems with Non-Zero Initial Conditions

Moonmangmee,

Juyploy,

Chatlatanagulchai

2023

Trends Sci

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“…Structural damage localization is conventionally handled by mapping shifts in vibration features, such as transfer functions or modal parameters, from the reference and damaged states to the structural domain [1]. This mapping can be conducted either directly, in which case we refer to the approach as data-driven, or by use of a theoretical model of the structure in question, implying that the approach is model-based [2]. Here, the theoretical model is typically established on the basis of a finite element (FE) formulation.…”

Section: Introductionmentioning

confidence: 99%

“…Besides circumventing system identification, the merits of the SDLID scheme include a userdefined spatial localization resolution (as postulated damage areas are selected), a low demand on output sensors (in principle, one may suffice), and conceptual simplicity. These merits have been highligted through numerical application examples with simple structural systems [11] and an offshore jacket structure [2]. The scope of the present paper is therefore to further test the applicability of the SDLID scheme by applying it in an experimental context with a frame structure, which is analyzed in its reference state and "damaged" states with different mass perturbations.…”

Section: Introductionmentioning

confidence: 99%

Damage localization using controllable inputs: an experimental study

Qadri¹,

Ulriksen²,

Klockmann³

et al. 2020

Preprint

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The recently proposed Shaped Damage Locating Input Distribution (SDLID) method locates structural damage by active interrogation with controllable inputs. The methodological premise is to shape these inputs such that certain steady-state vibration features (depending on the type of damage to be located) are rendered dormant in one subdomain at a time. As such, damage is localized when the vibration response induced by the shaped inputs in the damaged state corresponds to that stored for the reference state. Previously, the SDLID method, which operates free of system identification, has been tested through numerical simulations and, in this context, demonstrated its merits; namely, a low demand on output sensors, robustness towards noise, and conceptual simplicity. This paper presents an experimental application study, in which the SDLID method is used to locate different mass perturbations in a frame structure investigated using two actuators delivering harmonic excitation. Based on steady-state acceleration measurements, it is shown how the method succeeds in locating all the added mass perturbations.

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