Experiments in spatial H ∞ control of a piezoelectric laminate beam

Halim, Dunant; Moheimani, S. O. Reza

doi:10.1007/bfb0110617

Cited by 2 publications

(3 citation statements)

References 9 publications

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“…The observed good fitting indicates that the shear band is formed in a process that is closely related with mobile dislocation's dynamics and its propagation speed is strongly related to the amount of the mobile dislocations. This argument is consistent with the prevailing theory regarding the micromechanism [50][51][52][53][54][55][56]. It is also consistent with the above-mentioned (see the paragraph under Equation ( 18)) self-driven nature of the evolution of deformation to fracture in association with an increase in the volume expansion rate (∇ • v).…”

Section: Propagation Of Elasto-plastic Wavesupporting

confidence: 91%

“…On the formation of a shear band, the material experiences a recoverable partial fracture and this causes the particles on the opposite sides of the partial fracture to recoil sharply, as if a stretched spring breaks. This speculation is consistent with the instantaneous stress drop accompanied by the formation of a shear band, as a number of authors [54][55][56][57] observed. The reduction in the amplitude of solitary wave relative to the pulling rate indicates that the increase in the mobile dislocation density lowers the amplitude of the solitary wave (because the onset mobile dislocation density is higher for the lower pulling rate).…”

Section: Propagation Of Elasto-plastic Wavesupporting

confidence: 90%

“…The authors of refs. [54][55][56][57] made thorough analyses on the relation between the appearance of shear bands and serration and found clear correlation between them. Basically, a shear band is formed when the stress drops sharply, and it disappears when the stress rises again.…”

Section: Propagation Of Elasto-plastic Wavementioning

confidence: 98%

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Nondestructive Evaluation of Solids Based on Deformation Wave Theory

2020

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The application of a recent field theory of deformation and fracture to nondestructive testing (NDT) is discussed. Based on the principle known as the symmetry of physical laws, the present field theory formulates all stages of deformation including the fracturing stage on the same theoretical basis. The formalism derives wave equations that govern the spatiotemporal characteristics of the differential displacement field of solids under deformation. The evolution from the elastic to the plastic stage of deformation is characterized by a transition from longitudinal (compression) wave to decaying longitudinal/transverse wave characteristics. The evolution from the plastic to the fracturing stage is characterized by transition from continuous wave to solitary wave characteristics. Further, the evolution from the pre-fracturing to the final fracturing stage is characterized by transition from the traveling solitary wave to stationary solitary wave characteristics. In accordance with these transitions, the criterion for deformation stage is defined as specific spatiotemporal characteristics of the differential displacement field. The optical interferometric technique, known as Electronic Speckle-Pattern Interferometry (ESPI), is discussed as an experimental tool to visualize those wave characteristics and the associated deformation-stage criteria. The wave equations are numerically solved for the elastoplastic stages, and the resultant spatiotemporal behavior of the differential displacement field is compared with the experimental results obtained by ESPI. Agreement between the experimental and numerical results validates the present methodology at least for the elastoplastic stages. The solitary wave characteristics in the fracturing stages is discussed based on the experimental results and dislocation theory.

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Section: Propagation Of Elasto-plastic Wavesupporting

confidence: 91%

Section: Propagation Of Elasto-plastic Wavesupporting

confidence: 90%

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Nondestructive Evaluation of Solids Based on Deformation Wave Theory

2020

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Spatial system identification of a simply supported beam and a trapezoidal cantilever plate

Fleming

Moheimani

Proceedings of the 41st IEEE Conference on Decision and Control, 2002.

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Dynamic models of structural and acoustic systems are usually obtained by means of either modal analysis or finite element modeling. Detrimentally, both techniques rely on a comprehensive knowledge of the system's physical properties. As a consequence, experimental data and a nonlinear optimization are required to refine the model. For the purpose of control, system identification is often employed to estimate the dynamics from disturbance and command inputs to set of outputs. Such discretization of a spatially distributed system places unknown weightings on the control objective, in many cases, contradicting the original goal of optimal control. This paper introduces a frequency domain system identification technique aimed at obtaining spatially continuous models for a class of distributed parameter systems. The technique is demonstrated by identifying a simply supported beam and a trapezoidal cantilever plate, both with bonded piezoelectric transducers. The plate's dimensions are based on the scaled side elevation of a McDonnell Douglas FA-18 vertical stabilizer.

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Experiments in spatial H ∞ control of a piezoelectric laminate beam

Cited by 2 publications

References 9 publications

Nondestructive Evaluation of Solids Based on Deformation Wave Theory

Nondestructive Evaluation of Solids Based on Deformation Wave Theory

Spatial system identification of a simply supported beam and a trapezoidal cantilever plate

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