Dynamical properties of a composite microcracked bar based on a generalized continuum formulation

Settimi, Valeria; Trovalusci, Patrizia; Rega, Giuseppe

doi:10.1007/s00161-019-00761-7

Cited by 17 publications

(18 citation statements)

References 49 publications

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“…All the aforementioned non-local models are then defined as non-local because the governing equations contain one or more parameters that inherit a micro-structural character which affects the macroscopic behavior and because of dispersion properties in wave propagation [42][43][44][45][46]. Numerical simulations can be performed by fitting numerical experiments which have a physical evidence of the presence of such non-locality.…”

Section: Introductionmentioning

confidence: 99%

Material Symmetries in Homogenized Hexagonal-Shaped Composites as Cosserat Continua

Fantuzzi

Trovalusci

2020

Symmetry

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In this work, material symmetries in homogenized composites are analyzed. Composite materials are described as materials made of rigid particles and elastic interfaces. Rigid particles of arbitrary hexagonal shape are considered and their geometry described by a limited set of parameters. The purpose of this study is to analyze different geometrical configurations of the assemblies corresponding to various material symmetries such as orthotetragonal, auxetic and chiral. The problem is investigated through a homogenization technique which is able to carry out constitutive parameters using a principle of energetic equivalence. The constitutive law of the homogenized continuum has been derived within the framework of Cosserat elasticity, wherein the continuum has additional degrees of freedom with respect to classical elasticity. A panel composed of material with various symmetries, corresponding to some particular hexagonal geometries defined, is analyzed under the effect of localized loads. The results obtained show the difference of the micropolar response for the considered material symmetries, which depends on the non-symmetries of the strain and stress tensor as well as on the additional kinematical and work-conjugated statical descriptors. This work underlines the importance of resorting to the Cosserat theory when analyzing anisotropic materials.

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Section: Introductionmentioning

confidence: 99%

Material Symmetries in Homogenized Hexagonal-Shaped Composites as Cosserat Continua

Fantuzzi

Trovalusci

2020

Symmetry

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“…When an incident ultrasonic wave interacts with a microcrack, the former will be modulated, resulting in a minor waveform distortion without changing the basic synchronism between the incident ultrasonic wave and its response signal. Moreover, the dynamical analysis of a microcracked bar characterized by a uniform distribution of fibers and cracks has been performed [ 30 ], through which some useful hints can be furnished to interpret the response of one-dimensional structures with widespread damage.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Microcrack Orientation Using the Directivity of Secondary Sound Source Induced by an Incident Ultrasonic Transverse Wave

Wang

Zhao

et al. 2020

Materials

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In this paper, characterization of the orientation of a microcrack is quantitatively investigated using the directivity of second harmonic radiated by the secondary sound source (SSS) induced by the nonlinear interaction between an incident ultrasonic transverse wave (UTW) and a microcrack. To this end, a two-dimensional finite element (FE) model is established based on the bilinear stress–strain constitutive relation. Under the modulation of contact acoustic nonlinearity (CAN) to the incident UTW impinging on the microcrack examined, the microcrack itself is treated as a SSS radiating the second harmonic. Thus, the directivity of the second harmonic radiated by the SSS is inherently related to the microcrack itself, including its orientation. Furthermore, the effects of the stiffness difference between the compressive and tensile phases in the bilinear stress–strain model, and the UTW driving frequency, as well as the radius of the sensing circle on the SSS directivity are discussed. The FE results show that the directivity pattern of the second harmonic radiated by the SSS is closely associated with the microcrack orientation, through which the microcrack orientation can be characterized without requiring a baseline signal. It is also found that the SSS directivity varies sensitively with the driving frequency of the incident UTW, while it is insensitive to the stiffness difference between the compressive and tensile phases in the bilinear stress–strain model and the radius of the sensing circle. The results obtained here demonstrate that the orientation of a microcrack can be characterized using the directivity of the SSS induced by the interaction between the incident UTW and the microcrack.

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“…On the other hand, model-based approaches, such as the techniques based on one-dimensional elements [10,11], usually need to rely on accurate structural modeling and to select proper response signals. Damage effects have been also investigated, using non-classical continuum approaches, developed for materials with microstructure, by investigating displacement fields and wave propagation [12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Optimal Sensors Placement in Dynamic Damage Detection of Beams Using a Statistical Approach

Lofrano

Pingaro

Trovalusci

et al. 2020

J Optim Theory Appl

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Structural monitoring plays a central role in civil engineering; in particular, optimal sensor positioning is essential for correct monitoring both in terms of usable data and for optimizing the cost of the setup sensors. In this context, we focus our attention on the identification of the dynamic response of beam-like structures with uncertain damages. In particular, the non-localized damage is described using a Gaussian distributed random damage parameter. Furthermore, a procedure for selecting an optimal number of sensor placements has been presented based on the comparison among the probability of damage occurrence and the probability to detect the damage, where the former can be evaluated from the known distribution of the random parameter, whereas the latter is evaluated exploiting the closed-form asymptotic solution provided by a perturbation approach. The presented case study shows the capability and reliability of the proposed procedure for detecting the minimum number of sensors such that the monitoring accuracy (estimated by an error function measuring the differences among the two probabilities) is not greater than a control small value.

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Dynamical properties of a composite microcracked bar based on a generalized continuum formulation

Cited by 17 publications

References 49 publications

Material Symmetries in Homogenized Hexagonal-Shaped Composites as Cosserat Continua

Material Symmetries in Homogenized Hexagonal-Shaped Composites as Cosserat Continua

Characterization of Microcrack Orientation Using the Directivity of Secondary Sound Source Induced by an Incident Ultrasonic Transverse Wave

Optimal Sensors Placement in Dynamic Damage Detection of Beams Using a Statistical Approach

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