Numerical Investigation on the Feasibility of Estimating the Thickness of Europa’s Ice Shell by a Planned Impact

Lloyd, Stephen; Jeong, Chanseok; Okutsu, Masataka

doi:10.1061/(asce)as.1943-5525.0000621

Cited by 3 publications

(2 citation statements)

References 45 publications

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“…However, the aforementioned FDM works did not use such a small element to model a void, so they could suffer from the additional error of wave solutions. To address this issue, the authors suggest explicitly using fluid elements to model voids filled with water (or air) so that accurate fluid-solid coupling (Everstine 1997;Lloyd et al 2016) can be incorporated into the wave solver. Then, using such a wave solver, inverse modeling could identify accurately the interfaces between fluid and solids as well as the material profiles of solids.…”

Section: Introductionmentioning

confidence: 99%

Multilevel Genetic Algorithm–Based Acoustic–Elastodynamic Imaging of Coupled Fluid–Solid Media to Detect an Underground Cavity

Guidio

Nam

Jeong

2023

J. Comput. Civ. Eng.

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This work studied the feasibility of imaging a coupled fluid-solid system using the elastodynamic and acoustic waves initiated from the top surface of a computational domain. A one-dimensional system, in which a fluid layer was surrounded by two solid layers, was considered. The bottom solid layer was truncated using a wave-absorbing boundary condition (WABC). The wave responses were measured by a sensor located on the top surface, and the measured signal contained information about the underlying physical system. Using the measured wave responses, the elastic moduli of the solid layers and the depths of the interfaces between the solid and fluid layers were identified. A multilevel genetic algorithm (GA) combined with a frequency-continuation scheme to invert the values of sought-for parameters was employed. The numerical results showed that (1) the depths of solid-fluid interfaces and elastic moduli can be reconstructed by the presented method, (2) the frequency-continuation scheme improves the convergence of the estimated values of parameters toward their targeted values, and (3) a preliminary inversion using an all-solid model can be employed to identify if a fluid layer exists in the model by showing one layer with a very large value of Young's modulus (with a value similar to that of the bulk modulus of water) and a mass density similar to that of water. Then the primary GA inversion method, based on a fluid-solid model, can be utilized to adjust the soil characteristics and fine-tune the locations of the fluid layer. If this work is extended to a 3D setting, it can be instrumental in finding unknown locations of fluid-filled voids in geological formations that can lead to ground instability and/or collapse (e.g., natural or anthropogenic sinkholes, urban cave-in subsidence, and so forth).

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Section: Introductionmentioning

confidence: 99%

Multilevel Genetic Algorithm–Based Acoustic–Elastodynamic Imaging of Coupled Fluid–Solid Media to Detect an Underground Cavity

Guidio

Nam

Jeong

2023

J. Comput. Civ. Eng.

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“…Many such methods utilize modal data to formulate an optimization problem to identify the structural damage. Finally, signal‐based methods (e.g., full‐waveform inversion methods) identify the damage characteristics (e.g., crack and/or holes) by minimizing the difference between wave response signals obtained from the “true” structures and those computed from the possibly damaged structure.…”

Section: Introductionmentioning

confidence: 99%

An iterative total least squares‐based estimation method for structural damage identification of 3D frame structures

Wang

Tapia

et al. 2020

Struct Control Health Monit

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Summary Identifying structural damage can usually be modeled as a problem with the use of linear equations. Due to measurement noise and spatial incompleteness of the measured mode shapes, these linear equations are usually ill conditioned, which will significantly reduce the accuracy of subsequent damage assessment. This study develops an iterative total least squares (TLS) based estimation method, which can effectively mitigate such ill conditioning and avoid propagating noise into estimates of structural damage severity. In particular, a procedure, called the δ–p curve method, is proposed to choose the effective rank of a TLS estimation. Further, an iterative approach of TLS‐based estimation is proposed to eliminate spurious damage estimates due to modal expansion and measurement noise. To investigate the effectiveness of the proposed iterative TLS‐based estimation method, detailed numerical studies of damage assessment are first conducted on a simulated 3D frame structure, in which both noise pollution and spatial incompleteness of the mode shapes are considered. Additionally, experimental tests with a laboratory structure are performed to validate the proposed method. Results indicate that the proposed iterative TLS‐based method can accurately identify the structural damage, even with noise‐polluted and spatially incomplete modes.

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Genetic Algorithm–Based Acoustic-Source Inversion Approach to Detect Multiple Moving Wave Sources of an Arbitrary Number

Jeong

Peixoto

Aquino

et al. 2017

J. Comput. Civ. Eng.

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Numerical Investigation on the Feasibility of Estimating the Thickness of Europa’s Ice Shell by a Planned Impact

Cited by 3 publications

References 45 publications

Multilevel Genetic Algorithm–Based Acoustic–Elastodynamic Imaging of Coupled Fluid–Solid Media to Detect an Underground Cavity

Multilevel Genetic Algorithm–Based Acoustic–Elastodynamic Imaging of Coupled Fluid–Solid Media to Detect an Underground Cavity

An iterative total least squares‐based estimation method for structural damage identification of 3D frame structures

Genetic Algorithm–Based Acoustic-Source Inversion Approach to Detect Multiple Moving Wave Sources of an Arbitrary Number

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