Accuracy and Convergence Using a Local Interaction Simulation Approach in One, Two, and Three Dimensions

2009 ◽  
Vol 76 (3) ◽  
Author(s):  
Shankar Sundararaman ◽  
Douglas E. Adams
Keyword(s):  
Guided Waves ◽  
Wave Dispersion ◽  
Guided Wave ◽  
Local Interaction ◽  
Three Dimensions ◽  
Simulation Approach ◽  
Sharp Interface Model ◽  
Transform Method ◽  
Broadband Pulse ◽  
Interaction Simulation

Guided waves are utilized in structural health monitoring for identifying damage in material components. Simulations can be used to examine how elastic waves propagate in components to help in selecting measurement and data analysis techniques. In this work, the influence of grid size and the frequency sample rate on the amplitude accuracy and convergence of local interaction simulation approach/sharp interface model (LISA/SIM) numerical simulations are studied as they pertain to guided wave propagation in structural materials. These issues are studied in all three dimensions, and amplitude distortion with respect to the Courant–Friedrich–Lewy criterion is explored. The LISA/SIM enables accurate and fast modeling of localized and sharp changes in material properties across interfaces associated with heterogeneities and/ or boundaries. The validity of the simulation is demonstrated by comparing simulated responses with experimentally measured data. Additionally, Lamb wave dispersion curves are extracted through the course of the convergence study using a broadband pulse and the two-dimensional fast Fourier transform method.

Modeling Guided Waves for Damage Identification in Isotropic and Orthotropic Plates Using a Local Interaction Simulation Approach

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Shankar Sundararaman ◽  
Douglas E. Adams
Keyword(s):  
Lamb Waves ◽  
Wave Length ◽  
Local Interaction ◽  
Wave Form ◽  
Multiple Site ◽  
Simulation Approach ◽  
Orthotropic Plates ◽  
Sharp Interface Model ◽  
Multiple Site Damage ◽  
Interaction Simulation

In this paper, a numerical simulation technique based on the local interaction simulation approach (LISA)/sharp interface model (SIM) is used to study the propagation of Lamb waves in aluminum and orthotropic plates and wave interactions with damage. The LISA/SIM model allows for accurate and fast simulations of sharp changes in material properties across interfaces associated with damage or specimen boundaries. Damage in the form of holes and changes in density and/or stiffnesses are studied for three different plates. These local changes in density and stiffness have dimensions not exceeding the wave length of the interrogating wave form. Wave scatter from these damage sites is shown at different time instants and at specific spatial locations. Multiple site damage cases are studied for all the plate structures. The different scatter patterns associated with intersecting and nonintersecting surface cracks are also studied. Results obtained from a combination of single site damage cases are compared with the composite multiple site damage case to study the usability of commonly applied algorithms for identifying damage. The benefits of observing multiple directions of the displacement field are demonstrated. It is shown that the out-of-plane measurements give a clearer indication of damage sites than the in-plane measurements.

A Simplified Dispersion Compensation Algorithm for the Interpretation of Guided Wave Signals

2019 ◽  
Vol 141 (2) ◽  
Author(s):  
Wenjun Wu ◽  
Yuemin Wang
Keyword(s):  
Guided Waves ◽  
Matching Pursuit ◽  
Dispersion Compensation ◽  
Wave Dispersion ◽  
Guided Wave ◽  
Center Frequency ◽  
Practical Applications ◽  
Compensation Algorithm ◽  
Nonlinear Phase ◽  
Mode Separation

Due to the multimodal and dispersive characteristics of guided waves, guided wave testing signals are always overlapped and difficult to separate for correct interpretations. To this end, a simplified dispersion compensation algorithm is put forward in this paper. The dispersion elimination is accomplished by compensating the second-order nonlinear phase shift of guided wave signals, which is the cause of the dispersion when narrow band exciting signals are used. This algorithm is easy to implement and has no need of prior knowledge of the guided wave dispersion relationship. Considering that the center frequency, which is a key parameter for this algorithm, is nearly impossible to determine accurately in practical applications, the effect of the center frequency deviation on the algorithm is further studied. Both theoretical analysis and numerical simulation indicate the insensitivity of the algorithm to the deviation of the center frequency, and hence, there is no need to determine the center frequency accurately, facilitating the practical use of the algorithm. Based on this simplified dispersion compensation algorithm and in cooperation with the matching pursuit method, the mode separation is further performed for interpreting of overlapped guided wave signals. Dispersion compensation is first applied to the testing signal with respect to a certain mode which will compress the waveform of the mode while the others still spread. Then, this compressed waveform is separated with the Gabor based matching pursuit method. Both simulation and experiment are designed to demonstrate the effectiveness of the proposed methods.

Seismic inversion of shale reservoir properties using microseismic-induced guided waves recorded by distributed acoustic sensing (DAS)

Geophysics ◽  
2021 ◽  
pp. 1-58
Author(s):  
Bin Luo ◽  
Ariel Lellouch ◽  
Ge Jin ◽  
Biondo Biondi ◽  
James Simmons
Keyword(s):  
Hydraulic Fracturing ◽  
Guided Waves ◽  
Wave Dispersion ◽  
Seismic Inversion ◽  
Dispersion Relations ◽  
Guided Wave ◽  
Low Velocity ◽  
Propagator Matrix ◽  
Shale Formation ◽  
Shale Reservoir

Shale formation properties are crucial for the hydrocarbon production performance of unconventional reservoirs. Microseismic-induced guided waves, which propagate within the low-velocity shale formation, are an ideal candidate for accurate estimation of the shale thickness, velocity, and anisotropy. A DAS fiber deployed along the horizontal section of a monitor well can provide a high-resolution recording of guided waves excited by microseismic events during hydraulic fracturing operations. These guided waves manifest a highly dispersive behavior that allows for seismic inversion of the shale formation properties. An adaptation of the propagator matrix method is presented to estimate guided wave dispersion curves and its accuracy is validated by comparison to 3-D elastic wavefield simulations. The propagator matrix formulation holds for cases of vertical transverse isotropy (VTI) as well. A sensitivity analysis of the theoretical dispersion relations of the guided waves shows that they are mostly influenced by the thickness and S-wave velocity of the low-velocity shale reservoir. The VTI parameters of the formation are also shown to have an impact on the dispersion relations. These physical insights provide the foundation for a dispersion-based model inversion for a 1-D depth-dependent structure of the reservoir and its surroundings. The inversion procedure is validated in a synthetic case and applied to the field records collected in an Eagle Ford hydraulic fracturing project. The inverted structure agrees well with a sonic log acquired several hundred meters away from the monitor well. Seismic inversion using guided wave dispersion therefore shows promise to become a novel and cost-effective strategy for in-situ estimation of reservoir structure and properties, which complements microseismic-based interpretation and production-related information.

Local Interaction Simulation Approach vs. Finite Element Modelling for Fault Detection in Medical Ultrasonic Transducer

2013 ◽  
Vol 588 ◽  
pp. 157-165 ◽  
Author(s):  
Z. Hashemiyan ◽  
Pawel Packo ◽  
W. Kochański ◽  
Wieslaw Jerzy Staszewski ◽  
Tadeusz Uhl ◽  
...  
Keyword(s):  
Fault Detection ◽  
Finite Element Modelling ◽  
Ultrasonic Transducer ◽  
Poor Quality ◽  
Local Interaction ◽  
Ultrasonic Transducers ◽  
Medical Applications ◽  
Simulation Approach ◽  
Element Modelling ◽  
Interaction Simulation

Ultrasonic transducers are extensively used in medical applications. Any deterioration in their performance can lead to poor quality images. The Local Interaction Simulation Approach (LISA) and Finite Elements are used to model medical ultrasonic transducers. The entire analysis attempts to find out whether the LISA-based methodology could be used for transducer modelling in fault detection applications based on in-air reverberation patterns.

Sign in / Sign up

Export Citation Format

Share Document