scholarly journals Time-Domain Hybrid Global-Local Prediction of Guided Waves Interaction with Damage

2013 ◽  
Vol 558 ◽  
pp. 116-127 ◽  
Author(s):  
Matthieu Gresil ◽  
Victor Giurgiutiu
Keyword(s):  
Finite Element ◽  
Wave Propagation ◽  
Time Domain ◽  
Guided Waves ◽  
Lamb Waves ◽  
Mode Conversion ◽  
Wave Interaction ◽  
Guided Wave ◽  
Element Mesh ◽  
The Time Domain

This paper presents a hybrid finite element and analytical method to predict the 1-D guided wave propagation interaction with damage for nondestructive evaluation (NDE) and structural health monitoring (SHM) application. The finite element mesh is used to describe the region around the damage (defects or flaws). In contrast to other hybrid models developed elsewhere, the interaction between Lamb waves and defects is computed in the time domain using the explicit solver of the commercial finite element method (FEM) software ABAQUS. Analytical methods can perform efficient modeling of wave propagation but are limited to simple geometries. Realistic structures with complicated geometries are usually modeled with the FEM. However, to obtain an accurate wave propagation solution at ultrasonic frequencies is computationally intensive and may become prohibitive for realistic structures. In response to today's complex cases not covered by the simulation tools available, we aim to develop an efficient and accessible tool for SHM applications. This tool will be based on a hybrid coupling between analytical solutions and time domain numerical codes. Lamb wave interaction with a notch is investigated by using this method, and the results obtained are with respect to transmission, reflection and mode conversion. Because of the symmetric mode shape, S0 is more sensitive to the shallow notch than A0. By making use of the fact that the reflection increases with increase in notch depth and mode conversion are maximized when the notch is around half through the thickness of the plate, the reflection and conversion coefficients can be used to characterize the depth of the notch.

NUMERICAL MODELING OF WALL THINNING DEFECTS CHARACTERIZATION: APPLICATIONS IN LAMB WAVE GENERATION AND INTERACTION

2008 ◽  
Vol 22 (11) ◽  
pp. 935-940
Author(s):  
HYUNJO JEONG ◽  
SEUNG-SEOK LEE ◽  
YOUNG-GIL KIM
Keyword(s):  
Guided Waves ◽  
Lamb Waves ◽  
Mode Conversion ◽  
Wave Interaction ◽  
Guided Wave ◽  
Destructive Interference ◽  
Wall Thinning ◽  
Mode Dispersion ◽  
Periodic Ring ◽  
Axisymmetric Scattering

The generation of axisymmetric Lamb waves and interaction with wall thinning (corrosion) defects in hollow cylinders are simulated using the finite element method. Guided wave interaction with defects in cylinders is challenged by the multi-mode dispersion and the mode conversion. In this paper, two longitudinal, axisymmetric modes are generated using the concept of a time-delay periodic ring arrays (TDPRA), which makes use of the constructive/destructive interference concept to achieve the unidirectional emission and reception of guided waves. The axisymmetric scattering by the wall thinning extending in full circumference of a cylinder is studied with a two-dimensional FE simulation. The effect of wall thinning depth, axial extension, and the edge shape on the reflections of guided waves is discussed.

scholarly journals Longitudinal Guided Wave Inspection of Small-Diameter Elbowed Steel Tubes with a Novel Squirrel-Cage Magnetostrictive Sensor

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Yao Liu ◽  
Xiucheng Liu ◽  
Chehua Yang ◽  
Wenxin Guo ◽  
Bin Wu ◽  
...  
Keyword(s):  
Finite Element ◽  
Guided Waves ◽  
Mode Conversion ◽  
Small Diameter ◽  
Longitudinal Mode ◽  
Guided Wave ◽  
Wall Defect ◽  
Squirrel Cage ◽  
Simulation Results ◽  
Magnetostrictive Sensor

In the study, ultrasonic longitudinal mode guided waves were employed to detect defects in elbowed tubes (without welds) with a diameter of 10 mm. Finite element simulation results highlighted that the emitted L(0,1) mode guided waves experienced strong reflection and mode conversion at the elbow region to generate F(1,1) mode, followed by slow and weak F(2,1) mode. The guided wave reflected from the elbow with a through-wall defect was manifested as two overlapped wave packets, which were good indicators of a defective elbow. To conduct L(0,1) mode guided waves inspection on the small-diameter elbowed tubes, a novel tailored squirrel-cage magnetostrictive sensor was employed in the experiment. The new sensor employed the configuration of segmental iron-cobalt strips and small-size permanent magnet arrays. The entire sensor is composed of two identical C-shaped sensor elements and can be recycled and installed conveniently. Experimental results obtained from healthy and defective tubes were consistent with the conclusions obtained from finite element simulations. An artificial through-wall defect at the elbow and a notch defect at the straight part of the tube could be simultaneously detected by L(0,1) mode guided waves through comparing experimental signals with simulation results.

A Hermite Spline Layerwise Time Domain Spectral Finite Element for Guided Wave Prediction in Laminated Composite and Sandwich Plates

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
C. S. Rekatsinas ◽  
D. A. Saravanos
Keyword(s):  
Finite Element ◽  
Time Domain ◽  
Guided Waves ◽  
Mass Matrix ◽  
Time Integration ◽  
Laminated Composite ◽  
Guided Wave ◽  
Sandwich Plates ◽  
Transverse Displacement ◽  
Lumped Mass

A new time domain spectral plate finite element (FE) is developed to provide fast numerical calculations of guided waves and transient phenomena in laminated composite and sandwich plates. A new multifield layerwise laminate theory provides the basis for the FE, which incorporates cubic Hermite polynomial splines for the approximation of the in-plane and transverse displacement fields through the thickness of the plate, enabling the modeling of symmetric and antisymmetric wave modes. The time domain spectral FE with multi-degrees-of-freedom (DOF) per node is subsequently formulated, which uses integration points collocated with the nodes to yield consistent diagonal lumped mass matrix which expedites the explicit time integration process. Numerical simulations of wave propagation in aluminum, laminated carbon/epoxy and thick sandwich plates are presented and validated with an analytical solution and a three-dimensional (3D) solid element; moreover, the capability to accurately and rapidly predict antisymmetric and symmetric guided waves is demonstrated.

Guided Wave Propagation Mechanics Across a Pipe Elbow

2003 ◽  
Author(s):  
Takahiro Hayashi ◽  
Koichiro Kawashima ◽  
Zongqi Sun ◽  
Joseph L. Rose
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Wave Propagation ◽  
Coordinate System ◽  
Guided Waves ◽  
Guided Wave ◽  
Cylindrical Coordinate System ◽  
Pipe Elbow ◽  
Guided Wave Propagation ◽  
Cylindrical Coordinate

Wave propagation across a pipe elbow region is complex. Subsequent reflected and transmitted waves are largely deformed due to mode conversions at the elbow. This prevents us to date from applying guided waves to the nondestructive evaluation of meandering pipeworks. Since theoretical development of guided wave propagation in a pipe is difficult, numerical modeling techniques are used. We have introduced a semi-analytical finite element method, a special modeling technique for guided wave propagation, because ordinary finite element methods require extremely long computational times and memory for such a long-range guided wave calculation. In this study, the semi-analytical finite element method for curved pipes is developed. A curved cylindrical coordinate system is used for the curved pipe region, where a curved center axis of the pipe elbow region is an axis (z′ axis) of the coordinate system, instead of the straight axis (z axis) of the cylindrical coordinate system. Guided waves in the z′ direction are described as a superposition of orthogonal functions. The calculation region is divided only in the thickness and circumferential directions. Using this calculation technique, echoes from the back wall beyond up to four elbows are discussed.

The Mode Conversion of a Guided Wave by a Part-Circumferential Notch in a Pipe

1998 ◽  
Vol 65 (3) ◽  
pp. 649-656 ◽  
Author(s):  
M. J. S. Lowe ◽  
D. N. Alleyne ◽  
P. Cawley
Keyword(s):  
Finite Element ◽  
Guided Waves ◽  
Mode Conversion ◽  
Crack Opening ◽  
Element Model ◽  
Guided Wave ◽  
Axially Symmetric ◽  
Simple Analysis ◽  
Notch Length ◽  
Circumferential Notch

A study of the reflection of mode-converted guided waves from notches in pipes has been carried out. Measurements were made on a 76-mm bore diameter (nominal 3-inch), 5.5-mm wall thickness pipe with circumferentially oriented through-thickness notches of various lengths. In parallel, a finite element model was used to simulate the experiments. The axially symmetric L(0, 2) mode was incident on the notches and the L(0, 2), F(1, 3), and F(2, 3) modes were received in reflection. The results showed excellent agreement between the measurements and the predictions for all three modes. They also showed that the F(1, 3) mode reflects as strongly as the L(0, 2) mode when the notch length is short. Finally, it has been shown that a very simple analysis based on an assumed crack-opening profile may be used to make accurate predictions of the mode conversion.

Guided Wave Propagation Mechanics Across a Pipe Elbow

2005 ◽  
Vol 127 (3) ◽  
pp. 322-327 ◽  
Author(s):  
Takahiro Hayashi ◽  
Koichiro Kawashima ◽  
Zongqi Sun ◽  
Joseph L. Rose
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Wave Propagation ◽  
Coordinate System ◽  
Guided Waves ◽  
Guided Wave ◽  
Cylindrical Coordinate System ◽  
Pipe Elbow ◽  
Guided Wave Propagation ◽  
Cylindrical Coordinate

Wave propagation across a pipe elbow region is complex. Subsequent reflected and transmitted waves are largely deformed due to mode conversions at the elbow. This prevents us to date from applying guided waves to the nondestructive evaluation of meandering pipeworks. Since theoretical development of guided wave propagation in a pipe is difficult, numerical modeling techniques are useful. We have introduced a semianalytical finite element method, a special modeling technique for guided wave propagation, because ordinary finite element methods require extremely long computational times and memory for such a long-range guided wave calculation. In this study, the semianalytical finite element method for curved pipes is developed. A curved cylindrical coordinate system is used for the curved pipe region, where a curved center axis of the pipe elbow region is an axis (z′ axis) of the coordinate system, instead of the straight axis (z axis) of the cylindrical coordinate system. Guided waves in the z′ direction are described as a superposition of orthogonal functions. The calculation region is divided only in the thickness and circumferential directions. Using this calculation technique, echoes from the back wall beyond up to four elbows are discussed.

Guided Wave Focusing Mechanics in Pipe

2003 ◽  
Author(s):  
Takahiro Hayashi ◽  
Koichiro Kawashima ◽  
Zongqi Sun ◽  
Joseph L. Rose
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Guided Waves ◽  
Wave Structure ◽  
Guided Wave ◽  
Pipe Inspection ◽  
Specific Point ◽  
Wave Focusing ◽  
Beam Focusing ◽  
Subsequent Time

Guided waves can be used in pipe inspection over long distances. Presented in this paper is a beam focusing technique to improve the S/N ratio of the reflection from a tiny defect. Focusing is accomplished by using non-axisymmetric waveforms and subsequent time delayed superposition at a specific point in a pipe. A semi-analytical finite element method is used to present wave structure in the pipe. Focusing potential is also studied with various modes and frequencies.

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