Abstract
This paper presents a study on the scattering of the fundamental flexural Lamb wave mode (A0) by an edge delamination around the circumference of a circular through hole in a plate. Although edge delaminations are recognized as an important form of structural damage in fiber-composite laminates, there is little previous work on Lamb wave scattering by this form of damage This study uses a 3D laser vibrometer to obtain a detailed experimental characterization of the angular dependence of the scattered field from an edge delamination, for an incident probing wave at various angles of incidence. These experimental observations are correlated with computational results obtained by using the commercial Finite Element package ABAQUS, showing excellent correlation. To assist with a detailed quantitative analysis of this complicated scattering process, Aluminium is used instead of a composite laminate, as this removes further complications that arise due to the anisotropic and multilayer nature of the material in composites. A simulated semi-circular delamination is introduced at the boundary of a circular hole of 20mm diameter, in the mid plane location of the plate using cutting tool. The probing signal is a narrowband 5.5-cycle tone burst with a center frequency of 200 kHz, for which the corresponding A0 wavelength is λ = 10 mm. The relatively small damage size studied corresponds to early damage detection which is the main area of interest for SHM applications The Scattered Amplitude Pattern is used to study the relationship between the scattered field and damage orientation relative to the incident wave. Results obtained indicate a strong dependence between the scattering amplitude pattern and angle of incidence. The results show that the scatter field amplitude and directivity information can be used to detect and quantify the damage in any orientation around the through hole, which confirms and extends the correlations obtained in our previous work for delaminations at a straight edge. This forward scattering problem provides a necessary pre-requisite for addressing the more challenging inverse problem of characterizing the damage from observations of the scattered field, particularly for complex geometries involving detection on the blind side of through holes.
| Original language | English |
|---|---|
| Title of host publication | 8th European Workshop on Structural Health Monitoring, EWSHM 2016 |
| Subtitle of host publication | Bilbao, Spain; 5-8 July 2016 |
| Place of Publication | Bad Breisig, Germany |
| Publisher | NDT Internet Publishing |
| Pages | 1077-1086 |
| Number of pages | 10 |
| Volume | 2 |
| ISBN (Print) | 9781510827936 |
| Publication status | Published - 2016 |
| Event | 8th European Workshop on Structural Health Monitoring - Bilbao, Spain Duration: 5 Jul 2016 → 8 Jul 2016 Conference number: 8 |
Conference
| Conference | 8th European Workshop on Structural Health Monitoring |
|---|---|
| Abbreviated title | EWSHM 2016 |
| Country | Spain |
| City | Bilbao |
| Period | 5/07/16 → 8/07/16 |
Keywords
- Delamination damage
- Experimental validation.
- Lamb waves
- Wave Scattering
Cite this
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An experimental and computational study of Lamb wave scattering by edge delaminations around circular holes. / Nadarajah, Nithurshan; Francis Rose, L. R.; Chiu, Wing Kong.
8th European Workshop on Structural Health Monitoring, EWSHM 2016: Bilbao, Spain; 5-8 July 2016. Vol. 2 Bad Breisig, Germany : NDT Internet Publishing, 2016. p. 1077-1086.Research output: Chapter in Book/Report/Conference proceeding › Conference Paper › Research
TY - GEN
T1 - An experimental and computational study of Lamb wave scattering by edge delaminations around circular holes
AU - Nadarajah, Nithurshan
AU - Francis Rose, L. R.
AU - Chiu, Wing Kong
PY - 2016
Y1 - 2016
N2 - This paper presents a study on the scattering of the fundamental flexural Lamb wave mode (A0) by an edge delamination around the circumference of a circular through hole in a plate. Although edge delaminations are recognized as an important form of structural damage in fiber-composite laminates, there is little previous work on Lamb wave scattering by this form of damage This study uses a 3D laser vibrometer to obtain a detailed experimental characterization of the angular dependence of the scattered field from an edge delamination, for an incident probing wave at various angles of incidence. These experimental observations are correlated with computational results obtained by using the commercial Finite Element package ABAQUS, showing excellent correlation. To assist with a detailed quantitative analysis of this complicated scattering process, Aluminium is used instead of a composite laminate, as this removes further complications that arise due to the anisotropic and multilayer nature of the material in composites. A simulated semi-circular delamination is introduced at the boundary of a circular hole of 20mm diameter, in the mid plane location of the plate using cutting tool. The probing signal is a narrowband 5.5-cycle tone burst with a center frequency of 200 kHz, for which the corresponding A0 wavelength is λ = 10 mm. The relatively small damage size studied corresponds to early damage detection which is the main area of interest for SHM applications The Scattered Amplitude Pattern is used to study the relationship between the scattered field and damage orientation relative to the incident wave. Results obtained indicate a strong dependence between the scattering amplitude pattern and angle of incidence. The results show that the scatter field amplitude and directivity information can be used to detect and quantify the damage in any orientation around the through hole, which confirms and extends the correlations obtained in our previous work for delaminations at a straight edge. This forward scattering problem provides a necessary pre-requisite for addressing the more challenging inverse problem of characterizing the damage from observations of the scattered field, particularly for complex geometries involving detection on the blind side of through holes.
AB - This paper presents a study on the scattering of the fundamental flexural Lamb wave mode (A0) by an edge delamination around the circumference of a circular through hole in a plate. Although edge delaminations are recognized as an important form of structural damage in fiber-composite laminates, there is little previous work on Lamb wave scattering by this form of damage This study uses a 3D laser vibrometer to obtain a detailed experimental characterization of the angular dependence of the scattered field from an edge delamination, for an incident probing wave at various angles of incidence. These experimental observations are correlated with computational results obtained by using the commercial Finite Element package ABAQUS, showing excellent correlation. To assist with a detailed quantitative analysis of this complicated scattering process, Aluminium is used instead of a composite laminate, as this removes further complications that arise due to the anisotropic and multilayer nature of the material in composites. A simulated semi-circular delamination is introduced at the boundary of a circular hole of 20mm diameter, in the mid plane location of the plate using cutting tool. The probing signal is a narrowband 5.5-cycle tone burst with a center frequency of 200 kHz, for which the corresponding A0 wavelength is λ = 10 mm. The relatively small damage size studied corresponds to early damage detection which is the main area of interest for SHM applications The Scattered Amplitude Pattern is used to study the relationship between the scattered field and damage orientation relative to the incident wave. Results obtained indicate a strong dependence between the scattering amplitude pattern and angle of incidence. The results show that the scatter field amplitude and directivity information can be used to detect and quantify the damage in any orientation around the through hole, which confirms and extends the correlations obtained in our previous work for delaminations at a straight edge. This forward scattering problem provides a necessary pre-requisite for addressing the more challenging inverse problem of characterizing the damage from observations of the scattered field, particularly for complex geometries involving detection on the blind side of through holes.
KW - Delamination damage
KW - Experimental validation.
KW - Lamb waves
KW - Wave Scattering
UR - http://www.scopus.com/inward/record.url?scp=84994494436&partnerID=8YFLogxK
M3 - Conference Paper
AN - SCOPUS:84994494436
SN - 9781510827936
VL - 2
SP - 1077
EP - 1086
BT - 8th European Workshop on Structural Health Monitoring, EWSHM 2016
PB - NDT Internet Publishing
CY - Bad Breisig, Germany
ER -