scholarly journals Reflection and transmission behavior of Lamb waves at an adhesive lap joint of plates

2019 ◽  
Author(s):  
Naoki Mori ◽  
Takayuki Kusaka
Keyword(s):  
Lamb Waves ◽  
Lap Joint ◽  
Reflection And Transmission

Study of the Transmission of Ultrasonic Guided Wave at the Junction of Two Different Elastic Plates with the Presence of a Defect

2011 ◽  
Vol 482 ◽  
pp. 21-29
Author(s):  
Taoufiq Belhoussine Drissi ◽  
Bruno Morvan ◽  
Mihai Predoi ◽  
Jean Louis Izbicki ◽  
Pascal Pareige
Keyword(s):  
Lamb Waves ◽  
Guided Wave ◽  
Elastic Plates ◽  
The Finite Element Method ◽  
Reflection And Transmission ◽  
Modal Approach ◽  
Limit Value ◽  
Numerical Studies ◽  
Ultrasonic Guided Wave ◽  
Orthogonality Relations

We are interested in a right junction of two plates of different materials (aluminum and copper) placed in contact edge to edge. The aim of this study is the interaction of Lamb waves with a defect located at the junction. The reflection and transmission of the fundamental symmetrical S0 wave is analyzed. The theoretical coefficients of reflection and transmission are obtained by a multi-modal approach based on the orthogonality relations involving different modes. Using the Finite Element Method (FEM), we estimate the limit value of the ratio between the dimension of the defect and the thickness of the structure, for which the multi-modal approach is applicable. In experimental and numerical studies, it is also brought to light the effects of diffraction by the defect.

scholarly journals Reflection and transmission of Lamb waves at an imperfect joint of plates

2013 ◽  
Vol 113 (7) ◽  
pp. 074901 ◽  
Author(s):  
Naoki Mori ◽  
Shiro Biwa ◽  
Takahiro Hayashi
Keyword(s):  
Lamb Waves ◽  
Reflection And Transmission

scholarly journals Lamb wave–based detection of a controlled disbond in a lap joint

2017 ◽  
Vol 17 (3) ◽  
pp. 668-683 ◽  
Author(s):  
Wern Hann Ong ◽  
Nik Rajic ◽  
Wing Kong Chiu ◽  
Cedric Rosalie
Keyword(s):  
Lamb Wave ◽  
Lamb Waves ◽  
Mode Conversion ◽  
Numerical Study ◽  
Lap Joints ◽  
Single Frequency ◽  
Lap Joint ◽  
Frequency Selection ◽  
Almost All ◽  
Shed Light

Lap joints are widely used across many critical structures such as aircraft and bridges. Lamb waves have long been proposed to monitor lap joints against defects such as disbonds. However, there are many challenges which must be answered to make use of Lamb wave technology. Frequency selection is often overlooked, and many authors will select a single frequency without knowing if other frequencies will result in better sensitivity. Another challenge is the features (mode conversion, attenuation, reflection) associated with damage are also inherent in a lap joint. This sharing of features can lead to confusion (false positive/negative) depending on the chosen damage detection strategy. Furthermore, almost all proposed methods require a baseline reading of the structure in its flawless state. Relying on a baseline reading can result in false positives due to shifts in sensor outputs caused by ageing and inconsistent environmental conditions. Instead of a baseline, this article proposes a technique which uses strategically positioned sensors to detect Lamb wave modes generated only in the presence of a disbond. The technique is first developed using a numerical study and then verified with an experimental study. Several frequencies are trialled and detailed in this article which shed light on the ideal frequency selection when using this method.

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