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Low Attenuation Waveguide for Structural Health Monitoring with Leaky Surface Waves
Bezdek, M.,Joseph, K.,Tittmann, B.R. The Korean Society for Nondestructive Testing 2012 한국비파괴검사학회지 Vol.32 No.3
Some applications require structural health monitoring in inaccessible components. This paper presents a technique useful for Structural Health Monitoring of double wall structures, such as double wall steam pipes and double wall pressure vessels separated from an ultrasonic transducer by three layers. Detection has been demonstrated at distances in excess of one meter for a fixed transducer. The case presented here is for one of the layers, the middle layer, being a fluid. For certain transducer configurations the wave propagating in the fluid is a wave with low velocity and attenuation. The paper presents a model based on wave theory and finite element simulation; the experimental set-up and observations, and comparison between theory and experiment. The results provide a description of the technique, understanding of the phenomenon and its possible applications in Structural Health Monitoring.
Recent Advances in Scanning Acoustic Microscopy for Adhesion Evaluation of Thin Films
Ju, Hyeong-Sick,Tittmann, Bernhard R. The Korean Society for Nondestructive Testing 2009 한국비파괴검사학회지 Vol.29 No.6
As the thin film technology has emerged in various fields, adhesion of the film interface becomes an important issue in terms of the longevity and durability of thin film devices. Diverse nondestructive methods utilizing acoustic techniques have been developed to assess the interfacial integrity. As an effective technique based on the ultrasonic wave focusing and the surface acoustic wave(SAW) generation, scanning acoustic microscopy(SAM) has been investigated for adhesion evaluation. Visualization of film microstructures and quantification of adhesion weakness levels by SAW dispersion are the recent achievements of SAM. To overcome the limitations in the theoretical dispersion model only suitable for perfectly elastic and isotropic materials, a new model has been more recently developed in consideration of film anisotropy and viscoelasticity and applied to the adhesion evaluation of polymeric films fabricated on semiconductive wafers.
Recent Ultrasonic Guided Wave Inspection Development Efforts
Rose, Joseph L.,Tittmann, Bernhard R. 한국비파괴검사학회 2001 한국비파괴검사학회지 Vol.21 No.4
The recognition of such natural wave guides as plates, rods, hollow cylinder, multi-layer structures or simply an interface between two material combined with an increased understanding of the physics and wave mechanics of guided wave propagation has led to a significant increase in the number of guided wave inspection applications being developed each year. Of primary attention is the ability to inspect partially hidden structure, hard to access areas, and coated or insulated structures, An inteoduction to some physical consideration of guided waves followed by some sample problem description in pipe, ice detection, fouling detection in the foods industry, aircraft, tar coated structures and acoustic microcopy is presented in this paper. A sample problem in Boundary Element Modeling is also presented to illustrate the move in guided wave analysis beyond detection and location analysis to quantification.
Recent Advances in Scanning Acoustic Microscopy for Adhesion Evaluation of Thin Films
Hyeong Sick Ju,Bernhard R. Tittmann 한국비파괴검사학회 2009 한국비파괴검사학회지 Vol.29 No.6
As the thin film technology has emerged in various fields, adhesion of the film interface becomes an important issue in terms of the longevity and durability of thin film devices. Diverse nondestructive methods utilizing acoustic techniques have been developed to assess the interfacial integrity. As an effective technique based on the ultrasonic wave focusing and the surface acoustic wave(SAW) generation, scanning acoustic microscopy(SAM) has been investigated for adhesion evaluation. Visualization of film microstructures and quantification of adhesion weakness levels by SAW dispersion are the recent achievements of SAM. To overcome the limitations in the theoretical dispersion model only suitable for perfectly elastic and isotropic materials, a new model has been more recently developed in consideration of film anisotropy and viscoelasticity and applied to the adhesion evaluation of polymeric films fabricated on semiconductive wafers.
Low Attenuation Waveguide for Structural Health Monitoring with Leaky Surface Waves
M. Bezdek,K. Joseph,B. R. Tittmann 한국비파괴검사학회 2012 한국비파괴검사학회지 Vol.32 No.3
Some applications require structural health monitoring in inaccessible components. This paper presents a technique useful for Structural Health Monitoring of double wall structures, such as double wall steam pipes and double wall pressure vessels separated from an ultrasonic transducer by three layers. Detection has been demonstrated at distances in excess of one meter for a fixed transducer. The case presented here is for one of the layers, the middle layer, being a fluid. For certain transducer configurations the wave propagating in the fluid is a wave with low velocity and attenuation. The paper presents a model based on wave theory and finite element simulation; the experimental set-up and observations, and comparison between theory and experiment. The results provide a description of the technique, understanding of the phenomenon and its possible applications in Structural Health Monitoring.