Sökning: "guided waves"

Visar resultat 1 - 5 av 16 avhandlingar innehållade orden guided waves.

1. 1. Ultrasonic Arrays for Sensing and Beamforming of Lamb Waves

   Författare :Marcus Engholm; Tadeusz Stepinski; Paul D. Wilcox; Uppsala universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; imaging; array processing; guided waves; Lamb waves; dispersive waves; multi-modal waves; spatial filtering; mode suppression; resonant ultrasound; transducer design; direction of arrival estimation; adaptive beamforming; Signal processing; Signalbehandling; Electronic measurement and instrumentation; Elektronisk mät- och apparatteknik;

   Sammanfattning : Non-destructive testing (NDT) techniques are critical to ensure integrity and safety of engineered structures. Structural health monitoring (SHM) is considered as the next step in the field enabling continuous monitoring of structures. LÄS MER

3. 2. Air-coupled microphone measurements of guided waves in concrete plates

   Författare :Henrik Bjurström; Nils Rydén; Björn Birgisson; Tadeusz Stepinski; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Non-destructive testing; Lamb waves; surface waves; air-coupled microphones; non-contact measurements;

   Sammanfattning : Quality control and quality assurance of pavements is today primarily based on core samples. Air void content and pavement thickness are parameters that are evaluated. However, no parameter connected to the stiffness is evaluated. LÄS MER

4. 3. Lamb wave evaluation of concrete plates

   Författare :Oskar Tofeldt; Teknisk geologi; []
   Nyckelord :Lamb waves; guided waves; impact-echo; concrete; non-destructive evaluation;

   Sammanfattning : This thesis is about the application of Lamb waves for non-destructive evaluation of plate-like concrete structures under one-sided access test condition using a portable equipment consisting of an accelerometer and impact hammer. With this type of equipment and based on array signal processing, the impact-echo (IE) method can be extended with measurements of surface waves; this extension allows an evaluation with Lamb waves. LÄS MER

5. 4. Surface Wave Testing of Pavements

   Författare :Nils Rydén; Teknisk geologi; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; geographical and geological engineering; Hydrogeologi; teknisk geologi; teknisk geografi; Hydrogeology; inversion; guided waves; road; pavement; Surface waves; non-destructive testing;

   Sammanfattning : A novel approach for surface wave testing of pavements is presented. It is a non-destructive testing (NDT) technique that can be used to obtain the thickness and stiffness properties of the different layers in a pavement. LÄS MER

7. 5. Guided Elastic Waves along Periodically Corrugated Structures

   Författare :Ahmed M. A. El-Bahrawy; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

   Sammanfattning : The present thesis consider time-harmonic surface and guided elastic waves propagating along periodically corrugated structures. The problems discussed deal with various configurations where the surfaces are sinusoidally - singly or doubly - periodic, and the interest is focused on investigating the roots of the dispersion relations and in particular the stopband and cross-over resonances. LÄS MER