Sökning: "Crack"

Visar resultat 31 - 35 av 544 avhandlingar innehållade ordet Crack.

1. 31. Modeling of Scattering by Cracks in Anisotropic Solids - Application to Ultrasonic Detection

   Författare :Johan Mattsson; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; elastic wave; ultrasonics; crack; integral equations; transducer; anisotropy; scattering; nondestructive testing;

   Sammanfattning : Elastodynamic wave scattering in anisotropic solids with application to ultrasonic nondestructive testing (NDT) is treated and mathematically modeled in this thesis. The scatterers are infinite strip-like cracks and the solids are homogeneous and linearly elastic with negligible damping. LÄS MER

3. 32. Nonlinear Interaction Between Ultrasonic Waves and Cracks and Interfaces

   Författare :Milan Poznic; Leif Kari; Bruce Drinkwater; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; ultrasonic waves; crack; modulation; rough interface; partially closed; surface-breaking; fluid-filled; Acoustics; Akustik;

   Sammanfattning : The subject of this thesis is the development of new ultrasound inspection techniques for detection of cracks that are smaller than the wavelength of the inspecting wave and the characterization of cracks in fluid-filled pipes as either surface-breaking or subsurface. The spectrum of the scattered field of a partially closed crack comprises harmonic components not expected to be found in the case of linear scatterers such as pores or inclusions. LÄS MER

4. 33. Ultrasonic NDT in Defect Detection - Mathematical modelling

   Författare :Håkan Wirdelius; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; crack; null field approach; transducers; optimisation; ultrasonics; elastic waves; nondestructive testing; T matrix method; inverse problem;

   Sammanfattning : This thesis is concerned with the mathematical modelling of the ultrasonic nondestructive testing situation. The first part of the thesis treats a simplified model of an ultrasonic transducer and its implementation into a T-matrix method-based solution to a crack scattering problem. LÄS MER

5. 34. Comprehensive numerical analysis of stress state in adhesive layer of joint including thermal residual stress and material non-linearity

   Författare :Nawres Jabar Al-Ramahi; Roberts Joffe; Janis Varna; Lars Mikkelsen; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Single-lap adhesive joint; Double-lap adhesive joint; Unbalanced bi-material DCB; Residual thermal stresses; Finite element method; Crack path; Crack closure; Polymeric Composite Materials; Polymera kompositmaterial;

   Sammanfattning : The main objective of this work is to improve understanding of the stress state in the adhesive layer of bonded joints and identify key parameters which govern performance of adhesive joints. This information is crucial for the prediction of the failure initiation and propagation with the further estimation of the durability and strength of adhesively bonded structures. LÄS MER

7. 35. Degradation of railway rails from a materials point of view

   Författare :Martin Schilke; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Anisotropy; White etching layer; Rail grade; Rolling contact fatigue; Three dimensions; Plastically deformed layer; Railway Rail; Crack;

   Sammanfattning : From time to time railway rails need to be replaced. In that case and when new track is built, a decision has to be made about which rail grade that is going to be installed. The intention of this work was to compare different rail steels concerning their suitability from a mechanical durability perspective. LÄS MER