Sökning: "Closed cracks"

Visar resultat 1 - 5 av 16 avhandlingar innehållade orden Closed cracks.

  1. 1. Closed-die forging and slab hot rolling with focus on material yield : some industrial problems analysed by FEM

    Författare :Esa Ervasti; Ulf Ståhlberg; Hans Keife; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Material yield; Closed-die forging; Hot rolling; Cracks; Macro-inclusions; Steel; FEM; Industrial engineering and economy; Industriell teknik och ekonomi;

    Sammanfattning : The thesis is focussed on improving the material yield in closed-die forging and rolling. The former is restricted to the manufacturing of heavy crown wheels and front axle beams and the latter to the hot rolling of steel slabs. To enhance the yield the commercial FE-codes Form2D and Dyna3D are used. LÄS MER

  3. 2. 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. 3. Initiation and early crack growth in VHCF of stainless steels : Experimental and theoretical analysis

    Författare :Muhammad Waqas Tofique; Jens Bergstöm; Nils Hallbäck; Thierry Pallin-Luc; Karlstads universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Very High Cycle Fatigue; Stainless steel; Ultrasonic fatigue testing; Crack initiation; Crystallographic crack growth; Distributed Dislocation Dipole Technique; Closed cracks; Materialteknik; Materials Engineering;

    Sammanfattning : Mechanical fatigue is a failure phenomenon that occurs due to repeated application of mechanical loads. Very High Cycle Fatigue (VHCF) is considered as the domain of fatigue life greater than 10 million load cycles. LÄS MER

  5. 4. Elastic Wave Scattering by Closed Cracks and Thin Flaws - Multiple Scattering and Resonances

    Författare :Arne S. Eriksson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; SH-wave; evaluation of materials; direct integral equation; singularity expansion; ultrasonic testing;

    Sammanfattning : In this thesis we study elastic wave scattering by thin flaws and closed cracks, which finds applications in ultrasonic testing and evaluation of materials. First we consider the scattering of an SH-wave by a thin finite elastic layer between two elastic half-spaces. LÄS MER

  7. 5. Elastic Wave Scattering by Cracks - Interfacial Forces and High Frequency Diffraction

    Författare :Gert Persson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; ultrasonic testing; Wiener-Hopf calculations; Geometrical Theory of Diffraction; edge diffracted body waves; PEDGE; two-dimensional diffraction; geometrical elastodynamic waves;

    Sammanfattning : This thesis treats elastic wave scattering by cracks with interfacial forces. The results are of practical interest in ultrasonic testing and includes development of numerical methods used to predict such testing. First the canonical problem of two-dimensional (2-D) diffraction from a semi-infinite crack is solved. LÄS MER