Sökning: "Shear band"

Visar resultat 21 - 25 av 27 avhandlingar innehållade orden Shear band.

1. 21. On the Modelling and Numerics of Gradient-Regularized Plasticity Coupled to Damage

   Författare :Thomas Svedberg; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

   Sammanfattning : This thesis is primarily concerned with issues that arise in conjunction with the modelling of localization phenomena in solids using gradient-regularized plasticity with coupling to damage. The thermodynamic framework for a larger class of models is established, whereby gradients of the internal variables are included as arguments of the free energy. LÄS MER

3. 22. Synthesis and characterization of nanocarbons as reinforced particles in metal composites

   Författare :Vicente Benavides; Alberto Vomiero; Frank Mücklich; Olga Chernogorova; Jordi Ibañez Inza; Luleå tekniska universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Nanocarbons; super elastic hard carbon; Fullerenes under pressure; Disordered carbon; Experimentell fysik; Experimental Physics;

   Sammanfattning : In this work, several scientific problems related to high pressure–high temperature (HP–HT) synthesis of new materials using fullerite as a precursor were studied: first, the mechanism of the transformation of C60 crystal into a nano-clustered graphene phase (NGP) at a pressure of 8 GPa; and second, the effect of disorder introduced into C60 crystals by ball milling prior to HP–HT synthesis on the structure and properties of the NGP. A separate set of experiments was devoted to compression of C60 precursor at unexplored before pressure of 25 GPa and elevated temperatures in search for new type of disordered carbon-based materials. LÄS MER

4. 23. Fracture mechanics analysis of concrete structures

   Författare :Ulf Ohlsson; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Structural Engineering; Konstruktionsteknik;

   Sammanfattning : This thesis presents results from numerical and analytical analyses of concrete structures as well as results from laboratory tests. Numerical methods based on the finite element method and fracture mechanics are used. The thesis comprises five papers and a general introductory part. LÄS MER

5. 24. Boundary layer streaks as a novel laminar flow control method

   Författare :Sohrab Sattarzadeh Shirvan; Jens H. M. Fransson; Edward B. White; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; boundary layer stability; laminar to turbulent transition; laminar flow control; drag reduction; Tollmien-Schlichting waves; oblique waves; streaky boundary layers; miniature vortex generators; discrete suction;

   Sammanfattning : A novel laminar flow control based on generation of spanwise mean velocity gradients (SVG) in a flat plate boundary layer is investigated where disturbances of different types are introduced in the wall-bounded shear layer. The experimental investigations are aimed at; (i) generating stable and steady streamwise streaks in the boundary layer which set up spanwise gradients in the mean flow, and (ii) attenuating disturbance energy growth in the streaky boundary layers and hence delaying the onset of turbulence transition. LÄS MER

7. 25. Phase stability and physical properties of nanolaminated materials from first principles

   Författare :Andreas Thore; Johanna Rosén; Björn Alling; Martin Dahlqvist; Tilmann Hickel; Linköpings universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

   Sammanfattning : The MAX phase family is a set of nanolaminated, hexagonal materials typically comprised of three elements: a transition metal (M), an A-group element (A), and carbon and/or nitrogen (X). In this thesis, first-principles based methods have been used to investigate the phase stability and physical properties of a number of MAX and MAX-like phases. LÄS MER