Sökning: "constant amplitude load"

Visar resultat 1 - 5 av 15 avhandlingar innehållade orden constant amplitude load.

1. 1. Fatigue crack growth experiments and analyses - from small scale to large scale yielding at constant and variable amplitude loading

   Författare :Pär Ljustell; Fred L. Nilsson; Bo Alfredsson; Gunnar Härkegård; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Fracture mechanics; fatigue crack growth; finite elements analysis; small scale yielding SSY ; large scale yielding LSY ; low cycle fatigue LCF ; crack tip opening displacement CTOD ; crack closure; potential drop method; constant amplitude load; variable amplitude load; inconel 718; stainless steel 316L;

   Sammanfattning : This thesis is on fatigue crack growth experiments and assessments of fatigue crack growth rates. Both constant and variable amplitude loads in two different materials are considered; a nickel based super-alloy Inconel 718 and a stainless steel 316L. LÄS MER

3. 2. Fatigue improvement of steel bridges with high-frequency mechanical impact treatment

   Författare :Poja Shams Hakimi; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; HFMI; thickness effect; bridge; steel; variable amplitude; fatigue;

   Sammanfattning : This thesis investigates the performance of fatigue-improved welds with high-frequency mechanical impact (HFMI) for application on new bridges. Fatigue strength improvement with HFMI can enable lightweight design of bridges and allow the utilisation of the benefits of high-strength steels. LÄS MER

4. 3. Rolling Contact Fatigue of Railway Rails with Emphasis on Crack Initiation

   Författare :Jonas Ringsberg; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; variable amplitude; crack closure; rolling contact fatigue; crack propagation; railway rails; damage accumulation; critical plane approach; crack initiation; plasticity; multiaxial fatigue;

   Sammanfattning : Increased traffic density and the heavier axle loads of modern trains have led to severe problems with rolling contact fatigue (RCF) which cause initiation of surface cracks in railheads. In this thesis, a specific type of surface crack, the head check, is studied numerically with emphasis on fatigue crack initiation. LÄS MER

5. 4. Augmenting L1 Adaptive Control of Piecewise Constant Type to Aerial Vehicles

   Författare :Anders Pettersson; Institutionen för reglerteknik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

   Sammanfattning : In aerial vehicle control design, the industrial baseline is to use robust control methods together with gain-scheduling to cover the full airspeed and altitude flight envelope. An adaptive controller could possibly add value by increasing performance while keeping robustness to deviation from nominal assumptions. LÄS MER

7. 5. Wheels, Rails and Insulated Joints - Damage and Failure Probability at High Speed and Axle Load

   Författare :Johan Sandström; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; rail breaks; probability; railway mechanics; contact mechanics; insulated joints; defects; fatigue;

   Sammanfattning : The thesis deals with some fatigue related problems in railway mechanics related to increased axle loads and speeds. The focus is on defects and discontinuities in the wheel--rail system that affect the risk of fatigue and fracture of railway components such as wheels, rails and insulated joints. LÄS MER