Sökning: "crack initiation"

Visar resultat 11 - 15 av 147 avhandlingar innehållade orden crack initiation.

1. 11. On the hot crack formation during solidification of iron-base alloys

   Författare :Karin Hansson; KTH; []
   Nyckelord :hot cracking; hot tearing; cracking fracturing ; tearing; ductility; brittleness; embrittlement; fractures; ductile brittle transition; solidification; iron; copper; nickel; Invar; steels; free machining steels; stainless steels; penetration; crack;

   Sammanfattning : Hot cracking during solidification is a severe problem inmany casting processes, for example in continuous casting.Combinations of low strength and low ductility of the materialat high temperatures and applied tensile stress can cause hotcracking. LÄS MER

3. 12. Fatigue crack initiation and propagation in sandwich structures

   Författare :Magnus Burman; KTH; []
   Nyckelord :TECHNOLOGY; TEKNIKVETENSKAP;

   Sammanfattning : The focus throughout this thesis is on the fatigue characteristics of core materials used insandwich structures. Three sandwich configurations are investigated, two with cellular foamsand one with honeycomb core material These corresponds to typical materials and dimensionsused in the marine and aeronautical industry. LÄS MER

4. 13. Micro-crack initiation and propagation in fiber reinforced composites

   Författare :Andrejs Pupurs; Stephen L. Ogin; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Polymera konstruktionsmaterial; Polymeric Composite Materials;

   Sammanfattning : Predicting micro-damage initiation and evolution is one of the key challenges for safe design of fiber reinforced polymer composites. Micro-scale damage such as, for example, single fiber break may be unnoticeable and negligible during the initial service life of composite, however, with many loading and unloading cycles this initially micro-scale damage may propagate forming macroscopic scale cracks that can significantly reduce the service lifetime or even lead to unforeseen catastrophic failure of the composite structure. LÄS MER

5. 14. 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. 15. Oxidation induced failure of superalloys: High temperature crack growth and oxide scale properties

   Författare :Anand Harihara Subramonia Iyer; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; micromechanical testing; crack growth; Nickel superalloys; scanning electron microscopy; focused ion beam microscopy;

   Sammanfattning : Gas turbine materials are designed to work in extreme environments in high temperature with an oxidising environment and variable mechanical loading. The study of high temperature fatigue properties of these materials is therefore important. LÄS MER