Search for dissertations about: "Janis Varna"

Showing result 1 - 5 of 10 swedish dissertations containing the words Janis Varna.

2. 1. Analysis of transverse composite cross-ply laminates

   Author : Janis Varna; Luleå tekniska universitet; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Polymera konstruktionsmaterial; Polymeric Composite Materials;

   Abstract : Advanced polymer composites are commonly based on thin prepreg plies stacked at different angles to form a laminate. When the laminate is loaded, intralaminar transverse cracking in off-axis plies is one of the first damage modes. In the presented thesis, cross-ply laminates are used to study the transverse cracking phenomenon. READ MORE

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

   Author : Nawres Jabar Al-Ramahi; Roberts Joffe; Janis Varna; Lars Mikkelsen; Luleå tekniska universitet; []
   Keywords : 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;

   Abstract : 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. READ MORE

5. 3. Numerical stress analysis in hybrid adhesive joint with non-linear materials

   Author : Nawres Al-Ramahi; Roberts Joffe; Janis Varna; Rickard Östlund; Luleå tekniska universitet; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Polymeric Composite Materials; Polymera kompositmaterial;

   Abstract : This thesis presents systematic numerical study of stresses in the adhesive of a single-lap joint subjected to various loading scenarios (mechanical and thermal loading). The main objective of this work is to improve understanding of the main material and geometrical parameters determining performance of adhesive joint for the future analysis of failure initiation and development in these structures. READ MORE

6. 4. Stress-transfer mechanisms in wood-fibre composites

   Author : Karin Almgren; Kristofer Gamstedt; Janis Varna; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Engineering mechanics; Teknisk mekanik;

   Abstract : .... READ MORE

7. 5. Micro-cracking and delaminations of composite laminates under tensile quasi-static and cyclic loading

   Author : Hiba Ben Kahla; Janis Varna; Zoubir Ayadi; Federica Daghla; Luleå tekniska universitet; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Laminate; Fatigue; damage growth; stiffness reduction; NCF; Polymeric Composite Materials; Polymera kompositmaterial;

   Abstract : Aerospace industry is devoted to improving the aircraft performance while reducing its weight and limiting the emissions. Part of this objective can be accomplished with the use of high-performance long fibre reinforced polymer laminated composites. READ MORE