| 1. |
- Varna, Janis, et al.
(författare)
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A study of the opening displacement of transverse cracks in cross-ply laminates
- 1993
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Ingår i: International journal of damage mechanics. - : SAGE Publications. - 1056-7895 .- 1530-7921. ; 2:3, s. 272-289
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Tidskriftsartikel (refereegranskat)abstract
- Transverse cracks in cross-ply laminates are investigated experimentally to reveal the essential characteristics of their opening displacement under tensile loads. The average crack opening displacement is studied as a function of the longitudinal overall strain and the effects of matrix toughness and transverse ply thickness on this parameter are examined. The interactive effects between closely spaced transverse cracks are also ex amined and found to be significant. Implications of the experimentally observed features on the micromechanics and continuum damage type models are discussed.
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| 2. |
- Frishfelds, Vilnis, et al.
(författare)
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Bubble motion through non-crimp fabrics during composites manufacturing
- 2008
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Ingår i: Composites. Part A, Applied science and manufacturing. - : Elsevier BV. - 1359-835X .- 1878-5840. ; 39:2, s. 243-251
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Tidskriftsartikel (refereegranskat)abstract
- Bubbles motion through inter bundle channels in bi-axial non crimp fabrics is modelled. The scenario is that formed bubbles move with the resin through these channels and are trapped if the channels become too narrow. By usage of a permeability network model, existing criteria on bubble deformation and a variety of analytical and probabilistic methods it is found that the paths of the bubbles depend significantly on the position of the threads keeping the fabric together and the number of fibres crossing the interbundle channels. Another result is that the pressure difference over a trapped bubble increases with 50 % in a 3D geometry possible helping the bubble to escape. A third result is that, on average, the bubbles move biased to the direction of the tows. Finally it is found that the predicted void distribution of bubbles after a major part of bubbles have moved through the system are in qualitative agreement with experimental data.
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| 3. |
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| 4. |
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| 5. |
- Nordlund, Markus, et al.
(författare)
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Permeability network model for non-crimp fabrics
- 2006
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Ingår i: Composites. Part A, Applied science and manufacturing. - : Elsevier BV. - 1359-835X .- 1878-5840. ; 37:6, s. 826-835
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Tidskriftsartikel (refereegranskat)abstract
- In this work a global permeability model is developed and applied to a biaxial Non-crimp stitched fabric (NCF). This model focuses on a detailed meso-scale description of the fabric geometry, which takes into account the local permeability distribution in a fabric due to perturbations of the geometry as well as the geometrical features which arise from the stitching process. It is shown in this work that these features significantly affects the global permeability. The influence of the amount and type of perturbation of a fabric is also studied in this work. It is shown that perturbation of the fabric geometry affect the global permeability but not as much as the stitching process. The model developed is finally validated with experimental permeability data and it is suggested how to use the model for an arbitrary lay-up.
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