| 1. |
- Isaksson, Per, et al.
(författare)
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The onset and progression of damage in isotropic paper sheets
- 2006
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Ingår i: International Journal of Solids and Structures. - : Elsevier BV. - 0020-7683 .- 1879-2146. ; 43:3-4, s. 713-726
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Tidskriftsartikel (refereegranskat)abstract
- The validity of existing criteria and relations for the onset and evolution of damage in paper is investigated and it is found that a non - local theory has to be utilized.
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| 2. |
- Kulachenko, Artem, et al.
(författare)
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Analysis of Paper Web Tension Profiles
- 2005
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Ingår i: Journal of Graphic Technology. - 1544-9599 .- 1544-9602. ; :2, s. 72-81
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Tidskriftsartikel (refereegranskat)abstract
- The tension profiles of paper webs are very important for determining the runnability in printing presses. Uneven tension profiles, with lower web tension toward the edges, develop in the paper machine due to many factors such as moisture content, residual strains related to drying and draw conditions, fibre orientation etc. This study presents some simple relations regarding the initial strain distribution, but also a method for adjusting the tension profile by choosing an appropriate moisture distribution. The method is verified on web tension and moisture measurements in a pressroom.
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| 3. |
- Kulachenko, Artem, et al.
(författare)
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Basic Mechanisms of Fluting
- 2006
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Ingår i: Annual Meeting of the Pulp and Paper Technical Association of Canada (PAPTAC). - Que., Canada : Pulp and Paper Technical Association of Canada. ; , s. A161-A173, s. 161-173
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Konferensbidrag (refereegranskat)abstract
- Out-of-plane deformations of paper, such as fluting, significantly deteriorate the quality of a printed product. There are several explanations of fluting presented in the literature but there is no unanimously accepted theory regarding fluting formation consistent with all field observations. The present paper reviews the existing theories and proposes a mechanism that might give an answer to most of the questions regarding the fluting. The fluting formation has been considered as a post-buckling phenomenon which is analysed with the help of the finite element method. Fluting retention has been modelled by introducing an ink layer over the paper surface with ink stiffness estimated from experimental results. The impact of fast drying on fluting has been assessed numerically and experimentally. The result of the study suggests that fluting occurs due to small-scale strain variations, which in turn are caused by the moisture variations created during fast convection drying. The result also showed that ink stiffening alone cannot explain the fluting amplitudes observed in practice, suggesting the presence of other mechanisms of fluting retention.
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| 4. |
- Kulachenko, Artem, et al.
(författare)
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Basic mechanisms of fluting formation and retention in paper
- 2007
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Ingår i: Mechanics of materials. - : Elsevier BV. - 0167-6636 .- 1872-7743. ; 39:7, s. 643-663
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Tidskriftsartikel (refereegranskat)abstract
- Out-of-plane deformations of paper, such as fluting, significantly deteriorate the quality of a printed product. There are several explanations of fluting presented in the literature but there is no unanimously accepted theory regarding fluting formation and retention which is consistent with all field observations. This paper first reviews the existing theories and proposes a mechanism that might give an answer to most of the questions regarding fluting. The fluting formation has been considered as a post-buckling phenomenon which has been analysed with the help of the finite element method. Fluting retention has been modelled by introducing an ink layer over the paper surface with the ink stiffness estimated from experimental results. The impact of fast drying on fluting has been assessed numerically and experimentally. The result of the study suggests that fluting occurs due to small-scale hygro-strain variations, which in turn are caused by the moisture variations created during fast convection (through-air) drying. The result also showed that ink stiffening alone cannot explain the fluting amplitudes observed in practice, but that high drying temperatures promote inelastic (irreversible) deformations in paper and this may itself preserve fluting.
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| 5. |
- Kulachenko, Artem, 1978-, et al.
(författare)
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Direct simulations of fiber network deformation and failure
- 2012
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Ingår i: Mechanics of materials. - : Elsevier BV. - 0167-6636 .- 1872-7743. ; 51, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- A finite element model for 3D random fiber networks was constructed to simulate deformation and failure behavior of networks with dynamic bonding/debonding properties. Such fiber networks are ubiquitous among many living systems, soft matters, bio-materials, and engineering materials (papers and non-woven). A key feature of this new network model is the fiber–fiber interaction model that is based on AFM measurements from our earlier study. A series of simulations have been performed to investigate strain localization behavior, strength statistics, in particular, the variations of strength, strain-to-failure and elastic modulus, and their size dependence. Other variables investigated are fiber geometries. The result showed that, in spite of its disordered structure, strength and elastic modulus of a fiber network varied very little statistically, as long as the average number of fibers in the simulated specimen and the degree of fiber orientation are kept constant. However, strain-to-failure showed very significant statistical variations, and thus more sensitivity to the disordered structures.
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| 6. |
- Kulachenko, Artem, 1978-, et al.
(författare)
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Elastic properties of cellulose nanopaper
- 2012
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Ingår i: Cellulose. - : Springer. - 0969-0239 .- 1572-882X. ; 19:3, s. 793-807
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Tidskriftsartikel (refereegranskat)abstract
- Nanopaper is a transparent film made of network-forming nanocellulose fibers. These fibers are several micrometers long with a diameter of 4-50 nm. The reported elastic modulus of nanopaper often falls short of even conservative theoretical predictions based on the modulus of crystalline cellulose, although such predictions usually perform well for other fiber composite materials. We investigate this inconsistency and suggest explanations by identifying the critical factors affecting the stiffness of nanopaper. A similar inconsistency is found when predicting the stiffness of conventional paper, and it is usually explained by the effects introduced during drying. We found that the effect of the drying cannot solely explain the relatively low elastic modulus of nanopaper. Among the factors that showed the most influence are the presence of non-crystalline regions along the length of the nanofibers, initial strains and the three-dimensional structure of individual bonds.
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| 7. |
- Kulachenko, Artem, et al.
(författare)
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Modelling the dynamical behaviour of a paper web : Part I
- 2007
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Ingår i: Computers and Structures. - : Elsevier BV. - 0045-7949 .- 1879-2243. ; 85:3-4, s. 131-147
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Tidskriftsartikel (refereegranskat)abstract
- A new shell element has been proposed for geometrically non-linear, finite element analyses of axially moving paper web. Web instability problems of paper travelling in a printing system, such as wrinkling and fluttering, pose special challenges in the numerical analyses. For examples, these are finite bending stiffness (as opposed to membrane), orthotropy, and non-uniform distributions of mechanical and hygro-properties (in different length scales). The new formulation has accounted for paper transport velocity and paper bending stiffness based on a mixed Lagrangian-Eulerian description of the motion. A natural coordinate system has been employed in the analytical and finite element formulations. Benchmarking with different finite elements in various tests showed that the proposed element is indeed more stable and reliable for the chosen application than existing elements. The usability of the shell element has been successfully demonstrated by two example problems: wrinkling of stretched isotropic and orthotropic membranes, and the vibration of a web showing a speed-tensioning effect above a critical web transport velocity.
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| 8. |
- Kulachenko, Artem, et al.
(författare)
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Modelling the dynamical behaviour of a paper web. Part II
- 2007
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Ingår i: Computers & structures. - : Elsevier BV. - 0045-7949 .- 1879-2243. ; 85:3-4, s. 148-157
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a finite element procedure is used to study the dynamic behaviour of a paper web in a free span between two rollers, including effects of transport velocity and surrounding air. The paper web is modelled as a three-dimensional orthotropic structure. The influence of air is accounted for by utilizing fluid-solid interaction analyses based on acoustic theory. The contribution of transport velocity is included through gyroscopic matrices and forces. The structural response on harmonic excitations has been studied using linear and non-linear models. Results show that air significantly reduces eigenfrequencies of the web. So called "edge-flutter" is nothing but the result of skew tension profile. Excessive web vibration can be eliminated by adjusting the web tension.
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| 9. |
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| 10. |
- Kulachenko, Artem, et al.
(författare)
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Reinventing mechanics of fibre network
- 2008
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Ingår i: Progress in Paper Physics Seminar. - Helsinki : Helsinki University Press. ; , s. 185-193
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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