| 1. |
- Eric, Linvill
(författare)
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Dynamic Mechanical Thermal Analysis Data of Sheets Made from Wood-Based Cellulose Fibers Partially Converted to Dialcohol Cellulose
- 2017
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Annan publikationabstract
- This data article contains the dynamic mechanical thermal analysis (DMTA) results for sheets made from cellulose fibers partially converted to dialcohol cellulose. See Larsson and Wågberg [1] for a description and characterization of the material as well as how the material is produced. See also Linvill et al. [2] for tensile testing and 3-D forming of the material. The DMTA tests were conducted at four different relative humidity levels: 0, 50, 60, and 70 % RH, and the temperature was swept between 10 and 113 °C. The DMTA results enable the understanding of the elastic, viscoelastic, and viscoplastic mechanical properties of this material at a wide range of temperature and relative humidity combinations.
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| 2. |
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| 3. |
- Linvill, Eric
(författare)
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3-D Forming of Paper Materials
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Paper materials have a long history of use as a packaging material, although traditional paper-based packaging is limited in its shape, complexity, and design. In order to better understand the deformation and failure mechanisms during 3-D forming, two experimental studies of paper materials have been conducted. Furthermore, constitutive modeling combined with explicit finite element modeling have been validated against numerous experimental setups and utilized to develop further understanding of 3-D forming processes.Two experimental studies were necessary to further investigate and model the 3-D formability of paper materials. The combined effect of moisture and temperature on the uniaxial mechanical properties of paper was investigated, providing new insights into how moisture and temperature affect both the elastic and plastic properties of paper materials. Furthermore, the in-plane, biaxial yield and failure surfaces were experimentally investigated in both stress and strain space, which gave an operating window for 3-D forming processes as well as input parameters for the constitutive models.The constitutive modeling of paper materials and explicit finite element modeling were directed towards two 3-D forming processes: deep drawing and hydroforming. The constitutive models were calibrated and validated against simple (typically uniaxial) mechanical tests, and the explicit finite element models (which utilize the developed constitutive models) were validated against 3-D forming experiments. Hand-made papers with fibers partially oxidized to dialcohol cellulose, which has greater extensibility than typical paper materials, was furthermore characterized, modeled, and 3-D formed as a demonstration of the potential of modified paper fiber products for 3-D forming applications.
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| 4. |
- Linvill, Eric, et al.
(författare)
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A constitutive model for paperboard including wrinkle prediction and post-wrinkle behavior applied to deep drawing
- 2017
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Ingår i: International Journal of Solids and Structures. - : Elsevier. - 0020-7683 .- 1879-2146. ; 117, s. 143-158
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Tidskriftsartikel (refereegranskat)abstract
- A simple, one-dimensional model for perfectly plastic hinges, utilizing a hinge yield strength, was applied to wrinkled paperboard and validated. The hinge model was incorporated into a three-dimensional constitutive model of paperboard including wrinkle initiation, wrinkle compression, as well as tensile reloading of wrinkled paperboard. The constitutive model enables the explicit finite element simulation of the deep drawing of a non-creased paperboard blank, including spring-back after the forming process. The results of the simulated deep-drawing process were validated against experimental deep-drawn paperboard cups, and parametric studies were conducted to investigate the effects of process and material parameters on three different quality measures (spring-back magnitude, asymmetry, and punch force). In addition to aiding the development of the simulation of paperboard deep drawing, the hinge yield strength was also found to be the only studied material property which could simultaneously improve all three quality measures.
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| 5. |
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| 6. |
- Linvill, Eric, et al.
(författare)
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Advanced three-dimensional paper structures : Mechanical characterization and forming of sheets made from modified cellulose fibers
- 2017
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Ingår i: Materials & design. - : Elsevier. - 0264-1275 .- 1873-4197. ; 128, s. 231-240
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose partially converted to dialcohol cellulose has been identified as a potential breakthrough material for the production of bio-based, complex, double-curved surfaces due to its extensive strain-at-break characteristics (reaching as great as 80% in tensile loading). Tensile testing of handsheets made from modified cellulose fibers was conducted from 50 to 90% relative humidity (RH) and from 23 to 150 °C. Strain-at-break of the handsheets ranged from 35 to 80% over this humidity and temperature range, which is significantly greater than typical cellulose-based materials. The combined effect of moisture and temperature was further investigated by dynamic mechanical thermal analysis, which was utilized to determine the glass-transition temperature of the handsheets as a function of relative humidity. Based on the tensile test results and verified by the three-dimensional (3-D) forming and simulation, a forming limit diagram (strain-based failure surface which describes and illustrates the formability of the material) for the handsheets was generated. This forming limit illustrates significant extent to which this bio-based material can be 3-D formed into advanced structures. Furthermore, temperature was identified as the best, quickest, and most controllable method of improving extensibility of this material during 3-D forming.
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| 7. |
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| 8. |
- Linvill, Eric, et al.
(författare)
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Biaxial (In-Plane) Failure and Yield of Paperboard
- 2016
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Understanding the biaxial (in-plane) failure behavior of paperboard is crucial to understand the limits of 3-D forming of paper materials, because the biaxial strain failure limit determines the extent to which paperboard can be formed in different conditions.A traditional cruciform biaxial specimen has been redesigned and modified with the help of laser engraving. By the use of laser engraving, 90 % of the effective thickness of the specimen in the center of the cruciform was removed, thus making the cruciform specimen more likely to fail in the center than at the edges. A variety of strain ratios were utilized to test the specimens with a biaxial testing machine, and the strain field was measured utilizing digital image correlation.The results of the biaxial testing were analyzed in order to determine both the strain-based yield and failure surfaces. Additionally, the stresses in the center of the specimen were estimated based on the forces measured during the test. Based on these estimated stresses, stress-based yield and failure surfaces were also constructed. Furthermore, various models for the strain- and stress-based yield surfaces were applied to the data and compared.
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| 9. |
- Linvill, Eric, 1989-, et al.
(författare)
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Biaxial In-Plane Yield and Failure of Paperboard
- 2016
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Ingår i: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 31:4, s. 659-667
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Tidskriftsartikel (refereegranskat)abstract
- Paperboard is oftentimes subjected to biaxial in-plane stress and strain states, although very few experimental studies of the biaxial in-plane yield and failure of paperboard have been conducted. A new biaxial testing method to determine the in-plane stress- and strain-based yield and failure surface of paperboard was proposed and implemented. The method utilized cruciform specimens containing a reduced-thickness region (prepared by laser engraver) to increase probability of failure in that region, and digital image correlation was utilized to measure strain. The obtained stress-based failure surface was similar to previously reported results in the literature, but the obtained strain-based failure surface differed from the one previously reported strain-based failure surface. The obtained yield and failure surfaces had similar shape, providing confidence in both results due to the related deformation and failure mechanisms in paperboard. Furthermore, the overall shape of the stress- and strain-based yield surfaces was unaffected by the definition of the yield point. The obtained strain-based failure surface revealed the forming limits and therefore strengths and limitations of various 3-D forming methods for paperboard.
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| 10. |
- Linvill, Eric
(författare)
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Box Compression Strength : A Crippling Approach
- 2015
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Ingår i: Packaging technology & science. - : Wiley. - 0894-3214 .- 1099-1522. ; 28:12, s. 1027-1037
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Tidskriftsartikel (refereegranskat)abstract
- A crippling analysis method has been utilized to estimate the compression strength paperboard boxes. Crippling analysis is typically utilized in the aerospace industry to predict the compressive failure strength of thin, slender structures with complex cross-sectional geometry. This type of analysis is investigated, because crippling is a simple, predictive method that can provide very good estimates of the compressive failure strength of thin, slender structures. This preliminary study investigates the possibility of applying crippling analysis to estimate paperboard box compression strength by comparing experimental and theoretical results for box compression tests of milk and cigarette boxes in various loading scenarios and with various materials. This preliminary study shows that the crippling method provides results which are almost as accurate as pre-existing methods, although significant work remains to verify the validity and applicability of the crippling approach for paper-based boxes.
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