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Analysis of the plastic and elastic energy during the deformation and rupture of a paper sample using thermography
KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Metrology and Optics.ORCID iD: 0000-0002-1467-7413
Innventia AB.
Innventia AB.
2012 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 2, 329-334 p.Article in journal (Refereed) Published
Abstract [en]

Thermography has been used to quantitatively analyze the plastic and elastic energy during deformation of paper. Sack paper samples were subjected to uniaxial tensile testing until rupture occurred. The temperature of the sample was simultaneously recorded with an infrared camera. The mechanical energy invested in the deformation was determined based on the force and deformation data. The thermal energy that accumulated in the sample during testing was estimated using the temperature measurements. Here, special attention was put on using the correct emittance values for the sack paper by measuring it with a new method. When comparing exerted mechanical energy with released thermal energy up to the time of sample rupture, about 40% to 60% of the mechanical energy could be detected as thermal energy. The lacking share of heat was most likely lost due to cooling of the sample during the experiments, as a lower share of detected mechanical energy was obtained for longer experiments. When comparing the increase in thermal energy during rupture to the elastic energy stored in the sample, an agreement of better than 90% was found.

Place, publisher, year, edition, pages
2012. Vol. 27, no 2, 329-334 p.
Keyword [en]
Elastic deformation, Emittance, Paper mechanics, Plastic deformation, Rupture work, Thermal energy, Thermography, Elastic energy, Emittances, Infra-red cameras, Mechanical energies, Paper samples, Sack paper, Uniaxial tensile testing, Deformation, Elasticity, Experiments, Temperature measurement, Tensile testing, Thermography (imaging), Thermography (temperature measurement), Paper, Experimentation, Pyrometry, Tensile Tests, Thermal Analysis
National Category
Paper, Pulp and Fiber Technology
Identifiers
URN: urn:nbn:se:kth:diva-104882DOI: 10.3183/NPPRJ-2012-27-02-p329-334ISI: 000315696000022Scopus ID: 2-s2.0-84865201840OAI: oai:DiVA.org:kth-104882DiVA: diva2:567807
Funder
XPRES - Initiative for excellence in production research
Note

QC 20121114

Available from: 2012-11-14 Created: 2012-11-14 Last updated: 2017-12-07Bibliographically approved
In thesis
1. Infrared Emittance of Paper: Method Development, Measurements and Application
Open this publication in new window or tab >>Infrared Emittance of Paper: Method Development, Measurements and Application
2012 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Thermography is a non-destructive technique which uses infrared radiation to obtain the temperature distribution of an object. The technique is increasingly used in the pulp and paper industry. To convert the detected infrared radiation to a temperature, the emittance of the material must be known. For several influencing parameters the emittance of paper and board has not previously been studied in detail. This is partly due to the lack of emittance measurement methods that allow for studying the influence of these parameters.

An angle-resolved goniometric method for measuring the infrared emittance of a material was developed in this thesis. The method is based on the reference emitter methodology, and uses commercial infrared cameras to determine the emittance. The method was applied to study the dependence on wavelength range, temperature, observation angle, moisture ratio, sample composition, and sample structure of the emittance of paper and board samples. It was found that the emittance varied significantly with wavelength range, observation angle and moisture ratio. The emittance was significantly higher in the LWIR (Long-Wavelength Infrared) range than in the MWIR (Mid-Wavelength Infrared) range. The emittance was approximately constant up to an observation angle of 60° in the MWIR range and 70° in the LWIR range, respectively. After that it started to decrease. The emittance of moist samples was significantly higher than that of dry samples. The influence of moisture ratio on the emittance could be estimated based on the moisture ratio of the sample, and the emittance of pure water and dry material, respectively.

The applicability of measured emittance values was demonstrated in an investigation of the mechanical properties of sack paper samples. An infrared camera was applied to monitor the generation of heat during a tensile test of a paper sample. It was found that the observed increase in thermal energy at the time of rupture corresponded well to the value of the elastic energy stored in the sample just prior to rupture. The measured emittance value provided an increased accuracy in the thermal energy calculation based on the infrared images.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. 41 p.
Series
Trita-IIP, ISSN 1650-1888 ; 12:10
Keyword
Emittance, Emissivity, Thermography, Paper, Sheet, Papermaking, Paper mechanics, Moisture, Material properties, Reflectance, Transmittance, Absorptance, Infrared, Mid-wavelength infrared, MWIR, Long-wavelength infrared, LWIR, Angle-resolved, Directional
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-104755 (URN)
Presentation
2012-11-30, Sundbladsalen, Innventia AB, Drottning Kristingas Väg 61, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
XPRES - Initiative for excellence in production research
Note

QC 20121121

Available from: 2012-11-21 Created: 2012-11-12 Last updated: 2013-04-19Bibliographically approved
2. Image-based quantitative infrared analysis and microparticle characterisation for pulp and paper applications
Open this publication in new window or tab >>Image-based quantitative infrared analysis and microparticle characterisation for pulp and paper applications
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Measurements of process variations and particle morphology are widely employed in the pulp and paper industry. Two techniques with high potential, infrared thermography and microparticle characterisation, are mainly used qualitatively. Quantitative thermography requires knowledge of the emittance, a material property which has not been measured under many process-relevant conditions. Quantitative characterisation of microparticles, e.g. pulp fines and mineral fillers, requires the analysis of a large number of particles, which can be accomplished using flow microscopes. Flow microscopes for pulp analysis have had insufficient spatial resolution to resolve fines and fillers. Additionally, there has been a lack of methods which can differentiate between fines and fillers in a mixed suspension.

State-of-the-art instruments for particle image analysis were evaluated and compared to laser diffractometry, a measurement method based on scattering by diffraction. Laser diffractometry was found to be highly sensitive to the complex refractive index of the particles, and especially to its change due to moisture absorption. A high-resolution imaging flow cytometer and a high-resolution fibre analyser were found to be complementary for characterisation of pure fines and fines/filler mixtures, and superior to laser diffractometry. A method for differentiating between fines and fillers in a suspension based on their autofluorescence and side-scattering was proposed and qualitatively evaluated.

Furthermore, a method for measuring the directional and integrated emittance of paper was developed and its accuracy was determined. Measurements on a wide range of samples showed that the emittance of fibre-based materials vary significantly with wavelength, pulp type, observation angle, and moisture content. By applying measured quantitative values of the emittance, the thermal energy emitted by sack paper samples during mechanical deformation could be quantitatively calculated. The increase in thermal energy at the time of rupture was found to correlate well with the elastic share of the mechanical energy that was stored in the sample during its elongation.

In summary, the results of this work have facilitated the use of quantitative microparticle analysis and infrared thermography for pulp and paper applications. 

Abstract [sv]

Mätningar av processvariationer och partiklars form och storlek utförs i stor skala inom massa- och pappersindustrin. Två mättekniker med stor potential, infraröd termografi och mikropartikel-karaktärisering, används mest kvalitativt idag. Kvantitativ termografi kräver att provets emittans är känd. Emittansen är en materialegenskap som inte har mätts för många förhållanden som är relevanta inom papperstillverkning. Kvantitativ karaktärisering av partiklar kräver att ett tillräckligt stort antal partiklar analyseras, något som kan göras med flödesmikroskop. Flödesmikroskop för mäldanalys har haft otillräcklig upplösning för att karaktärisera mikrometerstora partiklar, t.ex. fines och fyllmedel. Det har heller inte funnits någon metod som kan särskilja mellan fines och fyllmedel i en blandning.

Högupplösta mätinstrument för bildbaserad mikropartikelkaraktärisering utvärderades och jämfördes med en laserdiffraktometer, en mätmetod baserad på ljusspridning genom diffraktion. Laserdiffraktometerns mätresultat påverkades starkt av det brytningsindex som antogs för provet, och hur brytningsindexet ändrades med fukthalt. En högupplöst bildbaserad flödescytometer och en högupplöst fibermätare konstaterades komplettera varandra vid mätningar av mäldens finmaterial. De var även pålitligare än laserdiffraktometern vid mätningar av organiskt finmaterial. En metod för att skilja mellan organiskt och oorganiskt finmaterial i en mäld baserat på deras autofluorescens och ljusspridning presenterades och utvärderades kvalitativt.

En metod för att mäta den vinkelberoende och våglängdsintegrerade emittansen hos fiberbaserade material utvecklades och dess mätnoggrannhet utvärderades. Mätningar på ett stort antal prover visade att emittansen varierade betydligt med våglängd, mäldtyp, observationsvinkel, och fukthalt. Genom att använda den uppmätta emittansen kunde den termiska energin som frigjordes av ett säckpappersprov vid brottögonblicket beräknas. Denna energi korrelerade väl med den elastiska energi som lagrades i provet medan det töjdes, fram till tidpunkten för brottet.

Sammanfattningsvis har resultaten av detta arbete möjliggjort kvantitativ användning av mikropartikel-karaktärisering och infraröd termografi i massa- och papperstillämpningar.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. 132 p.
Series
TRITA-IIP, ISSN 1650-1888 ; 16:01
Keyword
Metrology, stock, papermaking, refining, fibrillation, fines, filler, morphology, classification, flow microscopy, fibre analyser, flow cytometry, laser diffraction, dynamic image analysis, process variation, thermography, emittance, emissivity, infrared, MWIR, LWIR, goniometer
National Category
Reliability and Maintenance Paper, Pulp and Fiber Technology
Research subject
Production Engineering; Fibre and Polymer Science
Identifiers
urn:nbn:se:kth:diva-180722 (URN)978-91-7595-843-9 (ISBN)
Public defence
2016-02-12, Innoversum, Innventia, Drottning Kristinas Väg 61, Solna, 10:00 (English)
Opponent
Supervisors
Funder
Swedish Energy AgencyÖnnesjö Foundation
Note

QC 20160122

Available from: 2016-01-22 Created: 2016-01-21 Last updated: 2016-01-22Bibliographically approved

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