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Visar resultat 1 - 5 av 6 avhandlingar som matchar ovanstående sökkriterier.

  1. 1. Modelling and strength grading of structural timber and glulam lamellae on the basis of optical scanning and dynamic excitation

    Författare :Andreas Briggert; Anders Olsson; Jan Oscarsson; Mikael Perstorper; Linnéuniversitetet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Fibre direction; finger joint; machine strength grading; knots; tracheid effect; Norway spruce; Byggteknik; Civil engineering;

    Sammanfattning : Machine strength grading of sawn timber is a sawmill process in which density, modulus of elasticity (MOE) and bending or tensile strength are predicted such that the timber can be assigned to strength classes. The predictions of these properties are performed using one or several so-called indicating properties (IPs), which represent a board property, or combination of board properties, measured non-destructively. LÄS MER

  3. 2. Local variation in bending stiffness in structural timber of Norway spruce : for the purpose of strength grading

    Författare :Min Hu; Marie Johansson; Linnéuniversitetet; []
    Nyckelord :LANTBRUKSVETENSKAPER; AGRICULTURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; digital image correlation; fibre angle; high resolution; laser scanning; local stiffness; MOE profile; mode shape curvature; strain field; strength grading; structural timber; tracheid effect; Digital image correlation; fibervinkel; laserskanning; lokal styvhet; MOE-profil; töjningsfält; hållfasthetssortering; konstruktionsvirke; trakeideffekt; Forestry and Wood Technology; Skog och träteknik;

    Sammanfattning : Most strength grading machines on the European market use an averagemodulus of elasticity (MOE), estimated on a relatively large distance along awood member, as the indicating property (IP) to bending strength. Theaccuracy of such grading machines in terms of coefficient of determination israther low at R2 ≈ 0.5. LÄS MER

  4. 3. Studies of the fibre direction and local bending stiffness of Norway spruce timber : for application on machine strength grading

    Författare :Min Hu; Marie Johansson; Mats Ekevad; Linnéuniversitetet; []
    Nyckelord :LANTBRUKSVETENSKAPER; AGRICULTURAL SCIENCES; digital image correlation; diving angle; fibre angle; grain angle; indicating property; laser scanning; modulus of elasticity; tracheid effect; Forestry and Wood Technology; Skog och träteknik;

    Sammanfattning : Machine strength grading is a production process in the sawmill industry used to grade sawn timber boards into different strength classes with specific characteristic values of the bending strength, modulus of elasticity (MOE) and density. These properties are called grade determining properties. LÄS MER

  5. 4. Automatic measurement of compression wood and spiral grain for the prediction of distortion in sawn wood products

    Författare :Jan Nyström; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Träteknik; Wood Technology;

    Sammanfattning : Distortion is one of the major obstacles for effective utilisation of wood, especially in the building process, where wood has lost market shares to other materials largely because of the lack of straightness. Bow and spring are often caused by compression wood, while twist is the cause of spiral grain. LÄS MER

  7. 5. Image based methods for nondestructive detection of compression wood in sawn timber

    Författare :Jan Nyström; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Träteknik; Wood Technology;

    Sammanfattning : Compression wood is an anomaly in wood formed by the living softwood tree to compensate for excessive, asymmetric loads by developing special fibres. Compression wood has special properties that are unwanted in the utilisation of sawn wood products and is thus desirable to detect and reject in an early stage. LÄS MER