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Visar resultat 1 - 5 av 66 avhandlingar som matchar ovanstående sökkriterier.

  1. 1. Variables affecting stress development and resin conversion in light-cured dental composites

    Författare :Nazanin Emami; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Machine Elements; Maskinelement; Polymeric Composite Materials; Polymera konstruktionsmaterial;

    Sammanfattning : The general aim of this dissertation was to identify and investigate factors that can be used to minimize stress development in light cured dental resins without compromising the conversion level of the polymer. Modulus of elasticity, polymerization contraction strain, degree of conversion and shrinkage of light-cure dental composites were determined after curing with three different light power densities where total irradiated energy (J/cm2) kept constant. LÄS MER

  3. 2. Non-linear model applied on composites exhibiting inelastic behavior: development and validation

    Författare :Liva Pupure; Maciej Wysocki; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Polymera konstruktionsmaterial; Polymeric Composite Materials;

    Sammanfattning : The polymeric composite materials are in high demand by industries where light and strong materials are required. Although manmade fiber (e.g. glass, carbon, aramid fibers) are most often used to reinforce polymers, natural fibers due to their environmental friendliness and sustainability have been also considered. LÄS MER

  4. 3. Comprehensive numerical analysis of stress state in adhesive layer of joint including thermal residual stress and material non-linearity

    Författare :Nawres Jabar Al-Ramahi; Roberts Joffe; Janis Varna; Lars Mikkelsen; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Single-lap adhesive joint; Double-lap adhesive joint; Unbalanced bi-material DCB; Residual thermal stresses; Finite element method; Crack path; Crack closure; Polymeric Composite Materials; Polymera kompositmaterial;

    Sammanfattning : The main objective of this work is to improve understanding of the stress state in the adhesive layer of bonded joints and identify key parameters which govern performance of adhesive joints. This information is crucial for the prediction of the failure initiation and propagation with the further estimation of the durability and strength of adhesively bonded structures. LÄS MER

  5. 4. Effect of light power density variation on dental light-cure resin composites

    Författare :Nazanin Emami; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Machine Elements; Maskinelement; Polymeric Composite Materials; Polymera konstruktionsmaterial;

    Sammanfattning : Dental resin based composites are tooth-colored filling materials composed of synthetic resins and particulate ceramic reinforcing filler particles. The resin system also contains molecules that promote and/or modify the polymerisation reaction of the dimethacrylate resin monomers. LÄS MER

  7. 5. Numerical analysis of the single fiber fragmentation test including the effect of interfacial friction

    Författare :Enrique Graciani; Bent F. Sörensen; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Polymera konstruktionsmaterial; Polymeric Composite Materials;

    Sammanfattning : A numerical analysis of the single fiber fragmentation test is presented in this thesis. The aim of the numerical study is elucidating the influence of friction in the growth of the debond cracks along the fiber-matrix interface. Two distinct approaches and numerical techniques have been employed in the analysis. LÄS MER