Change search
Refine search result
1 - 3 of 3
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Ekermann, Tomas
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Hallström, Stefan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Mechanical characterisation of composites with 3D-woven reinforcement2015In: ICCM International Conferences on Composite Materials, International Committee on Composite Materials , 2015Conference paper (Refereed)
    Abstract [en]

    Flat specimens made of carbon/epoxy composite material are manufactured by resin transfer moulding, using 3D-woven carbon fibre preforms with a grid of warp yarns interlaced with both horizontal and vertical wefts. The aim of the study is to bring more light to the coupling between the mechanical properties of the composite material and the internal fibre architecture of its 3D-woven reinforcement. Factors that are varied in the fibre architecture are the amount of fibres in the through-thickness reinforcement (vertical weft) and the warp's wavelength. Tensile, compressive, in-plane and out-of-plane shear and peel tests are performed for the mechanical characterisation. Tensile and compressive properties are found to decrease when the crimp of the warp yarns is increased, and even more so in compression. The in-plane shear strength is evaluated through use of a new test specimen, designed for the purpose. Results show that the strength is higher when the shear load is applied across the warp than across the weft, where the difference is attributed to varying fibre content in the two in-plane directions. The out-of-plane shear properties are compared through short beam shear tests and the inter-laminar shear strength (ILSS) is determined. It is shown that the ILSS increases with increasing yarn thickness in the vertical weft, which is intuitive. The peel strength is evaluated by the opening mode I interlaminar fracture toughness (GIc) through double cantilever beam tests. It is shown that GIc is greatly dependent on the amount of reinforcement in the vertical weft. 

  • 2.
    Ekermann, Tomas
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Hallström, Stefan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Pull-off tests of CFRP T-joints with conventional and 3D reinforced fillets2019In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 223Article in journal (Refereed)
    Abstract [en]

    A study of T-joints made of CFRP prepreg is presented where the joints contain either conventional uni-directional (UD) fillets or fillets with three-dimensional (3D) woven reinforcement in the joint cavity. Both pristine and impacted specimens are tested experimentally in a pull-off load case. The T-joints with UD fillets are stronger but also show greater spread in strength than T-joints with 3D fillets. The higher strength is attributed to the UD fillets' ability to deform transversely to their length direction and efficiently adapt to the T-joint cavity before curing. The 3D fillets do not admit the same level of transverse shape adaptability and if their cross sections do not fit the geometry of the T-joint cavity sufficiently well, local stress concentrations could emerge that reduce the strength of the T-joint. The UD fillets on the other hand are believed to be sensitive to manufacturing flaws causing the greater spread in strength. That in turn is attributed to a lack of crack-arresting capability in the UD fillet. The 3D fillets however have excellent crack-arresting properties due to their multidirectional fibre architecture. With a few exceptions the impact damages did not significantly affect the strength of the T-joints tested in this study.

  • 3.
    Oddy, Carolyn
    et al.
    Department of Industrial and Materials Science, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.
    Eckermann, Tomas
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Ekh, Magnus
    Department of Industrial and Materials Science, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.
    Fagerström, Martin
    Department of Industrial and Materials Science, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.
    Hallström, Stefan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures. KTH, Superseded Departments (pre-2005), Aeronautical Engineering.
    Stig, Fredrik
    Research Institutes of Sweden, SE-431 53 Mölndal, Sweden.
    Predicting damage initiation in 3D fibre-reinforced composites - the case for strain-based criteria2019In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, ISSN 0263-8223Article in journal (Refereed)
    Abstract [en]

    Three dimensional (3D) fibre-reinforced composites have shown weight effi- cient strength and stiffness characteristics as well as promising energy absorp- tion capabilities. In the considered class of 3D-reinforcement, vertical and horizontal weft yarns interlace warp yarns. The through-thickness reinforce- ments suppress delamination and allow for stable and progressive damage growth in a quasi-ductile manner.

    With the ultimate goal of developing a homogenised computational model to predict how the material will deform and eventually fail under loading, this work proposes candidates for failure initiation criteria. It is shown that the extension of the LaRC05 stress-based failure criteria for unidirectional lami- nated composites, to this class of 3D-reinforced composite presents a number of challenges and leads to erroneous predictions. Analysing a mesoscale rep- resentative volume element does however indicate, that loading the 3D fibre- reinforced composite produces relatively uniform strain fields. The average strain fields of each material constituent are well predicted by an equivalent homogeneous material response. Strain based criteria inspired by LaRC05 are therefore proposed. The criteria are evaluated numerically for tensile, compressive and shear tests. Results show that their predictions for the simulated load cases are qualitatively more reasonable.

1 - 3 of 3
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf