| 1. |
- Ericson, Mats, et al.
(författare)
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Deformation and fracture of glass-mat-reinforced polypropylene
- 1992
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Ingår i: Composites Science And Technology. - 0266-3538 .- 1879-1050. ; 43:3, s. 269-281
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Tidskriftsartikel (refereegranskat)abstract
- The mechanical properties of glass-mat-reinforced thermoplastics, GMT, can be varied within wide limits through the choice of glass mat, fibre content, and thermoplastic matrix. A great variety of fibre configurations and fibre contents is commercially available. In order to understand how the fibre structure of GMT materials controls the mechanical properties, two structurally different GMT materials were studied. Several grades with different fibre contents were used for each material. One material had short fibres (12 mm long), discretely dispersed with in-plane random orientation. The other material had in-plane continuous looped bundles of fibres. The deformation and fracture of these materials have been studied as a function of fibre content. The present work shows that the material with discretely dispersed fibres has higher values of tensile creep modulus, tensile strength, elongation at fracture, and work of fracture (area under the stress/strain curve). The results are discussed and related to the structural differences between the two materials.
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| 2. |
- Ericson, Mats L., et al.
(författare)
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Processing and mechanical properties of orientated preformed glass-mat-reinforced thermoplastics
- 1993
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Ingår i: Composites Science And Technology. - 0266-3538 .- 1879-1050. ; 49:2, s. 121-130
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Tidskriftsartikel (refereegranskat)abstract
- The stiffness and strength of moulded, glass-mat-reinforced thermoplastics (GMT) components would be increased by the presence of highly orientated fibres at critical locations. A previously described method to produce preformed GMT materials was therefore further developed to make orientation of the fibres in the preform possible. Two ‘orientation plates' were used to orientate the fibres during spray-up of a glass-fibre/polyethylene preform. The preform was then heated by hot gas and compression moulded. The ratio of the highest and lowest stiffnesses of a given plate was in the range of 27 to 38. Micromechanics equations were used with classical lamination theory to design a model laminate with stiffness properties in close agreement with experimental data. Reasons for the relatively wide fibre orientation distribution and low fibre length efficiency factor obtained for the model laminate are discussed and improvements suggested.
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| 3. |
- Kim, A.S., et al.
(författare)
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Fracture strength testing of δ-alumina fibres with variable diameters and lengths
- 1993
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Ingår i: Composites Science And Technology. - 0266-3538 .- 1879-1050. ; 47:4, s. 331-333
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Tidskriftsartikel (refereegranskat)abstract
- Tensile tests were performed on individual δ-alumina fibres (Saffil, RF grade). The results revealed a large scatter in strengths and a clear dependence of the fracture strength on the specimen volume. The tests were evaluated on the basis of the Weibull probability function, a special modification of the Weibull analysis being developed that successfully copes with the problem of testing fibres with various diameters and test lengths. For the sample studied the Weibull modulus, m, was found to be 2·2, with a scaling constant δ0 = 6·0 MPa (units of volume mm3; i.e. V0 = 1 mm3).
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| 4. |
- Gudmundson, Peter, et al.
(författare)
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Prediction Of Thermoelastic Properties Of Composite Laminates With Matrix Cracks.
- 1992
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Ingår i: Composites Science And Technology. - 0266-3538 .- 1879-1050. ; 44:2, s. 95-105
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Tidskriftsartikel (refereegranskat)abstract
- A theory is presented for the determination of changes in the elastic compliance tensor and the thermal expansion coefficients due to matrix cracking. Effects of residual stresses are taken into account. The theory is valid for two- or three-dimensional laminates of arbitrary lay-ups and is asymptotically exact for dilute micro-crack densities. For large micro-crack densities an alternative model is described which is asymptotically exact for large crack densities. Combined, the two models cover to a good approximation the whole range of micro-crack densities. The theory is applied to a micro-cracking cross-ply GFRP laminate for which the stress/strain curve is calculated. Data are also presented for changes in thermomechanical properties of angle ply laminates as functions of the lay-up angle.
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| 5. |
- Syvänen, Ann-Christine, et al.
(författare)
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Genetic analysis of the polymorphism of the human apolipoprotein E using automated solid-phase sequencing
- 1991
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Ingår i: Genetic Analysis, Techniques and Applications (GATA). - 1050-3862 .- 1879-1441. ; 8:4, s. 117-123
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Tidskriftsartikel (refereegranskat)abstract
- A direct sequencing approach has been used to analyze the polymorphism in the human apolipoprotein E gene. A method is described, in which the DNA is amplified by the polymerase chain reaction, immobilized, and sequenced by a semi-automatic procedure adaptable to clinical diagnosis. The three alleles of the apolipoprotein E gene, which differ from each other by two nucleotide substitutions and which influence serum cholesterol levels, were analyzed. The solid-phase method was able to resolve the correct nucleotide sequence in samples from both homozygous and heterozygous individuals. No cloning steps are needed and the immobilization and separation of the DNA is accomplished using magnetic beads.
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| 6. |
- Toll, Staffan, et al.
(författare)
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Notched strength of long- and short-fibre reinforced polyamide
- 1992
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Ingår i: Composites Science and Technology. - 0266-3538. ; 45:1, s. 43-54
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Tidskriftsartikel (refereegranskat)abstract
- A test programme has been conducted to evaluate the tensile strength of injection moulded plates with machined and moulded-in notches. The long-fibre compound, Verton, is consistently less notch sensitive than the short-fibre compound, Maranyl. Moulded-in holes appear to have several advantages over machined holes: they yield up to 25% higher strength and less sensitivity to plate thickness and injection speed. Five existing laminate fracture models are applied to the machine-notched plates; the average stress criterion and the damage zone model give the most accurate predictions. © 1992.
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