OS-C501

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Offshore Standard DNV-OS-C501, November 2013 Sec.4 Materials - laminates – Page 66 8.4.2 The test methods described in App.C should be preferred. 8.5 Representative data 8.5.1 If a sufficient number of direct measurements is available, data may be used to establish a set of representative data for a material property. To be considered representative, data should be based on at least 15 measurements per property. Other materials can be compared against the representative data as described in [8.6]. 8.5.2 Representative data are most useful if they can be used for a fairly wide range of materials. This will also allow to pool data of different properties that were obtained from slightly different materials. Requirements for to the individual materials that can be put into one group of representative data are given in Table 4-10: Table 4-10 Processing characteristics of the set of representative data Constituent materials: Requirements to group measurements from different laminates Generic Fibre type same for all tests Bundle type same trade name* Fibre trade name same trade name* Type of weave same trade name* Type of sizing same trade name* Fibre Manufacturer same for all tests Weaver same for all tests Fabric trade name and batch number same trade name Generic resin type (e.g. epoxy, polyester) same for all tests Specific resin type (trade name, batch number) same trade name* Catalyst (trade name and batch number) same trade name* Accelerator (trade name and batch number) same trade name* Fillers (trade name and batch number) same trade name* Additives (trade name and batch number) Process parameters: Laminator (company) Processing method Processing temperature Processing pressure Process atmosphere (e.g. vacuum) Post curing (temperature and time) Control of fibre orientation Fibre volume fraction Void content Conditioning parametersto be given with exposure time: Temperature Water content of the laminate (wet, dry) Chemical environment Loading rate same trade name* not relevant same for all tests maximum from all tests maximum from all tests minimum from all tests maximum from all tests best from all tests maximum from all tests minimum from all tests minimum from all tests same for all tests same for all tests same for all tests Number of specimens * a wider range may be chosen if data are the minimum of a wide variety of products. 8.5.3 Examples of representative data are given in Appendices F, G, H and I. 8.6 Qualification against representative data Reported individually for all properties 8.6.1 It is only necessary to qualify data that are needed in the design analysis and failure criteria. 8.6.2 A property of a laminate may be qualified against representative data if certain requirements are met for fibres, matrix and sizing: DET NORSKE VERITAS AS
Offshore Standard DNV-OS-C501, November 2013 Sec.4 Materials - laminates – Page 67 8.6.3 Similarity is described here on the ply level. Fibres, matrix and sizing may be exchanged or modified if the ply properties are not changed. 8.6.4 Similar fibres: Fibre reinforcements can be considered to be similar under the following conditions: — The fibre is of the same generic type, e.g. E-glass, high modulus carbon with the same generic precursor, etc. — The tensile and compressive characteristic fibre dominated ply strength ( ε ∧ 1t fibre and ε ∧ 1c fibre) fulfil the similarity requirements given in [8.7]. This requirement may be tested with a UD or 0/90 laminate. — The fibre-dominated modulus is within 5% of the reference ply. 8.6.5 Laminates with different arrangements of the fibres (weave or fabric type or bundle size) type may be considered similar if the requirements in [8.6.4] and [8.6.6] are fulfilled. 8.6.6 Laminates with larger fibre bundles relative to the reference laminate have usually lower strength and do not pass the similarity requirement. 8.6.7 A matrix can be considered to be similar under the following conditions: — the matrix is of the same generic type, e.g. iso-polyester, vinylester, phenolic — fillers and curing agents may be different — the tensile and compressive characteristic matrix dominated ply strength ( ε ∧ 2t matrix and ε ∧ 2c matrix) fulfil the similarity requirements given in [8.7]. This requirement may be tested with a UD or 0/90 laminate — it can be documented that the matrix-dominated modulus is within 5% of the reference ply. 8.6.8 A sizing can be considered to be similar under the following conditions: — the sizing is of the same generic type, e.g. glass-epoxy compatible — the tensile and compressive characteristic matrix dominated ply strength ( matrix and matrix) fulfil the similarity requirements given in [8.7]. This 2t 2c requirement may be tested with a UD or 0/90 laminate. 8.6.9 Documentation shall show that the properties of the combination of the reference material and the combination of the similar material give the results required above. The materials producers may provide this documentation. 8.6.10 If the above basic similarity requirements are met, individual static ply properties shall be qualified as described in Table 4-11. Some properties can be based directly on represented data or an equation to modify them is given. Other properties shall be confirmed by experiment (see [8.7]-[8.9]). 8.6.11 Instead of confirming all material parameters individually component testing may be used to qualify an analysis, as described in [8.11]. Table 4-11 Qualification against representative data In-plane orthotropic elastic constants Mechanical parameter Low safety class Normal safety class High safety class all elastic constants all elastic constants rep × 1 confirm E 1 and E 2 , confirm other constants rep * 1 In-plain strain to fail and strength all parameters rep × 0.8 confirm confirm ε 1t , ε 1c ,σ 2t Others: confirm if critical Through Thickness E 3 Modulus of elasticity normal to the rep or confirm confirm fibre plane = E 2 G 13 Shear modulus normal to the fibre rep or rep or confirm if plane, including the fibre direction = G 12 = G 12 critical for design G 23 ε ∧ ε ∧ Shear modulus normal to the fibre plane, including the direction normal to the fibre direction. rep or rep or confirm if = G 12 = G 12 critical for design DET NORSKE VERITAS AS
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OS-C501

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