OS-C501
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Offshore Standard DNV-<strong>OS</strong>-<strong>C501</strong>, November 2013<br />
Sec.4 Materials - laminates – Page 69<br />
Table 4-11 Qualification against representative data (Continued)<br />
In-plane orthotropic<br />
elastic constants<br />
Matrix dominated static<br />
rep<br />
strength reduction<br />
under fatigue load<br />
8.6.12 The entry “rep” in Table 4-11 means that representative data may be used without testing. In some cases<br />
the representative data shall be multiplied by a factor as indicated in Table 4-11.<br />
8.6.13 Confirm if critical for design means that the value or procedure of the lower safety class may be used<br />
for strength or strain to failure if the material safety factor γ m can be multiplied by 2 for this property in all<br />
relevant failure criteria. Otherwise the property should be confirmed by testing.<br />
8.6.14 Through thickness elastic properties should only be confirmed by testing if they influence the<br />
calculation of a critical strength or strain as defined in [8.6.13]. Otherwise the representative values my be used.<br />
8.6.15 Long term test data of fibre dominated properties do not have to be confirmed if the laminate has<br />
identical fibres, matrix and sizing compared to a laminate for which long term test data exist and the static<br />
similarity tests in [8.6.4] are fulfilled. The requirement to the same matrix and sizing can be waived if<br />
environmental attack on the fibres can be excluded.<br />
8.6.16 Long term test data of matrix dominated properties do not have to be confirmed if the laminate has<br />
identical fibres, matrix and sizing compared to a laminate for which long term test data exist and the static<br />
similarity tests in [8.6.4] are fulfilled.<br />
8.6.17 The procedure of the higher safety class may always be used to obtain better values than can be obtained<br />
by using the procedure of the lower safety class.<br />
8.6.18 If any of the confirmation tests show that the material is not similar to the representative material, all<br />
properties shall be re-qualified.<br />
8.6.19 A full experimental determination of a property may always be used as an alternative to using<br />
representative data or confirmation testing.<br />
8.7 Confirmation testing for static data<br />
Mechanical parameter Low safety class Normal safety class High safety<br />
8.7.1 If a material is similar to a material for which representative data exist (as described above) two methods<br />
can be used to demonstrate that the similar material is at least as good as the typical material. One is a simplified<br />
method, the other is similar data hypothesis testing.<br />
8.7.2 At least three measurements of the property in question shall be made in all cases. It is recommended to<br />
test five or more specimens.<br />
8.7.3 For the simplified method the following requirements shall be fulfilled:<br />
confirm if critical<br />
for design<br />
— the standard deviation estimated from at least three measurements shall not be larger than the standard<br />
deviation of the corresponding typical data<br />
— at least 50% of the measured values shall be larger than the mean of the typical data<br />
— at least 84% of the measured values shall be larger than the mean - 1 standard deviation of the typical data<br />
— at least 97.7% of the measured values shall be larger than the mean - 2 standard deviations of the typical<br />
data.<br />
8.7.4 If a material is similar to a material for which representative data exist (as described above) the<br />
hypothesis testing can be used to determine whether test data can be considered to belong to the same<br />
population.<br />
8.7.5 Let µ 0 denote the mean value of the typical data, and let σ 0 denote the standard deviation of the typical<br />
data. Calculate:<br />
n( x − µ<br />
0<br />
)<br />
T =<br />
ˆ σ<br />
where x is the mean value of the n measurements of the material to be checked for similarity.<br />
class<br />
confirm if<br />
critical for<br />
design<br />
DET NORSKE VERITAS AS