OS-C501

Offshore Standard DNV-OS-C501, November 2013
Sec.4 Materials - laminates – Page 47
.
200
E
II
FAILURE
E
0 + 90
E 0 + PARTIALLY DAMAGED 90
S
T
R
E
S
S
100
E 0 + TOTALLY DAMAGED 90
STRAIN AT ONSETT
OF MATRIX CRACKING
0
0.0
0.5
1.0
1.5
2.0
Figure 4-1
Example of a stress strain curve of a 0/90 laminate
STRAIN
2.8.4 The strain to failure transverse to the fibre direction is identical to the strain at onset of matrix cracking.
2.8.5 The strain to failure (rupture) of the laminate is the strain to failure of the fibres.
2.8.6 The remaining ply properties can be calculated with laminate theory and considering [2.3].
2.8.7 For properties with matrix cracking, see Sec.4 [9].
2.9 Experimental measurement of ply shear properties
2.9.1 The shear properties of a ply are typically non-linear. In order to perform a linear analysis an initial nondegraded
shear modulus should be defined.
2.9.2 For a strength analysis initial, undamaged shear modulus may be defined as the secant modulus between
0 and any point on the non-linear stress strain curve as long as:
— only nonlinear deformation, but no matrix cracking is observed in the experiments
— the point is below 80% of the failure strength
— the point is below 50% of the strain to failure
An example is given in Figure 4-2.
F A IL U R E
S h e a r
S tre s s
G
1 2
G 1 2 a t fa ilu re
G 1 2 a t 9 0 % o f fa ilu re lo a d
0
0 .0
Figure 4-2
Example of a shear stress strain curve
S h e a r s tr a in
2.9.3 For deflection calculations the modulus should be secant modulus at the maximum design shear stress
and all requirements of [2.9.2] should be fulfilled.
2.9.4 The remaining properties can be calculated by laminate theory and considering [2.3].
2.9.5 For properties with matrix cracking or non-linear deformations, see Sec.4 [9].
DET NORSKE VERITAS AS