OS-C501

Offshore Standard DNV-OS-C501, November 2013
Sec.5 Materials – sandwich structures – Page 80
Table 5-3 Mechanical static properties for core materials (Continued)
Mechanical parameter Unit Reference in Appendix D
yz
core non-linear Core shear stress normal to the core plane [N/mm 2 ]
(or MPa)
Fracture toughness
G Ic core Mode-I (opening) critical strain energy release rate [N/m] [D.2.5]
G II core Mode-II (shearing) critical strain energy release rate [N/m] [D.2.5]
2.2.7 The static data for adhesive materials are the following:
for measurement method
[D.2.4] for balsa
[D.2.3] for other materials
σ ∧ t
Table 5-4 Mechanical static properties for adhesive materials
Mechanical parameter Unit Reference in Appendix D
for measurement method
In-plane elastic constants
E adhesive linear Modulus of elasticity of adhesive in the linear range [N/mm 2 ]
(or MPa)
[D.3.2] or [D.3.3]
E adhesive non-linear Modulus of elasticity of adhesive at the failure point [N/mm 2 ] [D.3.2] or [D.3.3]
(or MPa)
G xy adhesive linear In plane shear modulus of adhesive in the linear range [N/mm 2 ] [D.3.4]
(or MPa)
G xy adhesive non-linear In plane shear modulus of adhesive at the failure point [N/mm 2 ]
(or MPa)
[D.3.4]
ν xy adhesive Major Poisson’s ratio of adhesive [-] [D.3.2] or [D.3.3]
In-plane strain to failure
adhesive Adhesive tensile strain at failure point [D.3.2]
ε ∧ t
In-plane strength
σ ∧
σ ∧ t
σ ∧
xy
adhesive Adhesive flatwise tensile strength [N/mm 2 ]
(or MPa)
adhesive Adhesive tensile strength [N/mm 2 ]
(or MPa)
adhesive Adhesive shear strength [N/mm 2 ]
(or MPa)
2.3 Relationship between strength and strain to failure
2.3.1 For material exhibiting a brittle type (type-I) of failure and a linear elastic behaviour up to ultimate failure
then, E = σ/ε.
2.3.2 For material exhibiting a ductile or plastic type of failure (respectively type-II and -III), the linear
relationship shall be used up to the upper bound of the linear elastic limit. Material properties listed in Tables
B1 and B2 pertaining to this regime are called linear.
2.3.3 Beyond the upper bound of the linear elastic limit, a different modulus shall be used; this one shall
represent the elastic behaviour related to the range of the stress-strain curve. Material properties, listed in Table
5-3 and Table 5-4 and pertaining to this regime, are called non-linear. In most cases, it is convenient to use a
linear secant modulus to describe the material.
2.3.4 When the stress-strain relationship can not be established for non-linear range, a non-linear analysis shall
be carried out.
2.4 Characteristic values
[D.3.3]
[D.3.2]
[D.3.4]
Fracture toughness
G Ic adhesive Mode-I (opening) critical strain energy release rate [N/m] [D.2.5] or [D.4.2]
G IIc adhesive Mode-II (shearing) critical strain energy release rate [N/m] [D.2.5] or [D.4.2]
2.4.1 Characteristic values shall be used for all strength values in this standard. The procedure to obtain
characteristic values is given in Sec.4 [2.4].
2.4.2 For most core materials the coefficient of variation (COV) of the test specimens is relatively independent
of the specimen size. However, for some materials, like balsa, the COV varies with specimen size. This
variation should be considered in the analysis.
DET NORSKE VERITAS AS