OS-C501

Offshore Standard DNV-OS-C501, November 2013
Sec.6 Failure mechanisms and design criteria – Page 99
1.1.3 For the material in consideration, all the relevant mechanisms of failure shall be listed. A minimum list
of failure mechanisms is given in Table 6-1. The failure mechanisms are linked to typical material types.
Table 6-1 Failure mechanisms for different materials
Failure Mechanisms
Fibre Failure
Matrix Cracking
Delamination
Yielding
Ultimate failure of isotropic or anisotropic homogenous materials
Elastic buckling
Unacceptably large displacements
Stress Rupture
Fatigue
Wear
Fire*
Explosive decompression*
Impact*
Chemical decomposition
Material Type
Laminates and Sandwich Skins
Laminates
Laminates and Sandwich Core/Skin Interface
Core materials, liners, resin rich areas
Core materials
All materials
All materials
All materials, all failure mechanisms.
All materials, all failure mechanisms.
All materials
All materials
All materials
All materials
All materials
* these items are load conditions, but are treated here as failure mechanisms to simplify the approach in the standard.
Guidance note:
The mechanisms of failure of composites can be discussed at different material levels. Failure can be considered to
happen in the matrix or in the fibre. On a larger scale, it can happen to the individual ply (or core). Eventually, one
can consider the whole thickness of the structure as one quantity, i.e. the laminate or the sandwich structure.
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1.1.4 In some cases, a critical sequence of mechanisms of failure may be required for a failure mode to occur.
That sequence should be specified (considering the “domino effect”), if relevant.
Guidance note:
Different sequences may lead to the same failure mode. In this case, the structure shall only be considered as failed,
if the whole sequence of mechanisms of failure modes has happened.
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1.1.5 The type of failure corresponding to each failure mechanism shall be determined. See Sec.2 [3.4] for the
definition of the three types of failure. Failure types for typical failure mechanisms are indicated in the
following chapters.
Guidance note:
The type of failure determines the partial safety factors (see Sec.2). The determination of the type of failure is a critical
step in the design process and can lead to significant differences in the magnitude of the partial safety factors.
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1.1.6 For each location, a link between possible mechanisms of failure and failure modes shall be established.
Possible links between failure modes and the failure mechanisms of FRP laminates and sandwich structures are
described in [1.5]. This is not exhaustive and it should be used for guidance only.
1.1.7 Special considerations for interfaces between laminates and steel or laminates and laminates are covered
in Sec.7.
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