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DNV-OS-C501 Composite Components
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Sec.7
D. Interfaces
Sec.7
D 100 General
Sec.7 D
101 If loads shall be transferred across an interface all aspects
related to joints shall be considered.
Sec.7 D
102 If interfaces only touch each other friction and wear should
be considered according to section 6
M.
Sec.7 D
103 Fluids may accumulate between interfaces. They may accumulate
in voids or debonded areas and/or break the bond of the
interface. The effect of such fluids should be analysed. Possible
rapid decompression of gases should be considered section 6 L.
Sec.7 D
104 Liners that do not carry any structural loads shall have a high
enough strain to failure or yield that they can follow all possible
movements of the interface. Yielding of liners should be avoided,
since yielding can cause local thinning or introduce permanent stresses
after yield. If yielding cannot be avoided it shall be analysed
carefully. The effect of local yielding on the surrounding structure
shall also be considered.
Sec.7 D
105 If one substrate may crack (e.g. have matrix cracks), but the
other shall not crack, it shall be shown that cracks cannot propagate
from one substrate across the interface into the other substrate.
Possible debonding of the interface due to the high stresses at
the crack tip should also be considered.
Sec.7 D
106 It is recommended to demonstrate by experiments that cracks
cannot propagate across the interface from one substrate to the
other. It should be shown that by stretching or bending both substrates
and their interface that no cracks forms in the one substrate even
if the other substrate has the maximum expected crack density.Guidance note:
This is a typical situation for pressure vessels with liners.
The load bearing laminate may have some matrix cracks, but the liner shall
not crack to keep the vessel tight. Local debonding of the liner
may be acceptable if the liner will not collapse due to its own
weight, negative internal pressure or other effects.---e-n-d---o-f---G-u-i-d-a-n-c-e---n-o-t-e---
Guidance note:
A weak bond between the substrates is beneficial to prevent crack
growth across the interface. However, it means that debonding may
happen easily.---e-n-d---o-f---G-u-i-d-a-n-c-e---n-o-t-e---
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