Page 282 - Marine Structural Design
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258 Part II Ultimate Strength
where, SCr and are a critical CTOD and an equivalent crack length, respectively. E, Q,, , and
.cy are Young's modulus, yield stress, and yield strain, respectively. It is noted that the applied
strain max is evaluated by disregarding the effects of the crack.
To achieve a more accurate CTOD prediction, we may used the level-3 CTOD method:
(1 3.25)
where oma and E,, are the maximum stress and strain respectively, and or denotes the
residual welding stress.
Failure is assumed to take place and the cracked member is removed from the structural
system when the specified equivalent strain satisfies the selected fracture mechanics criterion.
The element forces are applied as unbalanced forces to the system. This fi-acture mechanics
criteria are used for all of the elements presented in this paper.
After collision, the area where tension-tearing rupture has taken place is considered as the
"hole". This data is important for the simulation of oil spills resulting from collisions and
groundings.
Figure 13.4 Element Type
force orA
moment
0
0 displacement or
Figure 13.5 Force-displacement Curve for a Non-linear Spring
