The variation of the stress intensity factor (SIF) for
cracks growing in integrally machined stiffened skin
panels have been studied in an isotropic material.
The stringer-skin panel has been modelled using the
Nastran finite element system with allowance for
crack tip singularity by use of crack tip elements.
To allow for variations in stringer and skin
geometry, three stiffness ratios (stringer
stiffness-skin stiffness) were investigated.
The stress intensity factors have been converted into
nondimensionalised values of stress intensity factor
coefficients (K1/K0). A damage
tolerant and residual strength analysis has been
carried out using an in-house computer program.
Results indicate very little difference for the
different stiffness ratios examined.