engleski

Effect of secondary bending on fatigue crack growth in stiffened panels

Fatigue crack propagation tests with constant amplitude loading were carried out for a plate and a stiffened panel specimen with a central through crack. In damaged stiffened panels under tension out-of-plane displacements occur with local bending as a result, due to the geometric eccentricities introduced by the cracked cross-section. A secondary bending factor sbf is defined as the ratio of local bending and membrane stresses in the vicinity of a crack tip. Crack propagation simulation procedure based on numerical integration of the Paris equation, taking account of local bending, was introduced. The Mode I stress intensity factors (SIF), KI, associated with the plate free surface on which positive bending stresses occurs is determined from membrane SIF values calculated by ANSYS FE program and the sbf ratio. The introduced crack propagation simulations procedure which takes account of secondary bending proved to be conservative and gives slightly shorter crack propagation life, compared to experimental results.

fatigue of stiffened panels; stress intensity factor; secondary bending

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