PSI - Issue 5

Slobodanka Boljanović et al. / Procedia Structural Integrity 5 (2017) 801 – 808 Slobodanka Boljanović, Stevan Maksimović / Structural Integrity Procedia 00 (2017) 000–000

802

2

Nomenclature a

crack length

C

material constant of fatigue crack growth law

da / dN crack growth rate D diameter of the lug H

height of the lug head stress intensity factor number of loading cycles

K N P R S

applied force stress ratio applied stress

t

thickness

w

width

∆ K ∆ P ∆ S

stress intensity factor range

applied force range applied stress range

Poisson’s ratio

ν

Subscripts f

failure

max

maximum value

0

initial

The crack propagation behavior of the fracture critical lug-pin joint can be theoretically examined through the stress-intensity analysis in which relevant analytical and numerical approaches are employed. In this context, Antoni and Gaisne (2011) have taken into consideration the analytical method, whereas Mikheevsky et al. (2012) have performed numerical investigation using the weight function method to describe the failure behavior of lug. Wu et al . (2011) and later Boljanović and Maksimović (2013) applied the finite element method for the stress field evaluation of damaged lug subjected to cyclic loading. Further, in order to analyze the same fatigue problem Atluri and Nishioka (1986) have taken into account the finite element alternating method, whereas Rigby and Alibadi (1997) employed the J -integral method together with the boundary method. Furthermore, from the fracture mechanics theoretical point of view, the fatigue strength of damaged situations can be assessed by employing different crack growth concepts. Thus, for fatigue failure analysis Elber (1971) suggested the crack closure model, whereas Bodner et al . (1983) and Nicholls (1994) developed models based on an energy concepts. Further, Kujawski (2001) proposed the two-parameter driving force model in which the positive part of applied stress intensity factor range is involved. Huang and Moan (2007) found that the combination of the stress intensity factor range and stress ratio can be employed to describe the failure behavior under cyclic loading and introduced their crack growth concept. The present research work addresses the development of a computational model for the fatigue failure analysis of pin-loaded lug with initial through-the-thickness crack at a hole. The crack growth behavior is investigated through the stress analysis and the residual life estimation. Complex stress state field under cyclic loading is examined in terms of the stress distribution and the stress intensity factor calculation by applying analytical and numerical approaches. The fatigue life is estimated by taking into account the crack growth law proposed by Huan and Moan. The validity of fatigue failure assessments is verified by means of experimental crack growth observations.