PSI - Issue 41
Slobodanka Boljanović et al. / Procedia Structural Integrity 41 (2022) 704 – 711 Slobodanka Bo ljanović et al. / Structural Integrity Procedia 00 (2019) 000 – 000
706
3
a
b
R A C e K da
R B C e K db
f
f
N
N
,
(2)
m
m
A
B
a
b
A
B
0
0
Due to rising attention towards fatigue-induced hazard issues caused by surface flaw phenomena during service operations, the development of relevant computational design models is becoming one of the key aspects to ensure the full functioning of large moving systems. Thus, through the present research, a software program is generated for analyzing the detrimental effects of stress raisers coupled with cyclic load effect. Additionally, it is worth to be mentioned that, in next Section, several case studies are examined to verify the predictive power of failure-critical assessments.
Fig. 1. Elliptical corner flaw located at: (a) the dog bone plate and (b) the finite plate.
3. Crack-tip stress intensity modeling The continuous advances in the demands for better performances of modern moving systems require the development of analytical and/or numerical approaches (Kim et al., 2003, Mikheevskiy et al. , 2012, Boljanović et al., 2016, Boljano vić and Carpinteri, 202 1) for quality failure-strength control programs Therefore, in order to explore the safety-critical elliptical flaw (Fig. 1) under cyclic loading, a relevant stress-intensity solution (Newman and Raju, 1984, Carpinteri, 1994) can be employed, given by
Q K F S a qec
(3)
where S is the applied stress range, a and Q are the crack growth length in depth direction and the ellipse shape factor, respectively, and K is the stress intensity factor range. Non-linear driving force interactions due to a surface pre-existing flaw are here theoretically analyzed through the correction factor F qec , by considering the effects of crack shape and applied load via M 1 , M 2 , M 3 , g 1 , g 2 and Q (Newman and Raju, 1984). In the case of a / b ≤ 1, such parameters are expressed as follows:
2
4
qec t F M M a 2 1
t M a 3
g g f f 1 2
(4)
w
Made with FlippingBook - Online magazine maker