Authors: Akihide Saimoto, Yoshio Imai, Toshiyuki Hashida
327
Authors: Zhong Guang Wang, H. Zhang, Q.S. Zang, Zhe Feng Zhang, Z.M. Sun
693
Authors: Tomáš Denk, Vladislav Oliva, Aleš Materna
Abstract: A two-parameter constraint-based fracture mechanics approach is used to explain the effect of the constraint on the apparently anomalous behavior of short fatigue cracks. The different levels of stress constraint are quantified by the T-stress, and microstructurally as well as mechanically short cracks are discussed. Short cracks generally behave more sensitively to the constraint than the long ones. It is shown that in most cases, the existence of short cracks goes hand in hand with an intrinsic loss of the constraint, which contributes to a decrease of their fatigue
threshold values and accelerates their growth. In this paper, the above effect is quantified and conclusions concerning the applicability of the fracture mechanics parameters and approaches to the estimation of the residual fatigue life of structures are discussed.
307
Authors: Won Beom Kim, Jeom Kee Paik
Abstract: In this research, corrosion fatigue tests using 490MPa TMCP steel were performed in
synthetic seawater condition to investigate the corrosion fatigue crack propagation characteristics of
TMCP steel plate which is often used for ships and offshore structures from its weldability and weight
reduction purpose. In addition, relationships between boundary correlation factor F(α,β) and α(=
2a/W) of the fracture mechanics formula for the test specimen which was exerted by the pin load were
calculated for the evaluation of da/dN-.K. To get the boundary correlation factor F(α,β), the
calculation of J as a path-independent line integral was carried out. The solutions of J integral showed
similar value in spite of the different path. Crack propagation tests for the same steel in air condition
was carried out also for comparison. Finally, it was clear from the crack propagation test results that
the propagation rate of TMCP steel plate in synthetic seawater condition is faster than that of in air
condition at least twice.
1043
Authors: Won Beom Kim, Jeom Kee Paik
Abstract: In this research, corrosion fatigue tests using tensile strength of 490MPa TMCP steel
were performed in synthetic seawater condition to investigate the corrosion fatigue crack
propagation characteristics. The influence of cathodic protection at -800mV vs. SCE on the
corrosion fatigue crack propagation behavior was investigated. Relationships between da/dN versus
ΔK for the material were obtained by two types of test specimens. In the present study, F(α,β)
versus α(= 2a/W) relationship for the CCT specimen was calculated by J integral approach, while
that for the CT specimen was determined from ASTM E647. It is found that the fatigue crack
propagation rate of TMCP steel in synthetic seawater condition is faster than that in air condition at
least twice. Also, it is observed that the fatigue crack propagation rate of steel with cathodic
protection is in between those of seawater condition without cathodic protection and air condition.
1145