The fatigue crack growth in a coarse-grained Fe-2 wt% Si alloy is investigated in considerable detail. At room temperature, the material is quasi-brittle and the failure mode is mixed cleavage. Under a mode-I cyclic loading, the crack can overcome the barrier effect of grain boundaries, which dominates the overall damage evolution. Associated with the geometrically necessary crack front branchi...

Fatigue is the progressive, localized, permanent structural change that occurs in materials subjected to fluctuating stresses and strains that may result in cracks or fracture after a sufficient number of fluctuations. Fatigue fractures are caused by the simultaneous action of cyclic stress, tensile stress and plastic strain. If any one of these three is not present, fatigue cracking will not i...

present work shows the numerical determination of fatigue crack opening and closure stress intensity factors of a C(T) specimen under variable amplitude loading using a finite element method. A half compact tension C(T) specimen, assuming plane stress constraint was used by finite element method covering the effects in two-dimensional (2D) small scale yielding models of fatigue crack growth und...

Fatigue crack growth rate depends not only on the load amplitude, but also on the morphology of crack path. The strain energy density theory has the ability to analyze crack growth rate. A strain energy density crack growth model is proposed. It can predict the lifetime of fatigue crack growth for mixed mode cracks while an equation for mode I crack is also obtained. The validity of the model i...

microalloyed s355n steel plates are extensively used in bridge and high-rise building structures. one ofthe factors affecting the mechanical properties is the size and morphology of inclusions. in this research,microalloyed s355n steel plates with different sizes of inclusions were examined. one contained longmanganese sulfide inclusions (li material) and the other had short ones (si material)....

NASA has conducted an Airframe Structural Integrity Program to develop the methodology to predict the onset of widespread fatigue damage in lap-splice joints of fuselage structures. Several stress analysis codes have been developed or enhanced to analyze the lap-splice-joint configuration. Fatigue lives in lap-splicejoint specimens and fatigue-crack growth in a structural fatigue test article a...

Mixed-mode, high-cycle fatigue-crack growth thresholds are reported for through-thickness cracks (large compared to microstructural dimensions) in a Ti±6Al±4V turbine blade alloy with a bimodal microstructure. Speci®cally, the e€ect of combined mode I and mode II loading, over a range of phase angles b ˆ tanÿ1…DKII=DKI† from 0° to 82° …DKII=DKI 0±7), is examined for load ratios (ratio of minimu...

Effect of thermal treatment on the fatigue crack propagation behavior of a new Ni-base superalloy Xingbo Liu a,*, ling Xu a, Ever Barbero a, Wei-Di Cao b, Richard L. Kennedy b a West Virginia University, Morgantown, WV 26506-6106, USA b Allvac, an AT! Technologies Company, Monroe, NC 28111-5030, USA Received 22 October 2006; received in revised form 23 March 2007; accepted 10 May 2007 The effec...

The relationships between the fatigue crack growth rate ( d a / d N ) and stress intensity factor range ( Δ K ) are not always linear even in the Paris region. The stress ratio effects on fatigue crack growth rate are diverse in different materials. However, most existing fatigue crack growth models cannot handle these nonlinearities appropriately. The machine learning method provides a flexibl...

Ultrasonic in situ monitoring of metal alloys has been successfully demonstrated for determining the presence and size of fatigue damage within a stracture. Ultrasonic techniques, however, only provide an estimate of the state of the stracture at that time and do not predict the remaining fatigue life. On the other hand, a statistical crack propagation approach, which models the expected remain...