Service conditions of turbine blades involve fatigue, creep, and environmental corrosion. Themanner in which these mechanisms interact to initiate cracks is complex. These physicalmechanisms have been observed through observation and measurement of damage in adirectionally-solidified (DS) GTD-111 Ni-base superalloy. Experiments include high temperaturelow cycle fatigue with and ...

This paper outlines a new durability model to assess the most economical first inspection period for structures. Practical scatter factor formulae are presented to determine the safe fatigue crack initiation and propagation lives from the result of a single full-scale test of a complete structure. Theoretical prediction techniques are developed to establish the relationship equation between the...

A new multiaxial high-cycle fatigue initiation life prediction model for railroad wheels is proposed in this paper. A general fatigue damage analysis methodology for complex mechanical components is developed and applied to the wheel/rail rolling contact fatigue problem. A 3-D elasto-plastic finite element model is used for stress analysis. A submodeling technique is used to achieve both comput...

The objective of the current study is to determine the fatigue limit of a clean and high-performance material named as HSLA-100 steel and to compare the obtained fatigue limit with that of theoretically predicted fatigue limit by statistics of extreme value (SEV) method. Also, the size of inclusions located at the site of fatigue crack nucleation on the fracture surface of the fatigue test spec...

In this work, the effects of loading condition and corrosion solution on the corrosion fatigue behavior of smooth steel wire were discussed. The results of polarization curves and weight loss curves showed that the corrosion of steel wire in acid solution was more severe than that in neutral and alkaline solutions. With the extension of immersion time in acid solution, the cathodic reaction of ...

The fundamentals associated with acoustic emission monitoring of fatigue crack initiation and propagation of Ti-6AI-4V were studied. Acoustic emission can detect and locate incipient fatigue crack extensions of approximately 1 0 gm. The technique therefore can serve as a sensitive warning to material failure. There are three distinct stages during which acoustic emission is generated. These sta...

The fatigue behavior of polyether ether ketone (PEEK) thermoplastic was investigated under uniaxial strain-controlled cyclic loading condition with various mean strains (Rε 1⁄4 0, 0.2, and 0.25). The mean stress responses of PEEK from all mean strain fatigue tests were found to be fully-relaxed. As a result, minimum mean strain effect on fatigue behavior of PEEK was observed. Fractography analy...

In situ ultrasonic fatigue with a cyclic frequency of 20 kHz was employed in an environmental scanning electron microscope (ESEM) to characterize fatigue crack formation and growth in the near alpha titanium alloy Ti–6242S. The role of environment on small fatigue crack initiation and growth was investigated in vacuum and in variable pressures of saturated water vapor, as well as in laboratory ...

Axial loading tests with stress ratios R of -1, 0 and 0.3 were performed to examine the fatigue failure behavior of a carburized Cr-Ni steel in the long-life regime from 10⁴ to 10⁸ cycles. Results show that this steel represents continuously descending S-N characteristics with interior inclusion-induced failure under R = -1, whereas it shows duplex S-N characteristics with surface defect-induce...

The fatigue behaviour of single lap bonded joints under fatigue loading was already investigated and a suitable life prediction model was presented and validated [1-2]. The model is based on the actual damage evolution under fatigue load: a crack initiation followed by its propagation up to a critical length [2, 3]. In the present paper the evolution of fatigue damage in single lap joints is ex...