Yan Gao , Nigel Martin , Jamie Moschini , David Dye
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引用次数: 0
Abstract
The hypothesis is examined that the macrozones that can occur in large Ti-6Al-4V forgings, in combination with the effects of stressed volume and sustained loads, can result in a debit in high cycle fatigue (HCF) performance, which would be of concern in jet engine applications. Here, the effect of placing a notch root in hard vs. soft oriented macrozones, i.e. parallel or perpendicular to the loading direction, respectively, were examined. The deformation features associated with crack initiation were analysed. A significant () variation in life was observed, as low as 5.6 × 106 cycles in hard macrozones compared to 58.6 × 106 cycles in soft macrozones, at a peak notch root stress of 912 MPa and load ratio of 0.5. Local macrozones were found neighbouring the initiation facets, which were subsurface. Compared to plain fatigue, LCF or dwell fatigue, the initiating faceted grains possessed low dislocation density, which were predominantly of basal character.
期刊介绍:
Typical subjects discussed in International Journal of Fatigue address:
Novel fatigue testing and characterization methods (new kinds of fatigue tests, critical evaluation of existing methods, in situ measurement of fatigue degradation, non-contact field measurements)
Multiaxial fatigue and complex loading effects of materials and structures, exploring state-of-the-art concepts in degradation under cyclic loading
Fatigue in the very high cycle regime, including failure mode transitions from surface to subsurface, effects of surface treatment, processing, and loading conditions
Modeling (including degradation processes and related driving forces, multiscale/multi-resolution methods, computational hierarchical and concurrent methods for coupled component and material responses, novel methods for notch root analysis, fracture mechanics, damage mechanics, crack growth kinetics, life prediction and durability, and prediction of stochastic fatigue behavior reflecting microstructure and service conditions)
Models for early stages of fatigue crack formation and growth that explicitly consider microstructure and relevant materials science aspects
Understanding the influence or manufacturing and processing route on fatigue degradation, and embedding this understanding in more predictive schemes for mitigation and design against fatigue
Prognosis and damage state awareness (including sensors, monitoring, methodology, interactive control, accelerated methods, data interpretation)
Applications of technologies associated with fatigue and their implications for structural integrity and reliability. This includes issues related to design, operation and maintenance, i.e., life cycle engineering
Smart materials and structures that can sense and mitigate fatigue degradation
Fatigue of devices and structures at small scales, including effects of process route and surfaces/interfaces.