In support of Douglas Aircraft Co. structural damage tolerance analysis, crack propagation rates were measured in humid air from lo-\* to 10m3 mm/cycle of several high strength martensitic steels at stress ratios of R = 0.1 and R = 0.5. Increasing the stress ratio was found to decrease the threshold
Discrete dislocation modelling of near threshold fatigue crack propagation
โ Scribed by R. Pippan; H. Weinhandl
- Publisher
- Elsevier Science
- Year
- 2010
- Tongue
- English
- Weight
- 809 KB
- Volume
- 32
- Category
- Article
- ISSN
- 0142-1123
No coin nor oath required. For personal study only.
โฆ Synopsis
At low crack propagation rate in metals and alloys the discrete nature of plasticity is essential to understand the fatigue phenomena. A short overview of the different types of performed discrete dislocation simulations of cyclically loaded cracks and their essential results are presented. The discrete dislocation mechanics deliver the changes of the stresses and displacement during cyclic loading. However, it does not give directly the crack propagation rate. In the simulations one has to assume a propagation mechanism. A comparison implies two things: the different simulations, the experimentally observed crack growth behaviour and crystallographic features will be used to show, which crack propagation mechanism is more appropriate in which case.
๐ SIMILAR VOLUMES
This paper presents a stochastic dislocation model of fatigue crack propagation in ductile alloys under variable-amplitude load. The model is built through collective motion of a large number of dislocations. Four basic dislocation mechanisms, the generation, gliding, annihilation and pinning of dis