Three-dimensional fracture and fatigue crack propagation analysis in structures with multiple cracks

2015 ◽  
Vol 158 ◽  
pp. 259-273 ◽  
Author(s):  
Hakan Dündar ◽  
Ali O. Ayhan
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Three Dimensional ◽  
Multiple Cracks ◽  
Propagation Analysis

Fatigue crack propagation analysis for multiple weld toe cracks in cut-out fatigue test specimens from a girth welded pipe

2017 ◽  
Vol 94 ◽  
pp. 158-165 ◽  
Author(s):  
John H.L. Pang ◽  
Hsin Jen Hoh ◽  
Kin Shun Tsang ◽  
Jason Low ◽  
Shawn Caleb Kong ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Test ◽  
Fatigue Crack Propagation ◽  
Propagation Analysis ◽  
Weld Toe ◽  
Welded Pipe

Numerical Investigations of Corner Singularities in Cracked Bodies

2007 ◽  
Vol 348-349 ◽  
pp. 377-380 ◽  
Author(s):  
Pavel Hutař ◽  
Luboš Náhlík ◽  
Zdeněk Knésl
Keyword(s):  
Fatigue Crack ◽  
Free Surface ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Three Dimensional ◽  
Stress Singularity ◽  
Crack Propagation Rate ◽  
Propagation Rate ◽  
Dimensional Structure ◽  
Fatigue Crack Propagation Rate

The influence of corner singularity on the distribution of the stresses around the crack front for a three-dimensional structure is described in this paper. The distribution of stress singularity through the thickness of the middle tension specimen provides us an indication of crack behaviour close to a free surface. An estimation of the region where the change of singularity exponent plays an important role in fatigue crack propagation rate was carried out. A decrease in fatigue crack propagation rate close to the free surface was found. The lower fatigue crack propagation rate in the boundary layer in comparison with the interior of the specimen leads to a change of intersecting angle between crack and free surface and depends on Poisson’s ratio.

Three-Dimensional LEFM Prediction of Fatigue Crack Propagation in a Gas Turbine Disk Material at Component Near Conditions

2015 ◽  
Vol 138 (4) ◽  
Author(s):  
Christian Busse ◽  
David Gustafsson ◽  
Patrik Rasmusson ◽  
Björn Sjödin ◽  
Johan J. Moverare ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Gas Turbine ◽  
Plastic Flow ◽  
Fatigue Crack Propagation ◽  
Three Dimensional ◽  
Turbine Disk ◽  
Material Behavior ◽  
Linear Elastic ◽  
Disk Material

In this paper, the possibility to use linear elastic fracture mechanics (LEFM), with and without a superimposed residual stress field, to predict fatigue crack propagation in the gas turbine disk material Inconel 718 has been studied. A temperature of 400 °C and applied strain ranges corresponding to component near conditions have been considered. A three-dimensional crack propagation software was used for determining the stress intensity factors (SIFs) along the crack path. In the first approach, a linear elastic material behavior was used when analyzing the material response. The second approach extracts the residual stresses from an uncracked model with perfectly plastic material behavior after one loading cycle. As a benchmark, the investigated methods are compared to experimental tests, where the cyclic lifetimes were calculated by an integration of Paris' law. When comparing the results, it can be concluded that the investigated approaches give good results, at least for longer cracks, even though plastic flow was taking place in the specimen. The pure linear elastic simulation overestimates the crack growth for all crack lengths and gives conservative results over all considered crack lengths. Noteworthy with this work is that the 3D-crack propagation could be predicted with the two considered methods in an LEFM context, although plastic flow was present in the specimens during the experiments.

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