Residual Stress Around the Fatigue Crack front in a Rectangular Sample cut from CT Specimen

2021 ◽  
Author(s):  
Ales Materna ◽  
Hynek Lauschmann ◽  
Jan Ondracek
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Crack Front

Comparison of DBEM and FEM Crack Path Predictions with Experimental Findings for a SEN-Specimen under Anti-Plane Shear Loading

2007 ◽  
Vol 348-349 ◽  
pp. 129-132 ◽  
Author(s):  
Roberto G. Citarella ◽  
Friedrich G. Buchholz
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Front ◽  
Crack Path ◽  
Shear Loading ◽  
Crack Growth Behaviour ◽  
3D Crack Growth ◽  
Corner Points ◽  
Experimental Findings

In this paper detailed results of computational 3D fatigue crack growth simulations will be presented. The simulations for the crack path assessment are based on the DBEM code BEASY, and the FEM code ADAPCRACK 3D. The specimen under investigation is a SEN-specimen subject to pure anti-plane or out-of-plane four-point shear loading. The computational 3D fracture analyses deliver variable mixed mode II and III conditions along the crack front. Special interest is taken in this mode coupling effect to be found in stress intensity factor (SIF) results along the crack front. Further interest is taken in a 3D effect which is effective in particular at and adjacent to the two crack front corner points, that is where the crack front intersects the two free side surfaces of the specimen. Exactly at these crack front corner points fatigue crack growth initiates in the experimental laboratory test specimens, and develops into two separate anti-symmetric cracks with complex shapes, somehow similar to bird wings. The computational DBEM results are found to be in good agreement with these experimental findings and with FEM results previously obtained. Consequently, also for this new case, with complex 3D crack growth behaviour of two cracks, the functionality of the proposed DBEM and FEM approaches can be stated.

High Dense Compressive Residual Stress Produced in Laser Shock Processing on Ti6Al4V Alloys

2007 ◽  
Vol 353-358 ◽  
pp. 1617-1620 ◽  
Author(s):  
Xu Dong Ren ◽  
Yong Kang Zhang ◽  
Jian Zhong Zhou ◽  
Yong Yu Gu ◽  
Y.Y. Xu ◽  
...  
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Surface Stress ◽  
Compressive Residual Stress ◽  
High Energy ◽  
Laser Shock ◽  
Laser Shock Processing ◽  
Large Spot ◽  
Small Spot ◽  
Shock Processing

Laser shock processing (LSP) employs high-energy laser pulses from a solid-state laser system to create intense shock waves into a material, which can induce compressive residual stresses in the target surface and improve its mechanical property efficiency. Residual stress of Ti6Al4V alloy both before and after LSP with multishocks was analysised. The depth of compressive residual stress was found to have a dependence on the number of shocking layers and a slight dependence on the level of irradiance. Surface stress improvements of more than 50% increases are possible after laser shock processing with either large spot or small spot patterns. The large spot gave a surface stress of 432MPa and a depth of over 1mm. The low intensity small spot gave a surface stress of 285MPa with a depth comparable to the large spot. Laser shock processing induces a compressive residual stress field, which increases fatigue crack initiation life and reduces fatigue crack growth rate.

Three-Dimensional Study of Fatigue Crack Growth in a Rotating Disc

2013 ◽  
Vol 3 (2) ◽  
pp. 45-62
Author(s):  
Eskandari Hadi ◽  
Nami Mohammad Rahim
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Front ◽  
Numerical Technique ◽  
Three Dimensional ◽  
Crack Orientation ◽  
Rotating Disc ◽  
Mesh Density ◽  
Three Dimensional Finite Element

The problem of fatigue-crack-growth in a rotating disc at different crack orientation angles is studied by using an automated numerical technique, which calculates the stress intensity factors on the crack front through the three-dimensional finite element method. Paris law is used to develop the fatigue shape of initially semi-elliptical surface crack. Because of needs for the higher mesh density and accuracy near the crack, the sub-modeling technique is used in the analysis. The distribution of SIF’s along the crack front at each step of growth is studied and the effect of crack orientation on the rate of crack-growth is investigated. The calculated SIF’s are reasonable and could be used to predict the probable crack growth rates in fracture mechanics analysis and can help engineers to consider in their designing and to prevent any unwanted failure of such components.

scholarly journals Residual Stress Measurements on a Metal Matrix Composite Using the Contour Method with Brittle Fracture

2014 ◽  
Vol 996 ◽  
pp. 349-354 ◽  
Author(s):  
Jeferson Araujo de Oliveira ◽  
Michael E. Fitzpatrick ◽  
Jan Kowal
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Brittle Failure ◽  
Metal Matrix ◽  
Crack Surface ◽  
Contour Method ◽  
Wire Edm ◽  
Stress Measurements ◽  
Fatigue And Fracture ◽  
Cut Surface

In this work we evaluate the application of the contour method to fatigue and fracture surfaces. Residual stress measurements were made on quenched and aged AA2124-SiCp composite using neutron diffraction, the contour method with wire EDM, and the contour method on a fatigue crack surface including brittle failure. The contour method successfully measured residual stresses from a wire electro-discharge cut surface, but the fracture method results suggest that residual stress information is lost due to plasticity during fatigue crack growth.

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