scholarly journals Fatigue Crack Control in Structural Details Using Surface Peening

2008 ◽  
Vol 24 (03) ◽  
pp. 147-151
Author(s):  
Shi Song Ngiam ◽  
Feargal P. Brennan
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Compressive Residual Stress ◽  
Cold Working ◽  
Fatigue Performance ◽  
Shape Evolution ◽  
Crack Shape

This paper presents an analytical and experimental study of crack shape evolution in steel plate specimens under cyclic loading. It is widely known that the introduction of compressive residual stresses by cold working the surface can be highly beneficial in improving the fatigue performance of structural components. Although it is recognized that relaxation of surface compressive residual stress can reduce the potential benefits, the effects of residual stress on crack shape evolution are often overlooked. Previous studies have shown that the intensity of the surface compressive residual stress has a pronounced effect on fatigue crack initiation. A recently developed technique termed controlled stitch cold working, which applies differing intensities of compressive residual stress at specific regions in a structure, is shown in the paper to influence fatigue crack propagation life considerably. The approach can be used to prevent crack growth in particular directions, for example, encouraging a controlled or fail-safe scenario. The paper describes fatigue crack growth tests on shot peened specimens tested under uniaxial tension. The specimens were peened to varying intensities and of differing coverage areas. Cracks were initiated from starter notches after peening, meaning the approach can be used for fatigue performance enhancement at the construction stage or later as part of a maintenance and repair strategy. Crack growth retardation is apparent in all tests, and this is attributed to the constrained crack shape. Further work will consider the use of laser and ultrasonic peening to contain cracks from rapidly propagating from stress concentrations. This approach used with careful design of stiffness can significantly extend the fatigue crack propagation resistance of ship and offshore structures.

Heterogeneous Microstructure Effect on Residual Stress and Fatigue Crack Resistance in Dual-Phase Materials

2009 ◽  
Author(s):  
Masahito Mochizuki ◽  
Yoshiki Mikami
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Stress Distribution ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Compressive Residual Stress ◽  
Fatigue Tests ◽  
Residual Stress Distribution ◽  
Experimental Result ◽  
Microstructure Effect

The effect of transformation-induced microscopic residual stress on fatigue crack propagation behaviour of ferrite-martensite lamellar steel was discussed. Fatigue tests of prestrained and non-prestrained specimens were performed. Inflections and branches at ferrite-martensite boundaries were observed in the non-prestrained specimens. On the other hand, less inflections and branches were found in the prestrained specimens. The experimental results showed that the transformation induced microscopic residual stress has influence on the fatigue crack propagation behaviour. To estimate the microscopic residual stress distribution, a numerical simulation of microscopic residual stress induced by martensitic transformation was performed. The simulation showed that compressive residual stress was generated in martensite layer, and the result agree with the experimental result that inflections and branches were observed at ferrite-martensite boundaries. In addition, the change in the microscopic residual stress distribution by prestraining was also calculated to show the compressive residual stress changed to tensile by prestraining. This also agree with the experimental result of the observation of fatigue crack path.

scholarly journals Effect of Compressive Residual Stress on Fatigue Crack Propagation

2015 ◽  
Vol 130 ◽  
pp. 1057-1065 ◽  
Author(s):  
Y. Morikage ◽  
S. Igi ◽  
K. Oi ◽  
Y. Jo ◽  
K. Murakami ◽  
...  
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Compressive Residual Stress

Critical Assessment of a Local Strain-Based Fatigue Crack Growth Model Using Experimental Data Available for the P355NL1 Steel

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Abílio M. P. De Jesus ◽  
José A. F. O. Correia
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Crack Tip ◽  
Element Analysis ◽  
R Ratio ◽  
Crack Growth Model

Fatigue crack growth models based on elastic–plastic stress–strain histories at the crack tip region and strain-life damage models have been proposed in the literature. The UniGrow model fits this particular class of fatigue crack propagation models. The residual stresses developed at the crack tip play a central role in these models, since they are used to assess the actual crack driving force, taking into account mean stress and loading sequence effects. The performance of the UniGrow model is assessed based on available experimental constant amplitude crack propagation data, derived for the P355NL1 steel. Key issues in fatigue crack growth prediction using the UniGrow model are discussed; in particular, the assessment of the elementary material block size, the elastoplastic analysis used to estimate the residual stress distribution ahead of the crack tip and the adopted strain-life damage relation. The use of finite element analysis to estimate the residual stress field, in lieu of a simplified analysis based on the analytical multi-axial Neuber's approach, and the use of the Morrow's strain-life equation, resulted in fatigue crack propagation rates consistent with the experimental results available for P355NL1 steel, for several stress R-ratios. The use of the Smith–Watson–Topper (SWT) (=σmax.Δɛ/2) damage parameter, which has often been proposed in the literature, over predicts the stress R-ratio effects.

Assessment of Fatigue Crack Growth Data Available for the P355NL1 Steel Using a Local Strain-Based Approach

2011 ◽  
Author(s):  
Abi´lio M. P. de Jesus ◽  
Jose´ A. F. O. Correia
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Crack Tip ◽  
Local Strain ◽  
Element Analysis ◽  
R Ratio

Fatigue crack growth models based on elastic–plastic stress–strain histories at the crack tip region and strain-life damage models have been proposed in literature. The UniGrow model fits this particular class of fatigue crack propagation models. The residual stresses developed at the crack tip play a central role in these models, since they are used to assess the actual crack driving force, taking into account mean stress and loading sequence effects. The performance of the UniGrow model is assessed based on available experimental constant amplitude crack propagation data, derived for P355NL1 steel. Key issues in fatigue crack growth prediction using the UniGrow model are discussed; in particular, the assessment of the elementary material block size, the elastoplastic analysis used to estimate the residual stress distribution ahead of the crack tip and the adopted strain-life relation. The use of finite element analysis to estimate the residual stress field, in lieu of a simplified analysis based on the analytical multiaxial Neuber approach, and the use of the Morrow strain-life equation, resulted in fatigue crack propagation rates consistent with the experimental results available for P355NL1 steel, for several stress R-ratios. The use of the SWT parameter for the local strain-life relation, which has often been proposed in the literature, leads to overprediction of stress R-ratio effects.

scholarly journals Residual stress effects on fatigue crack propagation in Butt–Welded joints for 304 stainless steel sheets

2021 ◽  
Vol 8 ◽  
pp. 19
Author(s):  
Eman El Shrief ◽  
Abla El-Megharbel ◽  
Aly El Domiaty ◽  
Hassan Abd El-Hafez
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Welded Joints ◽  
304 Stainless Steel ◽  
Stress Effects ◽  
Steel Sheets ◽  
Simulation Results

Welded joints are sensitive to fatigue failure due to cyclic loading, as well as fatigue crack propagation influenced by the distribution of welding residual stress. In this study, the fatigue crack propagation rates in butt-welded joints for 304 stainless steel sheets were evaluated in the presence of welding residual stresses. The analysis consisted of two separate models: first, a 3D-finite element (FE) model was used to predict the residual stresses due to welding; second, a numerical study was undertaken to predict fatigue crack propagation in the presence and absence of residual stress using the extended finite element method (XFEM). The crack growth model (NASGRO) and available experimental data were applied to verify the simulation results. The XFEM without residual stress effects shows good agreement with the experimental data and the NASGRO model. However, in the presence of residual stress, the simulation results show less agreement with the NASGRO model. The level and the nature of residual stress have significant effects on crack growth. A faster crack propagation rate is recognized due to the effect of tensile residual stress at the crack tip, while a higher resistance to crack growth is developed due to a compressive residual stress field.

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