scholarly journals A Study on the Forming Process of the Compressive Residual Stress Field around the Crack Tip

2013 ◽  
Vol 79 (803) ◽  
pp. 925-933
Author(s):  
Yuzuru ITO ◽  
Masahiro SAITO
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Compressive Residual Stress ◽  
Crack Tip ◽  
Residual Stress Field ◽  
Forming Process

Crack Tip Stress Analysis of the Steam Generator Dissimilar Steel Welded Joint under Residual Stress Field

2019 ◽  
Vol 795 ◽  
pp. 451-457
Author(s):  
Bao Yin Zhu ◽  
Xian Xi Xia ◽  
He Zheng ◽  
Guo Dong Zhang
Keyword(s):  
Residual Stress ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Stress Field ◽  
Numerical Method ◽  
Steam Generator ◽  
Welded Joint ◽  
Crack Tip ◽  
Residual Stress Field

An typical mode of a structural integrity failure in dissimilar steel welded joints. This paper aims at studying crack tip stress of a steam generator dissimilar welded joint under residual stress field with the method of interaction integral and XFEM. Firstly, the corresponding weak form is obtained where the initial stress field is involved, which is the key step for the XFEM. Then, the interaction integral is applying to calculate the stress intensity factor. In addition, two simple benchmark problems are simulated in order to verify the precision of this numerical method. Finally, this numerical method is applying to calculate the crack tip SIF of the addressed problem. This study finds that the stress intensity factor increases firstly then decreases with the deepening of the crack. The main preponderance of this method concerns avoiding mesh update by take advantage of XFEM when simulating crack propagation, which could avoid double counting. In addition, our obtained results will contribute to the safe assessment of the nuclear power plant steam generator.

Effect of Residual Stress Field in Front of the Slant Precrack Tip on Bent Fatigue Crack Propagation

2007 ◽  
Vol 353-358 ◽  
pp. 1207-1210 ◽  
Author(s):  
Kenichi Shimizu ◽  
Tashiyuki Torii ◽  
J. Nyuya ◽  
Y. Ma
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Stress Field ◽  
Mixed Mode ◽  
Compressive Residual Stress ◽  
Fatigue Cracks ◽  
Crack Opening ◽  
Residual Stress Field ◽  
Method Analysis ◽  
Crack Sliding Displacement

Fatigue crack bending and propagation behaviors were studied under mixed-mode conditions using annealed and fatigue slant precracks. The bent fatigue crack initiated from the fatigue slant precrack propagated under mixed-mode conditions with mode II stress intensity factor evaluated from the crack sliding displacement measured along the crack. On the other hand, bent fatigue cracks propagated under the mode I condition for an annealed slant precrack specimen. The forces which suppress the crack opening/sliding were calculated along the slant precrack and the bent crack by FEM (Finite Element Method) analysis. As a result, the crack opening suppress forces were generated by the compressive residual stress around the fatigue slant precrack, while the forces which promote the crack sliding were caused by the residual stress field in front of the fatigue slant precrack.

scholarly journals Direct Observation of Elastic and Plastic Strain Fields During Ductile Tearing of a Ferritic Steel

2016 ◽  
Author(s):  
Harry E. Coules ◽  
Graeme C. M. Horne ◽  
Matthew J. Peel ◽  
Sam J. Oliver ◽  
Derreck G. A. Van Gelderen ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Plastic Strain ◽  
Crack Tip ◽  
Image Correlation ◽  
Pressure Vessel Steel ◽  
X Ray Diffraction ◽  
Residual Stress Field ◽  
Ductile Tearing ◽  
X Ray

Residual and thermal stresses have a considerable effect on the process of brittle fracture. In addition to this, the effect of these stresses on elastic-plastic fracture is known to be significant. This is accounted for in structural integrity assessment methodologies such as R6 Rev 4 and BS 7910:2013 by introducing factors representing the interaction between primary and secondary stresses (those that do and do not contribute towards plastic collapse, respectively). The initiation of ductile tearing in a ferritic pressure vessel steel was studied experimentally. Energy-dispersive X-ray diffraction was used to determine lattice strains in the vicinity of a crack tip in modified compact tension specimens at incremental loading steps until the initiation of ductile tearing. The X-ray diffraction measurements allowed the stress field to be evaluated with a high spatial resolution. At the same time, the pattern of total strain at the surface of the specimen was observed using digital image correlation. Prior to the experiment, two samples were subjected to localised out-of-plane compression ahead of the crack tip to introduce a residual stress field and hence significant crack loading in the absence of external load. Stress and strain field data for cracked specimens, with and without a pre-existing residual stress field, indicated significant differences in the development of plastic strain up to the point of tearing initiation. It is shown that this can only be explained when both residual stress and prior material hardening are taken into account.

Numerical Simulation of Residual Stress during Stamping-Forging Forming of 2024 Aluminum Alloy Sheet Metal

2012 ◽  
Vol 602-604 ◽  
pp. 1903-1909
Author(s):  
Da Li ◽  
Lei Deng ◽  
Xin Yun Wang ◽  
Jun Song Jin ◽  
Ju Chen Xia
Keyword(s):  
Residual Stress ◽  
Aluminum Alloy ◽  
Stress Field ◽  
Dimensional Accuracy ◽  
Alloy Sheet ◽  
Residual Stress Field ◽  
Forming Process ◽  
2024 Aluminum Alloy ◽  
Dimensional Precision ◽  
Finite Element Software

The unreasonable residual stress field in sheet part has an adverse effect on the dimensional accuracy and performance. A forming method combined stamping and forging was proposed to reduce the residual stress of the sheet part. The residual stress field in 2024 aluminum alloy V-shaped piece after bending and forging was analyzed by the finite element software Abaqus. The results showed that the stamping-forging forming process can significantly reduce the residual stress in round corner of V-shaped piece, and simultaneously decrease springback and improve the dimensional precision of sheet part.

scholarly journals Characterisation of Residual Stress due to Fillet Rolling on Bolts Made of a Nickel Base Superalloy

2014 ◽  
Vol 996 ◽  
pp. 670-675 ◽  
Author(s):  
Wei Li ◽  
Shu Yan Zhang ◽  
Saurabh Kabra ◽  
Anton Tremsin ◽  
Brian Abbey ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Compressive Residual Stress ◽  
Hole Drilling ◽  
Nickel Base Superalloy ◽  
Residual Stress Field ◽  
Neutron Transmission ◽  
Incremental Hole Drilling ◽  
Nickel Base ◽  
Base Superalloy

This paper investigates residual stress due to fillet rolling on bolts made of ATI 718Plus® superalloy. Incremental hole drilling, neutron diffraction and neutron transmission have been used to assess residual stress near the bolt head fillet. A compressive residual stress field was identified in the first 0.5 mm from the surface. Post fillet rolling solution anneal can relieve the residual stress at the fillet.

scholarly journals Small–Scale Experimental Investigation of Fatigue Performance Improvement of Ship Hatch Corner with Shot Peening Treatments by Considering Residual Stress Relaxation

2021 ◽  
Vol 9 (4) ◽  
pp. 419
Author(s):  
Jin Gan ◽  
Zi’ang Gao ◽  
Yiwen Wang ◽  
Zhou Wang ◽  
Weiguo Wu
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Fatigue Life ◽  
Stress Relaxation ◽  
Stress Field ◽  
Shot Peening ◽  
Compressive Residual Stress ◽  
Fatigue Performance ◽  
Residual Stress Field ◽  
Residual Stress Relaxation

Ship hatch corner is a common structure in a ship and its fatigue problem has always been one of the focuses in ship engineering due to the long–term high–stress concentration state during the ship’s life. For investigating the fatigue life improvement of the ship hatch corner under different shot peening (SP) treatments, a series of fatigue tests, residual stress and surface topography measurements were conducted for SP specimens. Furthermore, the distributions of the surface residual stress are measured with varying numbers of cyclic loads, investigating the residual stress relaxation during cyclic loading. The results show that no matter which SP process parameters are used, the fatigue lives of the shot–peened ship hatch corner specimens are longer than those at unpeened specimens. The relaxation rate of the residual stress mainly depends on the maximum compressive residual stress (σRSmax) and the depth of the maximum compressive residual stress (δmax). The larger the values of σRSmax and δmax, the slower the relaxation rates of the residual stress field. The results imply that the effect of residual stress field and surface roughness should be considered comprehensively to improve the fatigue life of the ship hatch corner with SP treatment. The increase in peening intensity (PI) within a certain range can increase the depth of the compressive residual stress field (CRSF), so the fatigue performance of the ship hatch corner is improved. Once the PI exceeds a certain value, the surface damage caused by the increase in surface roughness will not be offset by the CRSF and the fatigue life cannot be improved optimally. This research provides an approach of fatigue performance enhancement for ship hatch corners in engineering application.

scholarly journals Influence of Residual Stress on Fatigue Design of AISI 304 Stainless Steel

2011 ◽  
Vol 7 (2) ◽  
pp. 44 ◽  
Author(s):  
L. Singh ◽  
R.A. Khan ◽  
M.L. Aggarwal
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Stainless Steel ◽  
Fatigue Strength ◽  
Stress Field ◽  
Shot Peening ◽  
Compressive Residual Stress ◽  
Residual Stress Field ◽  
Aisi 304 ◽  
Fatigue Design

 Austenitic stainless steel cannot be hardened by any form of heat treatment, in fact, quenching from 10000C merely softens them. They are usually cold worked to increase the hardness. Shot peening is a cold working process that changes micro-structure as well as residual stress in the surface layer. In the present work, the compressive residual stress and fatigue strength of AISI 304 austenitic stainless steel have been evaluated at various shot peening conditions. The improvement in various mechanical properties such as hardness, damping factors and fatigue strength was noticed. Compressive residual stress induced by shot peening varies with cyclic loading due to relaxation of compressive residual stress field. The consideration of relaxed compressive residual stress field instead of original compressive residual stress field provides reliable fatigue design of components. In this paper, the exact reductions in weight and control of mechanical properties due to shot peening process are discussed. 

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