Computational and Experimental Studies of High Temperature Crack Initiation in the Presence of Residual Stress

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Noel P. O’Dowd ◽  
Kamran M. Nikbin ◽  
Robert C. Wimpory ◽  
Farid R. Biglari ◽  
Manus P. O’Donnell
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Notch Root ◽  
Experimental Studies ◽  
Compressive Load ◽  
Compact Tension ◽  
Compact Tension Specimen ◽  
Element Analysis ◽  
Weld Material ◽  
Temperature Crack

Residual stresses have been introduced into a notched compact tension specimen of a 347 weld material by mechanical compression. The required level of compressive load has previously been determined from finite-element studies. The residual stress in the vicinity of the notch root has been measured using neutron diffraction and the results compared with those obtained from finite-element analysis. The effect of stress redistribution due to creep has been examined and it is found that a significant reduction in stress is measured after 1000h at 650°C. The implications of these results with regard to the development of damage in the specimen due to creep relaxation are examined.

Computational and Experimental Studies of High Temperature Crack Growth in the Presence of Residual Stress

2006 ◽  
Author(s):  
Noel P. O’Dowd ◽  
Kamran M. Nikbin ◽  
Robert C. Wimpory ◽  
Farid R. Biglari ◽  
Manus P. O’Donnell
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Notch Root ◽  
Experimental Studies ◽  
Compressive Load ◽  
Compact Tension ◽  
Compact Tension Specimen ◽  
Element Analysis ◽  
Weld Material ◽  
Temperature Crack

Residual stresses have been introduced into a notched compact tension specimen of a 347 weld material by mechanical compression. The required level of compressive load has previously been determined from finite element studies. The residual stresses in the vicinity of the notch root have been measured using neutron diffraction and the results compared with those obtained from finite element analysis. The effect of stress redistribution due to creep has been examined and it is found that significant reduction in stress is measured after 1000 hours at 650 °C. The implications of these results with regard to the development of damage in the specimen due to creep relaxation are examined.

Creep Crack Initiation in a Weld Steel: Effects of Residual Stress

2005 ◽  
Author(s):  
Noel P. O’Dowd ◽  
Kamran M. Nikbin ◽  
Farid R. Biglari
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Crack Initiation ◽  
Equivalent Stress ◽  
Stress Triaxiality ◽  
Compact Tension ◽  
Residual Stress Field ◽  
Element Analysis ◽  
Creep Ductility ◽  
Uniaxial Test

In this paper, the effect of residual stress on the initiation of a crack at high temperature in a Type 347 austenitic steel weld is examined using the finite element method. Both two and three dimensional analyses have been carried out. Residual stresses have been introduced by prior mechanical deformation, using a previously developed notched compact tension specimen. It has been found that for the 347 weld material, peak stresses in the vicinity of the notch are approximately three times the yield strength at room temperature and the level of stress triaxiality (ratio between hydrostatic and equivalent stress) is approximately 1 (considerably higher than that for a uniaxial test). The finite element analysis includes the effects of stress redistribution and damage accumulation under creep conditions. For the case examined the analysis predicts that crack initiation will occur under conditions of stress relaxation if the uniaxial creep ductility of the material is less than 2.5%. Furthermore, the predicted life of the component under constant load (creep conditions) is significantly reduced due to the presence of the residual stress field.

scholarly journals Numerical Investigation on Ultimate Compressive Strength of Welded Stiffened Plates Built by Steel Grades of S235–S390

2019 ◽  
Vol 9 (10) ◽  
pp. 2088 ◽  
Author(s):  
Chenfeng Li ◽  
Sen Dong ◽  
Tingce Wang ◽  
Weijun Xu ◽  
Xueqian Zhou
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Yield Strength ◽  
Ultimate Strength ◽  
Simulation Analysis ◽  
Compressive Load ◽  
Welding Residual Stress ◽  
Stiffened Plates ◽  
Element Analysis ◽  
Collapse Behavior

The welded stiffened plate is widely used in naval architecture and offshore engineering as a basic structural member. The aim of this study is to investigate the effect of welding residual stress and steel grade on the ultimate strength of stiffened plates under uniaxial compressive load by non-linear finite element analysis. Nineteen stiffened plates built with three types of stiffeners with various column slenderness ratios provided in the ISSC’2000 VI.2 benchmark calculations are employed in the present study. The commercial finite element code ABAQUS is applied to simulate the collapse behavior of the stiffened plates and verified against the benchmark calculations. Fabrication-related imperfections, such as initial deflections and residual stresses, are accounted for in the simulations. The ultimate strength of stiffened plates built in common shipbuilding steels, namely S235, S315, S355 and S390, are investigated by varying the yield strength of materials in the simulation. Analysis of the numerical results shows that the welding residual stress reduces the ultimate strength of stiffened plates, and increase in yield strength of the material can effectively improve the ultimate strength of common ship stiffened plates; and quantitative analyses of their influences have also been performed.

Crack Extensions in Compact Tension Specimens of Hydrided Irradiated Zr-2.5Nb Materials Using Cohesive Zone Model

2017 ◽  
Author(s):  
Shengjia Wu ◽  
Shin-Jang Sung ◽  
Jwo Pan ◽  
Poh-Sang Lam ◽  
Douglas A. Scarth
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cohesive Zone ◽  
Crack Extension ◽  
Cohesive Zone Model ◽  
Compact Tension ◽  
Compact Tension Specimen ◽  
Zone Model ◽  
Element Analysis ◽  
The Finite Element Analysis

The crack extension in a compact tension specimen of hydrided irradiated Zr-2.5Nb material is investigated by a two-dimensional plane stress finite element analysis. The stress-strain relation of the Zr-2.5Nb material for the finite element analysis is obtained from fitting the experimental tensile stress-strain curve of the irradiated Zr-2.5Nb material without hydrides by a three-dimensional finite element analysis. The calibration of the cohesive zone model with a trapezoidal traction-separation law is based on fitting the load-displacement-crack extension experimental data of a compact tension specimen of hydrided irradiated Zr-2.5Nb material. The general trends of the load-displacement, crack extension-displacement, and load-crack extension curves obtained from the finite element analysis based on the calibrated cohesive zone model are in agreement with the experimental data.

An elastic-plastic finite element analysis of a compact tension specimen

1983 ◽  
Vol 18 (1) ◽  
pp. 69-75 ◽  
Author(s):  
A P Kfouri
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Crack Tip ◽  
Compact Tension ◽  
Compact Tension Specimen ◽  
Tension Specimen ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Release Technique ◽  
Crack Tip Opening

Results from an elastic-plastic finite element analysis of a compact tension specimen (CTS) are presented and provide information on the growth of crack tip plastic zones, crack tip opening displacements, stresses and strains in the region of the crack tip, and Rice's J integral. The elastic-plastic crack separation energy rate GΔ is also evaluated when the crack extends at various loads by applying a crack tip node release technique.

Formulation of symmetry boundary modeling in non-ordinary state-based peridynamics and coupling with finite element analysis

2017 ◽  
Vol 23 (8) ◽  
pp. 1156-1176 ◽  
Author(s):  
Amin Yaghoobi ◽  
Mi G Chorzepa
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Solid Mechanics ◽  
Computational Cost ◽  
Local Symmetry ◽  
Compact Tension ◽  
Compact Tension Specimen ◽  
Coupling Method ◽  
Coupled Models ◽  
Element Analysis

Peridynamics is an effective method in computational solid mechanics for dealing with discontinuities. However, its computational cost limits its applications, especially when used in the most general form, non-ordinary state-based peridynamics. This paper considers two approaches which decrease the computational cost. The first approach accounts for symmetry boundary conditions in a peridynamic body. In nonlocal peridynamics, boundary conditions are applied to an area. Therefore, when modeling the symmetry boundary condition, assuming fixed particles around the symmetry axis yields incorrect results. The present formulation introduces constraints which allow modeling of local symmetry conditions. Second, the finite-element–peridynamic coupling method is adopted for non-ordinary state-based peridynamics. The coupling method enables the use of peridynamics around discontinuities like cracks, and the faster finite element for the surrounding body. These two methods effectively reduce the solution time with an acceptable accuracy. The validity of these approaches is studied through various examples. Also, ductile crack growth in a compact tension specimen is studied, applying the presented methods. Good agreement is found when comparing experimental results with corresponding numerical results obtained using either fully peridynamic or coupled models.

Influence of Laser Shock Processing on the Weld Line and Finite Element Simulation

2011 ◽  
Vol 464 ◽  
pp. 627-631
Author(s):  
Jie Zhang ◽  
Ai Hua Sun ◽  
Le Zhu ◽  
Xiang Gu
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Welding Residual Stress ◽  
Laser Shock ◽  
Analysis Software ◽  
Laser Shock Processing ◽  
Element Analysis ◽  
Welding Line ◽  
Simulation Results ◽  
Shock Processing

Welding residual stress is one of the main factors that affect the strength and life of components. In order to explore the effect on residual stress of welding line by laser shock processing, finite element analysis software ANSYS is used to simulate the welding process, to calculate the distribution of welding residual stress field. On this basis, then AYSYS/LS-DYNA is used to simulate the laser shock processing on welding line. Simulation results show that residual stress distributions of weld region, heat-affected region and matrix by laser shock processing are clearly improved, and the tensile stress of weld region effectively reduce or eliminate. The simulation results and experimental results are generally consistent, it offer reasons for parameter optimization of welding and laser shock processing by finite element analysis software.

Stress and Fatigue Life Modeling of Cannon Breech Closures Including Effects of Material Strength and Residual Stress

2000 ◽  
Vol 123 (1) ◽  
pp. 150-154
Author(s):  
John H. Underwood ◽  
Michael J. Glennon
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Fatigue Life ◽  
Yield Strength ◽  
Residual Stresses ◽  
Solid Mechanics ◽  
Element Model ◽  
Pressure Vessels ◽  
Material Strength ◽  
Element Analysis

Laboratory fatigue life results are summarized from several test series of high-strength steel cannon breech closure assemblies pressurized by rapid application of hydraulic oil. The tests were performed to determine safe fatigue lives of high-pressure components at the breech end of the cannon and breech assembly. Careful reanalysis of the fatigue life tests provides data for stress and fatigue life models for breech components, over the following ranges of key parameters: 380–745 MPa cyclic internal pressure; 100–160 mm bore diameter cannon pressure vessels; 1040–1170 MPa yield strength A723 steel; no residual stress, shot peen residual stress, overload residual stress. Modeling of applied and residual stresses at the location of the fatigue failure site is performed by elastic-plastic finite element analysis using ABAQUS and by solid mechanics analysis. Shot peen and overload residual stresses are modeled by superposing typical or calculated residual stress distributions on the applied stresses. Overload residual stresses are obtained directly from the finite element model of the breech, with the breech overload applied to the model in the same way as with actual components. Modeling of the fatigue life of the components is based on the fatigue intensity factor concept of Underwood and Parker, a fracture mechanics description of life that accounts for residual stresses, material yield strength and initial defect size. The fatigue life model describes six test conditions in a stress versus life plot with an R2 correlation of 0.94, and shows significantly lower correlation when known variations in yield strength, stress concentration factor, or residual stress are not included in the model input, thus demonstrating the model sensitivity to these variables.

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