J Estimation Method for a Semi-Elliptical Surface Flaw in a Cylinder

1995 ◽  
Vol 117 (1) ◽  
pp. 66-70 ◽  
Author(s):  
K. K. Yoon ◽  
D. E. Killian
Keyword(s):  
Crack Depth ◽  
Estimation Method ◽  
Pressure Vessels ◽  
Constitutive Law ◽  
Cylindrical Structures ◽  
Elastic Plastic ◽  
Surface Flaws ◽  
Deformation Plasticity ◽  
Material Constitutive Law ◽  
J Estimation

With the emergence of readily available simple J solutions for various types of structures through J estimation techniques, J-integral-based elastic-plastic fracture mechanics has become a common tool for analyzing ductile materials. This paper presents elastic-plastic solutions for semi-elliptical surface flaws of four different crack depths. Solutions are developed from a series of finite element analyses using the ABAQUS computer program with a deformation plasticity material constitutive law. Although the solutions are directly applicable to a single set of Ramberg-Osgood material parameters, they may be extended to include various amounts of strain hardening by a ratioing technique utilizing calibration functions from the EPRI handbook for continuous flaws. This paper addresses cylindrical structures loaded by internal pressure, and excludes any consideration of thermal loadings. Elasticplastic J solutions, determined for pressures up to 5000 psi (12700 Pa), or twice the design pressure, depart from plastic-zone-corrected linear elastic predictions at approximately 3000 psi (7620 Pa) pressure. The h1 plastic calibration functions derived in this paper are limited to the point of greatest crack depth in 6:1 aspect ratio semi-elliptical inside surface flaws in cylindrical pressure vessels.

Validation of the Deformation Plasticity Failure Assessment Diagram (DPFAD) Approach—The Case of an Axial Flaw in a Pressurized Cylinder

1990 ◽  
Vol 112 (3) ◽  
pp. 213-217 ◽  
Author(s):  
J. M. Bloom
Keyword(s):  
Crack Depth ◽  
Pressure Vessels ◽  
Inside Surface ◽  
Failure Assessment Diagram ◽  
Steel Technology ◽  
Failure Assessment ◽  
Deformation Plasticity ◽  
Structural Tests ◽  
Structural Configurations ◽  
Pressurized Cylinder

The validation of the deformation plasticity failure assessment diagram (DPFAD) approach for application to the prediction of failure pressures for pipes or pressure vessels with axial flaws is addressed in this paper. The DPFAD approach has been extensively documented with regard to its validity in open literature for various configurations of test specimens. For actual structural configurations, however, no such comparisons appear in open literature. In particular, the model of a part-through wall axial flaw in a pressurized cylinder has not been validated through comparisons with actual structural tests results. Two sources of test data from structural tests of axially flawed pressurized cylinders were evaluated. • Heavy-Section Steel Technology (HSST) intermediate test vessels. • Eiber/Battelle Columbus Laboratories (BCL) axially cracked pipes. The DPFAD axial flaw model was developed using finite-element results to generate calibration constants as functions of crack depth to wall thickness and crack depth to crack length for an axially oriented semi-elliptical flaw on the inside surface of a pressurized cylinder. The calibration constants were then used to generate failure assessment curves that can be used to assess or predict failure of pipes or vessels with axial flaws under pressure loading. A key assumption in the analysis was the use of the failure assessment curve for the inside surface flaw in the prediction of outside-surface-flawed cylinder failures. Based on the excellent results from the comparisons with predicted failures to actual vessel and pipe failures, this assumption was found to be reasonable. Furthermore, based on predicted test results of the HSST vessel tests and the Eiber/BCL pipe tests, it was concluded that the DPFAD semi-elliptical axial flaw model can be used reliably in assessing part-through flaws in pressurized vessels and pipes.

Elastic-Plastic Fracture Mechanics Method for Poor Penetration Crack in Welded Piping Branch Junction

2008 ◽  
Author(s):  
Yong-Qiang Bai ◽  
Tong Wang ◽  
Lianghai Lv ◽  
Liang Sun ◽  
Jian Shuai
Keyword(s):  
Fracture Mechanics ◽  
Crack Front ◽  
Crack Depth ◽  
Influence Functions ◽  
Stress Strain ◽  
Elastic Plastic ◽  
Inner Radius ◽  
Plastic Influence Functions ◽  
Remote Stress ◽  
J Estimation

This paper provides two types of engineering J estimation equations for welded piping branch junctions with poor penetration crack under internal pressure. The first type is the so-called GE/EPRI type J estimation equation based on Ramberg-Osgood (R-O) materials. Based on detailed 3-D FE results using deformation plasticity, plastic influence functions for fully plastic J components are tabulated for practical ranges of the inner radius of brace to the inner radius of chord ratio, the thickness of brace to the thickness of chord, the thickness of chord to the inner radius of chord ratio, the crack depth to the thickness of chord ratio, the strain hardening index for the R-O material, and the location along the poor penetration crack front. Based on tabulated plastic influence functions, the GE/EPRI-type J estimation equation along the crack front is proposed. For more general application, the effective remote stress method based on GE/EPRI-type solutions is provided. This method provides a simpler equation for J, which could be used for any stress-strain relationship material, including Ramborg-Osgood (R-O) material and non-R-O materials under monotonic increasing loading. The proposed effective remote stress based J estimation equation is compared with elastic-plastic 3-D FE results using actual stress–strain data for a Type 304 strainless steel. Good agreement between the FE results and the proposed reference stress based J estimation provides confidence in the use of the proposed method for elastic-plastic fracture mechanics of pressurized welded piping branch junction.

Elastic-Plastic Analysis of an Elbow With Axial Part-Through Internal Crack at Crown Under In-Plane Bending

2008 ◽  
Author(s):  
K. M. Prabhakaran ◽  
S. R. Bhate ◽  
V. Bhasin ◽  
A. K. Ghosh
Keyword(s):  
Finite Element ◽  
Crack Depth ◽  
Bending Moment ◽  
Internal Crack ◽  
J Integral ◽  
Finite Element Analyses ◽  
Integrity Assessment ◽  
Elastic Plastic ◽  
Axial Part ◽  
Plane Bending

Piping elbows under bending moment are vulnerable to cracking at crown. The structural integrity assessment requires evaluation of J-integral. The J-integral values for elbows with axial part-through internal crack at crown under in-plane bending moment are limited in open literature. This paper presents the J-integral results of a thick and thin, 90-degree, long radius elbow subjected to in-plane opening bending moment based on number of finite element analyses covering different crack configurations. The non-linear elastic-plastic finite element analyses were performed using WARP3D software. Both geometrical and material nonlinearity were considered in the study. The geometry considered were for Rm/t = 5, and 12 with ratio of crack depth to wall thickness, a/t = 0.15, 0.25, 0.5 and 0.75 and ratio of crack length to crack depth, 2c/a = 6, 8, 10 and 12.

Elastic-Plastic J-Estimation for Circumferentially Cracked Pipes Under Combined Mechanical and Thermal Loadings

2013 ◽  
Author(s):  
Chang-Young Oh ◽  
Yun-Jae Kim ◽  
R. A. Ainsworth
Keyword(s):  
Finite Element ◽  
Thermal Gradient ◽  
Order Effects ◽  
Assessment Procedure ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Defect Assessment ◽  
Failure Assessment ◽  
Two Parameters ◽  
J Estimation

This paper addresses load order effects on elastic-plastic J estimation under combined mechanical and thermal loads for circumferentially cracked pipes. The load order effects, for various thermal gradient types and mechanical loading, are evaluated for a range of magnitudes of the loadings, crack sizes and material hardening. Variations of elastic-plastic J obtained by finite element analysis are compared with existing and proposed methods for use with the R6 defect assessment procedure. The load order effects are presented on the R6 failure assessment diagram (FAD) by calculating the two parameters Kr and Lr from the finite element results. It is shown that there are significant load order effects at large secondary stress cases but these are successfully treated by simplified methods proposed for use with R6.

Critical Review of Strain Measures for Characterisation of Fatigue Damage in ASME Section III Fatigue Assessments

2019 ◽  
Author(s):  
Daniel Leary ◽  
Chris Currie ◽  
Keith Wright
Keyword(s):  
Strain Range ◽  
Pressure Vessels ◽  
Total Strain ◽  
Multiaxial Loading ◽  
Critical Plane ◽  
Total Strain Range ◽  
Elastic Plastic ◽  
Fatigue Evaluation ◽  
Von Mises ◽  
Strain Measures

Abstract Rules for fatigue evaluation of nuclear pressure vessels and piping components are provided in Subsection NB of Section III of the ASME code. The code prescribed fatigue procedure requires the comparison of an alternating stress amplitude with fatigue allowables (design fatigue curves), usually derived through uniaxial specimen testing. For elastic assessments of multiaxial loading, typical from thermal shocks, a Tresca stress is used to characterise the stress field into a single effective stress measure for comparison with ASME fatigue allowables. For nonlinear elastic-plastic assessments, Appendix XIII-3440(b) of Section III specifies that “the numerically maximum principal total strain range” (interpreted as Maximum Total Principal (MTP) strain range) should be used for comparison with fatigue allowables. Two alternative methods for the characterisation of multiaxial strain fields are presented in the ASME code. Section VIII Division 2 provides alternative rules for the construction of pressure vessels, with Part 5 specifying the use of a Von Mises based Effective Strain Range (ESR) for elastic-plastic analysis. Section III Division 5 Subsection NBB provides rules for the assessment of components at elevated temperatures, also specifying the use of a Von Mises based Equivalent Total Strain Range (ETSR) measure. The two alternative strain measures are differentiated by their treatment of the elastic strain contribution. In the ESR method an equivalent elastic strain is calculated and summated with the plastic strain component. In the ETSR method the total strain (elastic plus plastic) is used thus evaluating the elastic and plastic contributions simultaneously. More complex critical plane approaches have also been proposed in recent years to better characterise multiaxial loading conditions. This paper presents a comparison of the various ASME specified strain measures and simplified critical plane approaches for fatigue evaluation of complex multiaxial loading. In support of this comparison, predictions of initiation lives to 0.254 mm defect in the stepped pipe specimen reported in PVP2004-2748 are provided to quantify the additional conservatism contained in elastic-plastic fatigue assessments of nuclear components. Predictions use the methodology presented in the companion paper PVP2019-93847 for the generation of short crack fatigue curves and the associated modification to environmental enhancement factors. It is concluded that use of the ASME specified strain measures, in conjunction with lower bound stress-strain data, conservatively underestimate the initiation life to a 0.254 mm defect by a factor of four for the example considered. However, use of more complex critical plane strain measures were observed to provide significant improvement in prediction accuracy of elastic-plastic fatigue evaluations.

A modified parallel-sided shear zone model for determining material constitutive law

2016 ◽  
Vol 91 (1-4) ◽  
pp. 589-603 ◽  
Author(s):  
Jinhua Zhou ◽  
Junxue Ren ◽  
Yazhou Feng ◽  
Weijun Tian ◽  
Kaining Shi
Keyword(s):  
Shear Zone ◽  
Constitutive Law ◽  
Zone Model ◽  
Material Constitutive Law

Analysis of Interaction Behavior of Surface Flaws in Pressure Vessels

1986 ◽  
Vol 108 (1) ◽  
pp. 24-32 ◽  
Author(s):  
P. E. O’Donoghue ◽  
T. Nishioka ◽  
S. N. Atluri
Keyword(s):  
Finite Element ◽  
Stress Intensity ◽  
Pressure Vessels ◽  
Influence Functions ◽  
Surface Cracks ◽  
Intensity Factors ◽  
Alternating Method ◽  
Circumferential Crack ◽  
Magnification Factors ◽  
Surface Flaws

The evaluation of stress intensity factors for surface flaw problems and, in particular, semi-elliptical surface cracks in cylindrical pressure vessels has been well developed using the finite element alternating method. Some of the examples presented here include the interaction effects due to multiple internal longitudinal surface cracks in cylinders as recommended for analysis in the ASME Boiler and Pressure Vessel Code (Section XI). For each crack geometry, several loading cases are considered including internal pressure and polynomial pressure loadings from constant to fourth order. By the method of superposition, the magnification factors for internally pressurized cylinders are rederived using the polynomial influence functions. These influence functions give useful information for design purposes such as in the analysis of a thermally shocked cylinder. The problem of a single circumferential crack in a cylinder is also investigated using the finite element alternating method, and a number of results for such problems are also presented here.

An Expression of Elastic-Plastic Constitutive Law Incorporating Vertex Formation and Kinematic Hardening

1991 ◽  
Vol 58 (3) ◽  
pp. 617-622 ◽  
Author(s):  
Moriaki Goya ◽  
Koichi Ito
Keyword(s):  
Kinematic Hardening ◽  
Sufficient Conditions ◽  
Constitutive Law ◽  
Elastic Plastic ◽  
Hardening Rule ◽  
Direction Angle ◽  
Plastic Materials ◽  
Path Direction ◽  
Elastic Plastic Materials ◽  
Linear Loading

A phenomenological corner theory was proposed for elastic-plastic materials by the authors in the previous paper (Goya and Ito, 1980). The theory was developed by introducing two transition parameters, μ (α) and β (α), which, respectively, denote the normalized magnitude and direction angle of plastic strain increments, and both monotonously vary with the direction angle of stress increments. The purpose of this report is to incorporate the Bauschinger effect into the above theory. This is achieved by the introduction of Ziegler’s kinematic hardening rule. To demonstrate the validity and applicability of a newly developed theory, we analyze the bilinear strain-path problem using the developed equation, in which, after some linear loading, the path is abruptly changed to various directions. In the calculation, specific functions, such as μ (α) = Cos (.5πα/αmax) and β (α) = (αmax- .5π) α/αmax, are chosen for the transition parameters. As has been demonstrated by numerous experimental research on this problem, the results in this report also show a distinctive decrease of the effective stress just after the change of path direction. Discussions are also made on the uniqueness of the inversion of the constitutive equation, and sufficient conditions for such uniqueness are revealed in terms of μ(α), β(α) and some work-hardening coefficients.

Sign in / Sign up

Export Citation Format

Share Document