Analysis of Recent Fatigue Data Using the Structural Stress Procedure in ASME Div 2 Rewrite

2006 ◽  
Vol 129 (3) ◽  
pp. 355-362 ◽  
Author(s):  
Pingsha Dong ◽  
Jeong K. Hong ◽  
Abílio M. P. De Jesus
Keyword(s):  
Test Data ◽  
Hot Spot ◽  
Comparative Assessment ◽  
Structural Stress ◽  
Hot Spot Stress ◽  
Classification Approach ◽  
Fatigue And Fracture ◽  
Fatigue Data ◽  
Fatigue Evaluation ◽  
Assessment Procedures

In support of the ASME Div 2 Rewrite, a master S-N curve approach has been developed using a mesh-insensitive structural stress procedure for fatigue evaluation of welded components. The effectiveness of the master S-N curve approach has been demonstrated in a number of earlier publications for many joint types and loading conditions for pipe and vessel components as well as plate joints. To further validate the structural stress method, a series of recent test data (small weld details and a full-scale vessel) published by De Jesus et al. (2004, Fatigue and Fracture of Engineering Materials and Structures, 27, pp. 799–810) were analyzed in this paper. A comparative assessment of various existing procedures and their effectiveness in correlating the fatigue test data by De Jesus is also presented. These assessment procedures include current ASME Sec. VIII Div 2, weld classification approach in PD 5500, and the surface extrapolation-based hot spot stress approach in recently approved European EN 13445 Standards.

Analysis of Recent Fatigue Data Using the Structural Stress Procedure in ASME Div. 2 Rewrite

2005 ◽  
Author(s):  
P. Dong ◽  
J. K. Hong ◽  
A. M. P. De Jesus
Keyword(s):  
Fatigue Test ◽  
Test Data ◽  
Hot Spot ◽  
Comparative Assessment ◽  
Structural Stress ◽  
Hot Spot Stress ◽  
Classification Approach ◽  
Fatigue Data ◽  
Fatigue Evaluation ◽  
Assessment Procedures

In support of the ASME Div 2 Rewrite, a master S-N curve approach has been developed using a mesh-insensitive structural stress procedure for fatigue evaluation of welded components. The effectiveness of the master S-N curve approach has been demonstrated in a number of earlier publications for many joint types and loading conditions for pipe and vessel components as well as plate joints. To further validate the structural stress method, a series of recent test data (small weld details and a full scale vessel) published by De Jesus et al (2004) were analyzed in this paper. A comparative assessment of various existing procedures and their effectiveness in correlating the fatigue test data by De Jesus et al (2004) is also presented. These assessment procedures include current ASME Sec. VIII Div 2, weld classification approach in PD 5500, and the surface extrapolation-based hot spot stress approach in recently approved European EN 13445 Standards.

Fatigue of Tubular Joints: Hot Spot Stress Method Revisited

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Pingsha Dong ◽  
Jeong K. Hong
Keyword(s):  
Hot Spot ◽  
Life Assessment ◽  
Structural Stress ◽  
T Joints ◽  
Hot Spot Stress ◽  
Tubular Joints ◽  
Fatigue Design ◽  
Fatigue Data ◽  
Section Viii ◽  
Remaining Life Assessment

A series of well-known tubular joints tested in UKSORP II have been re-evaluated using the mesh-insensitive structural stress method as a part of the on-going Battelle Structural Stress JIP efforts. In this report, the structural stress based analysis procedure is first presented for applications in tubular joints varying from simple T joints, double T Joints, YT joints with overlap, and K joints with various internal stiffening configurations. The structural stress based SCFs are then compared with those obtained using traditional surface extrapolation based hot spot stress methods. Their abilities in effectively correlating the fatigue data collected from these tubular joints are demonstrated. These tests are also compared with the T curve typically used for fatigue design of tubular joints as well as the structural stress based master S-N curve adopted by ASME Section VIII Div 2. Finally, some of the implications on fracture mechanics based remaining life assessment for tubular joints are discussed in light of the results obtained in this investigation.

Analysis of Hot Spot Stress and Alternative Structural Stress Methods

2003 ◽  
Author(s):  
P. Dong ◽  
J. K. Hong
Keyword(s):  
Hot Spot ◽  
Relative Effectiveness ◽  
Sufficient Conditions ◽  
Offshore Structures ◽  
Structural Stress ◽  
Plate Structures ◽  
Hot Spot Stress ◽  
Necessary And Sufficient ◽  
Assessment Procedures ◽  
Calculation Procedures

There is a growing need for robust finite element based fatigue assessment procedures for welded joints in offshore/marine structures. Although widely accepted in tubular structures, the applications of the conventional hot spot stress (HSS) procedures in plate structures have proven to be problematic in some joint types. There are a series of on-going international efforts that are intended to address some of the issues to improve the consistency of the HSS calculation procedures for plate structures. In this regard, alternative structural stress (SS) procedures that share some similarities to conventional HSS methods have been developed. The SS method has been shown to be effective in calculating structural stresses directly at failure locations such as at weld toes with minimum mesh-sensitivity. In this paper, detailed analysis and assessments of the conventional HSS and the alternative SS procedures are presented. Starting with the fundamental definitions of both HSS and SS parameters, the underlying mechanics associated with the two types of the stress analysis methods will be discussed by considering series of typical joint types, particularly on some of the important stress concentration characteristics that separate tubular joints from plate joints. Then, the necessary and sufficient conditions required for a stress definition relevant to fatigue and its calculation procedures will be demonstrated for both methods. Areas of concerns and improvements for both methods will be demonstrated by using a series of selected joint types typical of those in marine/offshore structures. Finally, the corresponding S-N data will be used to demonstrate the relative effectiveness of HSS and SS methods in consolidating the data from drastically different joint types into a single S-N curve.

Fatigue of Tubular Joints: Hot Spot Stress Method Revisited

2008 ◽  
Author(s):  
Pingsha Dong ◽  
Jeong K. Hong
Keyword(s):  
Hot Spot ◽  
Life Assessment ◽  
Structural Stress ◽  
T Joints ◽  
Hot Spot Stress ◽  
Tubular Joints ◽  
Fatigue Design ◽  
Fatigue Data ◽  
Section Viii ◽  
Remaining Life Assessment

A series of well-known tubular joints tested in UKSORP II have been re-evaluated using the mesh-insensitive structural stress method as a part of the on-going Battelle Structural Stress JIP efforts. In this report, the structural stress based analysis procedure is first presented for applications in tubular joints varying from simple T joints, double T Joints, YT joints with overlap and K joints with various internal stiffening configurations. The structural stress based SCFs are then compared with those obtained using traditional surface extrapolation based hot spot stress methods. Their abilities in effectively correlating the fatigue data collected from these tubular joints are demonstrated. These tests are also compared with the T curve typically used for fatigue design of tubular joints as well as the structural stress based master S-N curve adopted by ASME Section VIII Div 2. Finally, some of the implications on fracture mechanics based remaining life assessment for tubular joints are discussed in light of the results obtained in this investigation.

A Case Study Comparison of Surface Extrapolation and Battelle Structural Stress Methodologies

2004 ◽  
Author(s):  
Brian E. Healy
Keyword(s):  
Convergence Analysis ◽  
Hot Spot ◽  
Structural Stress ◽  
Hot Spot Stress ◽  
Side Shell

A case study comparison of the surface extrapolation and Battelle structural stress methodologies has been performed on a side shell connection detail typical of a representative FPSO or tanker vessel. Computations of hot spot stress via either method are consistent with current recommended practice. Convergence analysis to determine the hot spot stresses that best serve as fatigue parameters and a fatigue comparison that employs hot spot stresses from the convergence analysis have been executed at various locations around the detail. Results are reported and discussed.

Low-Cycle Fatigue Evaluation Using the Weld Master S-N Curve

2006 ◽  
Author(s):  
P. Dong ◽  
Z. Cao ◽  
J. K. Hong
Keyword(s):  
Test Data ◽  
Low Cycle Fatigue ◽  
Strain Curve ◽  
Cyclic Stress ◽  
Structural Stress ◽  
Stress Strain ◽  
Strain Behavior ◽  
Scale Test ◽  
Stress Estimation ◽  
Fatigue Evaluation

In the context of fatigue evaluation in the low-cycle regime, the use of the master S-N curve in conjunction with elastic FE-based structural stress calculations is presented. An elastic pseudo structural stress estimation is introduced by assuming that Neuber’s rule applies in relating structural stress and strain concentration at a weld to the material’s cyclic stress-strain behavior. With the pseudo structural stress procedure, recent sources of recent full scale test data on pipe and vessel welds were analyzed as a validation of the proposed procedure. The estimated fatigue lives versus actual test lives show a reasonable agreement. Finally, the feasibility of using monotonic stress-strain curves as a first approximation is also examined for applications when cyclic stress-strain curve may not be readily found. The analysis results indicate that the life estimations using monotonic stress-strain curves are reasonable, with the recent test data falling within mean ± 2σ, where σ represents the standard deviation of the master S-N curve.

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