Effects of Weld Strength Mismatch on J and CTOD Estimation Procedures for SENT Fracture Specimens Based on Plastic Eta-Factors

2011 ◽  
Author(s):  
Marcelo Paredes ◽  
Claudio Ruggieri
Keyword(s):  
Mouth Opening ◽  
Estimation Procedure ◽  
Primary Objective ◽  
Weld Strength ◽  
Crack Mouth Opening Displacement ◽  
Evaluation Procedure ◽  
Opening Displacement ◽  
Wide Range ◽  
Extensive Body ◽  
Fracture Specimens

This work focuses on the evaluation procedure to determine the elastic-plastic fracture toughness J-integral and CTOD based upon the η-method for welded SENT fracture specimens with clamped ends. The primary objective is to gain additional understanding on the effect of weld strength mismatch on estimation techniques to determine J and CTOD fracture parameters for a wide range of a/W-ratios and mismatch levels. Very detailed non-linear finite element analyses for plane-strain and 3-D models of SENT fracture specimens with center cracked, square groove welds provide the evolution of load with increased crack mouth opening displacement and load line displacement which are required for the estimation procedure. The results show that levels of weld strength mismatch within the range 10∼20% mismatch do not affect significantly J and CTOD estimation expressions applicable to homogeneous materials. The present analyses, when taken together with previous studies, provide an extensive body of results which serve to determine parameters J and CTOD for different materials using SENT specimens with varying geometries and mismatch levels.

Improved J and CTOD Estimation Formulas for C(T) Fracture Specimens Including Overmatched Weldments

2011 ◽  
Author(s):  
Rafael G. Savioli ◽  
Claudio Ruggieri
Keyword(s):  
Mouth Opening ◽  
Estimation Procedure ◽  
Primary Objective ◽  
Weld Strength ◽  
Crack Mouth Opening Displacement ◽  
Evaluation Procedure ◽  
Opening Displacement ◽  
Wide Range ◽  
Extensive Body ◽  
Fracture Specimens

This work focuses on the evaluation procedure to determine the elastic-plastic J-integral and CTOD fracture toughness based upon the η-method for C(T) fracture specimens made of homogeneous and welded steels. The primary objective of this investigation is to enlarge on previous developments of J and CTOD estimation procedures for this crack configuration while, at the same time, addressing effects of strength mismatch on the plastic η-factors. The present analyses enable the introduction of a larger set of factor η for a wide range of crack sizes (as measured by the a/W-ratio) and material properties, including different levels of weld strength mismatch, applicable to structural, pipeline and pressure vessel steels. Very detailed non-linear finite element analyses for plane-strain models of square groove, center cracked C(T) fracture specimens provide the evolution of load with increased crack mouth opening displacement required for the estimation procedure. Overall, the present study, when taken together with previous investigations, provides a fairly extensive body of results to determine parameters J and CTOD for different materials using C(T) specimens with varying overmatch conditions.

Effects of Weld Strength Mismatch on Estimation Procedures for J and CTOD Fracture Parameters Using SE(B) Specimens

2007 ◽  
Author(s):  
Gustavo H. B. Donato ◽  
Claudio Ruggieri
Keyword(s):  
Mouth Opening ◽  
Estimation Procedure ◽  
Primary Objective ◽  
Weld Strength ◽  
Crack Mouth Opening Displacement ◽  
Opening Displacement ◽  
Fracture Parameters ◽  
Wide Range ◽  
Estimation Procedures ◽  
Fracture Specimens

This work presents an exploratory development of J and CTOD estimation procedures for welded fracture specimens under bending based upon plastic eta factors and plastic rotation factors. The techniques considered include: i) estimating J and CTOD from plastic work and ii) estimating CTOD from the plastic rotational factor. The primary objective is to gain additional understanding on the effect of weld strength mismatch on estimation techniques to determine J and CTOD fracture parameters for a wide range of a/W-ratios and mismatch levels. Very detailed non-linear finite element analyses for plane-strain models of SE(B) fracture specimens with center cracked, square groove welds provide the evolution of load with increased load-line displacement and crack mouth opening displacement which are required for the estimation procedure. The results show that levels of weld strength mismatch within the range ±20% mismatch do not affect significantly J and CTOD estimation expressions applicable to homogeneous materials, particularly for deeply cracked fracture specimens. The present analyses, when taken together with previous studies, provide a fairly extensive body of results which serve to determine parameters J and CTOD for different materials using bend specimens with varying geometries and mismatch levels.

Revised η-Factors for 3P SE(B) Fracture Specimens Incorporating 3-D Effects

2014 ◽  
Author(s):  
Rodolfo F. de Souza ◽  
Claudio Ruggieri
Keyword(s):  
Fracture Toughness ◽  
Mouth Opening ◽  
Estimation Procedure ◽  
Crack Mouth Opening Displacement ◽  
Evaluation Procedure ◽  
Specimen Thickness ◽  
Crack Mouth ◽  
Opening Displacement ◽  
Wide Range ◽  
Fracture Specimens

Standardized procedures to measure cleavage fracture toughness of ferritic steels in the DBT region most commonly employ three-point bend fracture specimens, conventionally termed SE(B) or SENB specimens. The evaluation protocol of fracture toughness for these crack configurations builds upon laboratory records of load and crack mouth opening displacement (CMOD) to relate plastic work with J (or, equivalently, CTOD). The experimental approach employs a plastic η-factor to relate the macroscale crack driving force to the area under the load versus crack mouth opening displacement for cracked configurations. This work provides revised η-factors derived from CMOD records applicable to estimate the J-integral and CTOD in SE(B) specimens with varying crack size and specimen configuration. Non-linear finite element analyses for plane-strain and 3-D models provide the evolution of load with increased CMOD which is required for the estimation procedure. The analysis matrix considers SE(B) specimens with W = 2B and W = B configurations with and without side grooves covering a wide range of specimen thickness, including precracked Charpy (PCVN) specimens. Overall, the present results provide further validation of the J and CTOD evaluation procedure currently adopted by ASTM 1820 while, at the same time, giving improved estimation equations for J incorporating 3-D effects which enter directly into more accurate testing protocols for experimental measurements of fracture toughness values using 3P SE(B) specimens.

Estimation Procedures for J and CTOD Fracture Parameters Using Three-Point Bend Specimens

2006 ◽  
Author(s):  
Gustavo H. B. Donato ◽  
Claudio Ruggieri
Keyword(s):  
Mouth Opening ◽  
Estimation Procedure ◽  
Primary Objective ◽  
Crack Mouth Opening Displacement ◽  
Opening Displacement ◽  
Fracture Parameters ◽  
Wide Range ◽  
Estimation Procedures ◽  
Point Bend ◽  
Extensive Body

This work presents the development of J and CTOD estimation procedures for deep and shallow cracked bend specimens based upon plastic eta factors and rotational factors. The techniques considered include: i) estimating J and CTOD from plastic work and ii) estimating CTOD from the plastic rotational factor. The primary objective is to derive estimation techniques which are applicable to determine J and CTOD fracture parameters for a wide range of a/W-ratios and material flow properties. Very detailed non-linear finite element analyses for plane-strain models provide the evolution of load with increased load-line displacement and crack mouth opening displacement which are required for the estimation procedure. Laboratory testing of a structural steel using shallow and deep crack bend specimens provide the data needed to determine the CTOD-values for the material based upon the proposed methodology. These fracture toughness values are compared against the results obtained based upon the estimation equations given by BS 7448. The present analyses, when taken together with previous studies, provide a fairly extensive body of results which serve to determine parameters J and CTOD using bend specimens with varying geometries.

Effects of Weld Strength Mismatch on Estimation Procedures for J Fracture Parameter Using Clamped SE(T) Specimens

2009 ◽  
Author(s):  
Gustavo H. B. Donato ◽  
Rodrigo Magnabosco ◽  
Claudio Ruggieri
Keyword(s):  
Mouth Opening ◽  
Primary Objective ◽  
The Body ◽  
Weld Strength ◽  
Crack Mouth Opening Displacement ◽  
Fracture Parameter ◽  
Opening Displacement ◽  
Fracture Parameters ◽  
Wide Range ◽  
Estimation Procedures

This work presents an exploratory development of J estimation procedures for deep and shallow cracked tension SE(T) specimens based upon plastic eta factors which incorporate the effects of weld strength mismatch. The considered technique includes estimation of J from plastic work. The primary objective is to derive estimation procedures which are applicable to determine J fracture parameters for a wide range of a/W-ratios, material flow properties and different levels of weld strength mismatch using clamped SE(T) specimens of varying geometries. Very detailed non-linear finite element analyses for plane-strain models provide the evolution of load with increased load-line displacement and crack mouth opening displacement, which are needed to determine the estimation procedures. Laboratory testing of a welded structural steel using SE(T) specimens provide the data needed to evaluate J evolution for the welded joints based upon the proposed methodology. The crack driving force evolution is compared against the results obtained using plastic eta factors for homogeneous specimens and demonstrates the importance of considering mismatch effects on crack-tip stress fields and fracture parameters. The present analyses, when taken together with previous studies, extend the body of results which serve to determine J integral using tension SE(T) specimens with varying geometries and mismatch levels.

Applicability of Plastic Eta Factor Solutions in J Estimation Procedures for Tensile SE(T) Fracture Specimens

2010 ◽  
Author(s):  
Claudio Ruggieri
Keyword(s):  
Strong Support ◽  
Mouth Opening ◽  
Weld Strength ◽  
Crack Mouth Opening Displacement ◽  
Opening Displacement ◽  
Load Line ◽  
Load Line Displacement ◽  
Edge Notch ◽  
Load Displacement ◽  
Fracture Specimens

This work investigates application of the η-factor (which bears direct connection with laboratory toughness measurements) on accurate and robust estimates of J for clamped single edge notch tension (SE(T)) specimens made of homogeneous and welded materials using load-displacement records. Very detailed nonlinear finite element analyses for plane-strain models provide the evolution of load with increased load-line displacement and crack mouth opening displacement to define the applied load as a separable function dependent upon crack geometry, material deformation and mismatch level. The procedure enables determining the corresponding separation parameters for each specimen geometry thereby allowing evaluation of factor η derived from a load separation analysis. The study shows that η-factors based on load-displacement records defining the plastic area provide effective and accurate toughness measurements for clamped SE(T) fracture specimens. The analyses also revealed that η-factors for clamped SE(T) fracture specimens based on load-line displacement (LLD) records and plastic area are relatively insensitive to weld strength mismatch. Overall, the present results provide a strong support to use η-based procedures in toughness measurements using clamped SE(T) fracture specimens.

Wide Range Compliance Solutions for Various Fracture Test Specimens Using Crack Mouth Opening Displacement

2017 ◽  
Author(s):  
Claudio Ruggieri ◽  
Rodolfo F. de Souza
Keyword(s):  
Mouth Opening ◽  
Crack Mouth Opening Displacement ◽  
Width Ratio ◽  
Fracture Test ◽  
Single Edge ◽  
Opening Displacement ◽  
Element Analysis ◽  
Single Edge Notch ◽  
Wide Range ◽  
Edge Notch

This work addresses the development of wide range compliance solutions for tensile-loaded and bend specimens based on CMOD. The study covers selected standard and non-standard fracture test specimens, including the compact tension C(T) configuration, the single edge notch tension SE(T) specimen with fixed-grip loading (clamped ends) and the single edge notch bend SE(B) geometry with varying specimen spam over width ratio and loaded under 3-point and 4-point flexural configuration. Very detailed elastic finite element analysis in 2-D setting are conducted on fracture models with varying crack sizes to generate the evolution of load with displacement for those configurations from which the dependence of specimen compliance on crack length, specimen geometry and loading mode is determined. The extensive numerical analyses conducted here provide a larger set of solutions upon which more accurate experimental evaluations of crack size changes in fracture toughness and fatigue crack growth testing can be made.

Applicability of J Estimation Procedures for Overmatched SE(T) Fracture Specimens

2010 ◽  
Author(s):  
Lenin M. Paredes ◽  
Henrique S. S. Carvalho ◽  
Claudio Ruggieri
Keyword(s):  
Primary Objective ◽  
Weld Strength ◽  
Evaluation Procedure ◽  
Single Edge ◽  
Load Line ◽  
Load Line Displacement ◽  
Edge Notch ◽  
Η Factor ◽  
Fracture Specimens ◽  
J Estimation

This work focuses on the evaluation procedure to determine the elastic-plastic fracture toughness J-integral based upon the η-method for welded SE(T) fracture specimens. The primary objective of this investigation is to address the significance of the η-factor on accurate and robust estimates of J clamped single edge notch tension (SE(T)) specimens using load-displacement records. Very detailed non-linear finite element analyses for plane-strain models provide the evolution of load with increased load-line displacement to define the applied load as a separable function dependent upon crack geometry, strength mismatch level and specimen deformation. The analyses reveal that η-factors for clamped SE(T) fracture specimens based on load-line displacement (LLD) records and plastic area are relatively insensitive to weld strength mismatch.

Estimation Procedures for J and CTOD Fracture Parameters Experimental Evaluation Using Homogeneous and Mismatched Pin-Loaded SE(T) Specimens

2010 ◽  
Author(s):  
Gabriel P. de Oliveira ◽  
Gustavo H. B. Donato
Keyword(s):  
Experimental Evaluation ◽  
Fracture Resistance ◽  
Structural Integrity ◽  
Mouth Opening ◽  
Pressure Vessels ◽  
Weld Strength ◽  
Crack Mouth Opening Displacement ◽  
J Integral ◽  
Opening Displacement ◽  
Conceptual Background

Experimental evaluation of geometry-dependent material’s fracture resistance using constraint-designed SE(T) specimens has proved to be an accurate option to assess the structural integrity of pipelines and pressure vessels reducing excessive conservatism. In this context, this work presents procedures for experimental J-integral and CTOD (δ) evaluation using the eta (η) method applied to tension pin-loaded SE(T) specimens made of homogeneous materials and also containing mismatched joints. Initially, the conceptual background is presented, followed by the description of the refined non-linear finite element models developed, which provide the necessary evolution of load with increased load-line and crack mouth opening displacement. As results, are presented η factors for J-integral estimation and CTOD calculations, which are not available in current standardized procedures. The main objective is to allow fracture resistance experimental evaluation using specimens of different a/W-ratios, material flow properties, weld joint configurations and levels of weld strength mismatch. The main motivation is the possibility of enhancing accuracy of pressure vessels and piping integrity assessments, since these later present very close fracture conditions if compared to SE(T) specimens. The present results, when taken together with previous developments, extend the knowledge about the use of pin-loaded SE(T) specimens. The reader should enhance the studies about the topic with the complimentary paper with the same title beginning but involving clamped SE(T) specimens.

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