scholarly journals Effect Range of the Material Constraint-I. Center Crack

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 67 ◽  
Author(s):  
Jie Yang ◽  
Lei Wang
Keyword(s):  
Welded Joints ◽  
Fracture Behavior ◽  
Solid Mechanics ◽  
Adjacent Area ◽  
Strain Fields ◽  
Integrity Assessment ◽  
Center Crack ◽  
Design Structure ◽  
Resistance Curves ◽  
Material Constraints

Material constraints are important factor effects on the fracture behavior of welded joints. The effect range of the material constraint is an important and interesting issue which needs to be clarified, including whether the effect range of a material constraint exists or not, who will affect it, and whether the material constraint is affected by the no adjacent area or not. In this study, different basic models which reflect different single metallic welded joints, bimetallic welded joints and dissimilar metal welded joints were designed, and the fracture resistance curves and crack tip strain fields of the different models with various material constraints were calculated. Based on the results, the questions above were answered. This study has significance for developing solid mechanics, optimizing joint design, structure integrity assessment, and so on.

scholarly journals Effect Range of the Material Constraint-II. Interface Crack

Metals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 696 ◽  
Author(s):  
Yue Dai ◽  
Jie Yang ◽  
Lei Wang
Keyword(s):  
Interface Crack ◽  
Welded Joints ◽  
Integrity Assessment ◽  
Center Crack ◽  
Fracture Behaviors ◽  
Selection Of ◽  
Material Constraints

The selection of fracture behaviors used in the structure integrity assessment has significant implications on the accuracy of the assessment. The effect range of the material constraint is an important factor which effects the fracture behaviors of structures and exists in the different kinds of welded joints with the center crack. However, for the material constraint induced by an interface crack, which also appears widely in the welded joints, it is not clear whether the effect range exists or not. The further study of the effect range of the material constraint for the welded joints with interface crack is meaningful. Thus, in this study, different basic models with interface crack were designed, the fracture behaviors of these basic models under different material constraints were calculated, and the effect range of the material constraint induced by interface crack were studied. This study about the interface crack and the previous study about the center crack provide an additional basis for an accurate structure integrity assessment.

scholarly journals In Situ studies of the dynamics of strain fields in welded joints of austenitic stainless steel under tensile loads

2020 ◽  
Vol 30 ◽  
pp. 53-58
Author(s):  
Kirill Kurgan ◽  
Anatoliy Klopotov ◽  
Vasiliy Klimenov ◽  
Michael Slobodyan ◽  
Artem Ustinov ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Welded Joints ◽  
Strain Fields ◽  
In Situ Studies

Determination of Ductile Tearing Resistance Curve in Weld Joints

2009 ◽  
Author(s):  
S. Marie ◽  
P. Gilles ◽  
P. Ould
Keyword(s):  
Welded Joints ◽  
Opening Displacement ◽  
Weak Point ◽  
Global Parameter ◽  
Ductile Tearing ◽  
Weld Joints ◽  
Resistance Curves ◽  
Reliable Solution ◽  
Tearing Resistance

Steels present in the ductile domain a tearing resistance which increase with the crack propagation up to the failure. This ductile tearing resistance is in general characterised with curves giving the variation of a global parameter (opening displacement at the crack tip δ, integral J) versus the crack extension Δa. These global approaches depend more or less on the specimen geometry and on the type of the imposed loading. Local approaches based on the description of the ductile tearing mechanisms provide reliable solution to the transferability problem (from the lab specimen to the component) but are complex and costly to use and are not codified. These problems get worse in the case of a weld joint where no standard is available for the measurement of their ductile tearing resistance. But the welded joints are often the weak point of the structure because of greater risk of defects, the heterogeneity of the microstructure of the weld, deformation along the interface between two materials with different yield stress (mismatch).... After briefly recalling the problems of transferability of the ductile tearing resistance curves obtained on lab specimen to the case of components, this article identifies the factors complicating the determination of the toughness in the welded joints and gives recommendations for the experimental determination of ductile tearing resistance curves of welded joints.

On the Constraint-Based Failure Assessment of Surface Cracks in T-Plate Welded Joints

2003 ◽  
Author(s):  
X. Wang ◽  
R. Bell ◽  
S. B. Lambert
Keyword(s):  
Lower Bound ◽  
Welded Joints ◽  
Structural Integrity ◽  
Constraint Effect ◽  
Engineering Structures ◽  
Integrity Assessment ◽  
Failure Assessment ◽  
Recent Developments ◽  
Failure Predictions ◽  
Crack Tip Constraint

The loss of crack tip constraint leads to enhanced resistance to both cleavage and ductile tearing. However, conventional failure assessment schemes (CEGB-R6, BS-7910) use lower bound toughness obtained from highly constrained test specimens. Cracks in many real engineering structures are not highly constrained, which makes failure predictions using conventional failure assessment schemes based on lower bound fracture toughness values overly pessimistic. Excessive pessimism in the structural assessment can lead to unwarranted repair or decommissioning of structures, and thus cause unneeded cost and inconvenience. Recent developments on constraint-based fracture mechanics have enabled the practical assessment of defective components including the constraint effect. For example, the recent revision of R6 and the newly developed structural integrity assessment procedures for European industry (SINTAP) have suggested a framework for failure assessments including the constraint effect. In this paper, the constraint-based failure assessment of surface cracked T-plate welded joints under tension load is presented. Different issues including the constraint-based failure assessment diagrams, the treatment of combining primary and the secondary loads, and the calculation of stress intensity factors, limit loads and constraint parameters for surface cracked T-plate joints are discussed. It is demonstrated that when the lower constraint effect is properly accounted for, the maximum allowable tensile stress level increases substantially.

206 Fatigue Fracture Behavior of Two Types of Spot Welded Joints Subjected to Shear Loading

2009 ◽  
Vol 2009.58 (0) ◽  
pp. 87-88
Author(s):  
Takahiro YAMAMOTO ◽  
Keiichiro TOHGO ◽  
Yoshinobu SHIMAMURA ◽  
Hiroyasu ARAKI ◽  
Hiroya ITOH ◽  
...  
Keyword(s):  
Fatigue Fracture ◽  
Welded Joints ◽  
Fracture Behavior ◽  
Shear Loading ◽  
Fatigue Fracture Behavior ◽  
Spot Welded

scholarly journals Effect of Zinc Coating on Delay Nugget Formation in Dissimilar DP600 - AISI304 Welded Joints Obtained by the Resistance Spot Welding Process

2021 ◽  
Author(s):  
Mercedes Pérez de la Parte ◽  
Alejandro Espinel Hernández ◽  
Mario César Sánchez Orozco ◽  
Angel Sánchez Roca ◽  
Emilio Jiménez Macias ◽  
...  
Keyword(s):  
Welded Joints ◽  
Resistance Spot Welding ◽  
Spot Welding ◽  
Zinc Coating ◽  
Welding Process ◽  
Dynamic Resistance ◽  
Time Duration ◽  
Resistance Spot ◽  
Nugget Formation ◽  
Resistance Curves

Abstract This paper researches the effect of zinc coating of galvanized DP600 steel on the dynamic resistance and the delayed nugget formation of dissimilar DP600 - AISI304 welded joints, obtained with resistance spot welding process (RSW). The RSW evaluations consisted of determining, from the dynamic resistance curves, the time involved in the different stages of the process, particularly the beginning of nugget formation. The experimental results showed that, from the dynamic resistance curves, it is possible to identify 8 distinct stages during the welding of galvanized DP600 steel and AISI304 stainless steel. In the case of the welding of uncoated DP600 steel with AISI304, only 6 stages are identified (except for stages 2 and 3), which are directly related to the heating, softening and melting of the galvanic coating. The energy used in stages 2 and 3, causes a delay in the beginning of nugget formation for welded joints obtained with galvanized DP600 steel compared to uncoated DP600 - AISI304 welded joints, reaching values between 37.28 ms and 52.29 ms for the welding conditions analyzed. Monitoring the time duration of stages 2 and 3, as defined from the analysis of the dynamic resistance curves, could be used as a tool to predict the beginning of nugget formation in the welding of galvanized steels, to avoid undesirable phenomena such as expulsion and to guarantee the quality of the welded joints.

Ductile Tearing Simulations to Support Design of Large Scale Tests on Ferritic Pipes to Be Performed in the European Project ATLAS+

2019 ◽  
Author(s):  
Tomas Nicak
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Fracture Behavior ◽  
Large Scale ◽  
High Stress ◽  
Stress Triaxiality ◽  
Local Approach ◽  
Integrity Assessment ◽  
European Project

Abstract The safety and reliability of all systems has to be maintained throughout the lifetime of a nuclear power plant (NPP). This requires a systematic ageing management procedure for justifying their safe long term operation. One fundamental part in this process is to demonstrate the integrity of the nuclear power plant components. The European project ATLAS+ aims to develop and validate advanced methods of structural integrity assessment applicable in the ageing and lifetime management of primary and secondary circuit components. To support development and validation of those methods, a large scale test program was developed with the aim to investigate fracture behavior of relevant piping material at the component level. Three of planned large scale experiments focus on the fracture behavior of ferritic piping made of material WB 36 (15 NiCuMoNb 5), that is representative of secondary feedwater lines installed in German NPPs. In order to verify design calculations conducted by means of the classical fracture mechanics approach based on J-Integral [1], detailed local approach analyses are performed for three mock-ups with different initial defects. The local approach analyses presented in this paper are based on the local micromechanical model proposed by Gurson and further modified by Tvergaard. Calibration of required material parameters and prediction of the mock-up behavior during the test is discussed. In order to support constraint investigations stress triaxiality ahead of the crack front during crack propagation in the mock-ups is evaluated and compared to the stress triaxiality in CT20 and SENT specimens. As high stress triaxiality generally limits plastic deformation and increases the crack tip constraint, it is a good parameter to look at if constraint effects are considered.

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