scholarly journals Investigating of Strain Effect on Cleavage Fracture for Reactor Pressure Vessel Material

2021 ◽  
Author(s):  
Kushal Bhattacharyya
Keyword(s):  
Cleavage Fracture ◽  
Master Curve ◽  
Strain Effect ◽  
Strain Diagram ◽  
Huge Number ◽  
Element Analysis ◽  
Different Temperatures ◽  
Clear Plastic ◽  
Vessel Material ◽  
Reactor Pressure

Failure mechanism of 20MnMoNi55 steel in the lower self of ductile to brittle transition (DBT) region is considered as brittle fracture but it has been observed from the experimental analysis of stress-strain diagram that clear plastic deformation is shown by the material before failure. Therefore, strain correction is implemented in the cleavage fracture model proposed by different researchers in the lower self of the DBT region with the help of finite element analysis. To avoid a huge number of experiments being performed, Monte Carlo simulation is used to generate a huge number of random data at different temperatures in the lower self of the DBT region for calibration of the cleavage parameters with the help of the master curve methodology. Fracture toughness calculated after strain correction through different models are validated with experimental results for the different probability of failures.

Variation of Beremin Model Parameters With Temperature by Monte Carlo Simulation

2019 ◽  
Vol 141 (2) ◽  
Author(s):  
K. Bhattacharyya ◽  
S. Acharyya ◽  
S. Dhar ◽  
J. Chattopadhyay
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Master Curve ◽  
Model Parameters ◽  
Three Point Bending ◽  
Brittle Transition ◽  
Different Temperatures ◽  
Ductile To Brittle Transition ◽  
Vessel Material ◽  
Reactor Pressure

In this work, variation of the Beremin parameters with temperature for reactor pressure vessel material 20MnMoNi55 steel is studied. Beremin model is used, including the effect of plastic strain as originally formulated in the Beremin model. A set of six tests are performed at a temperature of −110 °C in order to determine reference temperature (T0) and master curve for the entire ductile-to-brittle transition (DBT) region as per the ASTM Standard E1921. Monte Carlo simulation is employed to produce a large number of 1 T three-point bending specimen (TPB) fracture toughness data randomly drawn from the scatter band obtained from the master curve, at different temperatures of interest in the brittle dominated portion of DBT region to determine Beremin model parameters variation with temperatures.

Effects of Temperature and Crack Tip Constraint on Cleavage Fracture Toughness in the Weld Thermal Simulated X80 Pipeline Steels

2011 ◽  
Vol 197-198 ◽  
pp. 1595-1598 ◽  
Author(s):  
Jie Xu ◽  
Yu Fan
Keyword(s):  
Fracture Toughness ◽  
Cleavage Fracture ◽  
Crack Tip ◽  
Coarse Grained ◽  
Material Microstructure ◽  
Element Analysis ◽  
Pipeline Steels ◽  
Different Temperatures ◽  
Effects Of Temperature ◽  
Crack Tip Constraint

This paper studies the effects of temperature and crack tip constraint on cleavage fracture toughness of the weld thermal simulated X80 pipeline steels. A large number of fracture toughness (as denoted by CTOD) tests together with 3D finite element analysis are performed using single edge notched bending (SENB) and tension (SENT) specimens at different temperatures. Coarse-grained heat-affected zone (CGHAZ) is considered as the material microstructure in preparation of the weld thermal simulated fracture mechanics specimens.

Use of Master Curve Technology for Assessing Shallow Flaws in a Reactor Pressure Vessel Material

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
N. Taylor ◽  
P. Minnebo ◽  
B. R. Bass ◽  
D. Siegele ◽  
K. Wallin ◽  
...  
Keyword(s):  
Pressure Vessel ◽  
Master Curve ◽  
Biaxial Loading ◽  
Production Quality ◽  
Pressure Vessels ◽  
Reactor Pressure Vessel ◽  
Test Pieces ◽  
Fracture Tests ◽  
Vessel Material ◽  
Reactor Pressure

In the NESC-IV project, an experimental/analytical program was performed to develop validated analysis methods for transferring fracture toughness data to shallow flaws in reactor pressure vessels subject to biaxial loading in the lower-transition temperature region. Within this scope, an extensive range of fracture tests was performed on material removed from a production-quality reactor pressure vessel. The master curve analysis of these data is reported and its application to the assessment of the project feature tests on large beam test pieces is discussed.

Master Curve Testing of Reactor Pressure Vessel Multilayer Welding Seams

2015 ◽  
Author(s):  
Hans-Werner Viehrig ◽  
Mario Houska ◽  
Eberhard Altstadt
Keyword(s):  
Fracture Toughness ◽  
Crack Propagation ◽  
Cleavage Fracture ◽  
Crack Front ◽  
Pressure Vessel ◽  
Master Curve ◽  
Crack Tip ◽  
Specimen Axis ◽  
Multilayer Welding ◽  
Reactor Pressure

Reactor pressure vessel (RPV) multilayer welding seams show an inhomogeneous structure. It raises concerns that the evaluation of non-uniform material might not be amenable to the statistical analysis methods on which the Master Curve approach is based. In particular with regard to weld metals, it can be expected that the cleavage fracture toughness is strongly influenced by the orientation of the Charpy size SE(B) specimen. The T-L oriented SE(B) specimen (axis axial and crack propagation in circumferential direction) comprises of various welding beads along the crack front whereas in a L-S specimen (axis axial and crack propagation through the thickness) the crack tip is located in one welding bead with an approximately uniform structure. The paper summarises fracture toughness results measured on welding seams of decommissioned and non-commissioned RPVs of WWER type nuclear reactors and the non-commissioned Biblis-C RPV. Specimens of T-L and T-S orientation were tested. The results show, that in general the cleavage fracture toughness values, KJc-1T, follow the Master Curve description. However, the number of KJc-1T data outside the 2% and 98% tolerance bounds is larger than predicted by the underlying model, which indicates non-uniform material. There is a large variation in the evaluated through thickness T0 values of the investigated multilayer beltline welding seams. Within the sampling range of the surveillance specimens, T0 values vary with a span of 30 to about 60 K depending on the applied welding technology. The fracture toughness strongly depends on the intrinsic weld bead structure. Hence, the position of the fatigue crack tip of the pre-cracked SE(B) specimen at the multilayer welding seam is crucial and defines the cleavage fracture toughness. Modified Master Curve based evaluation procedures like the MC based approach of the SINTAP procedure were applied to get fracture toughness values which are representative for the most brittle fraction the test series. Despite of the pronounced non-homogeneity of the micro-structure along the crack front of T-L specimens, crack initiation sites are randomly distributed along the crack front. This means that one of the basic assumptions in ASTM E1921, i.e. the uniform distribution of initiation sites, is fulfilled also for the T-L specimens from the multilayer weld metal.

Use of Master Curve Technology for Assessing Shallow Flaws in a Reactor Pressure Vessel Material

2006 ◽  
Author(s):  
N. Taylor ◽  
P. Minnebo ◽  
R. B. Bass ◽  
D. Siegele ◽  
K. Wallin ◽  
...  
Keyword(s):  
Pressure Vessel ◽  
Master Curve ◽  
Biaxial Loading ◽  
Production Quality ◽  
Pressure Vessels ◽  
Reactor Pressure Vessel ◽  
Test Pieces ◽  
Fracture Tests ◽  
Vessel Material ◽  
Reactor Pressure

In the NESC-IV project an experimental/analytical program was performed to develop validated analysis methods for transferring fracture toughness data to shallow flaws in reactor pressure vessels subject to biaxial loading in the lower-transition temperature region. Within this scope an extensive range of fracture tests was performed on material removed from a production-quality reactor pressure vessel. The Master Curve analysis of this data is reported and its application to the assessment of the project feature tests on large beam test pieces.

Finite Element Analysis of the Stress on Cylinder of the Fluidized Bed Reactor for Fast Pyrolysis

2011 ◽  
Vol 201-203 ◽  
pp. 660-663
Author(s):  
Qing Ruo Xie ◽  
Yi Sun ◽  
Li Wen Zheng ◽  
Hu Qi Wang ◽  
Zhang Fa Tong
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fluidized Bed ◽  
Safety Assessment ◽  
Scale Up ◽  
Fast Pyrolysis ◽  
Fluidized Bed Reactor ◽  
Element Analysis ◽  
Ansys Analysis ◽  
Different Temperatures

A new experimental fluidized bed reactor was investigated and designed which has been widely utilized for fast pyrolysis under different temperatures (T=727–973 K).The stresses of the reactor cylinder are analyzed using finite element method(FEM, ANSYS Inc., U.S.A ) based on the safety assessment, and the cylinder is designed for installing scheme. The result of ANSYS analysis shows that the stress unstable positions are nearby both ends of the cylinder. The results of analysis are shown that the designing stresses are not beyond the allow able ones. So the designing parameters can possess sufficient reliability, and the design scheme can completely satisfy the strength requirement. Certainty of the stress could offered the valuable instruction for the application of the equipment on industrial scale-up.

scholarly journals Use of Mini-CT Specimens for Fracture Toughness Characterization of Low Upper-Shelf Linde 80 Weld Before and After Irradiation

2018 ◽  
Author(s):  
Mikhail A. Sokolov
Keyword(s):  
Fracture Toughness ◽  
Pressure Vessel ◽  
Master Curve ◽  
Collaborative Program ◽  
Before And After ◽  
Minimum Number ◽  
Real Practice ◽  
Reactor Pressure ◽  
Good Agreement

Mini-CT specimens are becoming a highly popular geometry for use in reactor pressure vessel (RPV) community for direct measurement of fracture toughness in the transition region using the Master Curve methodology. In the present study, Mini-CT specimens were machined from previously tested Charpy specimens of the Midland low upper-shelf Linde 80 weld in both, unirradiated and irradiated conditions. The irradiated specimens have been characterized as part of a joint ORNL-EPRI-CRIEPI collaborative program. The Linde 80 weld was selected because it has been extensively characterized in the irradiated condition by conventional specimens, and because of the need to validate application of Mini-CT specimens for low upper-shelf materials — a more likely case for some irradiated materials of older generation RPVs. It is shown that the fracture toughness reference temperatures, To, derived from these Mini-CT specimens are in good agreement with To values previously recorded for this material in the unirradiated and irradiated conditions. However, this study indicates that in real practice it is highly advisable to use a much larger number of specimens than the minimum number prescribed in ASTM E1921.

Temperature effect on the tensile behaviors of carbon/polyimide composite laminate

2016 ◽  
Vol 231 (24) ◽  
pp. 4592-4602 ◽  
Author(s):  
Liang Li ◽  
Purong Jia ◽  
Wenge Pan
Keyword(s):  
Temperature Effect ◽  
Composite Laminates ◽  
Three Dimensional ◽  
Thermomechanical Coupling ◽  
Single Element ◽  
Element Analysis ◽  
Open Hole ◽  
Dimensional Finite Element ◽  
Different Temperatures ◽  
Three Dimensional Finite Element

Experimental and numerical investigations were carried out to study the temperature effect on the stiffness, strength, and failure behaviors of carbon/polyimide composite laminates. Both unnotched laminates and open-hole laminates were tested under tension load at three temperatures (room temperature, 200 ℃, and 250 ℃). A three-dimensional finite element analysis was carried out to study the thermomechanical coupling behavior in the notched laminate. The model considers each layer and interface as a single element in the thickness direction so that in-plane stress and interlaminar stress could be analyzed in the model. The stresses around the open-hole changing characteristics with the temperature and tensile loading have been discussed in detail. Failure analysis was carried out to predict the residual strength of the notched laminates at different temperatures. Compared to the experimental data, the numerical results have an excellent agreement.

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