Mode I Ductile Crack Growth of CT Specimen Under Large Cyclic Loading

2017 ◽  
Author(s):  
Kiminobu Hojo ◽  
Shinichi Kawabata
Keyword(s):  
Growth Rate ◽  
Cyclic Loading ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Mode I ◽  
Ductile Crack ◽  
Hardening Rule ◽  
Ductile Crack Growth

Ductile crack growth calculation method under excessive cyclic loading in a fitness for service rule has not been established even in Mode I. The authors simulated ductile crack growth behavior of CT specimens under cyclic loading executed in a committee of the Japan Welding Society. Sensitivity of the used stress-strain curves by monotonic or cyclic loading and the effect of the hardening rule were investigated. For evaluation of the crack growth rate under excessive cyclic loading, the parameter ΔJ was applied and compared with the rate of the JSME rules for FFS.

Mode I Ductile Crack Growth of 1TC(T) Specimen Under Large Cyclic Loading: Part IV

2020 ◽  
Author(s):  
Kiminobu Hojo
Keyword(s):  
Growth Rate ◽  
Cyclic Loading ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Mode I ◽  
Ductile Crack ◽  
Hardening Rule ◽  
Reference Stress ◽  
Ductile Crack Growth ◽  
Combined Hardening

Abstract Ductile crack growth calculation method under excessive cyclic loading in a fitness for service rule has not been established even in Mode I. Since 2017 to 2019 the author had tried to establish how to determine the parameters of the combined hardening rule and applied it to simulate the ductile crack growth behavior of the 1TC(T) specimens of the different loading levels for ferritic steel. Also ΔJ calculation using the reference stress method, and the transferred crack growth rate from a code were applied to estimate the ductile crack growth. Several equations of the reference stress method were tried to apply in the previous paper. Further the prediction procedure using the ΔJ, the reference stress method and da/dN-ΔJ curve based on the JSME rules on fitness for service (FFS) was applied to the pipe fracture tests under cyclic loading and its applicability was discussed for the case of a pipe structure in the previous paper. In this paper similar procedures were applied to 1TC(T) specimens of stainless steel. The combined hardening rule was applied for the constitution law of stress-strain curve. The numerical simulation with the combined rule traced the load-load line displacement curve under the cyclic loading experiments of 1TC(T). Also austenitic stainless fatigue crack growth rate (FCGR) in air condition from the JSME rules on FFS bounded the experimental crack growth rate, which means the FCGR of the JSME rules is applicable to fatigue crack growth calculation.

Mode I Ductile Crack Growth of 1TCT Specimen Under Large Cyclic Loading: Part III

2019 ◽  
Author(s):  
Kiminobu Hojo
Keyword(s):  
Cyclic Loading ◽  
Crack Growth ◽  
Large Scale ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Mode I ◽  
Piping System ◽  
Ductile Crack ◽  
Reference Stress ◽  
Ductile Crack Growth

Abstract Fitness for service rules and a calculation method for ductile crack growth under large scale plastic cyclic loading have not been established even for Mode I. In a paper presented at the PVP2018 conference the authors presented methods to establish how to determine the parameters of the combined hardening plasticity rule and applied it to simulate the ductile crack growth behavior of 1TCT specimens of the different load levels. Also, ΔJ calculations using the reference stress method, and a ΔJ-basis fatigue crack growth rate derived from that on ΔK-basis according to JSME rules for FFS were applied to estimate the crack growth under cyclic loading in excess of yield. Since in the 2018 paper identified some gaps were found between experiments and the predicted crack growth behavior, several equations of the reference stress method are evaluated in the present paper. Additionally, the prediction procedure using the ΔJ calculation by the reference stress method and the da/dN−ΔJ curve based on the JSME rules for FFS are applied to pipe fracture tests under cyclic loading. Their applicability is discussed for the case of an example piping system.

Mode I Ductile Crack Growth of 1TCT Specimen Under Large Cyclic Loading: Part II

2018 ◽  
Author(s):  
Kiminobu Hojo ◽  
Shinichi Kawabata ◽  
Naoki Ogawa
Keyword(s):  
Cyclic Loading ◽  
Crack Growth ◽  
Load Cycle ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Mode I ◽  
Ductile Crack ◽  
Cycle Number ◽  
Ductile Crack Growth ◽  
Hardening Rules

The ductile crack growth calculation method under excessive cyclic loading has not been established in the rules for fitness for service, even for Mode I. On the paper for the PVP2017 conference, the authors simulated ductile crack growth behavior of CT specimens under cyclic loading within a committee of the Japan Welding Society, and showed that the Chaboche model and bilinear kinetic hardening rules underestimated the load in compression. The discrepancy between the prediction results and the experimental results were also shown to become larger with increasing load cycle number. In this paper, the authors tried to establish how to determine the parameters of the combined hardening rule and then applied it to simulate the ductile crack growth behavior of the 1TCT specimens for loading levels different from that of last year. Also, the simplified ΔJ calculation, for example the reference stress method, and the crack growth rate from the JSME rules for FFS were applied to estimate the ductile crack growth. Based on this approach, the crack growth analysis method was investigated in order to incorporate into the JSME rules for large cyclic loading.

Evaluation of Crack Growth Behavior of Alloy 625 Under Cyclic Loading in a Steam Environment at 750°C

2011 ◽  
Author(s):  
Yoichi Takeda ◽  
Hirofumi Sato ◽  
Shuhei Yamamoto ◽  
Takamichi Tokunaga ◽  
Akio Ohji
Keyword(s):  
Growth Rate ◽  
High Temperature ◽  
Cyclic Loading ◽  
Crack Growth Rate ◽  
Crack Length ◽  
Crack Growth ◽  
Loading Rate ◽  
Transition Period ◽  
Growth Behavior ◽  
Crack Growth Behavior

Advanced ultra supercritical (A-USC) steam power generation, in which high-pressure steam is raised to beyond 700°C, is being studied internationally. The creep strength of Ni-based super alloys evaluated at these high temperatures in an air environment makes these materials promising candidates for the material to be used for the structural components of these generators. Since they are exposed to high temperature steam, it is important that the effect of the environment on the degradation of these materials is investigated. In this investigation, the crack growth rate under cyclic loading in a 750°C steam environment using a compact tension specimen was evaluated. Crack length monitoring using the direct current potential drop technique was applied to the growing crack in a high temperature environment in order to evaluate the time-dependent behavior of the crack growth. The dependence of the loading rate and amplitude in terms of the stress intensity factor was obtained. The crack growth rate increased with decreasing loading rate and increasing amplitude. Multiple loading patterns were applied to a single specimen during crack length monitoring. When the loading pattern was changed to a different pattern, in most of the cases, the crack growth rate started to change and then became stable aftera transition period. The influence of intermetallics and different phases on the crack growth behavior is discussed based on the oxidation rate of these phases.

scholarly journals Ductile Crack Growth Behavior of Structural Steels under Cyclic Loading

2000 ◽  
Vol 2000 (188) ◽  
pp. 679-689 ◽  
Author(s):  
Mitsuru Ohata ◽  
Fumiyoshi Minami ◽  
Syusuke Fujita ◽  
Masaaki Hashimoto ◽  
Masao Toyoda
Keyword(s):  
Cyclic Loading ◽  
Crack Growth ◽  
Structural Steels ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Ductile Crack ◽  
Ductile Crack Growth

Influence of Weld Residual Stresses on Ductile Crack Behavior in AISI Type 316LN Stainless Steel Weld Joint

2018 ◽  
Author(s):  
Sai Deepak Namburu ◽  
Lakshmana Rao Chebolu ◽  
A. Krishnan Subramanian ◽  
Raghu Prakash ◽  
Sasikala Gomathy
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Crack Growth ◽  
Weld Joint ◽  
Volume Fraction ◽  
Growth Behavior ◽  
Welding Residual Stress ◽  
Crack Growth Behavior ◽  
Ductile Crack ◽  
Ductile Crack Growth

Welding residual stress is one of the main concerns in the process of fabrication and operation because of failures in welded steel joints due to its potential effect on structural integrity. This work focuses on the effect of welding residual stress on the ductile crack growth behavior in AISI 316LN welded CT specimens. Two-dimensional plane strain model has been used to simulate the CT specimen. X-ray diffraction technique is used to obtain residual stress value at the SS 316LN weld joint. The GTN model has been employed to estimate the ductile crack growth behavior in the CT-specimen. Results show that residual stresses influence the ductile crack growth behavior. The effect of residual stress has also been investigated for cases with different initial void volume fraction, crack lengths.

Experiment and Modeling of Fatigue Crack Growth With Altering Loading Direction

2009 ◽  
Author(s):  
Wenfeng Tu ◽  
Xiaogui Wang ◽  
Zengliang Gao
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Damage ◽  
Growth Behavior ◽  
Cyclic Plasticity ◽  
Crack Growth Behavior ◽  
Loading Direction

The experiments of mixed Mode I-II fatigue crack growth with altering loading direction were conducted with compact specimens made of 16MnR steel. The specimens were tested under three loading steps. When the crack reached a certain length in the first step, the loading direction was switched to a certain angle. Finally, the loading direction was returned to the original orientation. The crack grow direction had a tendency perpendicular to the loading axis. Right after the loading direction was changed, the crack growth rate was retarded. A new approach developed was used to predict the crack growth behavior. The elastic-plastic stress analysis was performed using the finite element method with the implementation of a cyclic plasticity model. Based on the stress-strain response, fatigue damage near the crack tip was determined by a multi-axial fatigue criterion. Both the crack growth rate and cracking direction were obtained according to the maximum fatigue damage distribution on the critical material plane. The predictions for the crack growth behavior including the crack growth rate and crack growth path were in agreement with the experimental data.

A Ductile Crack Growth Behavior of a Low USE Pressure Vessel

2000 ◽  
Vol 2000 (0) ◽  
pp. 433-434
Author(s):  
Masakazu YOSHINO ◽  
Yoshio URABE ◽  
Koji KOYAMA ◽  
Yasuhide ASADA
Keyword(s):  
Crack Growth ◽  
Pressure Vessel ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Ductile Crack ◽  
Ductile Crack Growth

scholarly journals Effect of Material Heterogeneity on Environmentally Assisted Cracking Growth Rate of Alloy 600 for Safe-End Welded Joints

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6186
Author(s):  
Kuan Zhao ◽  
Shuai Wang ◽  
He Xue ◽  
Zheng Wang
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Welded Joints ◽  
Welding Process ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Alloy 600 ◽  
Material Heterogeneity ◽  
Environmentally Assisted Cracking

Environmentally assisted cracking (EAC) is essential in predicting light water reactors’ structural integrity and service life. Alloy 600 (equivalent to Inconel 600) has excellent corrosion resistance and is often used as a welding material in welded joints, but material properties of the alloy are heterogeneous in the welded zone due to the complex welding process. To investigate the EAC crack growth behavior of Alloy 600 for safe-end welded joints, the method taken in this paper concerns the probability prediction of the EAC crack growth rate. It considers the material heterogeneity, combining the film slip-dissolution/oxidation model, and the elastic-plastic finite element method. The strain rate at the crack tip is a unique factor to describe the mechanical state. Still, it is challenging to accurately predict it because of the complicated and heterogeneous material microstructure. In this study, the effects of material heterogeneity on the EAC crack growth behavior are statistically analyzed. The results show that the material heterogeneity of Alloy 600 can not be ignored because it affects the prediction accuracy of the crack growth rate. The randomness of yield strength has the most influence on the EAC growth rate, while Poisson’s ratio has the smallest.

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