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 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 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.

Effect of Cyclic Loading on Crack Propagation of X-70 Pipeline Steel in Near-Neutral pH Solution

2005 ◽  
Vol 297-300 ◽  
pp. 2501-2507 ◽  
Author(s):  
Hao Guo ◽  
Guang Fu Li ◽  
Xun Cai ◽  
Jiasheng Bai ◽  
Wu Yang
Keyword(s):  
Growth Rate ◽  
Cyclic Loading ◽  
Crack Growth Rate ◽  
Tensile Stress ◽  
Crack Propagation ◽  
Crack Growth ◽  
Pipeline Steel ◽  
Stress Axis ◽  
Mode I ◽  
Propagation Period

Crack propagation of X-70 pipeline steel in near-neutral pH solution was studied under different modes of cyclic loading. A revised equation of crack growth rate vs. Δ K was obtained. Average crack growth rate increased with cycles under conditions of different R values. Linear shape notch specimen made cracks much easier to initiate and propagate than V-shaped notch specimen did. For different R values, the curves of crack growth rate with cycles were similar, but the platform propagation period and quick propagation period were different obviously. Crack growth rate at both periods increased and thus failure time decreased markedly with decrease of R value. The propagation directions of cracks were different under different cyclic loading conditions. Under mode I (single tensile stress) cyclic loading, cracks were straight and perpendicular to the tensile stress axis, while under mixed-mode I/III (tensile/shear stress) cyclic loading, cracks were sinuous and did not propagate in the direction perpendicular to the main tensile stress axis.

Ductile Crack Propagation Simulation of a Cylinder With a Through-Wall Circumferential Flaw Under Excessive Cyclic Torsion Loading

2014 ◽  
Author(s):  
Kiminobu Hojo ◽  
Daigo Watanabe ◽  
Shinichi Kawabata ◽  
Yasufumi Ametani
Keyword(s):  
Cyclic Loading ◽  
Crack Growth ◽  
Rotation Angle ◽  
Fe Analysis ◽  
The Other ◽  
J Integral ◽  
Ductile Crack ◽  
Elastic Plastic ◽  
Cyclic Torsion ◽  
Ductile Crack Growth

A lot of applications of elastic plastic FE analysis to flawed structural fracture behaviors of mode I have been investigated. On the other hand the analysis method has not been established for the case of the excessive cyclic torsion loading with mode II or III fracture. The authors tried simulating the fracture behavior of a cylinder-shaped specimen with a through-walled circumferential flaw subjected to excessive monotonic or cyclic loading by using elastic plastic FE analysis. Chaboche constitutive equation of the used FE code Abaqus was applied to estimate the elastic plastic cyclic behavior. As a result in the case of monotonic loading without crack extension, the relation of torque-rotation angle of the experiment was estimated well by the simulation. Also J-integral by the Abaqus’ function agreed with a simplified J-equation using the calculated torque-rotation angle relation. On the other hand under load controlled cyclic loading associated with ductile crack growth, the calculated torque-rotation angle relation did not agree with the experimental one because of high sensitivity of the used stress-strain curve. J-integral from Abaqus code did not increase regardless of the accumulated crack growth and plastic zone. Several simplified ΔJ calculations tried to explain the experimental ductile crack growth and it seemed that da/dN-ΔJ relation follows the Paris’ law. From these examinations an estimation procedure of the structures under excessive cyclic loading was proposed.

Simulation of Fatigue Initiation and Non-Self-Similar Fatigue Crack Growth under Mixed Mode I/II Loading

2012 ◽  
Vol 224 ◽  
pp. 303-306
Author(s):  
Chen Chen Ma ◽  
Xiao Gui Wang
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Mixed Mode ◽  
Mode I ◽  
Fatigue Initiation ◽  
Self Similar ◽  
Crack Growth Model

The fatigue initiation and non-self-similar fatigue crack growth behavior of three notched compact tension and shear specimens of 16MnR steel under mixed mode I/II loading were investigated. The plane-stress finite element model with the implemented Armstrong-Frederick type cyclic plasticity model was used to calculate the elastic-plastic stress-strain responses. A recently developed dynamic crack growth model was used to simulate the effects of loading history on the successive crack growth. With the outputted numerical results, a multiaxial fatigue damage criterion based on the critical plane was used to determine the location of fatigue initiation. A formula of fatigue crack growth rate, which is based on the postulation that the fatigue initiation and crack growth have the same damage mechanism, was then used to calculate the transient crack growth rate and determine the non-self-similar crack growth path. The predicted fatigue initiation position, crack path and crack growth rate are in excellent agreement with the experimental data.

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