scholarly journals Criterion for Ductile Cracking of Structural Steel under Cyclic Loading-Evaluation of Ductile Crack Initiation for Welded Structures Subjected to Large Scale Cyclic Loading (Report 1)-

2003 ◽  
Vol 21 (4) ◽  
pp. 592-602 ◽  
Author(s):  
Mitsuru OHATA ◽  
Masaki YOKOTA ◽  
Masahiko HIRONO ◽  
Osamu YASUDA ◽  
Masao TOYODA
Keyword(s):  
Cyclic Loading ◽  
Crack Initiation ◽  
Structural Steel ◽  
Large Scale ◽  
Ductile Crack ◽  
Welded Structures

Application of Equivalent Damage Concept to Evaluation of Ductile Cracking for Linepipe Under Large Scale Seismic Loading

2003 ◽  
Author(s):  
Mitsuru Ohata ◽  
Masao Toyoda
Keyword(s):  
Cyclic Loading ◽  
Crack Initiation ◽  
Safety Assessment ◽  
Large Scale ◽  
Seismic Loading ◽  
Steel Pipe ◽  
Small Scale ◽  
Ductile Crack ◽  
Hardening Material ◽  
Cyclic Straining

A large scale seismic loading sometimes produces local buckling in onshore or offshore linepipe and subsequent loading can lead to ductile cracking followed by ductile failure. It is important to assess the ductile crack initiation of linepipe subjected to a large scale cyclic straining induced by seismic loading for safety assessment of linepipe. This paper is mainly paid attention to the applicability of the damage concept proposed by authors for evaluation of ductile cracking of steel pipe under large scale cyclic loading. The damage concept is based on the “two-parameter criterion”, using the effective plastic strain, which is taken into account mechanical and microstructural aspects of Bauschinger effect of steel. The transferability of small scale tensile test results to the assessment of ductile crack initiation of steel pipe under seismic loading by using the effective damage concept is verified by conducting cyclic bending tests for straight pipe with initial deflection. The effective damage strain under cyclic loading, which is derived from the evolution of back stress, was calculated by FE-analysis employing a combined (isotropic/kinematic) hardening material model. It is found that the critical safety assessment of ductile crack initiation can be conducted based on the strain-based criterion in accordance with the proposed damage concept.

scholarly journals Ductile Crack Initiation Behavior of Structural Steel under Cyclic Loading

1999 ◽  
Vol 85 (1) ◽  
pp. 71-77 ◽  
Author(s):  
Nobuyuki ISHIKAWA ◽  
Yasuo KOBAYASHI ◽  
Masayoshi KURIHARA ◽  
Koichi OSAWA ◽  
Masao TOYODA
Keyword(s):  
Cyclic Loading ◽  
Crack Initiation ◽  
Structural Steel ◽  
Ductile Crack

Design of crack arrestors for ultra high grade gas transmission pipelines: simulation of crack initiation, propagation and arrest

2011 ◽  
Vol 2 (2) ◽  
pp. 307-319
Author(s):  
F. Van den Abeele ◽  
M. Di Biagio ◽  
L. Amlung
Keyword(s):  
Crack Initiation ◽  
Crack Propagation ◽  
Large Scale ◽  
Large Diameter ◽  
Pipe Material ◽  
High Grade ◽  
Gas Pipelines ◽  
Ductile Crack ◽  
Reinforced Plastics ◽  
Four Point Bending

One of the major challenges in the design of ultra high grade (X100) gas pipelines is the identification of areliable crack propagation strategy. Recent research results have shown that the newly developed highstrength and large diameter gas pipelines, when operated at severe conditions, may not be able to arrest arunning ductile crack through pipe material properties. Hence, the use of crack arrestors is required in thedesign of safe and reliable pipeline systems.A conventional crack arrestor can be a high toughness pipe insert, or a local joint with higher wall thickness.According to experimental results of full-scale burst tests, composite crack arrestors are one of the mostpromising technologies. Such crack arrestors are made of fibre reinforced plastics which provide the pipewith an additional hoop constraint. In this paper, numerical tools to simulate crack initiation, propagationand arrest in composite crack arrestors are introduced.First, the in-use behaviour of composite crack arrestors is evaluated by means of large scale tensile testsand four point bending experiments. The ability of different stress based orthotropic failure measures topredict the onset of material degradation is compared. Then, computational fracture mechanics is applied tosimulate ductile crack propagation in high pressure gas pipelines, and the corresponding crack growth inthe composite arrestor. The combination of numerical simulation and experimental research allows derivingdesign guidelines for composite crack arrestors.

A Strain Based Criterion to Evaluate the Tensile Capacity of Transmission Pipelines Under Large Scale Cyclic Bending

2018 ◽  
Author(s):  
Y. Andrés Plata Uribe ◽  
Claudio Ruggieri
Keyword(s):  
Structural Steel ◽  
Large Scale ◽  
Axial Loading ◽  
Tensile Failure ◽  
Void Coalescence ◽  
Ductile Crack ◽  
Tubular Specimen ◽  
Pipe Surface ◽  
Cracking Behavior ◽  
Tension Tests

This study explores the capability of a computational cell methodology and a stress-modified, critical strain (SMCS) criterion for void coalescence implemented into a large scale, 3-D finite element framework to model ductile fracture behavior in tensile specimens and in damaged pipelines. In particular, the cell methodology provides a convenient approach for ductile crack extension suitable for large scale numerical analyses which includes a damage criterion and a microstructural length scale over which damage occurs. A series of tension tests conducted on notched tensile specimens with different notch radius for a carbon steel pipe provides the stress-strain response of the tested structural steel from which the cell parameters and the SMCS criterion are calibrated. To investigate ductile cracking behavior in damaged pipelines, full scale cyclic bend tests were performed on a 165 mm O.D tubular specimen with 11 mm wall thickness made of a pipeline steel with very similar mechanical characteristics to the structural steel employed in the tension tests. The tubular specimen was initially subjected to indentation by 3-point bend loading followed by a compressive axial loading to generate large localized buckling in the dented region. The axial loading was then reversed to a tension loading applied until a visible ductile crack could be observed in the pipe surface. These exploratory analyses predict the tensile failure load for the pipe specimen associated with ductile crack initiation in the highly damaged area inside the denting and buckling zone which is in good agreement with experimental measurements.

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.

Crack Initiation and Propagation Clad Pipe Girth Weld Flaws

2014 ◽  
Author(s):  
Antonio Carlucci ◽  
Nicola Bonora ◽  
Andrew Ruggiero ◽  
Gianluca Iannitti ◽  
Gabriel Testa
Keyword(s):  
Crack Initiation ◽  
Large Scale ◽  
Damage Mechanics ◽  
High Fracture Toughness ◽  
Model Parameters ◽  
Equivalent Material ◽  
Ductile Crack ◽  
Crack Initiation And Propagation ◽  
Brittle Ductile Transition ◽  
Initiation And Propagation

At present, design standards and prescriptions do not provide specific design routes to perform engineering criticality assessment (ECA) of bimetallic girth welds. Although the authors has shown the possibility to implement ECA in accordance with available prescriptions of such flawed weld joint following the equivalent material method (EMM), when dealing with ductile crack initiation and propagation — as a result of the large scale yielding occurring at the crack tip for high fracture toughness material operating in the brittle-ductile transition region — fracture mechanics concepts such as JIc or critical CTOD may breakdown. In this work, the possibility to accurately determine the condition for ductile crack growth initiation and propagation in bi-metallic girth weld flaws using continuum damage mechanics is shown. Here, the base metal as well as the clad and the weld metal have been characterized to determine damage model parameters. Successively, the geometry transferability of model parameters has been validated. Finally, the model has been used to predict crack initiation for two bi-material interface circumferential crack configurations.

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