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.

A strain based criterion to assess ductile failure initiation in dented pipelines under tensile loading

2020 ◽  
pp. 030932472097527
Author(s):  
Yerlin Andres Plata Uribe ◽  
Claudio Ruggieri ◽  
Mitsuru Ohata
Keyword(s):  
Ductile Failure ◽  
Tensile Loading ◽  
Tensile Failure ◽  
Void Coalescence ◽  
Tubular Specimen ◽  
Cracking Behavior ◽  
Failure Initiation ◽  
Tension Tests ◽  
Bend Tests ◽  
Good Agreement

This work addresses the problem of describing ductile fracture behavior and predicting ductile failure initiation in dented pipelines under tensile loading based upon a 3-D computational cell approach coupled with a stress-modified, critical strain (SMCS) criterion for void coalescence. 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 SMCS criterion is calibrated. Full scale cyclic bend tests also performed on a 165 mm O.D tubular specimen with 11 mm wall thickness enable verification of the proposed approach in assessing ductile cracking behavior in damaged pipelines. 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 are in good agreement with experimental measurements.

A Micromechanics Approach to Assess Ductile Crack Initiation in Damaged Pipelines

2003 ◽  
Author(s):  
Claudio Ruggieri ◽  
Fernando F. Santos ◽  
Mitsuru Ohata ◽  
Masao Toyoda
Keyword(s):  
Ductile Fracture ◽  
Large Scale ◽  
Cell Model ◽  
High Strength ◽  
Void Coalescence ◽  
Model Parameters ◽  
Ductile Crack ◽  
Cracking Behavior ◽  
Damage Criterion ◽  
Limited Applicability

This study explores the capabilities of a computational cell framework into a 3-D setting to model ductile fracture behavior in tensile specimens and damaged pipelines. 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. Laboratory testing of a high strength structural steel provides the experimental stress-strain data for round bar and circumferentially notched tensile specimens to calibrate the cell model parameters for the material. The present work applies the cell methodology using two damage criterion to describe ductile fracture in tensile specimens: (1) the Gurson-Tvergaard (GT) constitutive model for the softening of material and (2) the stress-modified, critical strain (SMCS) criterion for void coalescence. These damage criteria are then applied to predict ductile cracking for a pipe specimen tested under cycling bend loading. While the methodology still appears to have limited applicability to predict ductile cracking behavior in pipe specimens, the cell model predictions of the ductile response for the tensile specimens show good agreemeent with experimental measurements.

scholarly journals Stress–strain relationship model of glulam bamboo under axial loading

2020 ◽  
Vol 29 ◽  
pp. 2633366X2095872
Author(s):  
Yang Wei ◽  
Mengqian Zhou ◽  
Kunpeng Zhao ◽  
Kang Zhao ◽  
Guofen Li
Keyword(s):  
Tensile Stress ◽  
Compressive Stress ◽  
Failure Modes ◽  
Axial Loading ◽  
Tensile Failure ◽  
Stress Strain ◽  
Laminated Bamboo ◽  
Bamboo Scrimber ◽  
Strain Relationship ◽  
Strain Model

Glulam bamboo has been preliminarily explored for use as a structural building material, and its stress–strain model under axial loading has a fundamental role in the analysis of bamboo components. To study the tension and compression behaviour of glulam bamboo, the bamboo scrimber and laminated bamboo as two kinds of typical glulam bamboo materials were tested under axial loading. Their mechanical behaviour and failure modes were investigated. The results showed that the bamboo scrimber and laminated bamboo have similar failure modes. For tensile failure, bamboo fibres were ruptured with sawtooth failure surfaces shown as brittle failure; for compression failure, the two modes of compression are buckling and compression shear failure. The stress–strain relationship curves of the bamboo scrimber and laminated bamboo are also similar. The tensile stress–strain curves showed a linear relationship, and the compressive stress–strain curves can be divided into three stages: elastic, elastoplastic and post-yield. Based on the test results, the stress–strain model was proposed for glulam bamboo, in which a linear equation was used to describe the tensile stress–strain relationship and the Richard–Abbott model was employed to model the compressive stress–strain relationship. A comparison with the experimental results shows that the predicted results are in good agreement with the experimental curves.

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.

Feasibility Study on Fabrication of Large-Scale Offshore Structural Steel Component Using Laam Technology

2021 ◽  
Author(s):  
Youxiang Chew ◽  
Joo Hong Ang ◽  
Sastry Yagnanna Kandukuri ◽  
Da Qin Xu ◽  
Simon Sow Hong Kuik ◽  
...  
Keyword(s):  
Structural Steel ◽  
Feasibility Study ◽  
Large Scale ◽  
Steel Component

STYLE: Modelling of the Extraction of Bend Specimens From Repair Weld and the Influence of Residual Stress on Fracture Testing

2014 ◽  
Author(s):  
Peter James ◽  
Mike Ford
Keyword(s):  
Residual Stress ◽  
Crack Growth ◽  
Large Scale ◽  
Crack Depth ◽  
Compact Tension ◽  
Materials Testing ◽  
Ductile Crack ◽  
Local Approach ◽  
Ductile Crack Growth ◽  
Low Constraint

Within the EU 7th framework programme, STYLE, a number of large-scale tests have been performed. One of these tests, Mock-Up 2 (MU-2), was performed on a through wall crack located at a repair weld adjacent to a multi-pass narrow-gap weld. The aim of MU-2 was to investigate ductile crack growth under conditions with significant levels of residual stress. As part of the materials testing programme, low-constraint fracture specimens (three-point bend specimens with a/t=0.1) were extracted from the weld to test the weld materials fracture toughness. An overview of these tests is provided here. However, these low constraint tests demonstrated somewhat unusual fatigue crack growth on inserting the crack, leading to the crack depth being shorter in the centre of the specimens to the outside. Subsequently, although it has not been possible to use these specimens to determine the materials J-R curve, it does provide a features test for ductile modelling with the Gurson-Tvergaard-Needleman (GTN) local approach model for ductile crack growth. This paper provides an overview of the modelling associated to understand these observations, including an estimate of the retained residual stress, fatigue growth estimates and subsequent ductile modelling. An overview of the calibration of the GTN model is also provided using the weld material’s tensile tests, high constraint compact-tension tests and MU-2.

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.

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