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 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.

scholarly journals An Analytical Model to Predict Fracture of Off-Axis Unidirectional Composites

2002 ◽  
Vol 11 (5) ◽  
pp. 096369350201100
Author(s):  
J. Petermann ◽  
A. Plumtree ◽  
K. Schulte
Keyword(s):  
Analytical Model ◽  
Stress Component ◽  
Tensile Loading ◽  
Uniaxial Tensile ◽  
Homogeneous Material ◽  
Stress Distributions ◽  
Material Behaviour ◽  
Unidirectional Composites ◽  
Failure Initiation ◽  
Good Agreement

An analytical model based on isotropic homogeneous material behaviour is proposed to predict fracture in unidirectional composites under general loading. The model calculates the internal stress distribution corresponding to the applied load. In conjunction with the respective strength values, the model is capable of assessing the dominant stress component for failure initiation. For uniaxial tensile loading a comparison of calculated analytical stress distributions reasonably agrees with results from FE-analysis. A comparison of the analytical predictions with fractographic results for different off-axis angles provides good agreement.

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.

Failure Analysis of Laminates Single-Lap Adhesive Joints under Uniaxial Tensile Loading

2012 ◽  
Vol 490-495 ◽  
pp. 2201-2204
Author(s):  
Yin Huan Yang
Keyword(s):  
Shear Stress ◽  
Tensile Loading ◽  
Adhesive Joints ◽  
Experimental Results ◽  
Uniaxial Tensile ◽  
Tension Tests ◽  
Different Types ◽  
Uniaxial Tensile Loading ◽  
Overlap Area ◽  
Main Factor

Tension tests on three different types of T700/EXOPY unidirectional laminates single-lap adhesive joints under uniaxial tensile loading were performed and effect of adherend thickness and spew fillets on strength of single-lap adhesive joints were analyzed in this paper. According to the experimental results, it is found that joint strength was not linear with the adherend thickness and much affected by spew fillets in overlap ends. At the same time, finite element simulations are carried out to analyze the peel/shear stress fields along joint interfaces and the intermediate layer of adhesive. The simulation results show that it is the main factor to leading to joint failure that the maximum peel/shear stress is occurred at overlap area edges and peel/shear stress of joints with spew fillet at the overlap area edges is less than that of joints with no spew fillet. Good agreements between the present simulations and the experimental results are found.

scholarly journals Void coalescence and ductile failure in IN718 investigated via high-energy synchrotron X-ray tomography and diffraction

2020 ◽  
Vol 145 ◽  
pp. 104155
Author(s):  
Diwakar P. Naragani ◽  
Jun-Sang Park ◽  
Peter Kenesei ◽  
Michael D. Sangid
Keyword(s):  
Ductile Failure ◽  
High Energy ◽  
Void Coalescence ◽  
X Ray

scholarly journals Finite Fracture Mechanics Assessment in Moderate and Large Scale Yielding Regimes

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 602 ◽  
Author(s):  
Ali Reza Torabi ◽  
Filippo Berto ◽  
Alberto Sapora
Keyword(s):  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Large Scale ◽  
Ductile Failure ◽  
Equivalent Material ◽  
Failure Initiation ◽  
Equivalent Material Concept ◽  
Finite Fracture Mechanics ◽  
Al 7075 ◽  
Scale Yielding

The coupled Finite Fracture Mechanics (FFM) criteria are applied to investigate the ductile failure initiation at blunt U-notched and V-notched plates under mode I loading conditions. The FFM approaches are based on the simultaneous fulfillment of the energy balance and a stress requirement, and they involve two material properties, namely the fracture toughness and the tensile strength. Whereas the former property is obtained directly from experiments, the latter is estimated through the Equivalent Material Concept (EMC). FFM results are presented in terms of the apparent generalized fracture toughness and compared with experimental data already published in the literature related to two different aluminium alloys, Al 7075-T6 and Al 6061-T6, respectively. It is shown that FFM predictions can be accurate even under moderate or large scale yielding regimes.

scholarly journals Experimental Investigation on Flexural Behavior of Granite Stone Slabs with Near Surface Mounted CFRP Bars and Screw-Thread Steels

2018 ◽  
Vol 2018 ◽  
pp. 1-30
Author(s):  
Xiaopeng Gao ◽  
Zhongfan Chen ◽  
Xiaomeng Ding ◽  
Erxiang Dong
Keyword(s):  
Failure Load ◽  
Ductile Failure ◽  
Flexural Behavior ◽  
Screw Thread ◽  
Test Results ◽  
Cracking Behavior ◽  
Near Surface ◽  
Four Point Bending ◽  
Calculation Results ◽  
Near Surface Mounted

An experimental study that investigates the behavior of stone slabs strengthened in fixure with near surface mounted (NSM) technique using screw-thread steels and carbon fiber-reinforced polymer (CFRP) bars is presented. A total of ten full-scale stone slabs were tested under a four-point bending loading to investigate the effect of groove dimension, reinforcement ratios, and reinforcement materials on the flexural performance of stone slabs. The test results included failure characteristics, yield and ultimate capacities, deflection of midspan, and cracking behavior of stone slabs. The test results indicate that with the increase of groove height and groove width, cracking load and middeflection decrease by 6.4%–14.18%; however, failure load and middeflection increase by 4.7%–41.2%. Cracking load, failure load, and failure displacement of stone slabs adopting NSM screw-thread steels increased by 10.9%, 167%, and 617%, respectively, under the maximum reinforcement ratios of 0.629% over the control slab without NSM bars. Meanwhile, with the increase of reinforcement ratios, the failure mode transforms from brittle failure to ductile failure. The calculation results of strength are in agreement with the experimental results. Finally, it can be concluded that NSM CFRP bars are more effective than NSM screw-thread steels to improve flexural capacity with the same reinforcement ratios.

Analysis on the Moment-Curvature Relationship for Prestressed UHPFRC Beams without Stirrup

2011 ◽  
Vol 255-260 ◽  
pp. 236-240
Author(s):  
Sang Mook Han ◽  
Qing Yong Guo
Keyword(s):  
Experimental Data ◽  
Tensile Strength ◽  
Steel Fibre ◽  
Fibre Reinforcement ◽  
Cracking Behavior ◽  
Perfectly Plastic ◽  
History Of ◽  
Elastic Perfectly Plastic ◽  
The Moment ◽  
Good Agreement

To simplify the analysis, an elastic perfectly plastic stress-strain law was presented for UHPFRC. The post-cracking behavior was described by the average constant post-crack tensile strength. A strain parameter μ is proposed to evaluate the performance and efficiency of steel fibre reinforcement. 8 rectangular beams were tested in this investigation. Based on the proposed constitutive model, the full history of their flexural moment-curvature relationship for UHPFRC beams was calculated and compared with experimental data on prestressed UHPFRC beams. Good agreement between calculated strengths and experimental data was obtained.

The Effect of the State of Stress on the Strain at Fracture

1974 ◽  
Vol 96 (3) ◽  
pp. 190-194
Author(s):  
E. A. Davis
Keyword(s):  
Hydrostatic Pressure ◽  
Internal Pressure ◽  
The State ◽  
Tubular Specimen ◽  
State Of Stress ◽  
Tension Tests ◽  
Pressure Tests

Tension tests on solid cylindrical specimens and internal pressure tests on one type of tubular specimen showed that a superimposed hydrostatic pressure increased the ductility. Internal pressure tests on a similar tubular specimen that was supported in a different manner showed that the hydrostatic pressure had almost no effect on the ductility.

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