Evolution of the Stress-Induced Magnetic Field of Pipeline Steel due to Fatigue Loading

2019 ◽  
Author(s):  
Sheng Bao ◽  
Zhengye Zhao ◽  
Qiang Luo ◽  
Yibin Gu
Keyword(s):  
Magnetic Field ◽  
Fatigue Life ◽  
Pipeline Steel ◽  
Fatigue Loading ◽  
Fatigue Tests ◽  
X80 Pipeline Steel ◽  
Three Stages ◽  
Loading And Unloading ◽  
Magnetic Field Variations ◽  
The Magnetic Field

Abstract The objective of this research is to explore the correlation between piezomagnetic fields and cyclic loading in X80 pipeline steel. A series of stress-controlled fatigue tests were carried out, and the magnetic field variations were recorded simultaneously during the whole loading process. The results demonstrate that the fatigue life of the investigated steel can be divided into three stages. The reversal points that appear during the loading and unloading processes can be used as new parameters to reflect the fatigue state and estimate the fatigue life.

Experimental Analysis of Ratcheting Failure Based on the Piezomagnetic Response of X80 Pipeline Steel

2017 ◽  
Author(s):  
Sheng Bao ◽  
Shengnan Hu ◽  
Yibin Gu
Keyword(s):  
Magnetic Field ◽  
Hysteresis Loop ◽  
Mechanical Response ◽  
Pipeline Steel ◽  
Failure Process ◽  
Failure Behavior ◽  
X80 Pipeline Steel ◽  
Test Analysis ◽  
Number Of Cycles ◽  
The Magnetic Field

The objective of this research is to explore the correlation between the piezomagnetic response and ratcheting failure behavior under asymmetrical cyclic stressing in X80 pipeline steel. The magnetic field variations from cycle to cycle were recorded simultaneously during the whole-life ratcheting test. Analysis made in the present work shows that the piezomagnetic hysteresis loop evolves systematically with the number of cycles in terms of its shape and position. Corresponding to the three-stage process in the mechanical response, piezomagnetic response can also be divided into three principal stages, but the evolution of magnetic parameter is more complex. Furthermore, the loading branch and unloading branch of the magnetic field-stress hysteresis loop separate gradually from each other during ratcheting failure process, leading to the shape of hysteresis loop changes completely. Therefore, the progressive degradation of the steel under ratcheting can be tracked by following the evolution of the piezomagnetic field. And the shape transition of the hysteresis loop can be regarded as an early warning of the ratcheting failure.

Study on the Piezomagnetic Response to Low-Cycle Fatigue of X80 Pipeline Steel

2016 ◽  
Author(s):  
Sheng Bao ◽  
Shengnan Hu ◽  
Meili Fu ◽  
Huangjie Lou
Keyword(s):  
Pipeline Steel ◽  
Low Cycle Fatigue ◽  
Fatigue Loading ◽  
Degradation Process ◽  
Fatigue Tests ◽  
Stable Phase ◽  
X80 Pipeline Steel ◽  
Steady Stage ◽  
Initial Stage ◽  
Microstructural Condition

The objective of this work is to explore the relationship between the progressive material degradation process of fatigue and the evolution of the piezomagnetic field surrounding a ferromagnetic sample. The continuous examination of changes in the magnetomechanical behavior during a series of strain-controlled fatigue tests was performed on X80 pipeline steel samples. Analysis of the data obtained allowed the division of the fatigue life of the investigated steel into three stages: incipient stage, steady stage and terminal stage. Furthermore, the piezomagnetic field evolution demonstrates conspicuous changes in the initial stage of fatigue loading, then reverts to a relatively stable phase, and finally, drastic variations appear again before terminal failure. The progressive degradation of the steel under cyclic loading can therefore be tracked by following the evolution of the piezomagnetic field. The characteristics of the evolution of the piezomagnetic responses are also discussed in terms of the mechanical and microstructural condition of the steel during the fatigue process.

The effect of repetitive magnetic and cyclic loading on the fatigue life prediction of a magnetorheological elastomer

2021 ◽  
pp. 009524432110386
Author(s):  
Seyyed Mohammad Hosseini ◽  
Mohammad Hassan Shojaeefard ◽  
Hamed Saeidi Googarchin
Keyword(s):  
Magnetic Field ◽  
Fatigue Life ◽  
Cyclic Loading ◽  
Maximum Stress ◽  
Fatigue Testing ◽  
Testing Machine ◽  
Fatigue Tests ◽  
Magnetorheological Elastomer ◽  
Hyper Elastic ◽  
The Magnetic Field

Prediction of fatigue life is particularly crucial in magnetorheological elastomer (MRE) based rubber components, especially when are exposed to repetitive magnetic and cyclic loading. MREs are smart composites that contain soft elastomer matrix and carbonyl iron particles (CIPs). In this research, silicon rubber was mixed with 20% of CIPs in the absence of an external magnetic field to produce MREs. Firstly, for the determination of material constants (including hyper elastic, magnetic, and viscoelastic), two types of tests such as uniaxial compression and relaxation, were performed on the samples. Then, fatigue tests were performed by a servo-hydraulic fatigue testing machine with cyclic loading in a repetitive magnetic field. Fatigue equations were obtained based on the number of fatigue life and maximum stress. The results confirmed that maximum stress could be used as a trustworthy fatigue life predictor for MREs when they are subjected to a combination of repetitive magnetic and cyclic loading. Scanning electron microscopy images from fatigue crack showed that the internal structure of MREs became stronger in the direction of the magnetic field. The maximum stress of the MRE was smaller in the absence of a magnetic field and decreased as the number of fatigue cycles increased with and without the magnetic field.

A Study of Nozzles in Pressure Vessels under Pressure Fatigue Loading

1967 ◽  
Vol 182 (1) ◽  
pp. 657-684 ◽  
Author(s):  
J. Spence ◽  
W. B. Carlson
Keyword(s):  
Fatigue Life ◽  
Mild Steel ◽  
Pressure Vessel ◽  
Special Interest ◽  
Maximum Stress ◽  
Fatigue Loading ◽  
Fatigue Tests ◽  
Pressure Vessels ◽  
Full Size

Nozzles in cylindrical vessels have been of special interest to designers for some time and have offered a field of activity for many research workers. This paper presents some static and fatigue tests on five designs of full size pressure vessel nozzles manufactured in two materials. Supporting and other published work is reviewed showing that on the basis of the same maximum stress mild steel vessels give the same fatigue life as low alloy vessels. When compared on the basis of current codes it is shown that mild steel vessels may have five to ten times the fatigue life of low alloy vessels unless special precautions are taken.

A two-dimensional analysis of the compressible flow near a reconnection site at the dayside magnetopause

2007 ◽  
Vol 73 (1) ◽  
pp. 89-115 ◽  
Author(s):  
LARS G. WESTERBERG ◽  
HANS O. ÅKERSTEDT
Keyword(s):  
Magnetic Field ◽  
Transition Layer ◽  
Alfven Wave ◽  
The North ◽  
Dayside Magnetopause ◽  
Reconnection Site ◽  
Ideal Magnetohydrodynamic ◽  
North And South ◽  
Magnetic Field Variations ◽  
The Magnetic Field

Abstract.A compressible model of the magnetosheath plasma flow is considered. Magnetic reconnection is assumed to occur in a region stretching from the sub-Solar point to the north. Two locations of the reconnection site are treated: two and four Earth radii from the sub-Solar point, respectively. By treating the transition layer as very thin, we solve the governing equations approximately using the method of matched asymptotic expansions. The behavior of the magnetic field and the plasma velocity close to a reconnection site during the transition from the magnetosheath to the magnetosphere is investigated. We also obtain the development of the transition layer thickness north and south of the reconnection point. The magnetopause transition layer is represented by a large-amplitude Alfvén wave implying that the density is approximately the same across the magnetopause boundary. In order to match the solutions we consider a compressible ideal magnetohydrodynamic model describing density, velocity and magnetic field variations along the outer magnetopause boundary. We also compare the analytical results with solutions from a numerical simulation. The compressible effects on the structure of the magnetic field and the total velocity evolution are visible but not dramatic. It is shown that the transition layer north of the reconnection point is thinner than to the south. The effect is stronger for reconnection at higher latitudes.

SEM In Situ Investigation on Fatigue Cracking Behavior of X80 Pipeline Steel with Inclusions

2011 ◽  
Vol 284-286 ◽  
pp. 1096-1100 ◽  
Author(s):  
Ke Tong ◽  
Yan Ping Zeng ◽  
Xin Li Han ◽  
Yao Rong Feng ◽  
Xiao Dong He
Keyword(s):  
Crack Initiation ◽  
Pipeline Steel ◽  
Fatigue Cracking ◽  
Fatigue Loading ◽  
In Situ Observation ◽  
X80 Pipeline Steel ◽  
Cracking Behavior ◽  
The Matrix ◽  
Extension Period

The micro-mechanical behavior of inclusions in X80 pipeline steel under fatigue loading was investigated by means of SEM in situ observation. The influence of sizes and shapes of inclusion on crack initiation and propagation was analyzed. The result shows that for large-size single-particle inclusion, cracks initiate from the interior under the fatigue loading. When a certain circulation cycles are reached, cracks initiate at the matrix near the sharp corner of the inclusion. The cracks extend at the matrix during the stable extension period and unstable extension period following the crack initiation, until fracture occurred. For chain inclusion, cracks first initiate at the interface between inclusion and matrix within the chain area, and the circulation cycles needed for initiation are far less than single inclusion. Cracks steadily extend after the initiation, and then fracture after very short circulation cycles. A chain of inclusion with the shape corners is serious harmful to the fatigue properties.

scholarly journals Global properties of magnetotail current sheet flapping: THEMIS perspectives

2009 ◽  
Vol 27 (1) ◽  
pp. 319-328 ◽  
Author(s):  
A. Runov ◽  
V. Angelopoulos ◽  
V. A. Sergeev ◽  
K.-H. Glassmeier ◽  
U. Auster ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Growth Phase ◽  
Timing Analysis ◽  
Wave Length ◽  
Global Properties ◽  
The Cross ◽  
Magnetic Field Variations ◽  
The Magnetic Field ◽  
Magnetotail Current Sheet

Abstract. A sequence of magnetic field oscillations with an amplitude of up to 30 nT and a time scale of 30 min was detected by four of the five THEMIS spacecraft in the magnetotail plasma sheet. The probes P1 and P2 were at X=−15.2 and −12.7 RE and P3 and P4 were at X=−7.9 RE. All four probes were at −6.5>Y>−7.5 RE (major conjunction). Multi-point timing analysis of the magnetic field variations shows that fronts of the oscillations propagated flankward (dawnward and Earthward) nearly perpendicular to the direction of the magnetic maximum variation (B1) at velocities of 20–30 km/s. These are typical characteristics of current sheet flapping motion. The observed anti-correlation between ∂B1/∂t and the Z-component of the bulk velocity make it possible to estimate a flapping amplitude of 1 to 3 RE. The cross-tail scale wave-length was found to be about 5 RE. Thus the flapping waves are steep tail-aligned structures with a lengthwise scale of >10 RE. The intermittent plasma motion with the cross-tail velocity component changing its sign, observed during flapping, indicates that the flapping waves were propagating through the ambient plasma. Simultaneous observations of the magnetic field variations by THEMIS ground-based magnetometers show that the flapping oscillations were observed during the growth phase of a substorm.

scholarly journals Effect of UV Ageing on the fatigue life of bulk polyethylene

2018 ◽  
Vol 165 ◽  
pp. 08002 ◽  
Author(s):  
Hamza Lamnii ◽  
Moussa Nait-Abdelaziz ◽  
Georges Ayoub ◽  
Jean-Michel Gloaguen ◽  
Ulrich Maschke ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Uv Irradiation ◽  
Chemical Structure ◽  
Fatigue Behavior ◽  
Crystalline Polymer ◽  
Fatigue Loading ◽  
Chain Scission ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Irradiation Effect

Polymers operating in various weathering conditions must be assessed for lifetime performance. Particularly, ultraviolet (UV) radiations alters the chemical structure and therefore affect the mechanical and fatigue properties. The UV irradiation alters the polymer chemical structure, which results into a degradation of the mechanical and fatigue behavior of the polymer. The polymer properties degradation due to UV irradiation is the result of a competitive process of chain scission versus post-crosslinking. Although few studied investigated the effect of UV irradiation on the mechanical behaviour of thermoplastics, fewer examined the UV irradiation effect on the fatigue life of polymers. This study focuses on investigating the effect of UV irradiation on the fatigue properties of bulk semi-crystalline polymer; the low density Polyethylene (LDPE). Tensile specimens were exposed to different dose values of UV irradiation then subjected to fatigue loading. The fatigue tests were achieved under constant stress amplitude at a frequency of 1Hz. The results show an important decrease of the fatigue limit with increasing absorbed UV irradiation dose.

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