The Strain Concentration of High Strength Girth Weld Subjected to Tensile Displacement

2019 ◽  
Author(s):  
Jian Shuai ◽  
Yinhui Zhang ◽  
Zhiyang Lv ◽  
Yaodong Shuai
Keyword(s):  
Constitutive Relations ◽  
High Strength ◽  
Element Model ◽  
Tensile Tests ◽  
Ground Movement ◽  
Mountainous Area ◽  
Strain Concentration ◽  
Strain Capacity ◽  
Inner Pressure ◽  
Weld Area

Abstract High grade pipelines have been the majority in China since the beginning of this century. Some pipelines in mountainous area and other places experienced the ground movement because of geohazards and the disturb of construction activities. The strain capacity is important to keep pipelines subjected to tensile displacement in safe. However, the strain capacity does not depend on the pipe body but on the girth weld because the girth weld is always non-homogeneous. The strain concentration may happen where material yields in advance. Therefore, the strength matching of the girth weld towards pipe body can greatly affects strain capacity of pipelines. Generally, girth weld is designed to over-matching to prevent the strain concentration. However, in pipeline engineering, actual strength of pipe body may be much higher than the specified minimum yield stress, leading the girth weld to be under-matching in fact. In addition, even in over-matching girth weld, there may be softening zone in HAZ. In this paper, the tensile tests of X80 girth weld were performed. Local constitutive relations at the weld, pipe body and HAZ were obtained by using the whole field strain on the specimens. The experiment showed under-matching in the specimen. Based on the results of local constitutive properties of the specimen, the finite element model of X80 pipeline girth weld subjected to tensile strain and inner pressure was established. It demonstrated that strain concentration happened in weld area in under-matching girth weld and softening zone in over-matching girth weld. Inner pressure has an impact on strain concentration in a case that strain exceed the certain limit.

Enhancing Tensile Strain Capacity Through the Optimization of Weld Profiles

2014 ◽  
Author(s):  
Yong-Yi Wang ◽  
Yaoshan Chen ◽  
Mamdouh Salama
Keyword(s):  
Tensile Strain ◽  
High Strength Steels ◽  
High Strength ◽  
Recent Analysis ◽  
Strain Concentration ◽  
Strain Capacity ◽  
Weld Defects ◽  
Weld Region ◽  
Girth Welds ◽  
Tensile Strain Capacity

In order to optimize cost and performance of high pressure gas pipelines by reducing the wall thickness, pipeline companies are considering the use of higher grade (X70 or above) steels or a composite pipe of thin steel liner and fiber wrap. The use of high strength steels and thinner pipes can result in challenges when the pipe is installed in areas imposing high strain demand such as discontinuous permafrost regions. For high strength steels, the difficulty of ensuring the strength overmatching of the weld metal and the potential softening of the heat affected zone (HAZ) can result in gross strain concentration in the weld region and thus reduce the strain capacity of the pipeline in the presence of weld defects. Also, a thinner pipe has lower strain capacity than a thicker pipe for the weld defect of the same dimensions. One of the economical and effective ways of mitigating the possibility of gross strain concentration and increasing the strain capacity of a weld region containing weld defects is through the use of appropriate weld profiles. For instance, adding a smooth and wide layer of weld reinforcement (termed weld overbuild) can increase the effective strength of the weld. The effectiveness of the weld overbuild in improving the tensile strain capacity of girth welds is evaluated using the Level 4a approach of the PRCI-CRES tensile strain models. The crack-driving force is obtained through finite element analysis (FEA) of welds with planar weld and HAZ flaws of various sizes. It was demonstrated that weld overbuild with appropriate dimensions is an effective method to increase the tensile strain capacity (TSC) of girth welds which may have limited TSC without the overbuild. The role of weld profiles in girth weld integrity is discussed from the perspectives of historical evidence and more recent analysis and experimental tests.

Evaluation of Compressive Strain Limit of X80 Saw Pipes With Girth Welding by FE Analysis

2010 ◽  
Author(s):  
Hidenori Shitamoto ◽  
Masahiko Hamada ◽  
Shuji Okaguchi ◽  
Nobuaki Takahashi ◽  
Izumi Takeuchi ◽  
...  
Keyword(s):  
High Pressure ◽  
Natural Gas ◽  
High Strength ◽  
Environmental Conservation ◽  
Ground Movement ◽  
Bending Test ◽  
Line Pipe ◽  
Strain Capacity ◽  
Girth Welding ◽  
Transmission Pipelines

The expansion of supply capacity of natural gas to market is expected from the concern of environmental conservation by less CO2 emission. Transportation cost has been focused for natural gas to be competitive in the market. High-pressure gas pipelines have constructed by large diameter and high strength line pipes to improve transportation efficiency of gas transmission pipelines. High strength line pipes have been developed to cope with high-pressure operation. Strength in circumferential direction on line pipe is the prime target to hold high pressure safely. In terms of pipe size, pipe diameter has been increased to lead larger D/t. Both of higher strength and larger D/t result in less favorable to deformability of pipeline. To apply strain based design to pipeline, the evaluation of strain capacity, which is related to deformability of line pipe, is required supposing the pipeline encounters large scale ground movement such as earthquake or landslide. It is not simple to find the criteria to prevent leak or rupture of pipeline in such events, as not only pipe property but also interaction between pipe and soil are needed to consider. Gas transmission pipelines are constructed by joint girth welding. The strain capacity of pipeline with girth weld has to be investigated for strain based design. Full scale bending test of joint welded pipe was conducted and FEA model to assess strain capacity of pipeline with girth weld is developed.

scholarly journals Experimental and numerical investigation of the effect of holes on the springback in cold roll forming of UHSS

2021 ◽  
Author(s):  
Zhi-min Liu ◽  
Pan Zhang ◽  
xiaoli liu ◽  
ming zhang ◽  
qiang ma ◽  
...  
Keyword(s):  
Finite Element ◽  
Elastic Modulus ◽  
Finite Element Model ◽  
High Strength ◽  
Element Model ◽  
Tensile Tests ◽  
Roll Forming ◽  
Cold Roll Forming ◽  
Cold Roll ◽  
Forming Precision

Abstract Ultra-high strength steel (UHSS) pre-notched sections are getting growing popularity in the automotive industry with the development of automotive lightweight. However, the springback of UHSS products is large, and the existence of holes also has an effect on the springback. Accurate prediction of springback of UHSS pre-notched products in cold roll forming ( CRF ) is a key issue to be solved. In this paper, the effect of holes on the springback of UHSS in CRF is discussed by simulation and experiment. The finite element model of pre-notched car threshold was constructed, and its accuracy was validated by continuous CRF experiment. The mathematical model of variable elastic modulus determined by tensile tests of martensite (MS) 1300 was applied in finite element model. The accuracy of springback was improved by 15% in the hole region by using variable elastic modulus . Several forming schemes were designed to research the effect of different features on the springback in the hole region. The results show that the existence of holes reduces the springback and the effect is different at different positions of the car threshold. The springback in the hole region decreases with the increase of the number of stands, the strip thickness and the hole diameter, and with the decrease of the distance between stands and the distance between holes. This study provides a help for reducing the influence of holes on the springback and improving the forming precision of pre-notched sections in the actual production of CRF.

Production of Grade X80 High Strain Linepipes for Seismic Region Application

2010 ◽  
Author(s):  
Ryuji Muraoka ◽  
Joe Kondo ◽  
Lingkang Ji ◽  
Hongyuan Chen ◽  
Yaorong Feng ◽  
...  
Keyword(s):  
High Strain ◽  
Uniform Elongation ◽  
High Strength ◽  
Longitudinal Direction ◽  
Full Scale ◽  
Ground Movement ◽  
Long Distance ◽  
Seismic Region ◽  
Strain Capacity ◽  
Pipe Bending

In order to achieve safety and reliability of long-distance gas transmission pipeline installed in seismic region while obtaining economical benefit by reducing material and construction cost, it is essential to apply the high-strength linepipes with sufficient strain capacity against buckling and weld fracture by seismic ground movement. At the same time, it is quite important to develop appropriate material requirement for strain capacity depending on the pipe dimension and strain demand of the region where the pipeline is installed. Grade X80 heavy gauge linepipes with excellent deformability were mass produced by applying advanced plate manufacturing technologies. These linepipes exhibit low Y/T and high uniform elongation in the longitudinal direction even after pipe coating. Strain capacity of the pipe against bending deformation with internal pressure was verified by conducting full scale pipe bending testing. In this paper, production results of high strain X80 linepipes for the application in long-distance pipelines in seismic region and full scale pipe bending and hydraulic burst test results were introduced.

scholarly journals Internal Force on and Deformation of Steel Assembled Supporting Structure of Foundation Pit under Thermal Stress

2021 ◽  
Vol 11 (5) ◽  
pp. 2225
Author(s):  
Fu Wang ◽  
Guijun Shi ◽  
Wenbo Zhai ◽  
Bin Li ◽  
Chao Zhang ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Bending Moment ◽  
High Strength ◽  
Element Model ◽  
Internal Force ◽  
Foundation Pit ◽  
Dimensional Finite Element ◽  
Influence Of Temperature On ◽  
Scale Experiment ◽  
Three Dimensional Finite Element

The steel assembled support structure of a foundation pit can be assembled easily with high strength and recycling value. Steel’s performance is significantly affected by the surrounding temperature due to its temperature sensitivity. Here, a full-scale experiment was conducted to study the influence of temperature on the internal force and deformation of supporting structures, and a three-dimensional finite element model was established for comparative analysis. The test results showed that under the temperature effect, the deformation of the central retaining pile was composed of rigid rotation and flexural deformation, while the adjacent pile of central retaining pile only experienced flexural deformation. The stress on the retaining pile crown changed little, while more stress accumulated at the bottom. Compared with the crown beam and waist beam 2, the stress on waist beam 1 was significantly affected by the temperature and increased by about 0.70 MPa/°C. Meanwhile, the stress of the rigid panel was greatly affected by the temperature, increasing 78% and 82% when the temperature increased by 15 °C on rigid panel 1 and rigid panel 2, respectively. The comparative simulation results indicated that the bending moment and shear strength of pile 1 were markedly affected by the temperature, but pile 2 and pile 3 were basically stable. Lastly, as the temperature varied, waist beam 2 had the largest change in the deflection, followed by waist beam 1; the crown beam experienced the smallest change in the deflection.

scholarly journals Heat Treatment Design for a QP Steel: Effect of Partitioning Temperature

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1136
Author(s):  
Marcel Carpio ◽  
Jessica Calvo ◽  
Omar García ◽  
Juan Pablo Pedraza ◽  
José María Cabrera
Keyword(s):  
Retained Austenite ◽  
High Strength Steels ◽  
High Strength ◽  
Tensile Tests ◽  
Quenching Temperature ◽  
Advanced High Strength Steels ◽  
New Family ◽  
Automotive Parts ◽  
Fresh Martensite ◽  
Industry Needs

Designing a new family of advanced high-strength steels (AHSSs) to develop automotive parts that cover early industry needs is the aim of many investigations. One of the candidates in the 3rd family of AHSS are the quenching and partitioning (QP) steels. These steels display an excellent relationship between strength and formability, making them able to fulfill the requirements of safety, while reducing automobile weight to enhance the performance during service. The main attribute of QP steels is the TRIP effect that retained austenite possesses, which allows a significant energy absorption during deformation. The present study is focused on evaluating some process parameters, especially the partitioning temperature, in the microstructures and mechanical properties attained during a QP process. An experimental steel (0.2C-3.5Mn-1.5Si (wt%)) was selected and heated according to the theoretical optimum quenching temperature. For this purpose, heat treatments in a quenching dilatometry and further microstructural and mechanical characterization were carried out by SEM, XRD, EBSD, and hardness and tensile tests, respectively. The samples showed a significant increment in the retained austenite at an increasing partitioning temperature, but with strong penalization on the final ductility due to the large amount of fresh martensite obtained as well.

scholarly journals Experimental and Numerical Investigation on the Perforation Resistance of Double-Layered Metal Shield under High-Velocity Impact of Armor-Piercing Projectiles

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 626
Author(s):  
Riccardo Scazzosi ◽  
Marco Giglio ◽  
Andrea Manes
Keyword(s):  
High Strength Steel ◽  
Steel Plate ◽  
Experimental Studies ◽  
Practical Interest ◽  
High Strength ◽  
Experimental Tests ◽  
Element Model ◽  
Transportation Systems ◽  
Metal Shield ◽  
Softening Parameter

In the case of protection of transportation systems, the optimization of the shield is of practical interest to reduce the weight of such components and thus increase the payload or reduce the fuel consumption. As far as metal shields are concerned, some investigations based on numerical simulations showed that a multi-layered configuration made of layers of different metals could be a promising solution to reduce the weight of the shield. However, only a few experimental studies on this subject are available. The aim of this study is therefore to discuss whether or not a monolithic shield can be substituted by a double-layered configuration manufactured from two different metals and if such a configuration can guarantee the same perforation resistance at a lower weight. In order to answer this question, the performance of a ballistic shield constituted of a layer of high-strength steel and a layer of an aluminum alloy impacted by an armor piercing projectile was investigated in experimental tests. Furthermore, an axisymmetric finite element model was developed. The effect of the strain rate hardening parameter C and the thermal softening parameter m of the Johnson–Cook constitutive model was investigated. The numerical model was used to understand the perforation process and the energy dissipation mechanism inside the target. It was found that if the high-strength steel plate is used as a front layer, the specific ballistic energy increases by 54% with respect to the monolithic high-strength steel plate. On the other hand, the specific ballistic energy decreases if the aluminum plate is used as the front layer.

scholarly journals Finite Element Method modeling of Additive Manufactured Compressor Wheel

2021 ◽  
Author(s):  
Márton Tamás Birosz ◽  
Mátyás Andó ◽  
Sudhanraj Jeganmohan
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Finite Element Method Simulation ◽  
Element Model ◽  
Tensile Tests ◽  
Raw Material ◽  
Isotropic Hardening ◽  
Compressor Wheel ◽  
Material Extrusion ◽  
Element Method

AbstractDesigning components is a complex task, which depends on the component function, the raw material, and the production technology. In the case of rotating parts with higher RPM, the creep and orientation are essential material properties. The PLA components made with the material extrusion process are more resistant than VeroWhite (material jetting) and behave similarly to weakly cross-linked elastomers. Also, based on the tensile tests, Young’s modulus shows minimal anisotropy. Multilinear isotropic hardening and modified time hardening models are used to create the finite element model. Based on the measurements, the finite element method simulation was identified. The deformation in the compressor wheel during rotation became definable. It was concluded that the strain of the compressor wheel manufactured with material extrusion technology is not significant.

Investigations on the Mechanical Properties and Formability of Friction Stir Welded Tailored Blanks

2007 ◽  
Vol 344 ◽  
pp. 143-150 ◽  
Author(s):  
Gianluca Buffa ◽  
Livan Fratini ◽  
Marion Merklein ◽  
Detlev Staud
Keyword(s):  
Mechanical Properties ◽  
Stress Condition ◽  
Research Effort ◽  
High Strength Steels ◽  
High Strength ◽  
Tensile Tests ◽  
Friction Stir ◽  
Tailored Blanks ◽  
Sheet Stamping ◽  
Wide Range

Tight competition characterizing automotive industries in the last decades has determined a strong research effort aimed to improve utilized processes and materials in sheet stamping. As far as the latter are regarded light weight alloys, high strength steels and tailored blanks have been increasingly utilized with the aim to reduce parts weight and fuel consumptions. In the paper the mechanical properties and formability of tailored welded blanks made of a precipitation hardenable aluminum alloy but with different sheet thicknesses, have been investigated: both laser welding and friction stir welding have been developed to obtain the tailored blanks. For both welding operations a wide range of the thickness ratios has been considered. The formability of the obtained blanks has been characterized through tensile tests and cup deep drawing tests, in order to show the formability in dependency of the stress condition; what is more mechanical and metallurgical investigations have been made on the welded joints.

Approximate Macroscale Constitutive Relations Using a Finite Element Based Constitutive Equations for Microscale Contact

2008 ◽  
Author(s):  
Ali Sepehri ◽  
Kambiz Farhang
Keyword(s):  
Finite Element ◽  
Contact Force ◽  
Rough Surfaces ◽  
Constitutive Relations ◽  
Cumulative Effect ◽  
Element Model ◽  
Tangential Component ◽  
Total Force ◽  
Asperity Contact ◽  
Elastic Plastic

Three dimensional elastic-plastic contact of two nominally flat rough surfaces is considered. Equations governing the shoulder-shoulder contact of asperities are derived based on the asperity-asperity constitutive relations from a finite element model of their elastic-plastic interaction. Shoulder-shoulder asperity contact yields a slanted contact force consisting of both tangential (parallel to mean plane) and normal components. Multiscale modeling of the elastic-plastic rough surface contact is presented in which asperity-level FE-based constitutive relations are statistically summed to obtain total force in the normal and tangential direction. The equations derived are in the form of integral functions and provide expectation of contact force components between two rough surfaces. An analytical fusion technique is developed to combine the piecewise asperity level constitutive relations. This is shown to yield upon statistical summation the cumulative effect resulting in the contact force between two rough surfaces with two components, one in the normal direction and a half-plane tangential component.

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