Ratcheting Study of Pressurized Elbows Subjected to Reversed In-Plane Bending

2005 ◽  
Vol 128 (4) ◽  
pp. 525-532 ◽  
Author(s):  
Xu Chen ◽  
Bingjun Gao ◽  
Gang Chen
Keyword(s):  
Internal Pressure ◽  
Kinematic Hardening ◽  
Low Carbon Steel ◽  
Test Machine ◽  
Low Carbon ◽  
Ratcheting Strain ◽  
Bending Load ◽  
Individual Specimen ◽  
Hardening Rules ◽  
Kim Model

With a multi-axial test machine, ratcheting was studied experimentally for pressurized low carbon steel elbows under reversed bending. The maximum ratcheting strain occurred mainly in the hoop direction at flanks. Hoop ratcheting strain was found at intrados for individual specimen. No ratcheting strain was found at the extrados for all tests. Ratcheting strain rate grew with increase of the bending loading level at the same internal pressure or with an increase of internal pressure at the same bending load. Ratcheting simulation was performed by EPFEA with ANSYS in which Ohno-Wang and Chen-Jiao-Kim kinematic hardening rules were applied by user programing. By comparing with the experimental data, it is found that predicted results by the Chen-Jiao-Kim model simulates reasonably. Ratcheting boundary was determined by C-TDF method with the Chen-Jiao-Kim model.

scholarly journals Ratcheting Simulation of a Steel Pipe with Assembly Parts under Internal Pressure and a Cyclic Bending Load

2019 ◽  
Vol 9 (23) ◽  
pp. 5025
Author(s):  
Yang ◽  
Dai ◽  
He
Keyword(s):  
Internal Pressure ◽  
Kinematic Hardening ◽  
Three Dimensional ◽  
Bending Moment ◽  
Element Model ◽  
Steel Pipe ◽  
Cyclic Bending ◽  
Ratcheting Strain ◽  
Bending Load ◽  
Transition Points

The ratcheting behavior of a steel pipe with assembly parts was examined under internal pressure and a cyclic bending load, which has not been seen in previous research. An experimentally validated and three dimensional (3D) elastic-plastic finite element model (FEM)—with a nonlinear isotropic/kinematic hardening model—was used for the pipe’s ratcheting simulation and considered the assembly contact effects outlined in this paper. A comparison of the ratcheting response of pipes with and without assembly parts showed that assembly contact between the sleeve and pipe suppressed the ratcheting response by changing its trend. In this work, the assembly contact effect on the ratcheting response of the pipe with assembly parts is discussed. Both the assembly contact and bending moment were found to control the ratcheting response, and the valley and peak values of the hoop ratcheting strain were the transition points of the two control modes. Finally, while the clearance between the sleeve and the pipe had an effect on the ratcheting response when it was not large, it had no effect when it reached a certain value.

Comparison of Pipe Bend Ratchetting/Shakedown Test Results With the Shakedown Boundary Determined via a Simplified Technique

2009 ◽  
Author(s):  
Hany F. Abdalla ◽  
Mohammad M. Megahed ◽  
Maher Y. A. Younan
Keyword(s):  
Internal Pressure ◽  
Experimental Testing ◽  
Kinematic Hardening ◽  
Low Carbon Steel ◽  
Test Results ◽  
Low Carbon ◽  
Pipe Bend ◽  
Bending Loading ◽  
Pressure Magnitude

Scarce experimental verification exits in the open literature concerning determination of the shakedown boundary for pipe bends subjected to steady internal pressure and cyclic bending loading. The objective of the present paper is to test the capability of a simplified technique presented by the authors in recent ASME JPVT publications and PVP conferences [1–4] in adequately predicting the shakedown boundary obtained through experimental testing. Recently, Chen et al. [5] published experimental and finite element (FE) simulation results on ratchetting of low-carbon steel pressurized 90-degree pipe bend specimens subjected to cyclic reversed in-plane bending forces. Chen et al. [5] performed experimental testing on a pipe bend specimen subjected to a steady internal pressure magnitude of 20.0 MPa. Through FE simulations employing a modified form of the Ohno-Wang non-linear kinematic hardening (KH) rule, Chen et al. [5] predicted a shakedown boundary for a steady internal pressure spectrum ranging from 10.0 to 25.0 MPa. Chen et al. [5] experimental and FE outcomes are utilized for comparison with the simplified technique outcomes. The simplified technique outcomes showed very good correlation with Chen et al. [5] shakedown boundary predictions for the 18.0 – 25.0 MPa steady internal pressure spectrum. On the contrary, noticeable disagreement was found for the lower magnitudes of steady internal pressure. Reasons behind the discrepancy are discussed.

scholarly journals Theoretical and Experimental Study of Bimetal-Pipe Hydroforming

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Zeng Dezhi ◽  
Deng Kuanhai ◽  
Shi Taihe ◽  
Lin Yuanhua ◽  
Zhu Hongjun ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Oil And Gas ◽  
Kinematic Hardening ◽  
Low Carbon Steel ◽  
Strain Curve ◽  
Accurate Method ◽  
Base Layer ◽  
Low Carbon ◽  
Forming Process ◽  
Corrosion Resistant Alloy

The corrosion of oil country tubular goods (OCTG) gets more and more serious especially in the acidic environment. So, it is very important to develop a perfect anticorrosion technology for exploring sour oil and gas fields economically and safely. Analysis indicates that the bimetal-pipe (BP) which consists of the base layer of low carbon steel and a corrosion resistant alloy (CRA) cladding layer is an economic and reliable anticorrosion technology and has broad application prospects in the transportation of acid medium. However, theoretical study of hydraulic expansion mechanism for BP is not enough. In this paper, the deformation compatibility condition of BP was obtained by studying the deformation rule of the (CRA) liner and the outer pipe of carbon steel in the forming process; the mechanical model which can compute the hydroforming pressure of BP has been established based on the nonlinear kinematic hardening characteristics of material; furthermore, based on the stress strain curve of inner pipe simultaneously, the calculation method of the plastic hardening stress has been proposed. Thus, the accurate method for computing the forming pressure was obtained. The experimental data show that results are consistent with results of the proposed model. It indicates that the model can be used to provide theoretical guidance for the design and production as well as use of BP.

Modeling the Hydrogen Effect on the Constitutive Response of a Low Carbon Steel in Cyclic Loading

2020 ◽  
Vol 88 (3) ◽  
Author(s):  
Zahra S. Hosseini ◽  
Mohsen Dadfarnia ◽  
Akihide Nagao ◽  
Masanobu Kubota ◽  
Brian P. Somerday ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Cyclic Loading ◽  
Constitutive Model ◽  
Kinematic Hardening ◽  
Low Carbon Steel ◽  
Cyclic Hardening ◽  
Hydrogen Effect ◽  
Low Carbon ◽  
Japanese Industrial Standard ◽  
Cyclic Straining

Abstract Hydrogen-accelerated fatigue crack growth is a most severe manifestation of hydrogen embrittlement. A mechanistic and predictive model is still lacking partly due to the lack of a descriptive constitutive model of the hydrogen/material interaction at the macroscale under cyclic loading. Such a model could be used to assess the nature of the stress and strain fields in the neighborhood of a crack, a development that could potentially lead to the association of these fields with proper macroscopic parameters. Toward this goal, a constitutive model for cyclic response should be capable of capturing hardening or softening under cyclic straining or ratcheting under stress-controlled testing. In this work, we attempt a constitutive description by using data from uniaxial strain-controlled cyclic loading and stress-controlled ratcheting tests with a low carbon steel, Japanese Industrial Standard (JIS) SM490YB, conducted in air and 1 MPa H2 gas environment at room temperature. We explore the Chaboche constitutive model which is a nonlinear kinematic hardening model that was developed as an extension to the Frederick and Armstrong model, and propose an approach to calibrate the parameters involved. From the combined experimental data and the calibrated Chaboche model, we may conclude that hydrogen decreases the yield stress and the amount of cyclic hardening. On the other hand, hydrogen increases ratcheting, the rate of cyclic hardening, and promotes stronger recovery.

Microstructure and Mechanical Properties of Ferritic Rolling Low Carbon Steel

2019 ◽  
Vol 944 ◽  
pp. 278-282
Author(s):  
Hu Zhao ◽  
Peng Fei Cheng ◽  
Xun Zhou
Keyword(s):  
Mechanical Properties ◽  
Carbon Steel ◽  
Low Carbon Steel ◽  
Test Machine ◽  
Interstitial Free ◽  
Low Carbon ◽  
Microstructure And Mechanical Properties ◽  
Interstitial Free Steel ◽  
Deformation Stress ◽  
Ferritic Rolling

The microstructure and mechanical properties of ferritic rolling low carbon steel are investigated by metallurgical microscope, thermal simulation testing machine, electron backscattered diffraction (EBSD) and universal tensile test machine. The finishing temperature of the transition from austenite to ferrite changed from 680°C to740 °C with different cooling rates, which was obvious lower than that of the interstitial free steel. The deformation stress of low carbon steel was larger than that of interstitial free steel. In addition, the deformation stress of the low carbon steel was more sensitive to the deformation rate than that of the interstitial free steel. The microstructure at the surface layer of the hot rolling plate was composed of fully recrystallized grains while the microstructure in the center was composed of fibrous deformed grains. The ferritic rolling low carbon steel has lower yield ratio and higher elongation than that of normal rolling low carbon steel.

Ratcheting Studies on Type 304LN Stainless Steel Elbows subjected to Combined Internal Pressure and In-Plane Bending Moment

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
S. Vishnuvardhan ◽  
G. Raghava ◽  
P. Gandhi ◽  
M. Saravanan ◽  
D. M. Pukazhendhi ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Internal Pressure ◽  
Accumulation Rate ◽  
Bending Moment ◽  
Cyclic Bending ◽  
Ratcheting Strain ◽  
Bending Load ◽  
304Ln Stainless Steel ◽  
Number Of Cycles ◽  
Opening And Closing

“Ratcheting” is a phenomenon which leads to reduction in fatigue life of a structural component by loss of ductility due to cycle by cycle accumulation of plastic strain. Ratcheting occurs in a structure subjected to a combination of steady/sustained and cyclic loads such that the material response is in inelastic region. Ratcheting studies were carried out on Type 304LN stainless steel elbows, subjected to steady internal pressure and cyclic bending. The elbows filled with water were pressurized between 27.6 MPa and 39.2 MPa. Cyclic bending load, under opening and closing moments, was applied on the elbows at ambient temperature. Number of cycles corresponding to occurrence of a through-wall crack was recorded. Crack was observed in the bent portion at one of the crown locations in all the four specimens. Maximum strain was observed at the intrados and crown locations of the elbows. The ratcheting strain increased with number of cycles at crown and intrados locations. However, the strain accumulation rate decreased with number of cycles. Strain was observed to be minimum at the extrados location and the same stabilized toward the end of the tests. The specimens have failed by occurrence of through-wall axial crack accompanied by simultaneous ballooning. The ballooning was found to be varying from 3.8% to 5.8% with respect to the original circumference in the bent portion. The reduction in thickness was found to be around 12%–15%.

Numerical Simulation of Aluminum Alloy Welding for Butt-Joint of AA2024 Considering Surface Effect Element

2013 ◽  
Vol 456 ◽  
pp. 478-481
Author(s):  
Wen Feng Zhu ◽  
Jie Wang ◽  
Pei Jian Lin ◽  
Bing Yang Zhang
Keyword(s):  
Numerical Simulation ◽  
Bauschinger Effect ◽  
Surface Effect ◽  
Kinematic Hardening ◽  
Low Carbon Steel ◽  
Butt Joint ◽  
Convection Coefficient ◽  
Low Carbon ◽  
Temperature Calculation ◽  
Simulation Results

Aluminum has higher conductivity, convection coefficient, and oxidability, which casuse low plasticity in high temperature compared to convectional low carbon steel. These properties make its welding numerical simulation much more difficult. Thermal simulation is the foundation of aluminums coupled calculations of thermo-elasto-plastic for welding. In this paper, a butt-joint of aluminum AA2024-T3s welding is numerical modeled based on surface effect element. And bilinear kinematic hardening is used to take into the Bauschinger effect. The simulation results agree well, which shows that node temperature calculation can be improved by this method.

Experimental and Numerical Analysis of Ratcheting Behavior of SS 316 L Thin-Walled Pipes Subjected to Cyclic Internal Pressure

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
R. Karimi ◽  
M. Shariati
Keyword(s):  
Internal Pressure ◽  
Kinematic Hardening ◽  
Pressure Amplitude ◽  
Steel Pipes ◽  
Ratcheting Strain ◽  
Mean Pressure ◽  
Thin Walled Pipe ◽  
Thin Walled ◽  
Hoop Direction ◽  
Good Agreement

Abstract This paper investigates ratcheting behavior of SS316 L thin-walled steel pipes subjected to cyclic internal pressure experimentally and numerically. Numerical simulations were performed using abaqus software, and nonlinear isotropic/kinematic hardening model. According to experimentations, it was found that the ratcheting strain is only significant in the hoop direction of a pipe subjected to cyclic internal pressure. The effects of pressure amplitude and mean pressure on ratcheting behavior of thin walled pipe in hoop direction were studied experimentally and numerically, and it was observed that increasing the pressure amplitude and mean pressure increased the percentage of ratcheting strain. Another important point about the results was the dominance of pressure amplitude on mean pressure. The results showed that at higher mean pressures the effect of pressure amplitude on increasing the percentage of ratcheting strain was greater. Finally, the experimental and numerical results were in good agreement.

Study of Bake Hardenability for Hot Rolling Low Carbon Steel

2011 ◽  
Vol 194-196 ◽  
pp. 331-335
Author(s):  
Wei Juan Li ◽  
Guo Dong Wang
Keyword(s):  
Small Volume ◽  
Volume Fraction ◽  
Low Carbon Steel ◽  
Test Machine ◽  
Low Carbon ◽  
Bake Hardening ◽  
Test Steel ◽  
Small Volume Fraction ◽  
Bainite Microstructure ◽  
Bake Hardenability

The TMCP and bake hardening experiments were carried out for the test steel，the microstructure analyses，mechanical properties and bake hardenability test were carried out by using SEM, TEM and tensile test machine. The results show that small volume fraction of bainite microstructure increased will improve BH value in the microstructure of F+P(little). compared with the microstructure that consists of ferrite mainly，which consists of bainite mainly has a higher BH value. The microstructure that consists of ferrite mainly shows the trendy of BH that increased first and then decreased, along with pre-strain increased. The microstructure that consists of bainite, under the condition of higher pre-strain, with the pre-strain increased, the BH value shows the trendy of increasing. While the BHT value is increasing monotonously.

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