Ratcheting Boundary Analysis of Straight and Elbow Piping

The ratcheting strains of the straight and elbow piping under two kinds of loads—pressurized piping under symmetric cyclic bending and pulsating cyclic pressure were analyzed based on Chaboche constitutive model. The locations of the maximum ratcheting strain were determined. The ratcheting boundaries of the two piping structures under two kinds of loads were compared and calculated by the C-TDF method. For the pressurized piping under symmetric cyclic bending, the allowable bending load increases from E90S to E90L under the same pressure. In the higher cyclic pressure range, the allowable pressure have little difference under the same bending load which indicates that the bend moment have a bit effects on the ratcheting boundary in the higher cyclic pressure range.

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

Journal of Pressure Vessel Technology ◽

10.1115/1.4005886 ◽

2012 ◽

Vol 134 (4) ◽

Cited By ~ 3

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%.

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

Applied Sciences ◽

10.3390/app9235025 ◽

2019 ◽

Vol 9 (23) ◽

pp. 5025

Author(s):

Yang ◽

Dai ◽

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.

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Identification of material parameters in constitutive model for sheet metals from cyclic bending tests

International Journal of Mechanical Sciences ◽

10.1016/s0020-7403(97)00052-0 ◽

1998 ◽

Vol 40 (2-3) ◽

pp. 237-249 ◽

Cited By ~ 87

Author(s):

F. Yoshida ◽

M. Urabe ◽

V.V. Toropov

Keyword(s):

Constitutive Model ◽

Sheet Metals ◽

Bending Tests ◽

Cyclic Bending ◽

Material Parameters

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Failure Behavior of Elbows With Local Wall Thinning Under Cyclic Load

Seismic Engineering, Volume 1 ◽

10.1115/pvp2004-2950 ◽

2004 ◽

Cited By ~ 2

Author(s):

Izumi Nakamura ◽

Akihito Otani ◽

Masaki Shiratori

Keyword(s):

Failure Modes ◽

Seismic Load ◽

Failure Behavior ◽

Cyclic Bending ◽

Wall Thinning ◽

Bending Load ◽

Piping Systems ◽

Out Of Plane ◽

Effects Of Aging ◽

Local Wall Thinning

Pressurized piping systems used in nuclear power plants are supposed to be degraded by the effects of aging. Local wall thinning is one of the defects considered to be caused in piping systems due to the effects of aging, but the failure behavior of thinned wall pipes under seismic load is still not clear. Therefore an experimental and analytical study to clarify the failure behavior of thinned wall pipes is being conducted. In this paper, the experimental results of locally thinned wall elbows under cyclic bending load are described. Displacement-controlled cyclic bending tests were conducted on elbows with local wall thinning. The test models were pressurized to 10MPa with room temperature water and were subjected to in-plane or/and out-of-plane cyclic bending load until their failures. From the tests, the failure modes of the thinned wall elbows were found to be fatigue failure at the flank of the elbow, or fatigue and buckling failure accompanied with ratchet deformation. It was also found that the life of the thinned wall elbow subjected to out-of-plane bending were extremely lower than that of the elbow without wall thinning. The failure modes and fatigue lives of elbows seemed to be affected by a ratchet phenomenon.

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Propagation Behavior of Main Crack in Reinforced Concrete Beams Strengthened with CFRP under Cyclic Bending Load

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.535-536.205 ◽

2013 ◽

Vol 535-536 ◽

pp. 205-208

Author(s):

Zheng Wei Li ◽

Pei Yan Huang ◽

Hao Zhou

Keyword(s):

Reinforced Concrete ◽

Crack Propagation ◽

Main Crack ◽

Fatigue Behavior ◽

Propagation Rate ◽

Reinforced Concrete Beams ◽

Rc Beam ◽

Cyclic Bending ◽

Propagation Behavior ◽

Bending Load

Fatigue behavior of reinforced concrete (RC) beam can be improved by externally bonded fiber reinforced polymer (FRP). However, propagation behavior of a crack on the RC beam will have serious effect on the fatigue life of the beam strengthened with FRP. In this paper, a finite element (FE) procedure was developed to analysis the stress intensity factor (SIF) of the main crack and an experimental study was conducted to investigate the propagation rate of the main crack of the RC beam strengthened with carbon fiber laminate (CFL) under cyclic bending load. The FE analysis results show that the SIF near the main crack tip increases at the beginning and then decreases with the fatigue crack propagation. When relative crack length α is equal to 0.3, the SIF is maximum. When α approaches 0.75, the SIF approaches zero. A total of 3 RC beams strengthened with CFL were tested. The experimental results show that it is possible to divide the process of the crack propagation into three distinct phases, including crack initiation and then quickly propagation, stable propagation and then rest and unstable propagation. A semi-empirical equation based on the Paris Law was developed to predict the crack propagation rate.

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Reliability and Failure Analysis of Lead-Free Solder Joints for PBGA Package Under a Cyclic Bending Load

IEEE Transactions on Components and Packaging Technologies ◽

10.1109/tcapt.2008.921650 ◽

2008 ◽

Vol 31 (2) ◽

pp. 478-484 ◽

Cited By ~ 20

Author(s):

Ilho Kim ◽

Soon-Bok Lee

Keyword(s):

Failure Analysis ◽

Solder Joints ◽

Lead Free ◽

Lead Free Solder ◽

Cyclic Bending ◽

Bending Load ◽

Free Solder

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Investigation on the Bending Ratcheting Behavior of Pressurized Z2CND18.12N Stainless Steel Elbows

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.573.69 ◽

2013 ◽

Vol 573 ◽

pp. 69-75 ◽

Cited By ~ 1

Author(s):

Xiao Hui Chen ◽

Duo Min Li ◽

Jian Bei Zhu ◽

Xu Chen

Keyword(s):

Finite Element Analysis ◽

Stainless Steel ◽

Axial Direction ◽

Element Analysis ◽

Ratcheting Strain ◽

Finite Element Analysis Simulation ◽

Bending Load ◽

Simulation And Experiment ◽

Bending Loading ◽

Hoop Direction

A series of ratcheting experiments and finite element analysis simulation under bending loading for Z2CND18.12N stainless steel elbows were carried out. Chaboche and modified Ohno-Wang model are applied to evaluate structural ratcheting response simulations. It is found that ratcheting strain initiates firstly in the hoop direction and increases in the axial direction with the increasing of loading. The Ratcheting strain rate grows with the increase of the reversed in-plane bending load or internal pressure for both specimens with different loadings. Comparison of simulation and experiment showed that modified Ohno-Wang model presented simulation more reasonably.

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Evaluation of material behavior of wire strips under cyclic bending load and preparation of an experimental test method

10.25518/esaform21.3826 ◽

2021 ◽

Author(s):

Alina Biallas ◽

Marion Merklein

Keyword(s):

Experimental Test ◽

Kinematic Hardening ◽

Strain Curve ◽

Test Method ◽

Material Behavior ◽

Steel Fibers ◽

Compression Tests ◽

Process Step ◽

Cyclic Bending ◽

Bending Load

Steel fibers as concrete reinforcement improve the building material’s mechanical properties and enlarges its field of application. The production of steel fibers by the process chain notch rolling and cyclic bending promises energetic improvement compared to the conventional manufacturing process wire drawing. The innovative procedure is not yet researched extensively and modelling of the material behavior brings with it many challenges. Different stress states of both process steps require various material models and material failure must be considered. The study brings an appropriate modelling of the test sheet metal DP600 with a thickness of t0=0.8 mm for the second process step into focus. The wire strip’s notches are exposed to a cyclic tension-compression load for which high strength steel exhibits early yielding and a distinct transient region of the stress-strain curve after load reversal. For this reason, the isotropic-kinematic hardening model by Chaboche and Rousselier determined in tension-compression tests is validated by cyclic bending tests. For considering crack initiation, an appropriate ductile damage model for depicting material fatigue is identified. To allow practical realization of the process and validation of the material model, an experimental test method for manufacturing wire strip samples by notch stamping is introduced.

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