scholarly journals Combined hardening parameters of steel CK45 under cyclic strain-controlled loading: Calibration methodology and numerical validation

2020 ◽  
Vol 14 (2) ◽  
pp. 6848-6855
Author(s):  
Bahman Paygozar ◽  
S.A Dizaji ◽  
M.A Saeimi Sadigh
Keyword(s):  
Cyclic Loading ◽  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Strain Curve ◽  
Experimental Tests ◽  
Isotropic Hardening ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
Hardening Model ◽  
Combined Hardening

This study is to indicate the methodology of investigating the behavior of materials in the plastic domain while bearing cyclic loading i.e. low cycle fatigue. Materials under such loading, which experience huge amount of plastic deformation, are affected by the hardening or softening effects of loading which should be taken into account in all applications and numerical simulations as well. This work investigates the methodology of obtaining the nonlinear isotropic and kinematic hardening of steel CK45. To find the parameters of the above mentioned combined nonlinear isotropic/kinematic hardening one tensile test as well as three strain-controlled low cycle fatigue tests are carried out to extract the monotonic stress/strain curve and three diagrams of hysteresis curves, respectively. Then, four parameters necessary to simulate the nonlinear isotropic/ kinematic behavior of the material are extracted by means of curve fitting technique using MATLAB software. Afterwards, the accuracy of the data extracted from the experimental tests using the proposed methodology, are verified in a finite element package, ABAQUS, through implementing two user defined subroutines UMAT written in FORTRAN. It is indicated that the computed constants draw stress-strain curves much closer to experimental responses than isotropic hardening model does.  Eventually, the numerical results acquired by simulating the behavior of the sample under cyclic loading with importing the constants, calculated via combined hardening model, to ABAQUS reflects results highly close to the experimentally obtained response of the sample. It means that the procedure used to find the constants is accurate enough and consequently the constants computed are able to be used in both ABAQUS and subroutines.     

scholarly journals Low- and High-Cycle Fatigue Behavior of FRCM Composites

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5412
Author(s):  
Angelo Savio Calabrese ◽  
Tommaso D’Antino ◽  
Pierluigi Colombi ◽  
Carlo Poggi
Keyword(s):  
Cyclic Loading ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Strain Curve ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
Static Tensile

This paper describes methods, procedures, and results of cyclic loading tensile tests of a PBO FRCM composite. The main objective of the research is the evaluation of the effect of low- and high-cycle fatigue on the composite tensile properties, namely the tensile strength, ultimate tensile strain, and slope of the stress–strain curve. To this end, low- and high-cycle fatigue tests and post-fatigue tests were performed to study the composite behavior when subjected to cyclic loading and after being subjected to a different number of cycles. The results showed that the mean stress and amplitude of fatigue cycles affect the specimen behavior and mode of failure. In high-cycle fatigue tests, failure occurred due to progressive fiber filaments rupture. In low-cycle fatigue, the stress–strain response and failure mode were similar to those observed in quasi-static tensile tests. The results obtained provide important information on the fatigue behavior of PBO FRCM coupons, showing the need for further studies to better understand the behavior of existing concrete and masonry members strengthened with FRCM composites and subjected to cyclic loading.

scholarly journals Stress-strain response in gears tooth root due to low cycle fatigue

2019 ◽  
Vol 287 ◽  
pp. 02002
Author(s):  
Marina Franulovic ◽  
Kristina Markovic ◽  
Zdravko Herceg
Keyword(s):  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Material Model ◽  
Strain Response ◽  
Tooth Root ◽  
Loading Conditions ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
Main Research ◽  
Damage Initiation

Gears are mechanical components which experience high dynamic loading during their exploitation period. Therefore, their load carrying capacity together with life expectancy are often the main research interest in various studies. The research presented in this paper is focused on the materials response in spur gears tooth root, with the attention given to the repeated overloads during gears operation. In order to simulate low cycle fatigue by using numerical modeling of stress - strain relationship within material, the material model which takes into account isotropic and kinematic hardening is used here. Material response of specimens produced out of steel 42CrMo4 in different loading conditions is used for the calibration of material model, which is then applied to simulate damage initiation and materials stress - strain response in gears tooth root. The results show that materials response to the given loading conditions non-linearly change through the loading cycles.

Cyclic Deformation and Buckling Behavior of Pipe With Local Metal Loss Subjected to Seismic Ground Motion

2011 ◽  
Author(s):  
Masaki Mitsuya ◽  
Hiroshi Yatabe
Keyword(s):  
Finite Element ◽  
Cyclic Loading ◽  
Cyclic Deformation ◽  
Deformation Behavior ◽  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Earthquake Resistance ◽  
Metal Loss ◽  
Cycle Fatigue ◽  
Longitudinal Length

Buried pipelines may be deformed due to earthquakes and also corrode despite corrosion control measures such as protective coatings and cathodic protection. In such cases, it is necessary to ensure the integrity of the corroded pipelines against earthquakes. This study developed a method to evaluate the earthquake resistance of corroded pipelines subjected to seismic ground motions. Axial cyclic loading experiments were carried out on line pipes subjected to seismic motion to clarify the cyclic deformation behavior until buckling occurs. The test pipes were machined so that each one would have a different degree of local metal loss. As the cyclic loading progressed, displacement shifted to the compression side due to the formation of a bulge. The pipe buckled after several cycles. To evaluate the earthquake resistance of different pipelines, with varying degrees of local metal loss, a finite-element analysis method was developed that simulates the cyclic deformation behavior. A combination of kinematic and isotropic hardening components was used to model the material properties. These components were obtained from small specimen tests that consisted of a monotonic tensile test and a low cycle fatigue test under a specific strain amplitude. This method enabled the successful prediction of the cyclic deformation behavior, including the number of cycles required for the buckling of pipes with varying degrees of metal loss. In addition, the effect of each dimension (depth, longitudinal length and circumferential width) of local metal loss on the cyclic buckling was studied. Furthermore, the kinematic hardening component was investigated for the different materials by the low cycle fatigue tests. The kinematic hardening components could be regarded as the same for all the materials when using this component as the material property for the finite-element analyses simulating the cyclic deformation behavior. This indicates that the cyclic deformation behavior of various line pipes can be evaluated only based on their respective tensile properties and common kinematic hardening component.

scholarly journals Low Cycle Fatigue Life Evaluation of Notched Specimens Considering Strain Gradient

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 1001
Author(s):  
Shenghuan Qin ◽  
Zaiyin Xiong ◽  
Yingsong Ma ◽  
Keshi Zhang
Keyword(s):  
Cyclic Loading ◽  
Constitutive Model ◽  
Strain Gradient ◽  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Plastic Behavior ◽  
Cycle Fatigue ◽  
New Model ◽  
Hysteresis Behavior ◽  
Notched Specimens

An improved model based on the Chaboche constitutive model is proposed for cyclic plastic behavior of metal and low cycle fatigue of notched specimens under cyclic loading, considering the effect of strain gradient on nonlinear kinematic hardening and hysteresis behavior. The new model is imported into the user material subroutine (UMAT) of the finite element computing software ABAQUS, and the strain gradient parameters required for model calculation are obtained by calling the user element subroutine (UEL). The effectiveness of the new model is tested by the torsion test of thin copper wire. Furthermore, the calibration method of strain gradient influence parameters of constitutive model is discussed by taking the notch specimen of Q235 steel as an example. The hysteresis behavior, strain distribution and fatigue failure of notched specimens under cyclic loading were simulated and analyzed with the new model. The results prove the rationality of the new model.

On the Applicability of Neuber’s Rule for Low-Cycle Fatigue

2016 ◽  
Author(s):  
Daniel W. Spring ◽  
Edrissa Gassama ◽  
Aaron Stenta ◽  
Jeffrey Cochran ◽  
Charles Panzarella
Keyword(s):  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Cycle Fatigue ◽  
Hardening Model ◽  
Elastic Plastic ◽  
Sufficient Detail ◽  
Complex Models ◽  
Educational Perspective ◽  
Neuber's Rule ◽  
Nonlinear Hardening

Neuber’s rule is commonly applied in fatigue analysis to estimate the plasticity of purely elastic FEA results. In certain cases, this is more efficient than running elastic-plastic models. However, the applicability of Neuber’s rule is not well understood for complex models and may not always be appropriate. In this paper, the applicability of Neuber’s rule is investigated. The background of Neuber’s rule is discussed, theoretical limitations are derived, and algorithmic outlines of the procedures are presented. Neuber’s plasticity correction procedure is applied to both the Ramberg-Osgood elastic-plastic constitutive relation and the advanced Chaboche isotropic/kinematic nonlinear hardening relation. Throughout the manuscript, the aspects of each model are discussed from an educational perspective, highlighting each step of the implementation in sufficient detail for independent reproduction and verification. This level of detail is often absent from similar publications and, it is hoped, may lead to the wider dissemination of Neuber’s rule for plasticity correction. The final component of the paper presents a multiaxial correction of the Chaboche hardening model. To the best of the authors’ knowledge, this is the first published application of Neuber’s rule to the multiaxial plasticity correction of the Chaboche combined isotropic/kinematic hardening model. Examples are used to illustrate the behavior of the method and to present some of the commonly overlooked components when assessing the applicability of Neuber’s method.

Low Cycle Fatigue Behavior of Original Ferritic P92 Steel at High Temperature: Experiments and Simulations

2015 ◽  
Author(s):  
Xiaowei Wang ◽  
Jianming Gong ◽  
Yong Jiang ◽  
Yanping Zhao
Keyword(s):  
Plastic Material ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Constant Strain Rate ◽  
Cyclic Softening ◽  
Isotropic Hardening ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
P92 Steel ◽  
Softening Behavior

Low cycle fatigue tests of original ferritic P92 steel at high temperatures and different strain amplitudes were conducted to investigate its cyclic softening behavior and fracture behavior. LCF tests of strain amplitudes ranging from ±0.2% to ±0.8% were performed in fully reversed manner with constant strain rate at 600 °C and 650 °C. In order to represent the different hysteresis stress-strain curves and the cyclic softening behavior of P92 steel, a cyclic plastic material model was used. In the model, improved nonlinear isotropic hardening parameter was proposed to make better simulation of the cyclic softening behavior. Based on the simulated stress-strain hysteresis loops, an energy-based life prediction model was used to predict the low cycle fatigue life. When compared with experimental responses, the simulations and predicted life were found to be quite reasonable. Low cycle fatigue fractography of the P92 steel was also observed, and it was found to be associated with the different strain amplitudes imposed on the specimen, the larger strain amplitude the more amounts of crack initiation sites could be found.

Cyclic Plastic Deformation of a Circular Plate With Work Hardening

1984 ◽  
Vol 106 (4) ◽  
pp. 336-341
Author(s):  
R. Winter
Keyword(s):  
Fatigue Life ◽  
Low Cycle Fatigue ◽  
Nonlinear Behavior ◽  
Strain Curve ◽  
Strain Range ◽  
Cyclic Strain ◽  
Cyclic Stress ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
Element Analysis

An experimental and theoretical study was performed of the nonlinear behavior of a simply supported flat circular aluminum plate under reversed cyclic central load. The application is for the analysis of cyclic stress and strain of structural components in the plastic range for predicting low-cycle fatigue life. The main purpose was to determine the relative accuracy of an elastic-plastic large deformation finite element analysis when the material properties input data are derived from monotonic (noncyclic) stress-strain curves versus that derived from cyclic stress-strain curves. The results showed that large errors could be induced in the theoretical prediction of cyclic strain range when using the monotonic stress-strain curve, which could lead to large errors in predicting low-cycle fatigue life. The use of cyclic stress-strain curves, according to the model developed by Morrow, et al., proved to be accurate and convenient.

Effects of Hardening Models on CUO Forming and Springback Simulation of High Strength Line Pipes

2015 ◽  
Vol 817 ◽  
pp. 8-13 ◽  
Author(s):  
Qiang Ren ◽  
Tian Xia Zou ◽  
Da Yong Li
Keyword(s):  
Bauschinger Effect ◽  
Oil And Gas ◽  
Kinematic Hardening ◽  
High Strength ◽  
Isotropic Hardening ◽  
Forming Process ◽  
Hardening Model ◽  
Hardening Models ◽  
Combined Hardening ◽  
Springback Prediction

The UOE process is an effective approach for manufacturing the line pipes used in oil and gas transportation. During the UOE process, a steel plate is crimped along its edges, pressed into a circular pipe with an open-seam by the successively U-O forming stages. Subsequently, the open-seam is closed and welded. Finally, the welded pipe is expanded to obtain a perfectly round shape. In particular, during the O-forming stage the plate is suffered from distinct strain reversal which leads to the Bauschinger effect, i.e., a reduced yield stress at the start of reverse loading following forward strain. In the finite element simulation of plate forming, the material hardening model plays an important role in the springback prediction. In this study, the mechanical properties of API X90 grade steel are obtained by a tension-compression test. Three popular hardening models (isotropic hardening, kinematic hardening and combined hardening) are employed to simulate the CUO forming process. A deep analysis on the deformation and springback behaviors of the plate in each forming stage is implemented. The formed configurations from C-forming to U-forming are almost identical with three hardening models due to the similar forward hardening behaviors. Since the isotropic hardening model cannot represent the Bauschinger effect, it evaluates the higher reverse stress and springback in the O-forming stage which leads to a failure prediction of a zero open-seam pipe. On the contrary, the kinematic hardening model overestimates the Bauschinger effect so that predicts the larger open-seam value. Specifically, the simulation results using the combined hardening model show good agreement in geometric configurations with the practical measurements.

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