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.

A Model for Low-Cycle Fatigue in Micro-Structured Materials

2019 ◽  
Vol 827 ◽  
pp. 134-140
Author(s):  
Francesco Parrinello ◽  
Vincenzo Gulizzi ◽  
Ivano Benedetti
Keyword(s):  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Boundary Integral ◽  
Future Application ◽  
Elastic Behaviour ◽  
Internal Variables ◽  
Zone Model ◽  
Cycle Fatigue ◽  
Structured Materials ◽  
Elastic Plastic

A microscale formulation for low-cycle fatigue degradation in heterogeneous materials is presented. The interface traction-separation law is modelled by a cohesive zone model for low-cycle fatigue analysis, which is developed in a consistent thermodynamic framework of elastic-plastic-damage mechanics with internal variables. A specific fatigue activation condition allows to model the material degradation related to the elastic-plastic cyclic loading conditions, with tractions levels lower than the static failure condition. A moving endurance surface, in the classic framework of kinematic hardening, enables a pure elastic behaviour without any fatigue degradation for low levels of cyclic traction. The developed model is then applied to micro-structured materials whose micro-mechanics is analysed using a boundary integral formulation. Preliminary results demonstrate the potential of the developed cohesive model. The future application of the proposed technique is discussed in the framework of multiscale modelling of engineering components and design of micro-electro-mechanical devices (MEMS).

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.     

A Thermodynamically Consistent CZM for Low-Cycle Fatigue Analysis

2018 ◽  
Vol 774 ◽  
pp. 576-582 ◽  
Author(s):  
Francesco Parrinello ◽  
Ivano Benedetti ◽  
Guido Borino
Keyword(s):  
Damage Mechanics ◽  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Fatigue Analysis ◽  
Elastic Behavior ◽  
Zone Model ◽  
Loading Conditions ◽  
Cycle Fatigue ◽  
Activation Condition ◽  
Elastic Plastic

A cohesive zone model for low-cycle fatigue analysis is developed in a consistent thermodynamic framework of elastic-plastic-damage mechanics with internal variable. A specific fatigue activation condition allows to model the material degradation related to the elastic-plastic cyclic loading conditions, with tractions levels lower than the damage activation condition. A moving endurance surface, in the classic framework of kinematic hardening, enables a pure elastic behavior without any fatigue degradation for low levels loading conditions.

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.

3-D Elastic-Plastic Constitutive Relationship of Mixed Hardening

2012 ◽  
Vol 249-250 ◽  
pp. 927-930
Author(s):  
Ze Yu Wu ◽  
Xin Li Bai ◽  
Bing Ma
Keyword(s):  
Finite Element ◽  
Constitutive Relation ◽  
Kinematic Hardening ◽  
Constitutive Relationship ◽  
Isotropic Hardening ◽  
Element Analysis ◽  
Hardening Model ◽  
Elastic Plastic ◽  
Mixed Hardening ◽  
Advantages And Disadvantages

In finite element calculation of plastic mechanics, isotropic hardening model, kinematic hardening model and mixed hardening model have their advantages and disadvantages as well as applicability area. In this paper, by use of the tensor analysis method and mixed hardening theory in plastic mechanics, the constitutive relation of 3-D mixed hardening problem is derived in detail based on the plane mixed hardening. Numerical results show that, the proposed 3-D mixed hardening constitutive relation agrees well with the test results in existing references, and can be used in the 3-D elastic-plastic finite element analysis.

High-Temperature Low-Cycle Fatigue Behavior of MarBN at 600 °C

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Richard A. Barrett ◽  
Eimear M. O'Hara ◽  
Padraic E. O'Donoghue ◽  
Sean B. Leen
Keyword(s):  
High Temperature ◽  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Fatigue Behavior ◽  
Strain Range ◽  
Material Model ◽  
Cyclic Softening ◽  
Cyclic Strength ◽  
Cycle Fatigue ◽  
Viscoplastic Material

This paper presents the high-temperature low-cycle fatigue (HTLCF) behavior of a precipitate strengthened 9Cr martensitic steel, MarBN, designed to provide enhanced creep strength and precipitate stability at high temperature. The strain-controlled test program addresses the cyclic effects of strain-rate and strain-range at 600 °C, as well as tensile stress-relaxation response. A recently developed unified cyclic viscoplastic material model is implemented to characterize the complex cyclic and relaxation plasticity response, including cyclic softening and kinematic hardening effects. The measured response is compared to that of P91 steel, a current power plant material, and shows enhanced cyclic strength relative to P91.

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