scholarly journals Cyclic Plasticity of the As-Built EOS Maraging Steel: Preliminary Experimental and Computational Results

2020 ◽  
Vol 10 (4) ◽  
pp. 1232
Author(s):  
Barry Mooney ◽  
Dylan Agius ◽  
Kyriakos I. Kourousis
Keyword(s):  
Maraging Steel ◽  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Plastic Anisotropy ◽  
Hysteresis Loops ◽  
Cyclic Plasticity ◽  
Anisotropic Plasticity ◽  
Ongoing Research ◽  
Yield Functions ◽  
Plastic Strain Energy

This short communication offers a preliminary view on ongoing research conducted on the as-built EOS maraging steel 300. The material’s cyclic elastoplastic characteristics under strain-controlled loading have been investigated experimentally. Specimens fabricated under two primary orientations, horizontally and vertically to the build plate, have been tested. The obtained stress–strain hysteresis loops exhibited symmetry, with the vertical specimen showing a higher plastic strain energy dissipation capability than the horizontal specimen. Modelling of the material’s elastoplastic behaviour was performed with a commonly used kinematic hardening rule, combined with both isotropic and anisotropic yield functions and elasticity moduli. The obtained simulations of the hysteresis loops, from the implementation of these two plasticity models, indicate the advantage of the anisotropic modelling approach over the isotropic approach. The anisotropic plasticity model describes in a more representative way the inherent elastic and plastic anisotropy of the as-built material. Further research is underway to explore the low cycle fatigue performance of this additively manufactured metal.

Applicability of Nonlinear Kinematic Hardening Models to Low Cycle Fatigue Simulation of C(T) Specimen

2018 ◽  
Author(s):  
Hune-Tae Kim ◽  
Gyo-Geun Youn ◽  
Jong-Min Lee ◽  
Yun-Jae Kim ◽  
Jin-Weon Kim
Keyword(s):  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Hysteresis Loops ◽  
Load Ratio ◽  
T Test ◽  
Model Parameters ◽  
Cycle Fatigue ◽  
Hardening Models ◽  
Chaboche Model ◽  
Loading Sequence

To perform low cycle fatigue analysis on nuclear structural materials under cyclic loading, cyclic hardening rules should be determined. In this study, the determination of linear and nonlinear kinematic hardening model parameters based on limited material test data is proposed. Chaboche model parameters are determined from hysteresis loops for the purpose of comparison. Simulation of cyclic C(T) test is performed using the hardening models. In cyclic C(T) test, SA508 Gr.1a low alloy steel and SA312 TP316L stainless steel were taken and incremental loading sequence was adopted. In the loading sequence, displacement control was used for loading steps and load control was applied for unloading steps to maintain constant load ratio. A constant displacement increment was applied after each cycle. The simulation results using A&F model and Chaboche model are compared to verify the applicability of A&F model.

scholarly journals Cyclic plasticity and low cycle fatigue damage characterisation of thermally simulated X100Q heat affected zone

2018 ◽  
Vol 165 ◽  
pp. 03002 ◽  
Author(s):  
Ronan J. Devaney ◽  
Heiner Oesterlin ◽  
Padraic E. O’Donoghue ◽  
Sean B. Leen
Keyword(s):  
Fatigue Damage ◽  
Heat Affected Zone ◽  
Early Stage ◽  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Strain Range ◽  
Parent Material ◽  
Cyclic Plasticity ◽  
Cycle Fatigue ◽  
Constitutive Parameters

This paper presents the cyclic plasticity and low cycle fatigue (LCF) damage characterisation of thermally simulated heat affected zone (HAZ) for API 5L X100Q weldments. Microstructures representative of the HAZ for two cooling rates are generated using a Gleeble thermomechanical simulator for manufacture of strain-controlled cyclic plasticity test specimens. The simulated HAZ specimens are subjected to a strain controlled test programme which examines the cyclic effects of strain-range and the tensile response at room temperature. A modified version of the Chaboche rate independent plasticity model, which accounts for early stage damage is implemented to characterise the cyclic plasticity response, including isotropic and kinematic hardening effects. The constitutive parameters are fitted to experimental data using an optimisation procedure developed within a MATLAB code. The measured response of the simulated HAZ specimens is compared to that of the X100Q parent material (PM), and the simulated HAZ is shown to share the early stage fatigue damage behaviour of the PM, but exhibits significantly a higher yield and cyclic strength.

Effect of Tensile-Mean-Strain on Plastic Strain Energy and Cyclic Response

1985 ◽  
Vol 107 (2) ◽  
pp. 119-125 ◽  
Author(s):  
F. Ellyin
Keyword(s):  
Plastic Strain ◽  
Strain Energy ◽  
Low Cycle Fatigue ◽  
Hysteresis Loops ◽  
Material Behavior ◽  
Good Representation ◽  
Steady State Condition ◽  
Least Squares Fit ◽  
Plastic Strain Energy ◽  
Mean Strain

Tests have been conducted to determine the effect of tensile-mean-strain on cyclic properties, low cycle fatigue, and total absorbed plastic strain energy to failure of ASTM A-516 Grade 70 carbon low alloy steel. Stable hysteresis loops at half-life are presented for different strain controlled tests. The cyclic properties were determined by a least squares fit technique. The results of tensile-mean-strain are compared with fully-reversed fatigue tests. The absorbed plastic strain energy per cycle was measured and compared with a proposed relationship for non-Masing material behavior. A relationship of the form Wf=KNfα is found to be a good representation of the data. It is observed that the material tends toward a steady-state condition independent of the level of the mean strain provided the fatigue life is greater than one thousand cycles.

Thermal-Mechanical Fatigue Behavior of P92 T-Piece Pipe

2016 ◽  
Vol 853 ◽  
pp. 256-261
Author(s):  
Wei Zhang ◽  
Xiao Wei Wang ◽  
Jian Ming Gong ◽  
Yong Jiang ◽  
Xin Huang
Keyword(s):  
Plastic Strain ◽  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Fatigue Behavior ◽  
Branch Pipe ◽  
Equivalent Plastic Strain ◽  
Cyclic Plasticity ◽  
Horizontal Pipe ◽  
Thermal Mechanical Fatigue ◽  
Mechanical Fatigue

This paper presents a study on thermal-mechanical fatigue (TMF) behavior of P92 T-piece pipe at the most critical working fluctuations. Pressure and temperature in out-of-phase (OP) and in-phase (IP) conditions were both taken into account. Cyclic plasticity model considering the effect of temperature were used, in which both effects of kinematic hardening and isotropic hardening were included. All of the parameters used in the simulation were obtained from high temperature low cycle fatigue tests (HTLCF). These parameters have been validated through the comparison of experiment data with the simulated data. Then, in order to investigate the effect of OP and IP loadings, thermal-mechanical fatigue finite element model (FEM) of P92 T-piece pipe was also developed. Simulated results reveal that at the most critical working fluctuations, the most dangerous position occurs at the region where the inner surface of horizontal pipe and branch pipe crossed for both IP and OP loadings. With the cycle increases, the equivalent plastic strain is increasing. The peak hoop stress and equivalent plastic strain at IP loading are higher than OP which indicates that IP loadings are more dangerous than OP loadings.

Energy-Consistent Finite Element Modelling of Ferromagnetic Hysteresis

2012 ◽  
Author(s):  
Christophe Geuzaine ◽  
Laurent Stainier ◽  
Francois Henrotte
Keyword(s):  
Finite Element ◽  
Magnetic Energy ◽  
Kinematic Hardening ◽  
Hysteresis Loops ◽  
Macroscopic Model ◽  
Dissipated Energy ◽  
Internal Variables ◽  
Incremental Formulation ◽  
Ferromagnetic Hysteresis ◽  
Electromagnetic Models

In this article we propose a macroscopic model for ferromagnetic hysteresis that is well-suited for finite element implementation. The model is readily vectorial and relies on a consistent thermodynamic formulation. In particular, the stored magnetic energy and the dissipated energy are known at all times, and not solely after the completion of closed hysteresis loops as is usually the case. The obtained incremental formulation is variationally consistent, i.e., all internal variables follow from the minimization of a thermodynamic potential. This variational approach is directly inspired from the kinematic hardening theory of plasticity, which opens the door for novel energy-consistent coupled mechanical/electromagnetic models.

Low Cycle Fatigue Analysis of Marine Structures

2006 ◽  
Author(s):  
Xiaozhi Wang ◽  
Joong-Kyoo Kang ◽  
Yooil Kim ◽  
Paul H. Wirsching
Keyword(s):  
Welded Joints ◽  
Low Cycle Fatigue ◽  
Prediction Method ◽  
Local Stress ◽  
Cyclic Plasticity ◽  
Cycle Fatigue ◽  
Stress Concentrations ◽  
Damage Prediction ◽  
Marine Structure ◽  
Number Of Cycles

There are situations where a marine structure is subjected to stress cycles of such large magnitude that small, but significant, parts of the structural component in question experiences cyclic plasticity. Welded joints are particularly vulnerable because of high local stress concentrations. Fatigue caused by oscillating strain in the plastic range is called “low cycle fatigue”. Cycles to failure are typically below 104. Traditional welded joint S-N curves do not describe the fatigue strength in the low cycle region (< 104 number of cycles). Typical Class Society Rules do not directly address the low cycle fatigue problem. It is therefore the objective of this paper to present a credible fatigue damage prediction method of welded joints in the low cycle fatigue regime.

scholarly journals Simulation of Cyclic Loading on Pipe Elbows Using Advanced Plane-Stress Elastoplasticity Models1

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Konstantinos Chatziioannou ◽  
Yuner Huang ◽  
Spyros A. Karamanos
Keyword(s):  
Cyclic Loading ◽  
Large Scale ◽  
Mechanical Response ◽  
Low Cycle Fatigue ◽  
Constitutive Relations ◽  
Cyclic Plasticity ◽  
Integration Scheme ◽  
Repeated Loading ◽  
Finite Element Software ◽  
Hardening Models

Abstract This work investigates the response of industrial steel pipe elbows subjected to severe cyclic loading (e.g., seismic or shutdown/startup conditions), associated with the development of significant inelastic strain amplitudes of alternate sign, which may lead to low-cycle fatigue. To model this response, three cyclic-plasticity hardening models are employed for the numerical analysis of large-scale experiments on elbows reported elsewhere. The constitutive relations of the material model follow the context of von Mises cyclic elasto-plasticity, and the hardening models are implemented in a user subroutine, developed by the authors, which employs a robust numerical integration scheme, and is inserted in a general-purpose finite element software. The three hardening models are evaluated in terms of their ability to predict the strain range at critical locations, and in particular, strain accumulation over the load cycles, a phenomenon called “ratcheting.” The overall good comparison between numerical and experimental results demonstrates that the proposed numerical methodology can be used for simulating accurately the mechanical response of pipe elbows under severe inelastic repeated loading. Finally, this paper highlights some limitations of conventional hardening rules in simulating multi-axial material ratcheting.

Fatigue Damage Accumulation under the Complex Varying Loading

2014 ◽  
Vol 617 ◽  
pp. 187-192 ◽  
Author(s):  
Boris Melnikov ◽  
Artem Semenov
Keyword(s):  
Damage Accumulation ◽  
Low Cycle Fatigue ◽  
Damage Model ◽  
Hysteresis Loops ◽  
Fatigue Analysis ◽  
Wave Loads ◽  
Fatigue Damage Accumulation ◽  
History Of ◽  
Strain Stress ◽  
Irregular Loading

Fatigue analysis of steel parts of structures, which are subjected to complex irregular loading programs caused by wind, thermal, wave loads, earthquakes and combined imposed actions, requires in some cases using special methods of stress-strain evaluation. The model of the low cycle fatigue nonlinear damage accumulation is developed with taking into account the history of the deformation process. The damage is defined on the base of considering the quasi-static accumulation of maximal strain (stress) and hysteresis loops. The identification of material constants of the model is discussed. Application of the damage model for fatigue analysis of the antennas, pipelines, basements and fasteners units is considered and a comparison with experiments is given.

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