Numerical implementation of a multiaxial cyclic plasticity model for the Local Strain method in low cycle fatigue

The present work examines the behavior of pipe elbows subjected to strong cyclic in-plane bending loading in the presence of internal pressure. In the first part of this work the experimental procedure is presented in detail. The tests are conducted in a constant amplitude displacement-controlled mode resulting to failures in the low-cycle fatigue range. The overall behavior of each tested specimen, as well as the evolution and concentration of local strains are monitored throughout the testing procedure. Different internal pressure levels are used in order to examine their effect on the fatigue life of the specimens. The above experimental investigation is supported by rigorous finite element analysis. Using detailed dimensional measurements and material testing obtained prior to specimen testing, detailed numerical models are developed to simulate the conducted experiments. An advanced cyclic plasticity material model is employed for the simulation of the tests. Emphasis is given on the local strain development at the critical part of the elbow where cracking occurs. Finally, the results of the present investigation are compared with available design provisions in terms of both ultimate capacity and low-cycle fatigue.

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On the Numerical Implementation of a Multi-Mechanism Cyclic Plasticity Model Associated to a Dilation Second Gradient Model Aiming Strain Localization Mitigation

Advances in Bifurcation and Degradation in Geomaterials - Springer Series in Geomechanics and Geoengineering ◽

10.1007/978-94-007-1421-2_26 ◽

2011 ◽

pp. 201-208 ◽

Cited By ~ 2

Author(s):

A. Foucault ◽

F. Voldoire ◽

A. Modaressi

Keyword(s):

Strain Localization ◽

Cyclic Plasticity ◽

Plasticity Model ◽

Numerical Implementation ◽

Gradient Model ◽

Second Gradient ◽

Cyclic Plasticity Model

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Low-Cycle Fatigue of Pressurized Steel Elbows Under In-Plane Bending

Journal of Pressure Vessel Technology ◽

10.1115/1.4027316 ◽

2014 ◽

Vol 137 (1) ◽

Cited By ~ 14

Author(s):

George E. Varelis ◽

Spyros A. Karamanos

Keyword(s):

Low Cycle Fatigue ◽

Strain Curve ◽

Local Strain ◽

Material Model ◽

Fatigue Curve ◽

Cyclic Stress ◽

Cyclic Plasticity ◽

Cycle Fatigue ◽

Element Analysis ◽

Analysis And Design

The present study examines the mechanical behavior of steel process piping elbows, subjected to strong cyclic loading conditions. The work is numerical, supported by experimental data on elbow specimens subjected to in-plane cyclic bending, with or without internal pressure, resulting in failure in the low-cycle-fatigue range. The investigation of elbow behavior is conducted using rigorous finite element analysis accounting for measured elbow geometry and the actual material properties. An advanced cyclic plasticity material model is employed for the simulation of the tests. Emphasis is given on the value of local strain and its accumulation at the critical elbow location where cracking occurs. Based on the cyclic stress–strain curve of the material and the strain-based fatigue curve from the test data, the use of Neuber's formula leads to a fatigue analysis and design methodology, offering a simple and efficient tool for predicting elbow fatigue life.

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Strain Range Dependent Cyclic Hardening of 08Ch18N10T Stainless Steel—Experiments and Simulations

Materials ◽

10.3390/ma12244243 ◽

2019 ◽

Vol 12 (24) ◽

pp. 4243 ◽

Cited By ~ 1

Author(s):

Jaromír Fumfera ◽

Radim Halama ◽

Radek Procházka ◽

Petr Gál ◽

Miroslav Španiel

Keyword(s):

Stainless Steel ◽

Low Cycle Fatigue ◽

Strain Range ◽

Cyclic Hardening ◽

Austenitic Steels ◽

Cyclic Plasticity ◽

Experimental Program ◽

Isotropic Hardening ◽

Plasticity Model ◽

Cyclic Plasticity Model

This paper describes and presents an experimental program of low-cycle fatigue tests of austenitic stainless steel 08Ch18N10T at room temperature. The low-cycle tests include uniaxial and torsional tests for various specimen geometries and for a vast range of strain amplitude. The experimental data was used to validate the proposed cyclic plasticity model for predicting the strain-range dependent behavior of austenitic steels. The proposed model uses a virtual back-stress variable corresponding to a cyclically stable material under strain control. This internal variable is defined by means of a memory surface introduced in the stress space. The linear isotropic hardening rule is also superposed. A modification is presented that enables the cyclic hardening response of 08Ch18N10T to be simulated correctly under torsional loading conditions. A comparison is made between the real experimental results and the numerical simulation results, demonstrating the robustness of the proposed cyclic plasticity model.

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