Shakedown-Ratcheting Analysis of a Spherical Pressure Vessel by Anisotropic Continuum Damage Mechanics

2018 ◽  
Author(s):  
Ali Nayebi ◽  
Azam Surmiri ◽  
Hojjatollah Rokhgireh
Keyword(s):  
Pressure Vessel ◽  
Damage Mechanics ◽  
Kinematic Hardening ◽  
Continuum Damage Mechanics ◽  
Mapping Method ◽  
Anisotropic Damage ◽  
Continuum Damage ◽  
Interaction Diagram ◽  
Plastic Shakedown ◽  
Spherical Pressure

In cyclic loading and when plastic flow occurs, discontinuities grow. In this research, interaction diagram of Bree has been developed when the spherical pressure vessel contains discontinuities such as voids and microcracks. Bree’s diagram is used for ratcheting assessment of pressurized equipment in ASME III NH. Nature of these defects leads to an anisotropic damage. Anisotropic Continuum Damage Mechanics (CDM) is considered to account effects of these discontinuities on the behavior of the structure. Shakedown – ratcheting response of a hollow sphere under constant internal pressure and cyclic thermal loadings are studied by using anisotropic CDM theory coupled with nonlinear kinematic hardening of Armstrong-Frederick m’s model (A-F). Return mapping method is used to solve numerically the developed relations. Elastic, elastic shakedown, plastic shakedown and ratcheting regions are illustrated in the modified Bree’s diagram. Influence of anisotropic damage due to the plastic deformation is studied and it was shown that the plastic shakedown region is diminished because of the developed damage.

An Anisotropic Creep Damage Model for Anisotropic Weld Metal

2007 ◽  
Author(s):  
S. Peravali ◽  
T. H. Hyde ◽  
K. A. Cliffe ◽  
S. B. Leen
Keyword(s):  
Weld Metal ◽  
Test Data ◽  
Damage Evolution ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Isotropic Case ◽  
Anisotropic Damage ◽  
Secondary Creep ◽  
Continuum Damage ◽  
Anisotropic Creep

Past studies from creep tests on uniaxial specimens and Bridgman notch specimens, for a P91 weld metal, showed that anisotropic behaviour (more specifically transverse isotropy) occurs in the weld metal, both in terms of creep (steady-state) strain rate behaviour and rupture times (viz. damage evolution). This paper describes the development of a finite element (FE) continuum damage mechanics methodology to deal with anisotropic creep and anisotropic damage for weld metal. The method employs a second order damage tensor following the work of Murakami and Ohno [1] along with a novel rupture stress approach to define the evolution of this tensor, taking advantage of the transverse isotropic nature of the weld metal, to achieve a reduction in the number of material constants required from test data (and hence tests) to define the damage evolution. Hill’s anisotropy potential theory is employed to model the secondary creep. The theoretical model is implemented in a material behaviour subroutine within the general-purpose, non-linear FE code ABAQUS [2]. The validation of the implementation against established isotropic continuum damage mechanics solutions for the isotropic case is described. A procedure for calibrating the multiaxial damage constants from notched bar test data is described for multiaxial implementations. Also described is a study on the effect of uniaxial specimen orientation on anisotropic damage evolution.

CONTINUUM DAMAGE MECHANICS ANALYSIS OF THIN-WALLED TUBE UNDER CYCLIC BENDING AND INTERNAL CONSTANT PRESSURE

2013 ◽  
Vol 05 (04) ◽  
pp. 1350038 ◽  
Author(s):  
H. YAZDANI ◽  
A. NAYEBI
Keyword(s):  
Internal Pressure ◽  
Damage Mechanics ◽  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Damage Model ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Cyclic Bending ◽  
Thin Walled Tube ◽  
Thin Walled

Ratcheting and fatigue damage of thin-walled tube under cyclic bending and steady internal pressure is studied. Chaboche's nonlinear kinematic hardening model extended by considering the effect of continuum damage mechanics employed to predict ratcheting. Lemaitre damage model [Lemaitre, J. and Desmorat, R. [2005] Engineering Damage Mechanics (Springer-Verlag, Berlin)] which is appropriate for low cyclic loading is used. Also the evolution features of whole-life ratcheting behavior and low cycle fatigue (LCF) damage of the tube are discussed. A simplified method related to the thin-walled tube under bending and internal pressure is used and compared well with experimental results. Bree's interaction diagram with boundaries between shakedown and ratcheting zone is determined. Whole-life ratcheting of thin-walled tube reduces obviously with increase of internal pressure.

Finite Element Modeling of Fatigue Damage Using a Continuum Damage Mechanics Approach

2005 ◽  
Vol 127 (2) ◽  
pp. 157-164 ◽  
Author(s):  
Abı´lio M. P. De Jesus ◽  
Alfredo S. Ribeiro ◽  
Anto´nio A. Fernandes
Keyword(s):  
Finite Element ◽  
Fatigue Damage ◽  
Damage Mechanics ◽  
Kinematic Hardening ◽  
Fatigue Crack Initiation ◽  
Continuum Damage Mechanics ◽  
Cyclic Plasticity ◽  
Continuum Damage ◽  
Elastoplastic Behavior ◽  
Fatigue Model

In this paper, a fatigue model formulated in the framework of the continuum damage mechanics (CDM) is presented. The model is based on an explicit definition of fatigue damage and introduces a kinematic damage differential equation formulated directly as a function of the number of cycles and the stress cycle parameters. The model is initially presented for uniaxial problems, which facilitates the identification of its constants. An extension of the fatigue model to multiaxial problems is also proposed. This model was implemented in a nonlinear finite element code in conjunction with a constitutive model for cyclic plasticity. The cyclic plasticity model considered is based on a J2-plasticity theory with nonlinear isotropic and kinematic hardenings. In order to enhance the description of the cyclic elastoplastic behavior, the superposition of several nonlinear kinematic hardening variables is suggested. Both fatigue and plasticity models are identified for the P355NL1 (TStE355) steel. Finally, the numerical model is used to predict the fatigue crack initiation for a welded nozzle-to-plate connection, made of P355NL1 steel, and results are compared with experimental fatigue data.

Elasto-Plastic Analysis of a Functionally Graded Rotating Disk Under Cyclic Thermo-Mechanical Loadings Considering Continuum Damage Mechanics

2015 ◽  
Vol 07 (02) ◽  
pp. 1550026 ◽  
Author(s):  
Ali Nayebi ◽  
Ali Tirmomenin ◽  
Mohsen Damadam
Keyword(s):  
Damage Mechanics ◽  
Volume Fraction ◽  
Yield Criterion ◽  
Kinematic Hardening ◽  
Numerical Procedure ◽  
Rotating Disk ◽  
Continuum Damage Mechanics ◽  
Back Stress ◽  
Functionally Graded ◽  
Continuum Damage

The goal of this work is to study the influence of continuum damage mechanics on a functionally graded rotating disk subjected to cyclic temperature gradient loading through nonlinear kinematic hardening rule employed to model the back stress. The formulations have been developed on the basis of von Mises' yield criterion. The material properties are assumed to be independent of temperature and vary according to a power law volume fraction relation but Poisson's ratio is assumed to be constant. Return mapping algorithm (RMA), an incremental method, has been used in the numerical procedure. Material behaviors such as elastic shakedown, plastic shakedown and ratcheting were specified in the existence of continuum damage mechanics to obtain the Bree's interaction diagram for different temperatures and angular velocities.

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