Creep Behaviors Calculated by Varying Material Constants Obtained from Different Stress Regions for a Closed-End P91 Pipe

AbstractIn order to predict the creep life of a component at high temperature both accurately and economically, continuum damage mechanics approach is used based on experimental creep data. However, material constants used in the models have a great relationship with the performed stress range of creep tests. In this paper, several sets of material constants were obtained from a wide range of stresses on P91 steel. The creep damage tolerance parameter was used to classify these sets, and the modified continuum damage mechanics model was used to investigate a pipe under closed-end condition. Results have illustrated the main difference lies on the tertiary stage while slight difference on the primary and secondary stages, and the contribution of the tertiary stage to the total damage decreased when using material constants from higher stress region.

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Modelling the asymmetric tension–compression properties of additively manufactured alloys using continuum damage mechanics

Proceedings of the Institution of Mechanical Engineers Part L Journal of Materials Design and Applications ◽

10.1177/14644207211013434 ◽

2021 ◽

pp. 146442072110134

Author(s):

A Nayebi ◽

H Rokhgireh ◽

M Araghi ◽

M Mohammadi

Keyword(s):

Damage Mechanics ◽

Continuum Damage Mechanics ◽

Element Model ◽

Continuum Damage ◽

Compression Tests ◽

Compression Properties ◽

Mechanics Model ◽

Stress Components ◽

Tension And Compression ◽

Closure Effect

Additively manufactured parts often comprise internal porosities due to the manufacturing process, which needs to be considered in modelling their mechanical behaviour. It was experimentally shown that additively manufactured parts’ tensile and compressive mechanical properties are different for various metallic alloys. In this study, isotropic continuum damage mechanics is used to model additively manufactured alloys’ tension and compression behaviours. Compressive stress components can shrink discontinuities present in additively manufactured alloys. Therefore, the crack closure effect was employed to describe different behaviours during uniaxial tension and compression tests. A finite element model embedded in an ABAQUS’s UMAT format was developed to account for the isotropic continuum damage mechanics model. The numerical results of tension and compression tests were compared with experimental observations for additively manufactured maraging steel, AlSi10Mg and Ti-6Al-4V. Stress–strain curves in tension and compression of these alloys were obtained using the continuum damage mechanics model and compared well with the experimental results.

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Development of continuum damage in the creep rupture of notched bars

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1984.0021 ◽

1984 ◽

Vol 311 (1516) ◽

pp. 103-129 ◽

Cited By ~ 192

Keyword(s):

New York ◽

Damage Mechanics ◽

Axial Stress ◽

Numerical Procedure ◽

Creep Damage ◽

Continuum Damage Mechanics ◽

Constant Load ◽

Creep Rupture ◽

Continuum Damage ◽

Discrete Crack

The creep rupture of circumferentially notched, circular tension bars which are subjected to constant load for long periods at constant temperature is studied both experimentally and by using a time-iterative numerical procedure which describes the formation and growth of creep damage as a field quantity. The procedure models the development of failed or cracked regions of material due to the growth and linkage of grain boundary defects. Close agreement is shown between experimental and theoretical values of the representative rupture stress, of the zones of creep damage and of the development of cracks for circular (Bridgman, Studies in large plastic flow and fracture , New York: McGraw-Hill (1952)) and British Standard notched specimens (B.S. no. 3500 (1969)). The minimum section of the circular notch is shown to be subjected to relatively uniform states of multi-axial stress and damage while the B.S. notch is shown to be subjected to non-uniform stress and damage fields in which single cracks grow through relatively undamaged material. The latter situation is shown to be analogous to the growth of a discrete crack in a lightly damaged continuum. The continuum damage mechanics theory presented here is shown to be capable of accurately predicting these extreme types of behaviour.

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Predicting the wear coefficient and friction coefficient in dry point contact using continuum damage mechanics

Proceedings of the Institution of Mechanical Engineers Part J Journal of Engineering Tribology ◽

10.1177/1350650118785045 ◽

2018 ◽

Vol 233 (3) ◽

pp. 447-455 ◽

Cited By ~ 1

Author(s):

Sahar Ghatrehsamani ◽

Saleh Akbarzadeh

Keyword(s):

Friction Coefficient ◽

Damage Mechanics ◽

Point Contact ◽

Continuum Damage Mechanics ◽

Continuum Damage ◽

Wear Coefficient ◽

Mechanics Model ◽

Pin On Disk ◽

Disk Test ◽

The Continuum

Wear coefficient and friction coefficient are two of the key parameters in the performance of any tribo-system. The main purpose of the present research is to use continuum damage mechanics to predict wear coefficient. Thus, a contact model is utilized that can be used to obtain the friction coefficient between the contacting surfaces. By applying this model to the continuum damage mechanics model, the wear coefficient between dry surfaces is predicted. One of the advantages of using this model is that the wear coefficient can be numerically predicted unlike other methods which highly rely on experimental data. In order to verify the results predicted by this model, tests were performed using pin-on-disk test rig for several ST37 samples. The results indicated that the wear coefficient increases with increasing the friction coefficient.

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Finite Element Simulation of the Creep Behavior of 2.25Cr-1Mo-0.25V Steel Based on Continuum Damage Mechanics

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.750.266 ◽

2015 ◽

Vol 750 ◽

pp. 266-271 ◽

Cited By ~ 1

Author(s):

Yu Zhou ◽

Xue Dong Chen ◽

Zhi Chao Fan ◽

Yi Chun Han

Keyword(s):

Genetic Algorithm ◽

Finite Element ◽

Creep Behavior ◽

Constitutive Equations ◽

Damage Evolution ◽

Damage Mechanics ◽

Creep Damage ◽

Continuum Damage Mechanics ◽

Continuum Damage ◽

Element Simulation

The creep behavior of 2.25Cr-1Mo-0.25V ferritic steel was investigated using a set of physically-based creep damage constitutive equations. The material constants were determined according to the creep experimental data, using an efficient genetic algorithm. The user-defined subroutine for creep damage evolution was developed based on the commercial finite element software ANSYS and its user programmable features (UPFs), and the numerical simulation of the stress distribution and the damage evolution of the semi V-type notched specimen during creep were studied. The results showed that the genetic algorithm is a very efficient optimization approach for the parameter identification of the creep damage constitutive equations, and finite element simulation based on continuum damage mechanics can be used to analyze and predict the creep damage evolution under multi-axial stress states.

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