A precipitate evolution-based continuum damage mechanics model of creep behaviour in welded 9Cr steel at high temperature

2018 ◽  
Vol 233 (1) ◽  
pp. 39-51
Author(s):  
C Ó Murchú ◽  
SB Leen ◽  
PE O’Donoghue ◽  
RA Barrett
Keyword(s):  
Damage Mechanics ◽  
Volume Fraction ◽  
Creep Behaviour ◽  
Continuum Damage Mechanics ◽  
Time To Failure ◽  
Continuum Damage ◽  
State Variable ◽  
9Cr Steel ◽  
Mechanics Model ◽  
Physically Based

A multiaxial, physically based, continuum damage mechanics methodology for creep of welded 9Cr steels is presented, incorporating a multiple precipitate-type state variable, which simulates the effects of strain- and temperature-induced coarsening kinematics. Precipitate volume fraction and initial diameter for carbide and carbo-nitride precipitate types are key microstructural variables controlling time to failure in the model. The heat-affected zone material is simulated explicitly utilising measured microstructural data, allowing detailed investigation of failure mechanisms. Failure is shown to be controlled by a combination of microstructural degradation and Kachanov-type damage for the formation and growth of creep cavities. Comparisons with experimental data demonstrate the accuracy of this model for P91 material.

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

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.

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

2018 ◽  
Vol 233 (3) ◽  
pp. 447-455 ◽  
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.

scholarly journals On continuum damage mechanics

2019 ◽  
Vol 52 (3) ◽  
pp. 125-147
Author(s):  
Kari Juhani Santaoja
Keyword(s):  
Stress Tensor ◽  
Effective Stress ◽  
Elastic Strain ◽  
Damage Mechanics ◽  
Volume Fraction ◽  
Strain Tensor ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
The Matrix ◽  
Elastic Strain Tensor

A material containing spherical microvoids with a Hookean matrix response was shown to take the appearance usually applied in continuum damage mechanics. However, the commonly used variable damage D was replaced with the void volume fraction f , which has a clear physical meaning, and the elastic strain tensor \Bold {ε}^e with the damage-elastic strain tensor \Bold {ε}^{de}. The postulate of strain equivalence with the effective stress concept was reformulated and applied to a case where the response of the matrix obeys Hooke’s law. In contrast to many other studies, in the derived relation between the effective stress tensor \Bold {\Tilde{σ}} and the stress tensor \Bold {σ}, the tensor \Bold {\Tilde{σ}} is symmetric. A uniaxial bar model was introduce for clarifying the derived results. Other candidates for damage were demonstrated by studying the effect of carbide coarsening on creep rate.

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