Influence of rough surface on damage evolution and fatigue life of M50-bearing steel containing a spherical inclusion

2019 ◽  
Vol 28 (10) ◽  
pp. 1580-1604 ◽  
Author(s):  
Jian Guan ◽  
Liqin Wang ◽  
Yunfeng Li ◽  
Chuanwei Zhang ◽  
Le Gu
Keyword(s):  
Fatigue Life ◽  
Damage Evolution ◽  
Damage Mechanics ◽  
Spherical Inclusion ◽  
Frictional Coefficient ◽  
Elastohydrodynamic Lubrication ◽  
Continuum Damage Mechanics ◽  
Element Model ◽  
Bearing Steel ◽  
Hydrodynamic Effect

In this paper, a continuum damage mechanics model is incorporated into the finite element model which contains a spherical inclusion to investigate damage evolution and predict fatigue life of M50-bearing steel. Quasi-dynamic method, isothermal elastohydrodynamic lubrication analysis and non-Gaussian surface simulating technique are combined to obtain the contact pressure. The damage evolution process of the micro-domain considering roughness texture is simulated and the fatigue life is predicted. The result shows that transverse texture can weaken the damage accumulation due to the strengthening of hydrodynamic effect. The effects of surface roughness parameters on fatigue life are also analyzed. It should be noted that transverse texture, small mean square root value and kurtosis, negative skewness are helpful for enhancing the fatigue life of bearing steel. Meanwhile, the increase of frictional coefficient and radius, negative position of local region will reduce the fatigue life.

A Damage Mechanics Approach to Simulate Butterfly Wing Formation Around Nonmetallic Inclusions

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
Sina Mobasher Moghaddam ◽  
Farshid Sadeghi ◽  
Nick Weinzapfel ◽  
Alexander Liebel
Keyword(s):  
Damage Evolution ◽  
Damage Mechanics ◽  
Nonmetallic Inclusions ◽  
Continuum Damage Mechanics ◽  
Element Model ◽  
Butterfly Wing ◽  
Microstructural Changes ◽  
Damage Evolution Equation ◽  
Wing Formation ◽  
Cyclic Damage

Nonmetallic inclusions such as sulfides and oxides are byproducts of the steel manufacturing process. For more than half a century, researchers have observed microstructural alterations around the inclusions commonly referred to as “butterfly wings.” This paper proposes a model to describe butterfly wing formation around nonmetallic inclusions. A 2D finite element model is developed to obtain the stress distribution in a domain subject to Hertzian loading with an embedded nonmetallic inclusion. It was found that mean stress due to surface traction has a significant effect on butterfly formation. Continuum damage mechanics (CDM) was used to investigate fatigue damage and replicate the observed butterfly wing formations. It is postulated that cyclic damage accumulation can be the reason for the microstructural changes in butterflies. A new damage evolution equation, which accounts for the effect of mean stresses, was introduced to capture the microstructural changes in the material. The proposed damage evolution law matches experimentally observed butterfly orientation, shape, and size successfully. The model is used to obtain S-N results for butterfly formation at different Hertzian load levels. The results corroborate well with the experimental data available in the open literature. The model is used to predict debonding at the inclusion/matrix interface and the most vulnerable regions for crack initiation on butterfly sides. The proposed model is capable of predicting the regions of interest in corroboration with experimental observations.

Continuum damage mechanics application in low-cycle thermal fatigue

2012 ◽  
Vol 22 (2) ◽  
pp. 285-300 ◽  
Author(s):  
M Mashayekhi ◽  
A Taghipour ◽  
A Askari ◽  
M Farzin
Keyword(s):  
Fatigue Life ◽  
Thermal Fatigue ◽  
Damage Evolution ◽  
Damage Mechanics ◽  
Low Cycle Fatigue ◽  
Isothermal Condition ◽  
Continuum Damage Mechanics ◽  
Life Assessment ◽  
Continuum Damage ◽  
Fatigue Damage Accumulation

In this article, a fatigue model for low-cycle thermal fatigue formulated in a continuum damage mechanics framework is presented. The model is based on a unified damage law presented by Lemaitre for low-cycle fatigue, which has been extended to low-cycle thermal fatigue. The temperature dependencies of material parameters are considered in the damage evolution integration to take the non-isothermal condition of loading into account. This model considers the stress triaxiality and non-linearity of damage evolution, and it is developed to a fatigue damage accumulation rule in which the load sequence effect is also included. The stabilized structural response under thermomechanical loading motivates the use of uncoupled analysis approach making the model a fast tool suitable for design purposes in the costly and time-consuming field of thermomechanical fatigue life assessment. To demonstrate the capability and ease of use of this model for real industrial applications, the low-cycle thermal fatigue life of a stainless steel engine exhaust manifold which is in an early stage of design is assessed.

Fatigue Life of the Human Teeth: A Continuum Damage Approach

2019 ◽  
Vol 43 ◽  
pp. 1-19
Author(s):  
Theddeus Tochukwu Akano
Keyword(s):  
Fatigue Life ◽  
Damage Mechanics ◽  
Stress Amplitude ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Elastoplastic Model ◽  
Human Teeth ◽  
Proposed Model ◽  
Number Of Cycles ◽  
Cycles To Failure

Normal oral food ingestion processes such as mastication would not have been possible without the teeth. The human teeth are subjected to many cyclic loadings per day. This, in turn, exerts forces on the teeth just like an engineering material undergoing the same cyclic loading. Over a period, there will be the creation of microcracks on the teeth that might not be visible ab initio. The constant formation of these microcracks weakens the teeth structure and foundation that result in its fracture. Therefore, the need to predict the fatigue life for human teeth is essential. In this paper, a continuum damage mechanics (CDM) based model is employed to evaluate the fatigue life of the human teeth. The material characteristic of the teeth is captured within the framework of the elastoplastic model. By applying the damage evolution equivalence, a mathematical formula is developed that describes the fatigue life in terms of the stress amplitude. Existing experimental data served as a guide as to the completeness of the proposed model. Results as a function of age and tubule orientation are presented. The outcomes produced by the current study have substantial agreement with the experimental results when plotted on the same axes. There is a notable difference in the number of cycles to failure as the tubule orientation increases. It is also revealed that the developed model could forecast for any tubule orientation and be adopted for both young and old teeth.

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.

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

2015 ◽  
Vol 750 ◽  
pp. 266-271 ◽  
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.

scholarly journals Failure Analysis of Composite Pinned Joints Based on Continuum Damage Mechanics

2018 ◽  
Vol 36 (5) ◽  
pp. 848-855
Author(s):  
Hongliang Tuo ◽  
Xiaoping Ma ◽  
Zhixian Lu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Element Model ◽  
Fracture Plane ◽  
Continuum Damage ◽  
Bearing Strength ◽  
Matrix Damage ◽  
Pinned Joints

The paper conducted bearing tests on composite pinned joints with four different stacking sequences. The bearing strength and bearing chord stiffness were obtained. The influence of stacking sequences on failure modes, bearing strength and bearing chord stiffness was discussed. Based on continuum damage mechanics, a three-dimensional finite element model of composite pinned joint under bearing load was built, where the maximum strain criterion was employed for initiation and bi-liner damage constitutive relation for revolution of fiber damage, while the physical-based Puck criterion was used for matrix damage initiation, and matrix damage revolution depended on the effective strain on the fracture plane. The failure mode, bearing strength and bearing chord stiffness of composite pinned joint were discussed with this model under which the non-linear shear behavior and in-situ strength effects were considered. Good agreements between test results and numerical simulations validates the accuracy and applicability of the finite element model.

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.

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