Finite Element Analysis for Continuum Damage Evolution and Wellbore Stability of Transversely Isotropic Rock Considering Hydro-Mechanical Coupling

2020 ◽  
pp. 25-48
Author(s):  
Yongliang Wang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Damage Evolution ◽  
Transversely Isotropic ◽  
Wellbore Stability ◽  
Continuum Damage ◽  
Element Analysis ◽  
Mechanical Coupling ◽  
Transversely Isotropic Rock ◽  
Isotropic Rock

Finite-Element Analysis of Waspaloy Using Sinh Creep-Damage Constitutive Model Under Triaxial Stress State

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Mohammad Shafinul Haque ◽  
Calvin Maurice Stewart
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Creep Deformation ◽  
Damage Evolution ◽  
Rupture Life ◽  
Creep Damage ◽  
Nickel Base Superalloy ◽  
Element Analysis ◽  
Stress Levels ◽  
Nickel Base

The creep deformation and damage evolution of nickel base superalloy (Waspaloy) at 700 °C are studied using the classic Kachanov–Rabotnov (KR) and a recently developed Sin-hyperbolic (Sinh) model. Uniaxial creep deformation and Bridgman rupture data collected from literature are used to determine the model constants and to compare the KR and the Sinh solutions. Finite-element (FE) simulations on a single eight-node element are conducted to validate the accuracy of the FE code. It is observed that KR cannot predict the creep deformation, damage, and rupture life of nickel base superalloys accurately using one set of constants for all the stress levels. The Sinh model exhibits a superior ability to predict the creep behavior using one set of constants for all the stress levels. Finite-element analysis (FEA) on 3D Bridgman notched Waspaloy specimen using the Sinh model is conducted. The results show that the Sinh model when combined with a representative stress equation and calibrated with experimental data can accurately predict the “notch effect” observed in the rupture life of notched specimen. Contour plots of damage evolution and stress redistribution are presented. It is demonstrated that the Sinh model is less stress sensitive, produces unconditional critical damage equal to unity at rupture, exhibits a more realistic damage distribution around the crack tip, and offers better crack growth analysis than KR.

Damage Evaluation of Grade 91 Thick Cylinder Under Variable Thermal Cyclic Loading Using Continuum Damage Coupled Viscoplastic Models

2019 ◽  
Author(s):  
Nazrul Islam ◽  
Tasnim Hassan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
High Temperature ◽  
Creep Deformation ◽  
Continuum Damage ◽  
Element Analysis ◽  
Energy Agency ◽  
Creep Fatigue ◽  
Thick Cylinder ◽  
Grade 91

Abstract This study evaluates creep-fatigue damage in the modified Grade 91 thick-cylinder tested by Japan Atomic Energy Agency (JAEA), to understand the failure mechanism of critical components of Fast Reactor nuclear plants. As modified Grade 91 demonstrated creep-fatigue interaction induced failure mechanisms, finite element analysis of high-temperature components will require a unified constitutive model (UCM) that can simulate various creep-fatigue responses with reasonable accuracy. Hence, a UCM coupled with various advanced modeling features including the continuum damage modeling features is investigated to demonstrate their predictability of the fatigue, creep and creep-fatigue responses of the modified Grade 91 steel. The modified UCM is implemented into ABAQUS for analysis of creep deformation in the thick cylinder benchmark problem. Finite element analysis results are presented to demonstrate how the thermal cycling influences the creep-deformation of this high-temperature component. It is also demonstrated how thermal cycling’s influence on fatigue life can be determined based on the damage variable incorporated in the UCM.

A Simple Transversely Isotropic Hyperelastic Constitutive Model Suitable for Finite Element Analysis of Fiber Reinforced Elastomers

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Leslee W. Brown ◽  
Lorenzo M. Smith
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Energy Function ◽  
Strain Energy ◽  
Strain Energy Function ◽  
Transversely Isotropic ◽  
Material Model ◽  
Fiber Reinforced ◽  
Element Analysis ◽  
Material Tests

A transversely isotropic fiber reinforced elastomer’s hyperelasticity is characterized using a series of constitutive tests (uniaxial tension, uniaxial compression, simple shear, and constrained compression test). A suitable transversely isotropic hyperelastic invariant based strain energy function is proposed and methods for determining the material coefficients are shown. This material model is implemented in a finite element analysis by creating a user subroutine for a commercial finite element code and then used to analyze the material tests. A useful set of constitutive material data for multiple modes of deformation is given. The proposed strain energy function fits the experimental data reasonably well over the strain region of interest. Finite element analysis of the material tests reveals further insight into the materials constitutive nature. The proposed strain energy function is suitable for finite element use by the practicing engineer for small to moderate strains. The necessary material coefficients can be determined from a few simple laboratory tests.

Influence of temperature and strain rate on the longitudinal compressive crashworthiness of 3D braided composite tubes and finite element analysis

2016 ◽  
Vol 26 (7) ◽  
pp. 1003-1027 ◽  
Author(s):  
Xianyan Wu ◽  
Qian Zhang ◽  
Bohong Gu ◽  
Baozhong Sun
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Strain Rate ◽  
Coupling Effect ◽  
Three Dimensional ◽  
Composite Tubes ◽  
Element Analysis ◽  
Impact Compression ◽  
Mechanical Coupling ◽  
The Impact

This article reports the longitudinal compressive crashworthiness of three-dimensional four-step circular braided carbon/epoxy composite tubes at temperatures of 23, −50, and −100℃ under strain rate ranging from 340 to 760/s both experimentally and finite element analysis. The experimental results showed that the compression strength, stiffness, and specific energy absorption increased with the decrease in temperature and with the increase in strain rate. It also showed that, the compressive damage morphologies were sensitive to the change in temperature and strain rate. A coupled thermal-mechanical numerical analysis was conducted to find the thermo/mechanical coupling effect on the compressive crashworthiness of the three-dimensional composite tube. The temperature distributions in the braided preform and the resin during the impact compression were also calculated through finite element analysis. From the finite element analysis results, the inelastic heat generation was seen to be more in the preform than the matrix and its distribution and accumulation led to the damage progress along the loading direction.

Preliminary Evaluation of a New Dental Implant Design with Finite Element Analysis

2005 ◽  
Vol 288-289 ◽  
pp. 657-660
Author(s):  
Xue Jun Wang ◽  
R. Wang ◽  
J.M. Luo ◽  
Ji Yong Chen ◽  
Xing Dong Zhang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Dental Implant ◽  
Peak Stress ◽  
Implant Design ◽  
Preliminary Evaluation ◽  
Element Analysis ◽  
Mechanical Coupling ◽  
Stress Transmission ◽  
Reducing Stress

It is important to obtain mechanical coupling between dental implants and bone, because the lack of mechanical coupling may cause bone loss around implants. In this research, a new cylindrical dental implant composed of three parts was designed to offer favored mechanical environment for the bone. A special gap structure changed the means of the stress transmission and decreased the stress in the cortical bone around the neck of the implant. Through finite element analysis (FEA) of stress distribution in bone around implant-bone interface, the advantages of this new implant (reducing stress concentration in cervical cortex and satisfying varieties of clinical needs) were verified. The peak stress for the new design was about 30 percent less than that of the traditional implant and the flexibility of the design was also confirmed by changing the gap depth and the wall thickness.

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