3-D Anisotropic Damage Mechanics for Modeling Interaction Between Hydraulic and Natural Fracture Planes in a Layered Rock – Application to Eagle Ford and Wolfcamp

Author(s):  
Yamina Aimene ◽  
Chad Hammerquist ◽  
John A. Nairn ◽  
Ahmed Ouenes
Author(s):  
Ali Nayebi ◽  
Azam Surmiri ◽  
Hojjatollah Rokhgireh

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.


Author(s):  
S. Peravali ◽  
T. H. Hyde ◽  
K. A. Cliffe ◽  
S. B. Leen

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.


2015 ◽  
Vol 784 ◽  
pp. 258-265
Author(s):  
Yoshimi Sonoda

The aim of this paper is to propose the impact failure analysis of reinforced concrete beam using tensile softening technique based on the damage mechanics. In general, tensile crack is the most dominant factor for concrete and it is not appropriate to evaluate their effect by theory of plasticity. Thus mechanical failure of concrete is considered by not only conventional plastic theory but also damage mechanics. In the analysis to calculate the plastic deformation, Drucker-Prager yield surface model is employed, on the other hand Von-Mises yield surface model is applied for the reinforcing bar. Besides, mechanical influence of tensile crack in the concrete is also considered as the decrease of effective cross-section area using anisotropic damage variable. Several impact tests of RC beam are reviewed and their impact response are simulated by proposed analysis method. As a result, it is confirmed that proposed method can simulate impact response of RC beam and it could predict precise failure condition such as the distribution of concrete crack using anisotropic damage model.


2000 ◽  
Vol 123 (4) ◽  
pp. 403-408 ◽  
Author(s):  
C. L. Chow ◽  
X. J. Yang ◽  
Edmund Chu

Based on the theory of damage mechanics, a viscoplastic constitutive modeling of anisotropic damage for the prediction of forming limit curve (FLC) is developed. The model takes into account the effect of rotation of principal damage coordinates on the deformation and damage behaviors. With the aid of the damage viscoplastic potential, the damage evolution equations are established. Based on a proposed damage criterion for localized necking, the model is employed to predict the FLC of aluminum 6111-T4 sheet alloy. The predicted results agree well with those determined experimentally.


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