Papers by Santiago Serebrinsky
Springer eBooks, May 23, 2008
We develop a phenomenological model of electro-mechanical ferroelectric fatigue based on a ferroe... more We develop a phenomenological model of electro-mechanical ferroelectric fatigue based on a ferroelectric cohesive law that couples mechanical displacement and electric-potential discontinuity to mechanical tractions and surface-charge density. The ferroelectric cohesive law exhibits a monotonic envelope and loading-unloading hysteresis. The model is applicable whenever the changes in properties leading to fatigue are localized in one or more planar-like regions, modelled by the cohesive surfaces. We validate the model against experimental data for a simple test configuration consisting of an infinite slab acted upon by an oscillatory voltage differential across the slab and otherwise stress free. The model captures salient features of the experimental record including: the existence of a threshold nominal field for the onset of fatigue; the dependence of the threshold on the applied-field frequency; the dependence of fatigue life on the amplitude of the nominal field; and the size effect on the coercive field. Our results, although not conclusive, indicate that planar-like regions affected by cycling may lead to the observed fatigue in tetragonal PZT. A particularly appealing feature of the model is that it can be incorporated in a very natural and convenient way into a general finite element analysis of structures and devices for fatigue life assessment.
Effect of Dilatancy in Weak Mechanical Discontinuities on Their Interaction with Fluid Driven Fractures
All Days
Fluid driven fracturing plays a key role in several industrial applications, such as stimulation ... more Fluid driven fracturing plays a key role in several industrial applications, such as stimulation of O&G reservoirs, development of enhanced geothermal systems, and geological carbon storage, to name a few. In previous works we have introduced Y-FRAC®, a fluid driven fracture and rock mechanics simulation platform which makes use of the Discontinuous Galerkin method and a cohesive zone model to describe the deformation and fracture processes that take place in the rock, and standard finite elements to model the corresponding fluid flow inside the fractures during stimulation. In this work, we expand the previously used constitutive models in order to include the effects of dilatancy during shear deformation. We then evaluate the effect of dilatancy in some cases of practical interest, particularly for the hydraulic fracturing of unconventional reservoirs. INTRODUCTION The role of fluid driven fractures and their interaction with weak discontinuities in subsurface phenomena is of sign...
Physical Review E, Mar 31, 2011
We rigorously establish a physical time scale for a general class of kinetic Monte Carlo algorith... more We rigorously establish a physical time scale for a general class of kinetic Monte Carlo algorithms for the simulation of continuous-time Markov chains. This class of algorithms encompasses rejection-free (or BKL) and rejection (or "standard") algorithms. For rejection algorithms, it was formerly considered that the availability of a physical time scale (instead of Monte Carlo steps) was empirical, at best. Use of Monte Carlo steps as a time unit now becomes completely unnecessary.
Propagation regimes, transition times, and approximate universality in 2D hydraulic fracture propagation with fluid lag
Engineering Fracture Mechanics, Sep 1, 2021
Abstract During its lifetime, a hydraulic fracture is known to traverse a trajectory in a region ... more Abstract During its lifetime, a hydraulic fracture is known to traverse a trajectory in a region of a parametric space of non-dimensional evolutionary parameters. The topology of this diagram depends upon the phenomena considered. For the specific case of a 2D-plane strain fracture propagating in an elastic solid on a straight path normal to the minimum compressive stress, with a constant rate of injection of an incompressible newtonian fluid, and without leak-off, the diagram is a triangle whose vertices are typically called O, M, and K. The non-dimensional parameters are the toughness K and remote stress T (monotonically increasing with time). At each point in the trajectory P ( t ) = ( K , T ) ( t ) , the configuration of the fracture is essentially described by several non-dimensional variables, in this case the opening Ω 0 and pressure Π 0 at the inlet, and the length γ . When fluid lag is considered, as in this case, a fourth variable (e.g., the fluid fraction ξ f ) can be appended to build the descriptive set F 0 = { Ω 0 , Π 0 , γ , ξ f } . Various propagation regimes are observed across the MKO triangle. As the main results, we: (1) provide specific, K -dependent transition times among the propagation regimes; and (2) found that the transient evolutions of all propagating cracks with moderate values of the non-dimensional toughness ( K ≳ 0 . 3 ), from the OK edge to the MK edge, are contained in a thin bundle about a universal curve in the F 0 -space. This result can be applied, e.g., to readily setup approximate initial conditions for more detailed hydraulic fracture propagation simulations. In addition, we developed a four-parameter family of parametrizations of the MKO triangle suitable for plotting trajectories and other loci on the triangle.
Proceedings of SPIE, Jul 21, 2004
A cohesive fatigue-crack nucleation and growth model for ferroelectric materials under electro-me... more A cohesive fatigue-crack nucleation and growth model for ferroelectric materials under electro-mechanical loading is presented. The central feature of the model is a hysteretic cohesive law which couples the mechanical and electrical fields. This law can be used in conjunction with general constitutive relations of bulk behavior, possibly including domain switching, in order to predict fatigue crack growth under arbitrary loading conditions. Another appealing feature of the model is its ability to predict fatigue-crack nucleation. Despite the scarcity and uncertainty of the experimental data, comparisons with PZT fatigue-life data are encouraging.
International Journal of Hydrogen Energy, Apr 1, 2004
In this work, we present a parametrization of the density of states induced by a hydrogenic impur... more In this work, we present a parametrization of the density of states induced by a hydrogenic impurity in a metal that is described by a jellium. The parametrization has the most important features of the induced density of states (I-DOS). Among others, it includes the l = 0 shallow doubly occupied bound state observed at low jellium densities when rs is higher than the binding value rs;B, and is consistent with the charge pileup around the hydrogen due to the non-linear screening. It also addresses the inÿnite discontinuity in the l = 0 I-DOS at the bottom of the band when rs exceeds rs;B. Our results compare well with other calculations, including more sophisticated ones that include spin-polarized and many-body calculations. Many applications may take advantage of the tractability of this parametrization, as a reference or for speciÿc calculations.
International Journal of Hydrogen Energy, 2004
We evaluate the electronic contribution to the pressure dependence of the bulk modulus B of pure ... more We evaluate the electronic contribution to the pressure dependence of the bulk modulus B of pure metals using an e ective jellium model to characterize the electronic density. The partial derivative n=@B=@P evaluated at zero pressure (and at constant temperature) is the main parameter on which the Murnaghan equation of state depends. The general features of this method are discussed and the corresponding results are compared with experimental data.
Corrosion Science, Mar 1, 2004
Constant extension rate tests on smooth samples, with strain rate (SR) values from 10 À6 s À1 up ... more Constant extension rate tests on smooth samples, with strain rate (SR) values from 10 À6 s À1 up to 20 s À1 , were used to study stress corrosion cracking (SCC) systems in face-centred cubic alloys. It was found that by increasing the SR a monotonic increase of the log CPR (crack propagation rate) takes place. It was also observed that the slope a in log CPR vs. log SR plots had different values for different SCC morphologies. Intergranular SCC is more steeply accelerated by SR, a IG ¼ 0:5-0.7, than transgranular SCC, a TG ¼ 0:2-0.3. The differences found between intergranular SCC and transgranular SCC were analysed under the light of the available SCC mechanisms.
Journal of The Mechanics and Physics of Solids, Oct 1, 2004
We present a model of hydrogen embrittlement based upon: (i) a cohesive law dependent on impurity... more We present a model of hydrogen embrittlement based upon: (i) a cohesive law dependent on impurity coverage that is calculated from ÿrst principles; (ii) a stress-assisted di usion equation with appropriate boundary conditions accounting for the environment; (iii) a static continuum analysis of crack growth including plasticity; and (iv) the Langmuir relation determining the impurity coverage from its bulk concentration. We consider the e ect of the following parameters: yield strength, stress intensity factor, hydrogen concentration in the environment, and temperature. The calculations reproduce the following experimental trends: (i) time to initiation and its dependence on yield strength and stress intensity factor; (ii) ÿnite crack jump at initiation; (iii) intermittent crack growth; (iv) stages I and II of crack growth and their dependence on yield strength; (v) the e ect of the environmental impurity concentration on the threshold stress intensity factor; and (vi) the e ect of temperature on stage II crack velocity in the low-temperature range. In addition, the theoretically and experimentally observed intermittent cracking may be understood as being due to a time lag in the di usion of hydrogen towards the cohesive zone, since a buildup of hydrogen is necessary in order for the crack to advance. The predictions of the model are in good quantitative agreement with available measurements, suggesting that hydrogen-induced degradation of cohesion is a likely mechanism for hydrogen-assisted cracking.
MRS Proceedings, 2005
We develop a phenomenological model of electro-mechanical ferroelectric fatigue based on a ferroe... more We develop a phenomenological model of electro-mechanical ferroelectric fatigue based on a ferroelectric cohesive law that couples mechanical displacement and electric-potential discontinuity to mechanical tractions and surface-charge density. The ferroelectric cohesive law exhibits a monotonic envelope and loading-unloading hysteresis. The model is applicable whenever the changes in properties leading to fatigue are localized in one or more planar-like regions, modelled by the cohesive surfaces. We validate the model against experimental data for a simple test configuration consisting of an infinite slab acted upon by an oscillatory voltage differential across the slab and otherwise stress free. The model captures salient features of the experimental record including: the existence of a threshold nominal field for the onset of fatigue; the dependence of the threshold on the applied-field frequency; the dependence of fatigue life on the amplitude of the nominal field; and the size effect on the coercive field. Our results, although not conclusive, indicate that planar-like regions affected by cycling may lead to the observed fatigue in tetragonal PZT. A particularly appealing feature of the model is that it can be incorporated in a very natural and convenient way into a general finite element analysis of structures and devices for fatigue life assessment.
Acta Materialia, Feb 1, 2006
We develop a phenomenological model of electro-mechanical ferroelectric fatigue based on a ferroe... more We develop a phenomenological model of electro-mechanical ferroelectric fatigue based on a ferroelectric cohesive law that couples mechanical displacement and electric-potential discontinuity to mechanical tractions and surface-charge density. The ferroelectric cohesive law exhibits a monotonic envelope and loading-unloading hysteresis. The model is applicable whenever the changes in properties leading to fatigue are localized in one or more planar-like regions, modeled by the cohesive surfaces. We validate the model against experimental data for a simple test configuration consisting of an infinite slab acted upon by an oscillatory voltage differential across the slab and otherwise stress free. The model captures salient features of the experimental record including: the existence of a threshold nominal field for the onset of fatigue; the dependence of the threshold on the applied-field frequency; the dependence of fatigue life on the amplitude of the nominal field; and the dependence of the coercive field on the size of the component, or size effect. Our results, although not conclusive, indicate that planar-like regions affected by cycling may lead to the observed fatigue in tetragonal PZT.
Corrosion Science, 1999
The e}ect of strain rate "SR# on the stress corrosion crack propagation rate "CPR#\ for strain ra... more The e}ect of strain rate "SR# on the stress corrosion crack propagation rate "CPR#\ for strain rates covering a wide range of values "09 −5 s −0 ³19 s −0 # was studied for numerous systems[ The increase in the SR value was found to produce a monotonic increase in the CPR values[ It was also observed that the accelerating e}ect of the SR was always higher for intergranular stress corrosion cracking "IGSCC# than for transgranular stress corrosion cracking "TGSCC#[ Typi! cal slopes measured for log CPR vs log SR plots were a 9[4 to 9[6 for IGSCC and a 9[1 to 9[2 for TGSCC[ Þ 0887 Elsevier Science Ltd[ All rights reserved[
Coupled Simulation of the Interaction of a Hydraulic Fracture With a Natural Fracture
52nd U.S. Rock Mechanics/Geomechanics Symposium, Jun 17, 2018
Hydraulic Fracture Propagation in Strike-Slip Regime With Weak Interfaces
53rd U.S. Rock Mechanics/Geomechanics Symposium, Jun 23, 2019
Material Testing for the Prediction of the Effect of Deformation and Aging Thermal Treatments on Collapse Resistance of UOE Pipes
Oil & Gas offshore exploration and production increase continuously in deep waters. T... more Oil & Gas offshore exploration and production increase continuously in deep waters. This trend requires pipes with increasing collapse pressure (pc), which is the primary design variable. The prediction of pc, based on an appropriate set of input variables, allows for the appropriate design of deep and ultra-deep water projects. Elastic and plastic material behavior is one of the main factors affecting pc. International application codes (e.g., DNV OS-F101) incorporate the yield strength into their formulas for pc. In the present work, an assessment of the requirements on material characterization tests for a reliable prediction of pc has been performed. The most appropriate testing direction is the transverse compression. Moreover, since for large diameter pipes the plastic strain levels attained at collapse are often below 0.2%, the sample should allow for an accurate determination of compression behavior in this very low deformation range. This is particularly relevant for cold-formed pipes, as with the UOE process. Based on these guidelines, a testing procedure has been designed. This analysis has been applied to the prediction of the effect of thermal cycles on pc. Calculated values show a very good agreement with experimental pc values determined for a series of UOE processed pipes that had been thermally treated and collapsed.
Effect of Forming on Behavior of UOE Pipe Material
ABSTRACT
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Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, Mar 1, 2013
The concept of a ''Strain aging induced anisotropy in mechanical properties'', proposed by Richar... more The concept of a ''Strain aging induced anisotropy in mechanical properties'', proposed by Richards et al. [Mater. Sci. Eng. A 529 (2011) 184], is shown to be misleading. Anisotropy of strain aging kinetics is proposed as a possible source of confusion. & 2012 Elsevier B.V. All rights reserved. ''Because the directional nature of aging can result in mechanical properties that are directionally dependent (anisotropic), strain aging can produce unexpected mechanical behavior in certain situations.'' ''yif strain aging is a component of the processing of a material, whether intentional or not, its mechanical properties must be carefully characterized to ensure they are completely understood for design purposes.'' The concept posited in [1] is exemplified there by two cases largely dealt with in the literature. These are: (1) the strength and Contents lists available at SciVerse ScienceDirect
Mecánica Computacional, 2016
Scripta Materialia, Nov 1, 2005
We assess the ability of a hysteretic cohesive-law model to predict the number of cycles to fatig... more We assess the ability of a hysteretic cohesive-law model to predict the number of cycles to fatigue-crack initiation. Comparisons with experimental data for a 2048-T851 aluminum alloy, 300 M steel and AISI 4340 steel suggest that the approach captures salient aspects of the observed behavior.
Finite Elements Simulation of the Interaction of a Hydraulic Fracture With a Natural Fracture
51st U.S. Rock Mechanics/Geomechanics Symposium, Jun 25, 2017
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Papers by Santiago Serebrinsky