Journal articles on the topic 'Simulations; formation damage'
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Lohne, Arild, Liqun Han, Claas van Zwaag, Hans van Velzen, Anne-Mette Mathisen, Allan Twynam, Wim Hendriks, Roman Bulgachev, and Dimitrios G. Hatzignatiou. "Formation-Damage and Well-Productivity Simulation." SPE Journal 15, no. 03 (May 20, 2010): 751–69. http://dx.doi.org/10.2118/122241-pa.
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Summary In this paper, we describe a simulation model for computing the damage imposed on the formation during overbalanced drilling. The main parts modeled are filter-cake buildup under both static and dynamic conditions; fluid loss to the formation; transport of solids and polymers inside the formation, including effects of porelining retention and pore-throat plugging; and salinity effects on fines stability and clay swelling. The developed model can handle multicomponent water-based-mud systems at both the core scale (linear model) and the field scale (2D radial model). Among the computed results are fluid loss vs. time, internal damage distribution, and productivity calculations for both the entire well and individual sections. The simulation model works, in part, independently of fluid-loss experiments (e.g., the model does not use fluid-leakoff coefficients but instead computes the filter-cake buildup and its flow resistance from properties ascribed to the individual components in the mud). Some of these properties can be measured directly, such as particle-size distribution of solids, effect of polymers on fluid viscosity, and formation permeability and porosity. Other properties, which must be determined by tuning the results of the numerical model against fluid-loss experiments, are still assumed to be rather case independent, and, once determined, they can be used in simulations at altered conditions as well as with different mud formulations. A detailed description of the filter-cake model is given in this paper. We present simulations of several static and dynamic fluid-loss experiments. The particle-transport model is used to simulate a dilute particle-injection experiment taken from the literature. Finally, we demonstrate the model's applicability at the field scale and present computational results from an actual well drilled in the North Sea. These results are analyzed, and it is concluded that the potential effects of the mechanistic modeling approach used are (a) increased understanding of damage mechanisms, (b) improved design of experiments used in the selection process, and (c) better predictions at the well scale. This allows for a more-efficient and more-realistic prescreening of drilling fluids than traditional core-plug testing.
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Ding, D. Y. Y. "Modeling Formation Damage for Flow Simulations at Reservoir Scale." SPE Journal 15, no. 03 (May 20, 2010): 737–50. http://dx.doi.org/10.2118/121805-pa.
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Summary Formation damage generally is limited to the immediate nearwellbore region and needs a particular near-well-flow modeling using fine gridblocks. However, near-well models are usually developed as standalone models and are decoupled from reservoir models. Using a standalone near-well model that does not take into account production scenarios cannot predict well injectivity or productivity correctly. In this paper, we propose a new technique for the coupled modeling of a near-well-flow model and a reservoir model in a simple and consistent way. In this new approach, data are exchanged and updated through boundary conditions for the near-well model and through numerical productivity indices (PIs) (or skin factors) for the reservoir model. Examples show that this coupled modeling gives quite satisfactory results.
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Wang, Yitao, Teng Zhang, Yuting He, Jiyuan Ye, Hanzhe Zhang, and Xianghong Fan. "Analysis of Damage of Typical Composite/Metal Connecting Structure in Aircraft under the Influences of High-Velocity Fragments." Applied Sciences 12, no. 18 (September 15, 2022): 9268. http://dx.doi.org/10.3390/app12189268.
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A two-stage light gas gun was used to conduct a high-velocity impact test on the aircraft’s typical composite/metal connecting structure (CFRP/AL). The battle damage simulations used for the CFRP/AL connecting structure were carried out under different intersection conditions. Then, the damage morphology and mechanism of high-velocity prefabricated spherical fragments on typical structures, the dynamic process of hyper-velocity impact, and the formation of debris clouds on the secondary damage morphology of different component structures were investigated. Next, based on the X-ray computerized tomography (CT), the typical mode of different damage areas and evolution trends of CFRP under high-velocity impacts were explored. Finally, a simulation model was established for battle damages of typical structures by combining FEM methods, and structural components’ energy dissipation capabilities for fragments under different velocities were analyzed. The study results provide a reference and model support for the rapid repair of battle-damaged aircraft and aircraft survivability design.
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Voskoboinikov, Roman. "MD simulations of primary damage formation in L12 Ni3Al intermetallics." Journal of Nuclear Materials 522 (August 2019): 123–35. http://dx.doi.org/10.1016/j.jnucmat.2019.05.009.
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Khadke, Aniruddha, Somnath Ghosh, and Ming Li. "Numerical Simulations and Design of Shearing Process for Aluminum Alloys." Journal of Manufacturing Science and Engineering 127, no. 3 (July 21, 2004): 612–21. http://dx.doi.org/10.1115/1.1951787.
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This work combines experimental studies with finite element simulations to develop a reliable numerical model for the simulation of shearing process in aluminum alloys. The critical concern with respect to product quality in this important process is burr formation. Numerical simulations are aimed at understanding the role of process variables on burr formation and for recommending process design parameters. The commercial code ABAQUS-Explicit with the arbitrary Lagrangian-Eulerian kinematic description is used in this study for numerical simulations. An elastic-plastic constitutive model with experimentally validated damage models are incorporated through the user subroutine VUMAT in ABAQUS, for modeling deformation and ductile fracture in the material. Macroscopic experiments with microscopic observations are conducted to characterize the material and to calibrate the constitutive and damage models. Parametric study is done to probe the effect of process parameters and finally, a genetic algorithm (GA) based design method is used to determine process parameters for minimum burr formation.
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Kozlov, Alexander, Andrew V. Martin, and Harry M. Quiney. "Hybrid Plasma/Molecular-Dynamics Approach for Efficient XFEL Radiation Damage Simulations." Crystals 10, no. 6 (June 4, 2020): 478. http://dx.doi.org/10.3390/cryst10060478.
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X-ray free-electron laser pulses initiate a complex series of changes to the electronic and nuclear structure of matter on femtosecond timescales. These damage processes include widespread ionization, the formation of a quasi-plasma state and the ultimate explosion of the sample due to Coulomb forces. The accurate simulation of these dynamical effects is critical in designing feasible XFEL experiments and interpreting the results. Current molecular dynamics simulations are, however, computationally intensive, particularly when they treat unbound electrons as classical point particles. On the other hand, plasma simulations are computationally efficient but do not model atomic motion. Here we present a hybrid approach to XFEL damage simulation that combines molecular dynamics for the nuclear motion and plasma models to describe the evolution of the low-energy electron continuum. The plasma properties of the unbound electron gas are used to define modified inter-ionic potentials for the molecular dynamics, including Debye screening and drag forces. The hybrid approach is significantly faster than damage simulations that treat unbound electrons as classical particles, enabling simulations to be performed on large sample volumes.
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Wu, Shi, Han Cao, Dong Jie Wang, Li Xia Jia, and Yan Kun Dou. "Cascades Damage in γ-Iron from Molecular Dynamics Simulations." Materials Science Forum 993 (May 2020): 1011–16. http://dx.doi.org/10.4028/www.scientific.net/msf.993.1011.
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The degradation of austenitic stainless steels under irradiation environment is a known problem for nuclear reactors, which starts from atoms displacement cascade. Here, molecular dynamics (MD) simulations have been used to investigate the formation of atomic displacement cascade in γ-iron for energies of the primary knock-on atom (PKA) up to 40 keV at 300 K. The number of Frenkel pairs increased sharply until a peak value was reached, which occurred at a time in the range of 0.1-2 ps. After that, a number of defects gradually decreased and became stabilized. Compared with α-iron, there was less defects in the stable stage, and more clustered defects were produced in γ-iron. Within the range of PKA energies, two regimes of power-law energy-dependence of the defect production were observed, which converge on 16.8 keV. The transition energy also marks the onset of the formation of large self-interstitial atom (SIA) clusters and vacancy clusters. Interstitial and vacancy clusters were in the form of Shockley, Frank dislocation loops and Stir-Rod dislocation loops.
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Rahafrooz, M., M. Sanjari, M. Moradi, and Danial Ghodsiyeh. "Prediction of Rupture in Gas Forming Process Using Continuum Damage Mechanic." Advanced Materials Research 463-464 (February 2012): 1047–51. http://dx.doi.org/10.4028/www.scientific.net/amr.463-464.1047.
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The Continuum Damage Mechanics is a branch of applied mechanics that used to predict the initiation of cracks in metal forming process. In this article, damage definition and ductile damage model are explained, and also ductile damage model is applied to predict initiation of fracture in gas metal forming process with ABAQUS/EXPLICIT simulation. In this method instead of punch, the force is applied by air pressure. In this study, first the ductile damage criterion and its relations are taken into account and, subsequently, the process of gas-aid formation process is put into consideration and ductile damage model for prediction of rupture area is simulated using ABAQUS simulation software. Eventually, the process of formation via gas on the aluminum with total thickness of 0.24 [mm] was experimentally investigated and the results acquired from experiment were compared with relating simulations. The effect of various parameters such as radius of edge matrix, gas pressure and blank temperature has been evaluated. Simulation was compared with experimental results and good agreement was observed.
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Hu, M. S., M. Y. He, and A. G. Evans. "Solvent-induced damage in polyimide thin films." Journal of Materials Research 6, no. 6 (June 1991): 1374–83. http://dx.doi.org/10.1557/jmr.1991.1374.
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Solvent induced crazes formed in strained polyimide thin films on different substrates have been studied. A fracture mechanics approach has been used to simulate craze evolution. The experiments and simulations have identified a critical prestrain below which craze formation does not occur. This strain decreases with increase in solvent exposure time, but also exhibits a threshold. Diffusion of the solvent into the film is considered to be responsible for the time-dependent nature of damage formation.
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Voskoboinikov, Roman. "Optimal sampling of MD simulations of primary damage formation in collision cascades." Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 479 (September 2020): 18–22. http://dx.doi.org/10.1016/j.nimb.2020.06.001.
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Finzi, Yaron, Hans Muhlhaus, Lutz Gross, and Artak Amirbekyan. "Shear Band Formation in Numerical Simulations Applying a Continuum Damage Rheology Model." Pure and Applied Geophysics 170, no. 1-2 (April 3, 2012): 13–25. http://dx.doi.org/10.1007/s00024-012-0463-y.
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Öpöz, Tahsin Tecelli, and Xun Chen. "Influential Parameters in Determination of Chip Shape in High Speed Machining." Key Engineering Materials 496 (December 2011): 211–16. http://dx.doi.org/10.4028/www.scientific.net/kem.496.211.
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Cutting processes in machining involves the elastic and plastic formation where a layer of material is removed by a cutting tool to be removed from the workpiece in forms of various types of small chips. In this paper, a series of finite element simulations of 2D chip formation with various parameters are presented. Different types of chip shapes, such as continuous, discontinuous and serrated shape, are simulated under different conditions. A damage evolution technique based on fracture energy dissipation during material damage progression is used to demonstrate the influences on chip formation. It is concluded that the fracture energy in damage evolution is a crucial factor for the determination of chip shape. Further the influence of depth of cut and rake angle are considered in the simulations.
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Deo, Chaitanya S., Elton Y. Chen, and Rémi Dingeville. "Atomistic modeling of radiation damage in crystalline materials." Modelling and Simulation in Materials Science and Engineering 30, no. 2 (December 23, 2021): 023001. http://dx.doi.org/10.1088/1361-651x/ac2f83.
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Abstract This review discusses atomistic modeling techniques used to simulate radiation damage in crystalline materials. Radiation damage due to energetic particles results in the formation of defects. The subsequent evolution of these defects over multiple length and time scales requiring numerous simulations techniques to model the gamut of behaviors. This work focuses attention on current and new methodologies at the atomistic scale regarding the mechanisms of defect formation at the primary damage state.
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Feder, Judy. "Laboratory Formation Damage Test Data Upscaled With Computational Fluid Dynamics." Journal of Petroleum Technology 73, no. 03 (March 1, 2021): 63–64. http://dx.doi.org/10.2118/0321-0063-jpt.
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This article, written by JPT Technology Editor Judy Feder, contains highlights of paper SPE 199268, “Upscaling Laboratory Formation Damage Laboratory Test Data,” by Michael Byrne, SPE, Lesmana Djayapertapa, and Ken Watson, SPE, Lloyd’s Register, et al., prepared for the 2020 SPE International Conference and Exhibition on Formation Damage Control, Lafayette, Louisiana, 19-21 February. The paper has not been peer reviewed. Through several case histories, the complete paper demonstrates applications of computational fluid dynamics (CFD) modeling to upscaling of laboratory-measured formation damage and reveals implications for well and completion design. The value of laboratory testing is quantified and interesting challenges to conventional wisdom are highlighted. Introduction Laboratory formation damage testing is often used to help select optimal drilling and completion fluids. Test procedures such as sand retention and return permeability represent an attempt to simulate near-wellbore conditions during well construction and production. To determine what degree of permeability impairment is allowable, further interpretation that cannot be provided using classical nodal analysis or reservoir simulation methods is required. The complete paper describes the evolution of, and potential for, more-comprehensive upscaling and outlines the importance of consideration of full well geometry when designing and interpreting coreflood tests for formation damage. CFD simulations provide a means to upscale suitable laboratory test data to predict effect on well performance. Methods CFD simulations use a relatively simple, steady-state, static damage model that takes endpoint data from laboratory core tests and translates the data into parameters that are used for input into well geometry. Although this method has its merits and is a considerable advance on previous, more-simplistic upscaling attempts, it does not necessarily present the full picture of damage evolution in the near-wellbore. A transient model of damage with data again derived from laboratory coreflood data could reveal more about well cleanup and progressive damage removal. Steady-State Modeling. No API recommended practice for return permeability testing exists. Laboratories have their own procedures that comply broadly with recommended procedures developed some time ago. Operators and consultants, too, have their own procedures, which they often ask laboratories to follow. Although no recommended practice exists, evaluation of drilling and completion fluids usually involves measurement of a base permeability and remeasurement of a return permeability—or several—after application of the test fluid or fluids. In many cases, the laboratory removes the external mud cake or trims a slice of the end of the plug to measure return permeability without mud cake (Fig. 1).
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Belšak, Aleš, and Jože Flašker. "Vibration Analysis of Gears with Fatigue Crack in Tooth Root." Key Engineering Materials 324-325 (November 2006): 835–38. http://dx.doi.org/10.4028/www.scientific.net/kem.324-325.835.
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A crack in the tooth root, which often leads to failure in gear unit operation, is the most undesirable damage caused to gear units. This article deals with fault analyses of gear units with real damages. Numerical simulations of real operating conditions have been used in relation to the formation of those damages. A laboratory test plant has been used and a possible damage can be identified by monitoring vibrations. The influences of defects of a single-stage gear unit upon the vibrations they produce are presented. Signal analysis has been performed also in concern to a non-stationary signal, using the Time Frequency Analysis tools. Typical spectrograms, which are the result of reactions to damages, are a very reliable indication of the presence of damages.
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Yin, Jian Ping, Hong Cheng Zhang, Zhi Jun Wang, and Lu Fu. "Influence of Bar-Cutting Material on the Formation of MEFP." Advanced Materials Research 538-541 (June 2012): 1304–7. http://dx.doi.org/10.4028/www.scientific.net/amr.538-541.1304.
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The density of bar-cutting wire reflects the intensity of cutting material, in order to evaluate the influence of the cutting material on the formation and hitting probabilities of MEFP, numerical simulations of the forming process of MEFP passing through the cutting bar with different material like aluminum alloy, steel, copper and tungsten are carried out in Lagrange method of LS-DYNA. Then the influence of different cutting material on MEFP’s damage efficiency is analyzed based on the damage index of divergence angle. The results indicate that the cutting material has an obvious influence on the formation of MEFP, and the greater density of cutting material is, the better influence to the formation will be. Therefore, the shorter cutting time is, the better damage efficiency of MEFP will be.
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Otto, G., D. Kovač, and G. Hobler. "Coupled BC/kLMC simulations of the temperature dependence of implant damage formation in silicon." Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 228, no. 1-4 (January 2005): 256–59. http://dx.doi.org/10.1016/j.nimb.2004.10.054.
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Aoki, Takaaki, and Jiro Matsuo. "Molecular dynamics simulations of surface modification and damage formation by gas cluster ion impacts." Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 242, no. 1-2 (January 2006): 517–19. http://dx.doi.org/10.1016/j.nimb.2005.09.011.
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Wosatko, Adam. "Comparison of evolving gradient damage formulations with different activity functions." Archive of Applied Mechanics 91, no. 2 (February 2021): 597–627. http://dx.doi.org/10.1007/s00419-021-01889-2.
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AbstractIn the paper, two existing upgrades of the gradient damage model for the simulations of cracking in concrete are compared. The damage theory is made nonlocal via a gradient enhancement to overcome the mesh dependence of simulation results. The implicit gradient model with an averaging equation, where the internal length parameter is assumed as constant during the strain softening analysis, gives unrealistically broadened damage zones. The gradient enhancement of the scalar damage model can be improved via a function of an internal length scale, so an evolution of the gradient activity is postulated during the localization process. Two different modifications of the averaging equation and respective evolving gradient damage formulations are presented. Different activity functions are tested to see whether the formation of a too wide damage zone still occurs. Activating or localizing character of the gradient influence can be introduced and the impact of both approaches on the numerical results is shown in the paper. The aforementioned variants are implemented and examined using the benchmarks of tension in a bar and bending of a cantilever beam.
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Ma, Tianhui, Long Wang, Fidelis Tawiah Suorineni, and Chunan Tang. "Numerical Analysis on Failure Modes and Mechanisms of Mine Pillars under Shear Loading." Shock and Vibration 2016 (2016): 1–14. http://dx.doi.org/10.1155/2016/6195482.
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Severe damage occurs frequently in mine pillars subjected to shear stresses. The empirical design charts or formulas for mine pillars are not applicable to orebodies under shear. In this paper, the failure process of pillars under shear stresses was investigated by numerical simulations using the rock failure process analysis (RFPA) 2D software. The numerical simulation results indicate that the strength of mine pillars and the corresponding failure mode vary with different width-to-height ratios and dip angles. With increasing dip angle, stress concentration first occurs at the intersection between the pillar and the roof, leading to formation of microcracks. Damage gradually develops from the surface to the core of the pillar. The damage process is tracked with acoustic emission monitoring. The study in this paper can provide an effective means for understanding the failure mechanism, planning, and design of mine pillars.
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Voskoboinikov, R. E. "A study of primary damage formation in collision cascades in titanium." Voprosy Materialovedeniya, no. 4(108) (February 1, 2022): 216–32. http://dx.doi.org/10.22349/1994-6716-2021-108-4-216-232.
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Molecular dynamics (MD) simulations were applied to study radiation damage formation in collision cascades initiated by primary knock-on atoms (PKA) with energy EРКА = 5, 10, 15 and 20 keV in α-Ti at T = 100, 300, 600 and 900 K ambient temperatures. A series of 24 collision cascades was simulated for each (EРКА, Т) pair. The necessary sampling set size was justified by a simple a posteriori procedure. The number of Frenkel pairs and the fraction of vacancies, εv, and self-interstitial atoms (SIAs), εi in point defect clusters were evaluated as functions of (EРКА, Т). It was established that collision cascades in α-Ti are extended along PKA trajectories and tend to split into subcascades. In contrast to other elemental metals with close-packed crystal structure, εv≥ εi in collision cascades in α-Ti. Moreover, both εv and εi demonstrate weak temperature dependence. This is anindirect indication that both vacancy and SIA clusters created in collision cascades in α-Ti are stable in the considered temperature range
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Tisler, Witold, Wioletta Gorczewska-Langner, Rafał Ossowski, Marcin Cudny, and Adam Szymkiewicz. "Numerical simulations of overflow experiments on a model dike." MATEC Web of Conferences 262 (2019): 01003. http://dx.doi.org/10.1051/matecconf/201926201003.
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Dike failure due to overtopping is one of the important factors, which should be considered in the dike designing process. Although the overflow is characterized by the relatively low risk of occurrence, in many cases dikes are totally destroyed or seriously damaged. An interesting phenomenon occurring during overflow is the trapping of air in pores of the unsaturated soil material. As the infiltration progresses from all sides, the air pressure in the unsaturated region increases, which may ultimately lead to damage of the dike structure. It happens when the air is expulsed in form of bursts and forms large macropores. Such a behaviour evidenced in laboratory experiments. In this study we attempt to simulate the evolution of stress field in the model dike subjected to overtopping. The results are in qualitative agreement with observations, showing that formation of the first macropores occurs in the direction perpendicular to the minor principal stress in the soil mass along the dike slope edge.
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Suryanarayana, P. V., Zhan Wu, John Ramalho, and Ronald Earl Himes. "Dynamic Modeling of Invasion Damage and Impact on Production in Horizontal Wells." SPE Reservoir Evaluation & Engineering 10, no. 04 (August 1, 2007): 348–58. http://dx.doi.org/10.2118/95861-pa.
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Summary We present a novel approach that combines dynamic reservoir simulations and special core tests to model the extent of invasive damage and its impact on flowback during production. A radially adaptive 3D microsimulator is used to estimate the extent and impact of filtrate invasion on near-wellbore saturation and reservoir pressure. Time-varying reservoir exposure is used to simulate the acts of drilling, tripping, completions, and workovers. Extremely fine, core-scale grids are used to capture saturation and pressure in the invasion zone. Special core tests using a specially designed core holder are conducted on the subject reservoir core. Test results are interpreted to obtain an estimate of endpoint relative permeabilities, dynamic mudcake effect on filtrate loss, and impact of solids invasion on return permeability. The saturation and pressure profiles from this model are then used as initial conditions in a sector-scale simulator to model flowback effects. Absolute-permeability damage is modeled using the core-test results as an incremental and hyperbolically recovering effect during flowback simulations. A near-wellbore fine-grid overlay is used to capture the near-wellbore effects from the microsimulator results. Several sensitivities, including initial reservoir pressure, degree of overbalance and drawdown, heterogeneity, anisotropy, and mudcake effect, are examined. Equivalent skin factors that vary with time and depth are developed to enable comparison with full-field simulations. A horizontal-well example is used to illustrate the results of the study. Results illustrate the stark and often underappreciated effects of invasive damage on flowback and, therefore, on production performance. The methods described in this work can be used in reservoir-specific studies to quantify formation damage and aid in the selection of mud types, drilling techniques, and remediation methods required to improve performance. It is hoped that this work bridges the typically empirical damage-characterization methods and dynamic reservoir simulations. Introduction Conventional (or overbalanced) drilling and workover operations invariably result in invasion of filtrate and solids present in the drilling and workover fluids. In most cases, the damage caused is limited to a near-wellbore region and can reduce productivity because of degradation in effective permeability. Permeability degradation from filtrate and solids invasion could be caused by a variety of damage mechanisms, such as blockage of pore throats by solids, reduction in relative permeability to hydrocarbons because of a change in saturation, phase blockage, and clay swelling in the formation. Damage can be harsher in horizontal wells and mature reservoirs because of greater overbalance and longer duration of exposure to drilling fluids. During drilling, mudcake buildup can reduce the invasion depth. The buildup and effectiveness of mudcake depend greatly upon the formulation of the mud, the type and heterogeneity of the formation being drilled, the maturity of the reservoir, and the degree of overbalance during drilling or workovers. In horizontal wells, mudcake effectiveness is compromised further because of repeated movement of the pipe against the mudcake, leading to several events of removal and re-laying of the mudcake. The effects of damage also can be alleviated by the use of remedial stimulation techniques such as acidizing and hydraulic fracturing. These may not always produce the desired results, particularly in horizontal wells in highly heterogeneous formations. Moreover, implementing some of these techniques in horizontal wells is difficult. Given the potential for reduced productivity from invasion, characterization of invasion-induced damage has been of interest for decades. However, the implicit presumption when dealing with invasion-induced damage has been that it can be mitigated (by appropriate selection of muds and formation of mudcake), bypassed (through perforations), or remedied (through stimulation and fracturing). Most prior damage-characterization work has been empirical in nature, relying on log and core tests to assess damage parameters. More recently, some authors also have attempted to quantify and model formation damage from the fundamental principles of deep-bed filtration, fines migration, and percolation theory. Dynamic modeling of invasion with numerical simulations has also received much-needed attention in recent times. However, much of the numerical invasion-modeling work in the literature has focused on the invasion only (typically because of interest in the impact of the invasion zone on log accuracy), and very few works have dealt with the impact of invasion on flowback during production. The problem of bridging empirical models and dynamic simulations to obtain reasonable estimates of the impact on production has been one of the challenges. In this work, we present a novel approach that combines dynamic reservoir simulations and special core tests to model the extent of invasive damage and its impact on flowback during production. The approach uses an ultrafine-grid numerical simulator to model invasion, with parameters calibrated to special core tests. Flowback is then modeled using a sector-scale simulator with near-wellbore fine gridding, with the initial saturation and pressure profiles as determined by the invasion model and parameters calibrated to the core tests. The experimental and numerical approaches are described in detail, along with examples to illustrate the use of the methods we describe. Several sensitivity analyses are presented to demonstrate the often overlooked and underestimated impact of invasion on productivity. The method can be used to compare different mud types, evaluate the benefits of different remediation methods, and value the impact of underbalanced drilling (UBD) on productivity.
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JOHNSEN, ERIC, and TIM COLONIUS. "Numerical simulations of non-spherical bubble collapse." Journal of Fluid Mechanics 629 (June 15, 2009): 231–62. http://dx.doi.org/10.1017/s0022112009006351.
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A high-order accurate shock- and interface-capturing scheme is used to simulate the collapse of a gas bubble in water. In order to better understand the damage caused by collapsing bubbles, the dynamics of the shock-induced and Rayleigh collapse of a bubble near a planar rigid surface and in a free field are analysed. Collapse times, bubble displacements, interfacial velocities and surface pressures are quantified as a function of the pressure ratio driving the collapse and of the initial bubble stand-off distance from the wall; these quantities are compared to the available theory and experiments and show good agreement with the data for both the bubble dynamics and the propagation of the shock emitted upon the collapse. Non-spherical collapse involves the formation of a re-entrant jet directed towards the wall or in the direction of propagation of the incoming shock. In shock-induced collapse, very high jet velocities can be achieved, and the finite time for shock propagation through the bubble may be non-negligible compared to the collapse time for the pressure ratios of interest. Several types of shock waves are generated during the collapse, including precursor and water-hammer shocks that arise from the re-entrant jet formation and its impact upon the distal side of the bubble, respectively. The water-hammer shock can generate very high pressures on the wall, far exceeding those from the incident shock. The potential damage to the neighbouring surface is quantified by measuring the wall pressure. The range of stand-off distances and the surface area for which amplification of the incident shock due to bubble collapse occurs is determined.
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Lüders, Caroline, Michael Sinapius, and Daniel Krause. "Adaptive cycle jump and limits of degradation in micromechanical fatigue simulations of fibre-reinforced plastics." International Journal of Damage Mechanics 28, no. 10 (March 6, 2019): 1523–55. http://dx.doi.org/10.1177/1056789519833728.
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This research investigates the influence of numerical parameters of micromechanical fatigue damage models on the obtained progressive damage behaviour of fibre-reinforced plastics at transverse tensile fatigue loads. The simulated damage behaviour is evaluated using experimentally observed crack patters published in the literature. The investigated numerical model parameters are (1) whether or not the model considers static failure within a simulated load cycle, (2) the degree of material property degradation after sudden failure and (3) the size of the cycle jump. The results reveal a significant influence of the degree of material degradation and of the cycle jump on the simulated matrix crack formation at both higher and lower fatigue loads. Static failure within a simulated load cycle primarily affects the damage behaviour at higher fatigue loads. The paper gives recommendations of the parameter choice for plausible progressive fatigue damage simulation results. Regarding the cycle jump, an adaptive algorithm is proposed and implemented. This approach leads to plausible fatigue damage results paired with a significant reduction of computation time comparing to a cycle-by-cycle analysis.
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Russo, Michael F., Mostafa Maazouz, Lucille A. Giannuzzi, Clive Chandler, Mark Utlaut, and Barbara J. Garrison. "Gallium-Induced Milling of Silicon: A Computational Investigation of Focused Ion Beams." Microscopy and Microanalysis 14, no. 4 (July 4, 2008): 315–20. http://dx.doi.org/10.1017/s1431927608080653.
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Molecular dynamics simulations are performed to model milling via a focused ion beam (FIB). The goal of this investigation is to examine the fundamental dynamics associated with the use of FIBs, as well as the phenomena that govern the early stages of trench formation during the milling process. Using a gallium beam to bombard a silicon surface, the extent of lateral damage (atomic displacement) caused by the beam at incident energies of both 2 and 30 keV is examined. These simulations indicate that the lateral damage is several times larger than the beam itself and that the mechanism responsible for the formation of a V-shaped trench is due to both the removal of surface material, and the lateral and horizontal migration of subsurface silicon atoms toward the vacuum/crater interface. The results presented here provide complementary information to experimental images of trenches created during milling with FIBs.
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Nafar Dastgerdi, Jairan, Fariborz Sheibanian, Heikki Remes, and Hossein Hosseini Toudeshky. "Influences of Residual Stress, Surface Roughness and Peak-Load on Micro-Cracking: Sensitivity Analysis." Metals 11, no. 2 (February 12, 2021): 320. http://dx.doi.org/10.3390/met11020320.
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This paper provides further understanding of the peak load effect on micro-crack formation and residual stress relaxation. Comprehensive numerical simulations using the finite element method are applied to simultaneously take into account the effect of the surface roughness and residual stresses on the crack formation in sandblasted S690 high-strength steel surface under peak load conditions. A ductile fracture criterion is introduced for the prediction of damage initiation and evolution. This study specifically investigates the influences of compressive peak load, effective parameters on fracture locus, surface roughness, and residual stress on damage mechanism and formed crack size. The results indicate that under peak load conditions, surface roughness has a far more important influence on micro-crack formation than residual stress. Moreover, it is shown that the effect of peak load range on damage formation and crack size is significantly higher than the influence of residual stress. It is found that the crack size develops exponentially with increasing peak load magnitudes.
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Cheng, L. R., R. Chen, H. J. Shi, and F. Y. Lu. "The Pore Collapse “Hot-Spots” Model Coupled with Brittle Damage for Solid Explosives." Shock and Vibration 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/972414.
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This paper is devoted to the building of a numerical pore collapse model with “hot-spots” formation for the impacted damage explosives. According to damage mechanical evolution of brittle material, the one-dimensional elastic-viscoplastic collapse model was improved to incorporate the impact damage during the dynamic collapse of pores. The damage of explosives was studied using the statistical crack mechanics (SCRAM). The effects of the heat conduction and the chemical reaction were taken into account in the formation of “hot-spots.” To verify the improved model, numerical simulations were carried out for different pressure states and used to model a multiple-impact experiment. The results show that repeated weak impacts can lead to the collapse of pores and the “hot-spots” may occur due to the accumulation of internal defects accompanied by the softening of explosives.
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Yanikömer, Neslihan, Rahim Nabbi, and Klaus Fischer-Appelt. "Impact of Radiation-Induced Microstructures on the Integrity of Spent Nuclear Fuel (SNF) Elements in Long-Term Storage." Safety of Nuclear Waste Disposal 1 (November 10, 2021): 17–18. http://dx.doi.org/10.5194/sand-1-17-2021.
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Abstract. The current safety concept provides for a period in the range of 40 years for interim storage of spent fuel elements. Since the requirement for proof of safety for to up to 100 years arises, the integrity of the spent fuel elements in prolonged interim storage and long-term repositories is becoming a critical issue. In response to this safety matter, this study aims to assess the impact of radiation-induced microstructures on the mechanical properties of spent fuel elements, in order to provide reliable structural performance limits and safety margins. The physical processes involved in radiation damage and the effect of radiation damage on mechanical properties are inherently multiscalar and hierarchical. Damage evolution under irradiation begins at the atomic scale, with primary knock-on atoms (PKAs) resulting in displacement cascades (primary damage), followed by the defect clusters leading to microstructural deformations. In this context, we have developed and applied a multiscale simulation methodology consistent with the multistage damage mechanisms and the corresponding effects on the mechanical properties of spent fuel cladding and its integrity. Within the improved hierarchical modelling sequence, the effect of the radiation field on the fuel element cladding material (Zircalloy-4) is assessed using Monte Carlo methods. A molecular dynamics method is employed to model damage formation by PKAs and primary damage defect configurations. The formation of clusters and evolution of microstructures are simulated by extending the simulation sequence to a longer time scale with the kinetic Monte Carlo (KMC) method. Transferring the calculated radiation-induced microstructures into macroscopic quantities is ultimately decisive for the structural/mechanical behaviour and stability of the cladding material, and thus for long-term integrity of the spent fuel elements. Results of the multiscale modelling and simulations as well as a comparison with experimental results will be presented at the conference session.
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Plante, Mathieu, Bruno Tremblay, Martin Losch, and Jean-François Lemieux. "Landfast sea ice material properties derived from ice bridge simulations using the Maxwell elasto-brittle rheology." Cryosphere 14, no. 6 (July 1, 2020): 2137–57. http://dx.doi.org/10.5194/tc-14-2137-2020.
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Abstract. The Maxwell elasto-brittle (MEB) rheology is implemented in the Eulerian finite-difference (FD) modeling framework commonly used in classical viscous-plastic (VP) models. The role of the damage parameterization, the cornerstone of the MEB rheology, in the formation and collapse of ice arches and ice bridges in a narrow channel is investigated. Ice bridge simulations are compared with observations to derive constraints on the mechanical properties of landfast sea ice. Results show that the overall dynamical behavior documented in previous MEB models is reproduced in the FD implementation, such as the localization of the damage in space and time and the propagation of ice fractures in space at very short timescales. In the simulations, an ice arch is easily formed downstream of the channel, sustaining an ice bridge upstream. The ice bridge collapses under a critical surface forcing that depends on the material cohesion. Typical ice arch conditions observed in the Arctic are best simulated using a material cohesion in the range of 5–10 kN m−2. Upstream of the channel, fracture lines along which convergence (ridging) takes place are oriented at an angle that depends on the angle of internal friction. Their orientation, however, deviates from the Mohr–Coulomb theory. The damage parameterization is found to cause instabilities at large compressive stresses, which prevents the production of longer-term simulations required for the formation of stable ice arches upstream of the channel between these lines of fracture. Based on these results, we propose that the stress correction scheme used in the damage parameterization be modified to remove numerical instabilities.
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Lin, Pandong, Junfeng Nie, and Meidan Liu. "Study on displacement cascade and tensile simulation by molecular dynamics: Formation and properties of point defects." International Journal of Modern Physics B 35, no. 10 (April 20, 2021): 2150140. http://dx.doi.org/10.1142/s021797922150140x.
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The molecular dynamics method is used to investigate the formation and properties of irradiation-induced damage (point defects). Displacement cascade simulations are performed to study the effects of primary knock-on atom (PKA) energy, temperature, vacancy concentration and tensile pre-strain on irradiation-induced damage in [Formula: see text]-Fe. An increase in PKA energy, vacancy concentration and tensile pre-strain can lead to an increase in defect numbers. In contrast, an increase in temperature decreases the defect numbers. After cascade collisions, tensile tests are performed to investigate the effect of point defects on mechanical properties. The yield stress and corresponding strain of irradiated Fe decrease with an increase in the number density of Frenkel pairs. Results show that irradiation accelerates damage of the internal structure, decreases the number of slip bands and increases the instability of the structure during plastic deformation.
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Sun, Yi, and Fan Lin Zeng. "Molecule Mechanics Simulation on the Deformation and Damage Process in POSS Nanocomposite." Key Engineering Materials 348-349 (September 2007): 109–12. http://dx.doi.org/10.4028/www.scientific.net/kem.348-349.109.
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The deformation and damage process of POSS nanocomposite is investigated by molecule mechanics (MM) simulation. Firstly, the nano-scale models of two kinds of homopolymers, pure polystyrene (PS) and polystyrene attached with 5 mol% propyl-POSS (P-POSS-PS) were built. Then the mechanical behaviors of these two kinds of hybrid materials under focused uniaxial tensile loading and the remote uniaxial tensile loading are examined by MM simulations. It is found that a small quantity of POSS can observably increase the tensile modulus of the normal polymers. During tensile loadings, micro voids appear in the polymer matrix. With the increase of deformation, the micro voids become bigger and then connect to form the damage in bigger area. The POSS monomers prevent these micro voids from coalescence and thus retarding the formation of the damage. This would be helpful in understanding the reinforcement mechanism of POSS and provide important referential message for the applications of POSS.
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Omar, Karwan Ali, Karim Hasnaoui, and Aurélien de la Lande. "First-Principles Simulations of Biological Molecules Subjected to Ionizing Radiation." Annual Review of Physical Chemistry 72, no. 1 (April 20, 2021): 445–65. http://dx.doi.org/10.1146/annurev-physchem-101419-013639.
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Ionizing rays cause damage to genomes, proteins, and signaling pathways that normally regulate cell activity, with harmful consequences such as accelerated aging, tumors, and cancers but also with beneficial effects in the context of radiotherapies. While the great pace of research in the twentieth century led to the identification of the molecular mechanisms for chemical lesions on the building blocks of biomacromolecules, the last two decades have brought renewed questions, for example, regarding the formation of clustered damage or the rich chemistry involving the secondary electrons produced by radiolysis. Radiation chemistry is now meeting attosecond science, providing extraordinary opportunities to unravel the very first stages of biological matter radiolysis. This review provides an overview of the recent progress made in this direction, focusing mainly on the atto- to femto- to picosecond timescales. We review promising applications of time-dependent density functional theory in this context.
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Zalameda, Joseph, and William Winfree. "Detection and Characterization of Damage in Quasi-Static Loaded Composite Structures using Passive Thermography." Sensors 18, no. 10 (October 20, 2018): 3562. http://dx.doi.org/10.3390/s18103562.
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Real-time nondestructive evaluation is critical during composites load testing. Of particular importance is the real time measurement of damage onset, growth, and ultimate failure. When newly formed damage is detected, the loading is stopped for further detailed characterization using ultrasound inspections or X-ray computed tomography. This detailed inspection data are used to document failure modes and ultimately validate damage prediction models. Passive thermography is used to monitor heating from damage formation in a hat-stiffened woven graphite epoxy composite panel during quasi-static seven-point load testing. Data processing techniques are presented that enable detection of the small transient thermographic signals resulting from damage formation in real time. It has been observed that the temperature rise due to damage formation at the surface is composed of two thermal responses. The first response is instantaneous and conforms to the shape of the damage. This heating is most likely due to irreversible thermoelastic, plastic deformation, and microstructural heating. The second response is a transient increase in temperature due to mechanical heating at the interface of failure. Two-dimensional multi-layered thermal simulations based on quadrupole method are used to investigate the thermal responses. In particular, the instantaneous response is used as the transient response start time to determine damage depth. The passive thermography measurement results are compared to ultrasonic measurements for validation.
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Liao, Zonghu, Wei Li, Huayao Zou, Fang Hao, Kurt J. Marfurt, and Ze'ev Reches. "Composite damage zones in the subsurface." Geophysical Journal International 222, no. 1 (April 11, 2020): 225–30. http://dx.doi.org/10.1093/gji/ggaa158.
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SUMMARY The cumulative displacement by multiple slip events along faults may generate composite damage zones (CDZ) of increasing width, and could modify the hydraulic and mechanical properties of the faults. The internal architecture and fracture distribution within CDZs at the subsurface are analysed here by using seismic attributes of variance, curvature and dip-azimuth of the 3-D seismic reflection data from tight sandstone reservoirs in northeast Sichuan, China. The analysed faults intersect the reservoir within a depth range of 2.4–3.0 km. The damage intensity mapping revealed multiple CDZs with thicknesses approaching 1 km along faults ranging 3–15 km in length, and up to 1000 m of cumulative slip. The identification of numerous fault cores and associate damage zones led us to define three classes of CDZs: banded shape, box shape and dome shape. The mechanical strength contrasts and distortion of fault cores suggest potential weakening and strengthening (healing) mechanisms for formation of CDZs that can be extended to faulting processes and earthquake simulations.
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Vodorezov, Dmitry D. "Estimation of Horizontal-Well Productivity Loss Caused by Formation Damage on the Basis of Numerical Modeling and Laboratory-Testing Data." SPE Journal 24, no. 01 (September 26, 2018): 44–59. http://dx.doi.org/10.2118/194003-pa.
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Summary This paper presents a new numerical model of inflow to a well with a zone of damaged permeability. It is built on the principle of dividing the wellbore and damaged permeability zone into numerous segments. Simultaneous work of the segments is modeled with the method of velocity-potential theory. The model is applicable for wellbores of different trajectories including horizontal and multilateral wells. The model is focused on the extended application of results obtained during laboratory core testing that include a return-permeability (RP) profile of the core and cleanup parameters. The developed solution includes the effects of anisotropy, reservoir-boundary conditions, and a nonuniform distribution of formation damage in both radial and axial directions. The paper presents the new approach to include depth-variable distribution of damage in skin-factor models. The approach provides for the evaluation of pressure drop in a depth-variable damage zone by the resulting permeability that is defined by flow regime. Laboratory-obtained overall core permeability is associated with a linear flow, and when applied to a zone near the wellbore with radial or elliptic flow, it causes an error because of the depth-variable distribution of damage. The provided numerical simulations show that the impact of this factor on horizontal-well productivity is significant. The developed model is compared with existing analytical solutions of Furui et al. (2002) (FZH) and Frick and Economides (1993) (FE) for the case of a horizontal well with a cone-shaped damaged zone. The results show that a skin-factor transformation originally proposed by Renard and Dupuy (1991) for a case of a uniformly damaged well can be used successfully for the referred-to analytical solutions, which makes them applicable for wells with an elliptic drainage area. In this paper, we also suggest an approach whereby we relate the characteristics of the cleanup of the region near the wellbore to laboratory-testing conditions.
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Gray, R. L., M. J. D. Rushton, and S. T. Murphy. "Molecular dynamics simulations of radiation damage in YBa2Cu3O7." Superconductor Science and Technology 35, no. 3 (February 7, 2022): 035010. http://dx.doi.org/10.1088/1361-6668/ac47dc.
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Abstract The advent of high-temperature superconductors (HTS) with high field strengths offers the possibility of building smaller, cheaper magnetically confined fusion reactors. However, bombardment by high energy neutrons ejected from the fusion reaction may damage the HTS tapes and impair their operation. Recreating the conditions present in an operational fusion reactor is experimentally challenging, therefore, this work uses molecular dynamics simulations to understand how radiation modifies the underlying crystal structure of YBa2Cu3O7. To facilitate the simulations a new potential was developed that allowed exchange of Cu ions between the two symmetrically distinct sites without modifying the structure. Radiation damage cascades predict the formation of amorphous regions surrounded by regions decorated with Cu and O defects found in the CuO-chains. The simulations suggest that the level of recombination that occurs is relatively low, resulting in a large number of remnant defects and that there is a no substantial temperature effect.
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Van der Paal, Jonas, Sung-Ha Hong, Maksudbek Yusupov, Nishtha Gaur, Jun-Seok Oh, Robert D. Short, Endre J. Szili, and Annemie Bogaerts. "How membrane lipids influence plasma delivery of reactive oxygen species into cells and subsequent DNA damage: an experimental and computational study." Physical Chemistry Chemical Physics 21, no. 35 (2019): 19327–41. http://dx.doi.org/10.1039/c9cp03520f.
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The combination of phospholipid vesicle experiments and molecular dynamics (MD) simulations illustrate how lipid oxidation, lipid packing and rafts formation may influence the response of healthy and diseased cell membranes to plasma-derived RONS.
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Stolk, J., N. Verdonschot, K. A. Mann, and R. Huiskes. "Prevention of mesh-dependent damage growth in finite element simulations of crack formation in acrylic bone cement." Journal of Biomechanics 36, no. 6 (June 2003): 861–71. http://dx.doi.org/10.1016/s0021-9290(03)00003-4.
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Bosia, Federico, Nicola Maria Pugno, Giuseppe Lacidogna, and Alberto Carpinteri. "Modelling Damage Progression by a Statistical Energy-Balance Algorithm." Key Engineering Materials 347 (September 2007): 435–40. http://dx.doi.org/10.4028/www.scientific.net/kem.347.435.
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In this contribution some characteristics and predictive capabilities are discussed of a recently introduced model for damage progression and energy release, in view of modelling Acoustic Emission. The specimen is discretized in a network of connected springs, similar to a Fibre Bundle Model approach, with the spring intrinsic strengths statistically distributed according to a Weibull distribution. Rigorous energy balance considerations allow the determination of the dissipated energy due to crack surface formation and kinetic energy propagation. Based on results of simulations, the macroscopic behaviour emerging from different choices at “mesoscopic” level is discussed, in particular the relevance of model parameters such as the distribution of spring cross sections, Weibull modulus values, and discretization parameters in determining results like stressstrain curves and energy scaling versus time or specimen size.
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He, Zhongdu, Zongwei Xu, Mathias Rommel, Boteng Yao, Tao Liu, Ying Song, and Fengzhou Fang. "Investigation of Ga ion implantation-induced damage in single-crystal 6H-SiC." Journal of Micromanufacturing 1, no. 2 (August 6, 2018): 115–23. http://dx.doi.org/10.1177/2516598418785507.
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In order to investigate the damage in single-crystal 6H-silicon carbide (SiC) in dependence on ion implantation dose, ion implantation experiments were performed using the focused ion beam technique. Raman spectroscopy and electron backscatter diffraction were used to characterize the 6H-SiC sample before and after ion implantation. Monte Carlo simulations were applied to verify the characterization results. Surface morphology of the implantation area was characterized by the scanning electron microscope (SEM) and atomic force microscope (AFM). The ‘swelling effect’ induced by the low-dose ion implantation of 1014−1015 ions cm−2 was investigated by AFM. The typical Raman bands of single-crystal 6H-SiC were analysed before and after implantation. The study revealed that the thickness of the amorphous damage layer was increased and then became saturated with increasing ion implantation dose. The critical dose threshold (2.81 × 1014−3.26 × 1014 ions cm−2) and saturated dose threshold (˜5.31 × 1016 ions cm−2) for amorphization were determined. Damage formation mechanisms were discussed, and a schematic model was proposed to explain the damage formation.
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Fredrich, J. T., J. G. Arguello, G. L. Deitrick, and E. P. de Rouffignac. "Geomechanical Modeling of Reservoir Compaction, Surface Subsidence, and Casing Damage at the Belridge Diatomite Field." SPE Reservoir Evaluation & Engineering 3, no. 04 (August 1, 2000): 348–59. http://dx.doi.org/10.2118/65354-pa.
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Summary Geologic, and historical well failure, production, and injection data were analyzed to guide development of three-dimensional geomechanical models of the Belridge diatomite field, California. The central premise of the numerical simulations is that spatial gradients in pore pressure induced by production and injection in a low permeability reservoir may perturb the local stresses and cause subsurface deformation sufficient to result in well failure. Time-dependent reservoir pressure fields that were calculated from three-dimensional black oil reservoir simulations were coupled unidirectionally to three-dimensional nonlinear finite element geomechanical simulations. The reservoir models included nearly 100,000 gridblocks (100 to 200 wells), and covered nearly 20 years of production and injection. The geomechanical models were meshed from structure maps and contained more than 300,000 nodal points. Shear strain localization along weak bedding planes that causes casing doglegs in the field was accommodated in the model by contact surfaces located immediately above the reservoir and at two locations in the overburden. The geomechanical simulations are validated by comparison of the predicted surface subsidence with field measurements, and by comparison of predicted deformation with observed casing damage. Additionally, simulations performed for two independently developed areas at South Belridge, Secs. 33 and 29, corroborate their different well failure histories. The simulations suggest the three types of casing damage observed, and show that, although water injection has mitigated surface subsidence, it can, under some circumstances, increase the lateral gradients in effective stress that in turn can accelerate subsurface horizontal motions. Geomechanical simulation is an important reservoir management tool that can be used to identify optimal operating policies to mitigate casing damage for existing field developments, and applied to incorporate the effect of well failure potential in economic analyses of alternative infilling and development options. Introduction Well casing damage induced by formation compaction has occurred in reservoirs in the North Sea, the Gulf of Mexico, California, South America, and Asia.1–4 As production draws down reservoir pressure, the weight of the overlying formations is increasingly supported by the solid rock matrix that compacts in response to the increased stress. The diatomite reservoirs of Kern County, California, are particularly susceptible to depletion-induced compaction because of the high porosity (45 to 70%) and resulting high compressibility of the reservoir rock. At the Belridge diatomite field, located ~45 miles west of Bakersfield, California, nearly 1,000 wells have experienced severe casing damage during the past ~20 years of increased production. The thickness (more than 1,000 feet), high porosity, and moderate oil saturation of the diatomite reservoir translate into huge reserves. Approximately 2 billion bbl of original oil in place (OOIP) are contained in the diatomite reservoir and more than 1 billion bbl additional OOIP is estimated for the overlying Tulare sands. The Tulare is produced using thermal methods and accounts for three-quarters of the more than 1 billion bbl produced to date at Belridge.5 Production from the diatomite reservoir is hampered by the unusually low matrix permeability (typically ranging from 0.1 to several md), and became economical only with the introduction of hydraulic fracturing stimulation techniques in the 1970's.6 However, increased production decreased reservoir pressure, accelerated surface subsidence, and increased the number of costly well failures in the 1980's. Waterflood programs were initiated in the late 1980's to combat the reduced well productivity, accelerated surface subsidence, and subsidence-induced well failure risks. Subsidence rates are now near zero; however, the well failure rate, although lower than that experienced in the 1980's, is still economically significant at 2 to 6% of active wells per year. In 1994 a cooperative research program was undertaken to improve understanding of the geomechanical processes causing well casing damage during production from weak, compactable formations. A comprehensive database, consisting of historical well failure, production, injection, and subsidence data, was compiled to provide a unique, complete picture of the reservoir and overburden behavior.7,8 Analyses of the field-wide database indicated that two-dimensional approximations9–11 could not capture the locally complex production, injection, and subsidence patterns, and motivated large-scale, three-dimensional geomechanical simulations. Intermediary results for Sec. 33 that used preliminary reservoir flow and material models were reported earlier.8 This paper presents results for best-and-final simulations that used improved reservoir flow models, more sophisticated material models, and activated contact surfaces. The simulations were performed for two independently developed areas at South Belridge, Secs. 33 and 29.
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Gökay Korkmaz, Habip, Serkan Toros, Mehmet Halkaci, and Hüseyin Selçuk Halkaci. "Investigation of Hydro-piercing Method for Stainless Steels by Finite Element Method." MATEC Web of Conferences 220 (2018): 01003. http://dx.doi.org/10.1051/matecconf/201822001003.
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Researches and studies on hydroforming process, which is a method that is getting more and more popular every day thanks to its many advantages in application, are ongoing. It is possible to pierce- the holes on a tube or sheet hydroformed part using hydropiercing method after the forming operation. In this study, hydropiercing process of a 304 stainless steel is simulated via the LS-Dyna in 2D axial symmetry model. In the simulations two types of punch movement was investigated to determine the contribution to the burr formation. In the simulations, Jonson-Cook hardening and damage model were used to determine the initiation of the crack on the samples. As a result, the burr formation can be eliminated by the two step movement of the punch through the piercing operation.
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Chen, Shi Kuo, Tian Hong Yang, Hong Lei Liu, and Wan Cheng Zhu. "Water Inrush Monitoring of Zhangmatun Mine Grout Curtain and Seepage-Stress-Damage Research." Materials Science Forum 704-705 (December 2011): 558–62. http://dx.doi.org/10.4028/www.scientific.net/msf.704-705.558.
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Based on extensive literature review, the state of the art of coupled hydromechanical models and in-situ monitoring for groundwater inrush predictions are summarized in detail, based on which, it is proposed that the key issues for describing the seepage characteristics during groundwater inrush are to calibrate the equations for damage-induced evolution of permeability and of effective stress. Depending on in-situ experiments and numerical simulations, a new academic idea, i.e.“the rock micro seismicity induced by mining processes and water pressure disturbance is in essence the index of groundwater inrush” is put forward based on case studies, coupled hydro-mechanical theory, high-performance computing technology and microseismic monitoring. The authors propose that the tendency for analyzing and predicting the groundwater inrush is to synthetically inverse the inrush pathway formation, strata microseismic precursor and high performance computing results. And relying on the microseismic monitoring events, the groundwater inrush models are calibrated, which could be used to clarify the precursory characteristics and to locate the inrush pathway. This study will lay theoretical basis for establishing the models to predict the groundwater inrush in underground mining. Key words：rock mechanics, groundwater inrush models, calibrating, numerical simulation, microseismic monitoring
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Lin, Wenhua, Yeqing Wang, Youssef Aider, Mojtaba Rostaghi-Chalaki, Kamran Yousefpour, Joni Kluss, David Wallace, Yakun Liu, and Weifei Hu. "Analysis of damage modes of glass fiber composites subjected to simulated lightning strike impulse voltage puncture and direct high voltage AC puncture." Journal of Composite Materials 54, no. 26 (May 22, 2020): 4067–80. http://dx.doi.org/10.1177/0021998320927736.
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Understanding the damage mechanisms of fiber-reinforced polymer matrix composite materials under high voltage conditions is of great significance for lightning strike protection and high voltage insulation applications of composite structures. In this paper, we investigated effects of the lightning impulse (LI) voltage and high voltage alternating current (HVAC) puncture on damage modes of the electrically nonconductive glass fiber-reinforced polymer (GFRP) matrix composite materials through experimental tests and numerical simulations. The LI and HVAC tests represent the lightning strike and high voltage insulation cable puncture conditions, respectively. Our experimental examinations showed that GFRP composite specimens subjected to the LI voltage test exhibited distinct damage modes compared with those in the HVAC puncture test. The GFRP composite material suffered more charring and fiber vaporization in the HVAC puncture test, whereas less matrix charring and fiber vaporization but severe fiber breakage and delamination in response to the LI voltage tests. The findings indicate that the thermal effect dominates the damage of GFRP composites inflicted by the HVAC puncture test, whereas the mechanical impact effect governs the GFRP composite damage in the LI voltage test. In addition, the electric arc plasma formation during the puncture of the GFRP composite material was modeled through solving Maxwell’s equations and the heat generation equations using finite element analysis. Simulation results provided insights on the effects of duration and intensity of the high voltage electric discharge on the composite damage.
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Hyde, Jonathan M., Gérald DaCosta, Constantinos Hatzoglou, Hannah Weekes, Bertrand Radiguet, Paul D. Styman, Francois Vurpillot, et al. "Analysis of Radiation Damage in Light Water Reactors: Comparison of Cluster Analysis Methods for the Analysis of Atom Probe Data." Microscopy and Microanalysis 23, no. 2 (January 30, 2017): 366–75. http://dx.doi.org/10.1017/s1431927616012678.
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AbstractIrradiation of reactor pressure vessel (RPV) steels causes the formation of nanoscale microstructural features (termed radiation damage), which affect the mechanical properties of the vessel. A key tool for characterizing these nanoscale features is atom probe tomography (APT), due to its high spatial resolution and the ability to identify different chemical species in three dimensions. Microstructural observations using APT can underpin development of a mechanistic understanding of defect formation. However, with atom probe analyses there are currently multiple methods for analyzing the data. This can result in inconsistencies between results obtained from different researchers and unnecessary scatter when combining data from multiple sources. This makes interpretation of results more complex and calibration of radiation damage models challenging. In this work simulations of a range of different microstructures are used to directly compare different cluster analysis algorithms and identify their strengths and weaknesses.
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Allen, Jeffery M., Peter J. Weddle, Francois L. E. Usseglio-Viretta, Ankit Verma, Andrew M. Colclasure, and Kandler Smith. "Enhancing Lithium-Ion Battery Aging Simulations By Coupling a High-Resolution, 3D, Grain-Scale Electromechanical Model to a Single Particle Model." ECS Meeting Abstracts MA2022-02, no. 3 (October 9, 2022): 179. http://dx.doi.org/10.1149/ma2022-023179mtgabs.
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One of the main goals in modeling lithium-ion batteries is to improve/predict longevity and resilience of new chemistries. Unfortunately, this requires simulation of thousands of charge/discharge cycles, which can be rather time consuming depending on the fidelity of the simulation. The purpose of this talk is to discuss a new modeling framework that couples a high-resolution, continuous damage model (CDM) to a single particle model (SPM) resulting in a good combination of speed and fidelity. In previous work, a 3D, continuum-level chemo-mechanical model was developed to investigate cracking within a single cathode particle comprised of hundreds to thousands of randomly oriented grains. The CDM predicted that particle fracture is primarily due to non-ideal grain interactions with slight dependence on high-rate charge demands. Essentially, when neighboring grains were misaligned, they expanded different rates relative to one another leading to high stresses and ultimately the formation of intraparticle cracks. The model predicted that small particles with large grains develop significantly less damage than larger particles with small grains. Finally, the model predicted most of the chemo-mechanical damage accumulates in the first charge after formation. This chemo-mechanical “damage saturation” effect indicated that initial particle fracture occurs within the first few cycles, while long-term cathode degradation is not solely chemo-mechanically induced. This led to a need for simulating fatigue-like mechanism that degrade the battery over longer time scales. In order to reach the time scales, need to resolve fatigue-like degradation, the CDM needs to be complemented by a faster model. Therefore, recent efforts have been focused on using results from the CDM to inform parameters within the SPM. These parameters are homogenization factors that are associated with diffusion, particle radius, and/or exchange current density. By coupling the CDM to the SPM, the aging simulation is broken up into two domains: short-term and long-term degradation. The short-term degradation occurs over a single cycle and is handled by the CDM due of its high fidelity, but relatively expensive computational cost. Such mechanism include break-in crack caused by mismatches in grain orientation. The long-term degradation occurs over tens of cycles and is handled by the SPM due it’s computational efficiency. Most of the fatigue-like mechanism fall into this category. The eventual goal of this modeling framework is to upscale to a psudo-2D model allowing for full electrode simulation, which are informed by high-fidelity grain-scale simulations. Figure 1
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Arola, D., M. B. Sultan, and M. Ramulu. "Finite Element Modeling of Edge Trimming Fiber Reinforced Plastics." Journal of Manufacturing Science and Engineering 124, no. 1 (December 1, 2000): 32–41. http://dx.doi.org/10.1115/1.1428329.
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A finite element model was developed to simulate chip formation in the edge trimming of unidirectional Fiber Reinforced Plastics (FRPs) with orthogonal cutting tools. Fiber orientations (θ) within the range of 0 deg⩽θ⩽90 deg were considered and the cutting tool was modeled as both a rigid and deformable body in independent simulations. The principal and thrust force history resulting from numerical simulations for orthogonal cutting were compared to those obtained from edge trimming of unidirectional Graphite/Epoxy (Gr/Ep) using polycrystalline diamond tools. It was found that principal cutting forces obtained from the finite element model with both rigid and deformable body tools compared well with experimental results. Although the cutting forces increased with increasing fiber orientation, the tool rake angle had limited influence on cutting forces for all orientations other than θ=0 deg and 90 deg. However, the tool geometry did affect the degree of subsurface damage resulting from interlaminar shear failure as well as the cutting tool stress distribution. The finite element model for chip formation provides a means for optimizing tool geometry over the total range in fiber orientations in terms of the cutting forces, degree of subsurface trimming damage, and the cutting tool stresses.
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Riabenko, Oleksandr, Oksana Kliukha, Volodymyr Tumoshchuk, and Oksana Halych. "The particularities of near-critical flows formation in open channels." MATEC Web of Conferences 322 (2020): 01046. http://dx.doi.org/10.1051/matecconf/202032201046.
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This article considers the current problems of near-critical flows. It provides short characteristics of each phenomenon and describes the cases of near-critical flow formation during the operation of the different hydraulic structures. Each of the considered phenomena has a number of characteristic features which distinguish them from the usual subcritical and supercritical flows with smooth or slowly varied movement. Such properties include the wave-like or roller nature of free-surface curves, the presence of a streamline inclination and curvature, and also a non-hydrostatic pressure distribution in depth mainly in the vertical cross-section of these phenomena. Therefore, during mathematical and numerical simulations at the designing stage of hydraulic structures it is necessary to take into account the additional parameters which characterise the particularities of near-critical flows. In cases in which these moments are neglected, there are many cases of accidents and damage being caused to structures which are operated in conditions of near-critical flow formation. An objective of this work is to provide a detailed analysis of the particularities of near-critical flows and show their negative consequences on hydraulic structures. The article presents the results of the mathematical and hydraulic simulation of wavelike near-critical flows and a comparison of the full-scale measurement and a mathematical model of translation waves.
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Rajwa, Sylwester, Tomasz Janoszek, Janina Świątek, Andrzej Walentek, and Dominik Bałaga. "Numerical Simulation of the Impact of Unmined Longwall Panel on the Working Stability of a Longwall Using UDEC 2D—A Case Study." Energies 15, no. 5 (February 28, 2022): 1803. http://dx.doi.org/10.3390/en15051803.
Full textAbstract:
The main goal of the paper is numerical simulation for investigation of damage causes in the working of a longwall located under the unmined longwall panel. The paper presents the results of model-based research on the stability of the roof of a longwall working in a zone subject to cave-in mining, taking into account the influence of mining conditions in the form of an unmined coal seam located 115 m above the exploited seam. It presents the geometry of the rock mass under study, the discretization area of the solution, and gives an overview of the assumptions used to build the numerical model. The authors discuss the results of numerical simulations of the influence of mining phenomena on the formation of roof falls in the longwall. Based on the results of numerical simulations, the process of identifying the size of roof falls in a longwall working (loss of stability) was carried out through their appropriate classification. The case presented and analyzed in this paper occurred in one of Poland’s coal mines.