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A Computational Modeling Approach Of Fracture Induced Acoustic Emission
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Book Synopsis A Computational Modeling Approach of Fracture-Induced Acoustic Emission by : Jefferson A. Cuadra
Download or read book A Computational Modeling Approach of Fracture-Induced Acoustic Emission written by Jefferson A. Cuadra and published by . This book was released on 2015 with total page 562 pages. Available in PDF, EPUB and Kindle. Book excerpt: Acoustic Emission (AE) has become a prominent Nondestructive Testing (NDT) technique with capabilities to be used for Structural Health Monitoring (SHM) applications that entail in-service monitoring, detecting damage-prone areas, and establishing damage prognostics of structures. The next generation of acoustics-based techniques for SHM will rely upon the reliable and quantitative characterization of AE signals related to dominant damage mechanisms. In this context, the forward problem of simulating AE activity is addressed herein by proposing advanced finite element models for damage-induced stress wave generation and propagation. Acoustic emission for this purpose is viewed as part of the dynamic process of energy release caused by damage initiation. To form the computational approach, full field experimental information obtained from monitoring the damage initiation process using digital image correlation is used to construct constitutive laws, e.g. traction-separation law, and to define other damage related parameters. Subsequently, 3D FE simulations based on such experimental data are implemented using cohesive zone modeling and extended finite element method to create an initial failure. Numerically simulated AE signals from the dynamic response due to the onset of damage are evaluated in the context of the inverse problem of source identification and localization. The results successfully demonstrate material and geometry effects of the propagating source and describe completely the AE process from crack-induced isolated source to transient and steady-state dynamic response. Furthermore, the computational model is used to provide quantified measures of the energy release associated with crack. In addition, the effect of plasticity on simulated traveling waves ahead of the crack tip was investigated and revealed nonlinear interactions that had been postulated to exist. Ultimately, the forward AE methodology is applied to an aerospace structural component to recreate the debonding process and associated stress release propagation. All damage-induced wave propagation simulations presented in this dissertation create a pathway for the quantitative comparison between experimental and theoretical predictions of AE.
Book Synopsis Simulation of Hydraulic Stimulation by : Mohammad Komijani
Download or read book Simulation of Hydraulic Stimulation written by Mohammad Komijani and published by . This book was released on 2018 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydraulic Fracturing (HF) is an effective stimulation process for extracting oil and gas from unconventional low-permeable reservoirs. The process is conducted by injecting high-pressure fluids into the ground to generate fracture networks in rock masses and stimulate natural fractures to increase the permeability of formation and extract oil and gas. Due to the multiple and coupled-physics involved, hydraulic fracturing is a complex engineering process. The extent of the induced fractures and stimulated volume and reactivation of natural faults and fractures are some of the practical issues associated with hydraulic fracturing. Acoustic Emission (AE) monitoring and analysis are used to probe the behaviour of solid materials in such applications. The process of elastic wave propagation induced by an abrupt local release of stored strain energy is known as acoustic, microseismic, and seismic emission (depending on the context and the magnitude of the event). These emissions can be triggered by material bifurcation-instabilities like slope slipping, fault-reactivation, pore collapsing, and cracking - processes that are all categorized as localization phenomena. The microseismic monitoring industry attempts to relate acoustic emissions measured by geophones to the nature of the stimulated volume created during hydraulic fracturing. This process is full of uncertainties and researchers have not yet focused on both explicitly modeling the process of fracture reactivation and the accurate simulation of acoustic wave propagations resulting from the localization. The biggest gap in the modeling literature is that most of the previous works fail to accurately simulate the process of transient acoustic wave propagation through the fractured porous media following the elastic energy release. Instead of explicitly modeling fracturing and acoustic emission, most previous studies have aimed to relate energy release to seismic moment. To overcome some of the existing shortcomings in the numerical modeling of the coupled problem of interface localization-acoustic emission, this thesis is focused on developing new computational methods and programs for the simulation of microseismic wave emissions induced by interface slip instability in fractured porous media. As a coupled nonlinear mixed multi-physics problem, simulation of hydraulic stimulation involves several mathematical and computational complexities and difficulties in terms of modeling, stability, and convergence, such as the inf-sup stability problems that arise from mixed formulations due to the hydro-mechanical couplings and contact conditions. In AE modeling, due to the high-frequency transient nature of the problem, additional numerical problems emerging from the Gibbs phenomenon and artificial period elongation and amplitude decay are also involved. The thesis has three main objectives. The first objective is to develop a numerical model for simulation of wave propagation in discontinuous media, which is fulfilled in Chapter 2 of the thesis. In this chapter a new enriched finite element method is developed for simulation of wave propagation in fractured media. The method combines the advantages of the global Partition-of-Unity Method (PUM) with harmonic enrichment functions via the Generalized Finite Element Method (GFEM) with the local PUM via the Phantom Node Method (PNM). The GFEM enrichments suppress the spurious oscillations that can appear in regular Finite Element Method (FEM) analysis of dynamic/wave propagations due to numerical dispersions and Gibbs phenomenon. The PNM models arbitrary fractures independently of the original mesh. Through several numerical examples it has been demonstrated that the spurious oscillations that appear in propagation pattern of high-frequency waves in PNM simulations can be effectively suppressed by employing the enriched model. This is observed to be especially important in fractured media where both primary waves and the secondary reflected waves are present. The second objective of the thesis is to develop a mixed numerical model for simulation of wave propagation in discontinuous porous media and interface modeling. This objective is realized in Chapter 3 of the thesis. In this chapter, a new enriched mixed finite element model is introduced for simulation of wave propagation in fractured porous media, based on an extension of the developed numerical method in Chapter 2. Moreover, frictional contact at interfaces is modeled and realized using an augmented Lagrange multiplier scheme. Through various numerical examples, the effectiveness of the developed enriched FE model over conventional approaches is demonstrated. Moreover, it is shown that the most accurate wave results with the least amount of spurious oscillations are achieved when both the displacement and pore pressure fields are enriched with appropriate trigonometric functions. The third objective of the thesis is to develop computational models for the simulation of acoustic emissions induced by fracture reactivation and shear slip. This objective is realized in Chapter 4 of the thesis. In this chapter, an enriched mixed finite element model (introduced in Chapter 3) is developed to simulate the interface slip instability and the associated induced acoustic wave propagation processes, concurrently. Acoustic events are triggered through a sudden release of strain energy at the fracture interfaces due to shear slip instability. The shear slip is induced via hydraulic stimulation that switches the interface behaviour from a stick to slip condition. The superior capability of the proposed enriched mixed finite element model (i.e., PNM-GFEM-M) in comparison with regular finite element models in inhibiting the spurious oscillations and numerical dispersions of acoustic signals in both velocity and pore pressure fields is demonstrated through several numerical studies. Moreover, the effects of different characteristics of the system, such as permeability, viscous damping, and friction coefficient at the interface are investigated in various examples.
Book Synopsis A Novel Approach to Data-driven Modeling of Damage-induced Elastic Wave Propagation by : Daniel Paul Servansky
Download or read book A Novel Approach to Data-driven Modeling of Damage-induced Elastic Wave Propagation written by Daniel Paul Servansky and published by . This book was released on 2012 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: Adviser: Antonios Kontsos.
Book Synopsis Acoustic Emission by : Valentyn Skalskyi
Download or read book Acoustic Emission written by Valentyn Skalskyi and published by Springer Nature. This book was released on 2022-08-20 with total page 231 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book presents topical theoretical and experimental studies for developing advanced methods of detecting materials fracture and assessing their structural state using acoustic emission. It introduces new mathematical models characterizing the displacement fields arising from crack-like defects and establishes a new criterion for classifying different types of materials fracture based on specific parameters obtained from wavelet transforms of acoustic emission signals. The book applies this approach to experimental studies in three types of materials—fiber-reinforced composites, dental materials, and hydrogen-embrittled steels.
Book Synopsis Dissertation Abstracts International by :
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2005 with total page 858 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Acoustic Emission and Related Non-destructive Evaluation Techniques in the Fracture Mechanics of Concrete by : Masayasu Ohtsu
Download or read book Acoustic Emission and Related Non-destructive Evaluation Techniques in the Fracture Mechanics of Concrete written by Masayasu Ohtsu and published by Woodhead Publishing. This book was released on 2015-03-28 with total page 319 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of NDT (non-destructive testing) techniques used for the inspection of concrete structures is currently in high demand, because many existing structures have become aged and deteriorated in service. In order to formulate predictions on their stability and to estimate their safety, it is necessary to identify damage signals and to determine their causes. In this regard, the development and establishment of innovative and highly advanced non-destructive methods are required. Acoustic Emission (AE) and related NDE (non-destructive evaluation) techniques have been extensively used to determine crack detection and damage evaluation in concrete. With the move towards a more sustainable society, and the need to extend the long-term service life of infrastructure and aging and disastrous damage due to recent earthquakes, Acoustic Emission (AE) and Related Non-destructive Evaluation (NDE) Techniques in the Fracture Mechanics of Concrete: Fundamentals and Applications is a critical reference source for civil engineers, contractors working in construction and materials scientists working both in industry and academia. - Presents innovative Acoustic Emission (AE) and related non-destructive evaluation (NDE) techniques, used for damage detection and inspection of aged and deteriorated concrete structures - Contributions from recognized world-leaders in the application of acoustic emission (AE) and NDE techniques used for the damage assessment of concrete and concrete structures - With the move towards a more sustainable society, and the need to extend the long-term service life of infrastructure and damage due to recent earthquakes, this book is of critical importance - An essential knowledge resource for civil engineers, contractors working in construction and materials scientists working both in industry and academia
Book Synopsis Computational Methods for Fracture by : Timon Rabczuk
Download or read book Computational Methods for Fracture written by Timon Rabczuk and published by . This book was released on 2019 with total page 1 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book offers a collection of 17 scientific papers about the computational modeling of fracture. Some of the manuscripts propose new computational methods and/or how to improve existing cutting edge methods for fracture. These contributions can be classified into two categories: 1. Methods which treat the crack as strong discontinuity such as peridynamics, scaled boundary elements or specific versions of the smoothed finite element methods applied to fracture and 2. Continuous approaches to fracture based on, for instance, phase field models or continuum damage mechanics. On the other hand, the book also offers a wide range of applications where state-of-the-art techniques are employed to solve challenging engineering problems such as fractures in rock, glass, concrete. Also, larger systems such as fracture in subway stations due to fire, arch dams, or concrete decks are studied.
Download or read book קונטרס מפז יקרים written by and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Computational Modelling of Concrete Structures by : Nenad Bicanic
Download or read book Computational Modelling of Concrete Structures written by Nenad Bicanic and published by CRC Press. This book was released on 2014-03-04 with total page 1108 pages. Available in PDF, EPUB and Kindle. Book excerpt: The EURO-C conference series (Split 1984, Zell am See 1990, Innsbruck 1994, Badgastein 1998, St Johann im Pongau 2003, Mayrhofen 2006, Schladming 2010, St Anton am Alberg 2014) brings together researchers and practising engineers concerned with theoretical, algorithmic and validation aspects associated with computational simulations of concrete and concrete structures. The conference reviews and discusses research advancements and the applicability and robustness of methods and models for reliable analysis of complex concrete, reinforced concrete and pre-stressed concrete structures in engineering practice. Conference topics and invited papers cover both computational mechanics and computational modelling aspects of the analysis and design of concrete and concrete structures: * Constitutive and Multiscale Modelling of Concrete * Advances in Computational Modelling * Time Dependent and Multiphysics Problems * Performance of Concrete Structures The book is of special interest to researchers in computational concrete mechanics, as well as industry experts in complex nonlinear simulations of concrete structures.
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1985 with total page 1052 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Imaging and Modeling of Hydraulic Fractures in Crystalline Rock Via Induced Seismic Activity by : Peter Niemz
Download or read book Imaging and Modeling of Hydraulic Fractures in Crystalline Rock Via Induced Seismic Activity written by Peter Niemz and published by . This book was released on 2022* with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Enhanced geothermal systems (EGS) are considered a cornerstone of future sustainable energy production. In such systems, high-pressure fluid injections break the rock to provide pathways for water to circulate in and heat up. This approach inherently induces small seismic events that, in rare cases, are felt or can even cause damage. Controlling and reducing the seismic impact of EGS is crucial for a broader public acceptance. To evaluate the applicability of hydraulic fracturing (HF) in EGS and to improve the understanding of fracturing processes and the hydromechanical relation to induced seismicity, six in-situ, meter-scale HF experiments with different injection schemes were performed under controlled conditions in crystalline rock in a depth of 410 m at the Äspö Hard Rock Laboratory (Sweden). I developed a semi-automated, full-waveform-based detection, classification, and location workflow to extract and characterize the acoustic emission (AE) activity from the continuous recordings of 11 piezoelectric AE sensors. Based on the resulting catalog of 20,000 AEs, with rupture sizes of cm to dm, I mapped and characterized the fracture growth in great detail. [...].
Download or read book Energy Research Abstracts written by and published by . This book was released on 1995 with total page 782 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Acoustic Emission Testing by : Christian U. Grosse
Download or read book Acoustic Emission Testing written by Christian U. Grosse and published by Springer Science & Business Media. This book was released on 2008-07-12 with total page 403 pages. Available in PDF, EPUB and Kindle. Book excerpt: Acoustic Emission (AE) techniques have been studied in civil engineering for a long time. The techniques are recently going to be more and more applied to practical applications and to be standardized in the codes. This is because the increase of aging structures and disastrous damages due to recent earthquakes urgently demand for maintenance and retrofit of civil structures in service for example. It results in the need for the development of advanced and effective inspection techniques. Thus, AE techniques draw a great attention to diagnostic applications and in material testing. The book covers all levels from the description of AE basics for AE beginners (level of a student) to sophisticated AE algorithms and applications to real large-scale structures as well as the observation of the cracking process in laboratory specimen to study fracture processes.
Book Synopsis Fracture Behavior of Intact Rock Using Acoustic Emission by : Shuhong Wang
Download or read book Fracture Behavior of Intact Rock Using Acoustic Emission written by Shuhong Wang and published by . This book was released on 2013 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is well known that acoustic emission (AE) is a powerful nondestructive testing tool for examining the behavior of materials deforming under stress. One can use it to monitor fracture or damage in a rock mass by listening to AE events during failure under compressive loads. In this paper, an experimental study on the AE source location in square cylinder granite specimens under uniaxial compression is reported. In order to determine the three-dimensional location of AE events, eight AE sensors were mounted on the specimen. The AE source location was determined via the acquisition of eight channel AE sensors after filtering, processing, reporting, and visualizing seismic data. On the basis of the laboratory experiment results, the granite sample was numerically simulated via the Burgers model using the discrete element program PFC2D (Particle Flow Code in Two Dimensions) to further study the mechanism of fracture initiation and propagation in intact rock. In PFC2D, materials may be modeled as either bonded (cemented) or unbonded (granular) assemblies of particles. It can describe nonlinear behavior and localization with accuracy that cannot be matched by typical finite element programs. The consistency of stress-strain curves obtained with PFC2D and with the test results shows that PFC2D is a practical tool for reproducing AE events in rock, and use of the Burgers model is feasible in the field of rock failure and provides an analysis of the microcracking activity inside the rock volume to predict rock fracture patterns under uniaxial loading conditions.
Book Synopsis Modelling Rock Fracturing Processes by : Baotang Shen
Download or read book Modelling Rock Fracturing Processes written by Baotang Shen and published by Springer Science & Business Media. This book was released on 2013-10-07 with total page 181 pages. Available in PDF, EPUB and Kindle. Book excerpt: This text book provides the theoretical background of rock fracture mechanics and displacement discontinuity methods used for the modelling of geomechanical problems. The computer program FRACOD is used to analyse the fracture problems, assessing fracture initiation and propagation in tension (Mode I), shear (Mode II) and mixed mode I and II of solid intact or jointed geomaterials. The book also presents the fundamentals of thermo-mechanical coupling and hydro-mechanical coupling. Formulations of multiple regional mechanical, thermal and hydraulic functions, which allow analyses of fracture mechanics problems for structures made of brittle, rock-like materials, are provided. In addition, instructive examples of code verification and applications are presented. Additional material: The 2-D version of the FRACOD program, a manual on the program and a wealth of verification examples of classical problems in physics, mechanics and hydromechanics are available at http://extras.springer.com. A large number of applications related to civil, mining, petroleum and environmental engineering are also included. - The first textbook available on modelling of rock fracture propagation - Introduces readers to the fundamentals of rock fracturing - Uses a modern style of teaching with theory, mathematical modelling and applications in one package - The basic version of the FRACOD software, manual, verification examples and applications are available as additional material - The FRACOD program and manual enable the readers to solve fracture propagation problems on their own --------------------------- Ki-Bok Min, Department of Energy Resources Engineering, College of Engineering, Seoul National University, Korea “Challenging rock engineering applications require extreme conditions of stress, temperature and hydraulic pressure resulting in rock fracturing to a various extent. The FRACOD is one of few computer codes available in engineering rock mechanics that can simulate the initiation and propagation of fractures often interacting with natural fractures. Its capability has been significantly enhanced to include the hydraulic and thermal fracturing with concerted interaction from multi-national research and industry partners. My experience with the FRACOD is very positive and I am certain that its already-excellent track record will expand further in the future."
Book Synopsis Computational Methods for Fracture in Porous Media by : René De Borst
Download or read book Computational Methods for Fracture in Porous Media written by René De Borst and published by Elsevier. This book was released on 2017-10-18 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational Methods for Fracture in Porous Media: Isogeometric and Extended Finite Element Methods provides a self-contained presentation of new modeling techniques for simulating crack propagation in fluid-saturated porous materials. This book reviews the basic equations that govern fluid-saturated porous media. A multi-scale approach to modeling fluid transport in joins, cracks, and faults is described in such a way that the resulting formulation allows for a sub-grid representation of the crack and fluid flow in the crack. Interface elements are also analyzed with their extension to the hydromechanical case. The flexibility of Extended Finite Element Method for non-stationary cracks is also explored and their formulation for fracture in porous media described. This book introduces Isogeometric finite element methods and its basic features and properties. The rapidly evolving phase-field approach to fracture is also discussed. The applications of this book's content cover various fields of engineering, making it a valuable resource for researchers in soil, rock and biomechanics.
