A Coupled Bio-Chemo-Hydro-Mechanical Model for Bio-cementation in Porous Media

2021 ◽  
Author(s):  
Ronak Mehrabi ◽  
Kamelia Atefi-Monfared
Keyword(s):  
Reactive Transport ◽  
Theoretical Models ◽  
Porous Matrix ◽  
Spatiotemporal Variability ◽  
Attachment Rate ◽  
Unknown Parameters ◽  
Stress Strain ◽  
Precipitated Calcium Carbonate ◽  
Cement Distribution ◽  
Stiffness Characteristics

A key challenge involving microbial induced carbonate precipitation (MICP) is lack of rigorous yet practical theoretical models to predict the intricate biological-chemical-hydraulic-mechanical (BCHM) processes and the resulting bio-cement production. This paper presents a novel BCHM model based on multiphase, multispecies reactive transport approach in the framework of poroelasticity, aimed at achieving reasonable prediction of the produced bio-cement, and the enhanced geomechanical characteristics. The proposed model incorporates four key components: (i) coupling of hydro-mechanical stress/strain alterations with bio-chemical processes; (ii) stress/strain changes induced due to precipitation and growth of bio-cement within the porous matrix; (iii) spatiotemporal variability in hydraulic and stiffness characteristics of the treated medium; (iv) and velocity dependency of the attachment rate of bacteria. The fully-coupled BCHM model predicts key unknown parameters during treatment including: concentration of bacteria and chemical solutions, precipitated calcium carbonate, hydraulic properties of the solid skeleton, and in-situ pore pressures and strains. The model was able to reasonably predict bio-cementation from two different laboratory column experiments. The Kozeny–Carman permeability equation is found to underestimate permeability reductions due to bio-cementation, while the Verma–Pruess relation could be more accurate. A sensitivity analysis revealed bio-cement distribution to be particularly sensitive to the attachment rate of bacteria.

scholarly journals Early Manifestations of Short-Term Precursors in Stress-Strain State Dynamics of Southern California

2021 ◽  
Vol 57 (4) ◽  
pp. 508-519
Author(s):  
V. G. Bondur ◽  
M. B. Gokhberg ◽  
I. A. Garagash ◽  
D. A. Alekseev
Keyword(s):  
Strain State ◽  
Southern California ◽  
Surrounding Medium ◽  
Maximum Amplitude ◽  
Theoretical Models ◽  
Time Intervals ◽  
Stress Strain ◽  
Epicentral Zone ◽  
Stress Strain State ◽  
Shear Strains

Abstract—The stress-strain state before the М = 7.1 Ridgecrest earthquake in Southern California is analyzed based on spatiotemporal distribution of shear strains calculated in the geomechanical model within local ~100 × 100 km crustal segments at a depth of 3–7 km. In the epicentral zone of the earthquake, starting from three years before the event, a successive series of the time intervals, up to the occurrence of the earthquake, when shear deformations are completely absent and rocks are farthest from ultimate strength—the so-called quiescence zones—are established. The spatial distribution of shear strains in the vicinity of the epicentral zone is analyzed during the quiescence intervals and subsequent bursts of maximum amplitude in the epicentral zone itself. The time intervals of the bursts are called excursions. The successive emergence of maxima in shear strain amplitudes in the epicentral zone and surrounding medium during the excursions corresponds to the situation of a swing when the entire preparation region of a future earthquake is rocking up to the moment of event. Consistency of the obtained results with the existing theoretical models of earthquake preparation is discussed.

Multicomponent multiphase reactive fluid flow in viscoelastoplastic porous media: localization patterns of fluid flow and strain

2021 ◽  
Author(s):  
Lyudmila Khakimova ◽  
Nikolai Belov ◽  
Artyom Myasnikov ◽  
Anatoly Vershinin ◽  
Kirill Krapivin ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Reactive Transport ◽  
Transport Model ◽  
Shear Bands ◽  
Porous Matrix ◽  
Deformation Localization ◽  
Linear Free Energy ◽  
Constrained Minimization Problem ◽  
Spectral Finite Elements ◽  
The Impact

<p>This work is devoted to developing the self-consistent thermo-hydro-chemo-mechanical reactive transport model to predict and describe natural and industrial petroleum processes at different scales.</p><p>We develop a version of the front tracking approach for multicomponent multiphase flow in order to treat spontaneous splitting of discontinuities. We revisit the solution for the Riemann problem and systematically classify all possible configurations as functions of initial concentrations on both sides of the discontinuity. We validate the algorithm against finite volume high-resolution technics and high-order spectral finite elements.</p><p>To calculate the parameters of phase equilibria, we utilize an approach based on the direct minimization of the Gibbs energy of a multicomponent mixture. This method ensures the consistency of the thermodynamic lookup tables. The core of the algorithm is the non-linear free-energy constrained minimization problem, formulated in the form of a linear programming problem by discretization in compositional space.</p><p>The impact of the complex rheological response of porous matrix on the morphology of fluid flow and shear deformation localization is considered. Channeling of porosity waves and shear bands morphology and their orientation is investigated for viscoelastoplastic both shear and bulk rheologies.</p>

Pneumatic Pipe Modeling: Theory and Experimental Approach—Part II

2000 ◽  
Author(s):  
E. Bideaux ◽  
S. Scavarda
Keyword(s):  
Power Systems ◽  
Experimental Approach ◽  
Computing Time ◽  
Theoretical Models ◽  
Unknown Parameters ◽  
Adequate Model ◽  
Thermal Exchange ◽  
Modeling Theory ◽  
Fluid Power Systems ◽  
Predominant Effect

Abstract In fluid power systems, lines or pipes can have a predominant effect on dynamics. Although many studies have been carried out on hydraulic pipe modeling, there are only a few existing approaches for such problems in pneumatics. This paper proposes an experimental work in modeling of pneumatic pipes. A short state of the art situation, the nature of this problem, and different approaches of modeling pneumatic pipes are presented in Pneumatic Pipe Modeling: Theory and Experimental Approach (PART I). As the simulation of system with pipes may need an important computing time, it is crucial to use the adequate model. While it is not difficult to develop theoretical models, we need to tune them by adjusting the unknown parameters such friction factor and the thermal exchange parameter. We introduce then an experimental method to evaluate these parameters. The robustness of the models is proved through several examples and in order to validate our propositions, we compare experimental trails to the results given by the simulation.

Optimization Problems Arising from the Design of Pipes Made of Composite Materials

2020 ◽  
Vol 992 ◽  
pp. 1024-1029
Author(s):  
T. Bobyleva ◽  
A. Shamaev
Keyword(s):  
Strain State ◽  
Optimization Problems ◽  
Analytical Form ◽  
Radial Symmetry ◽  
Elastic Rod ◽  
Stress Strain ◽  
Stress Strain State ◽  
Fixed Weight ◽  
Applied Forces ◽  
Stiffness Characteristics

The work is devoted to the construction of analytical solutions for the stress-strain state of a cylindrical hollow elastic rod with a layered structure along the radius. Earlier, the problem of finding the stress-strain state of a rod of composite material fixed at one end with the applied forces and moments of forces at the other end was considered. An approximate representation of the solutions was given, which included auxiliary problems on one fragment of the cylinder, consisting of periodically repeating similar fragments. Such auxiliary problems in the general case do not have an analytical solution. In this paper it is shown that in the presence of radial symmetry of the rod section, it is possible to construct a stress-strain state in an analytical form. In addition, tensile and bending stiffness can be presented in an analytical form. The latter circumstance allows us to set a problem of optimizing the stiffness characteristics of a rod with its fixed weight. Optimization is carried out by varying the thickness of the layers of the same materials.

Damping parameters indentification of Lienard polynomial system

2021 ◽  
Vol 34 ◽  
pp. 28-35
Author(s):  
Nadiia Zhogoleva ◽  
Volodymyr Shcherbak
Keyword(s):  
Polynomial System ◽  
Original System ◽  
Theoretical Models ◽  
Approximate Model ◽  
Material Behavior ◽  
Nonlinear Material ◽  
Nonlinear Phenomena ◽  
Damping Force ◽  
Unknown Parameters ◽  
Scheme Design

In many applications of physics, biology, and other sciences, an approach based on the concept of model equations is used as an approximate model of complex nonlinear processes. The basis of this concept is the provision that a small number of characteristic types movements of simple mathematical models inherent in systems give the key to understanding and exploring a huge number of different phenomena. In particular, it is well known that the complex oscillatory motion can be modeled by a system consisting of one or more coupled nonlinear oscillators that governs by differential equation of a second-order. A Lienard system, namely $ \ddot x(t)+f(x(t))\dot x(t)+g(x(t)) = 0$, is a generalization of the such models. Here $f(x(t))$ and $g(x(t))$ are functions that represent various nonlinear phenomena. The typical sources of nonlinearities in Lienard systems are as follows: large displacements of the structure provoking geometric nonlinearities, a nonlinear material behavior, complex law of damping dissipation, etc. In fact, parameter identification is the base of several engineering tasks: identification can be used for the following: (i) to gain knowledge about the process behavior, (ii) to validate theoretical models, (iii) to tune controller parameters, (iv) to design adaptive control algorithms, (v) to process supervision and fault detection, (vi) to on-line optimization. Hence, in order to represent these nonlinearities, identifying the parameters characterizing their behaviors is essential. The problem of constructing globally convergent identificator for polynomial representation of damping force in general Lienar oscillator is addressed. The method of invariant relations is used for identification scheme design. This aproach is based on dynamical extension of original system and construct of appropriate invariant relations, from which the unknowns parameters can be expressed as a functions of the known quantities on the trajectories of extended system. The final synthesis is carried out from the condition of obtaining asymptotic estimates of unknown parameters. It is shown that an asymptotic estimate of the unknown states can be obtained by rendering attractive an appropriately selected invariant manifold in the extended state space.

Active Fixturing for Mesoscale Manufacturing Systems: Fixel Design Alternatives

2008 ◽  
Author(s):  
Gloria J. Wiens ◽  
Koustubh J. Rao ◽  
Troy B. Rippere
Keyword(s):  
Manufacturing Systems ◽  
Material Handling ◽  
Dynamic Range ◽  
Compliant Mechanisms ◽  
Slenderness Ratio ◽  
Theoretical Models ◽  
Contact Forces ◽  
Advantages And Disadvantages ◽  
Design Alternatives ◽  
Stiffness Characteristics

This paper presents an investigation of fixel design alternatives for active (dynamic) fixturing to be incorporated into mesoscale manufacturing systems. Using simple compliant mechanisms and components (e.g., monolithic four-bar mechanisms and/or cantilever beams), fixels exhibiting mechanically adjustable stiffness characteristics are achievable. Manually or automating the stiffness adjustments, these fixels provide a functionality for enabling greater control of the dynamic response of the workpiece due to vibrations and variation in contact forces at the tool-workpiece-fixture interface. To quantify the fixel functionality and its dynamic range, this paper presents the theoretical models of the stiffness characteristics expressed as a function of each fixel design’s mechanical variables. Upon establishing a common stiffness range for the different fixel designs, a metric is formed based on the sensitivity of stiffness expressed as a function of slenderness ratio and an operation range, bounded by a maximum possible stiffness value shared by all fixture models. Using this metric, results are generated to delineate the advantages and disadvantages of each design and their potential impact on fixturing and material handling in the creation of micron features on micro and macro parts.

scholarly journals Study Numerical Simulation of Stress-Strain Behavior of Reinforced Concrete Bar in Soil using Theoretical Models

2019 ◽  
Vol 5 (11) ◽  
pp. 2349-2358
Author(s):  
Ali Sabah Al Amli ◽  
Nadhir Al-Ansari ◽  
Jan Laue
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Three Dimensional ◽  
Theoretical Models ◽  
Element Model ◽  
Stress Strain ◽  
Strain Behavior ◽  
Concrete Members ◽  
Steel Bar ◽  
Three Dimensional Finite Element

Nonlinear analysis for reinforced concrete members (R.C.) with two types of bars also with unsaturated and saturated soils was used to represent the models. To control the corrosion in the steel bar that used in R.C. member and decrease the cost, the geogrid with steel bar reinforcement are taken in this study to determine the effect of load-deflection and stress-strain relationships. The finite element method is used to model the R.C. member, bars and soil. A three-dimensional finite element model by ABAQUS version 6.9 software program is used to predict the load versus deflection and stress versus strain response with soil. The results for the model in this study are compared with the experimental results from other research, and the results are very good. Therefore, it was concluded that the models developed in this study can accurately capture the behavior and predict the load-carrying capacity of such R.C. members with soil and the maximum stresses with strains. The results show plastic strain values in the R.C. member with saturated soil are larger than their values in unsaturated soil about (54%, 58%, and 55% and 52%) when the geogrid ratios are (without geogrid, 60%, 40% and 20%) respectively, with the same values of stresses.

MAGNETIC ANOMALIES OF THIN SHEETS AND THEIR INTERPRETATIONS

Geophysics ◽  
1972 ◽  
Vol 37 (6) ◽  
pp. 963-974 ◽  
Author(s):  
Buddhadeb Banerjee
Keyword(s):  
Iterative Process ◽  
Thin Sheet ◽  
Theoretical Models ◽  
Magnetic Anomalies ◽  
Graphic Method ◽  
Thin Sheets ◽  
Unknown Parameters ◽  
Actual Field ◽  
Depth Extent

A method of quantitative interpretation of the vertical magnetic anomaly (ΔZ) caused by a thin sheet infinite in horizontal extent but limited in depth extent is developed. The determination of the position of the point on the profile above the dike plays an important role in the analysis and is done either by a graphic method or with the help of a rapidly convergent iterative process. When the depth extent of the sheet, either vertical or inclined, becomes infinite, the mathematical steps become simpler, and evaluation of different unknown parameters of the causative body is possible without any prior knowledge of the positions of the cartesian axes. The proposed methods are applied both on theoretical models and on actual field cases.

Modeling and Analysis of Fixel Designs for Micromanufacturing Active Fixturing

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Troy B. Rippere ◽  
Koustubh J. Rao ◽  
Gloria J. Wiens
Keyword(s):  
Manufacturing Systems ◽  
Compliant Mechanisms ◽  
Variable Stiffness ◽  
Theoretical Models ◽  
Milling Process ◽  
Contact Forces ◽  
Modeling And Analysis ◽  
Design Alternatives ◽  
Expected Performance ◽  
Stiffness Characteristics

This paper presents an investigation of fixel design alternatives for active (dynamic) fixturing to be incorporated into mesoscale manufacturing systems. Using simple compliant mechanisms and components, fixels exhibiting mechanically adjustable stiffness characteristics are achievable. Via manual or automated stiffness adjustments, these fixels provide functionality for enabling greater control of the dynamic response of the workpiece subject to vibrations and/or variations in contact forces at the tool-workpiece-fixture interface. To quantify the fixel functionality, this paper presents theoretical models of the stiffness characteristics expressed as a function of the mechanical variable(s), thus forming a basis for exploring the adjustability in stiffness achievable for each fixel design. Also presented are results of the dynamic behavior of the active fixturing implemented in a milling process based on a “regenerative force, dynamic deflection model” augmented with the active fixturing variable stiffness model and inclusion of tool runout. These simulation results indicate the expected performance of the active fixturing upon its implementation in actual fixturing for the creation of micron features on micro- and macroparts.

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