Piezoelectric materials like lead zirconium titanate (PZT) are increasingly used in high power actuator applications. Modeling these actuators has presented a challenge to many researchers for quite some time. We pres...
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ISBN:
(纸本)9783950353709
Piezoelectric materials like lead zirconium titanate (PZT) are increasingly used in high power actuator applications. Modeling these actuators has presented a challenge to many researchers for quite some time. We present a homogenized micro-mechanically based model and discuss its efficient numerical solution by applying the Finite Element (FE) method.
the Augmented Lagrangian Method (ALM) is implemented for two-dimensional flows of viscoplastic fluids. the rheological model employed is the ideal Bingham model. As a test the lid-driven square-cavity benchmark proble...
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ISBN:
(纸本)9783950353709
the Augmented Lagrangian Method (ALM) is implemented for two-dimensional flows of viscoplastic fluids. the rheological model employed is the ideal Bingham model. As a test the lid-driven square-cavity benchmark problem, flows in wavy-walled channels and squeeze flow are considered. the results for the steady-state problem are faithfully reproduced as compared to those in the literature for the shape and location of the yield surface. the proposed method is very successful at capturing both yielded and unyielded regions.
Pricing American options under finite activity jump-diffusion models like Kou's model with discrete dividends is considered. the American option pricing problem is formulated as a linear complementarity problem (L...
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ISBN:
(纸本)9783950353709
Pricing American options under finite activity jump-diffusion models like Kou's model with discrete dividends is considered. the American option pricing problem is formulated as a linear complementarity problem (LCP). the derivatives in the partial integrodifferential operator are discretizing using finite differences. the discretization of the jump integral leads to a full matrix. the early exercise constraint is treated using an operator splitting method leading at each time step to two simpler substeps. For time discretization, implicit and implicit-explicit (IMEX) methods are considered. numerical results are presented under Kou's model without dividend and with fixed and stochastic discrete dividend. the results demonstrate the high speed and good accuracy of the proposed numericalmethods.
One of very interesting problem in civil engineering applications is reinforced concrete structures subjected to impact load which are often used in protective purpose. Fragmentation that may occur during impact canno...
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ISBN:
(纸本)9783950353709
One of very interesting problem in civil engineering applications is reinforced concrete structures subjected to impact load which are often used in protective purpose. Fragmentation that may occur during impact cannot be modelled by the continuum methods. Predicting of the behaviour of reinforced concrete structures under impact imposes the need to develop numerical model which will be able to include effects of the behaviour of concrete structures due to dynamic action in linear elastic stage, crack initiation and propagation, energy dissipation mechanisms due to non linear effects, inertial effects due to motion, contact impact and finally to attain state of the rest that is a consequence of energy dissipation mechanisms in the system. It is possible to include all previously mentioned effects withthe finite - discrete element method (FEM/DEM).
numerical study on multiphase flows was performed to analyze the compressibility effects to the cavitation model dependency of model constants. the computation was performed within converging-diverging nozzle. Compres...
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ISBN:
(纸本)9783950353709
numerical study on multiphase flows was performed to analyze the compressibility effects to the cavitation model dependency of model constants. the computation was performed within converging-diverging nozzle. Compressibility and incompressibility flows were compared in the present study to consider the compressibility effects in the two phase mixture. Two different cavitation models of Merkle et al. and Kunz et al. were used to simulate the evaporation and condensation processes. the governing equation was adapted the full unsteady compressible preconditioned Reynolds-Averaged Navier-Stokes equations. the results indicate that the addition of compressibility effects on multi-phase flows could reduce the cavitation model's dependency of model constants to get more significant physical accuracy, and Merkle's cavitation model has higher numerical accuracy rather than Kunz's cavitation model in compressible and incompressible systems.
A fully coupled finite element model for modeling flow and deformation in saturated soft rock is presented. Both mechanical and hydraulic behaviors are taken into account. the elasto-plastic deformation behavior is ca...
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ISBN:
(纸本)9783950353709
A fully coupled finite element model for modeling flow and deformation in saturated soft rock is presented. Both mechanical and hydraulic behaviors are taken into account. the elasto-plastic deformation behavior is captured using a bounding surface plasticity theory. the model is formulated incrementally within the framework of critical state concept. the hydraulic effect is accounted for through the effective stress concept. Spatial discretization is addressed using the Galerkin method and the temporal discretization using finite difference technique. the application of the coupled model is demonstrated by comparing numerical simulation and experimental data.
A Jointed rock mass presents a nonlinear compressible discontinuos mechanical system which is difficult to model using traditional continuum mechanics. Material models calibrated on small scale rock samples are often ...
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ISBN:
(纸本)9783950353709
A Jointed rock mass presents a nonlinear compressible discontinuos mechanical system which is difficult to model using traditional continuum mechanics. Material models calibrated on small scale rock samples are often applied in large scale engineering calculations. Yet, it is known that the response of rock masses at field scales is drastically different and depends both on rock and joint properties. the response of large scale jointed rock to dynamic loading is difficult to replicate or predict in numerical simulations because experimental studies are scarce and expensive as well as the computational efforts to study this response. We have developed tools to model such systems in a wide range of loading conditions which are based on advanced contact algorithms and hybrid FD/FE methods. the papers illustrates some of the ideas for meso-scale modeling which could be applied to build better continuum models for rock mechanic applications for specific conditions.
In the quasi-steady diverging detonation of insensitive explosives, the velocity of detonation (VOD) is dependent on the curvature of the detonation front. the relation between VOD and curvature can be gained by the c...
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ISBN:
(纸本)9783950353709
In the quasi-steady diverging detonation of insensitive explosives, the velocity of detonation (VOD) is dependent on the curvature of the detonation front. the relation between VOD and curvature can be gained by the costly experiments or the numericalmethods, this paper gives the numerical method for the relationship. By the use of the coordinate transformation to the one-dimensional cylindrical fluid dynamics, we obtain the algebraic equations containing VOD and curvature and the general sonic condition. When the reaction rates, equations of state of reactant and product are given, we can get the relation between VOD and curvature, and physical variables in the detonation driving reaction zone also. Our method is simple and rapid, so it can be used to assess the parameters of equations of state and reaction rate before the costly direct numerical simulations. Assuming VOD is linear withthe curvature, we use level set method to simulate the propagation of the detonation fronts. the term independent on curvature is discretized in space by the positive scheme, and the term dependent on curvature is discretized by the Galerkin isoparametric finite element method in space and semi-implicit time stepping. numerical examples show that our method is first order accuracy on quadrilaterals and triangles.
this paper presents a numerical approach based on the Integrated Radial Basis Functions (IRBF) for the Fokker Planck Equation (FPE) macro-micro multi-scale models of visco-elastic fluid flows. the FPE is for the calcu...
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ISBN:
(纸本)9783950353709
this paper presents a numerical approach based on the Integrated Radial Basis Functions (IRBF) for the Fokker Planck Equation (FPE) macro-micro multi-scale models of visco-elastic fluid flows. the FPE is for the calculation of extra stress and the conservation equations for the velocity field. In this approach, the stress is decoupled from the velocity field and computed deterministically without the need for a closed form rheological constitutive equation. the FPEs and momentum conservation equations are discretised using a spatially local collocation method where the IRBF based approximants improve the accuracy of the numerical solutions by avoiding the deterioration of accuracy caused by differentiation. the method is illustrated withthe time evolution of the planar Couette flow of a Hookean dumbbell model fluid.
the determination of the inflated configuration of membranes is further complicated in many structural applications by the presence of unilateral constraint conditions between the membrane and some other body (rigid o...
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ISBN:
(纸本)9783950353709
the determination of the inflated configuration of membranes is further complicated in many structural applications by the presence of unilateral constraint conditions between the membrane and some other body (rigid or deformable) lying in its neighborhood. this is the case, for example, when considering the contact between a road pavement and a tire rolling over it, or the contact between a balloon stent and the surrounding artery wall. In this paper we illustrate a simplified model for the solution of the inflation problem, which uses an expressly developed numerical method of solution able to determine the state of stress of inflated elastic membranes by accounting for wrinkling of the membrane itself. Some numerical results for linear elastic initially flat square membranes inflated between rigid parallel planes are shown. the influence of the elastic properties of the material and type of contact conditions is discussed.
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