3D Generalized Beam (GB) Lattice Model for Analysis of the Failure of Concrete

2013 ◽  
Vol 652-654 ◽  
pp. 1455-1465
Author(s):  
Han Wang ◽  
Ming Hao Zhao ◽  
Ji Gao ◽  
Guang Yuan Wang
Keyword(s):  
Lattice Model ◽  
Peak Load ◽  
Computational Effort ◽  
Numerical Results ◽  
Particle Content ◽  
Three Phase ◽  
3D Effects ◽  
Fracture Processes ◽  
Beam Lattice

Concrete is usually described as a three-phase material, where matrix, aggregate and interface zones are distinguished. The beam lattice model has been applied widely by many investigators to simulate fracture processes in concrete. Due to the extremely large computational effort, however, the beam lattice model faces practical difficulties. Moreover, real fracture processes are 3D and not 2D. In our investigation, a new 3D lattice called generalized beam (GB) lattice is developed to reduce computational effort. Numerical results obtained by the model are in agreement to what are observed in tests. The 3D effects of the particle content on the peak load and ductility are discussed as well as the 3D fracturing phenomenon.

scholarly journals Improved Genetic Algorithm for Phase-Balancing in Three-Phase Distribution Networks: A Master-Slave Optimization Approach

Computation ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 67
Author(s):  
Oscar Danilo Montoya ◽  
Alexander Molina-Cabrera ◽  
Luis Fernando Grisales-Noreña ◽  
Ricardo Alberto Hincapié ◽  
Mauricio Granada
Keyword(s):  
Genetic Algorithm ◽  
Reactive Power ◽  
Search Algorithm ◽  
Peak Load ◽  
Distribution Networks ◽  
Numerical Results ◽  
Optimization Approach ◽  
Three Phase ◽  
Operative Costs ◽  
Power Curves

This paper addresses the phase-balancing problem in three-phase power grids with the radial configuration from the perspective of master–slave optimization. The master stage corresponds to an improved version of the Chu and Beasley genetic algorithm, which is based on the multi-point mutation operator and the generation of solutions using a Gaussian normal distribution based on the exploration and exploitation schemes of the vortex search algorithm. The master stage is entrusted with determining the configuration of the phases by using an integer codification. In the slave stage, a power flow for imbalanced distribution grids based on the three-phase version of the successive approximation method was used to determine the costs of daily energy losses. The objective of the optimization model is to minimize the annual operative costs of the network by considering the daily active and reactive power curves. Numerical results from a modified version of the IEEE 37-node test feeder demonstrate that it is possible to reduce the annual operative costs of the network by approximately 20% by using optimal load balancing. In addition, numerical results demonstrated that the improved version of the CBGA is at least three times faster than the classical CBGA, this was obtained in the peak load case for a test feeder composed of 15 nodes; also, the improved version of the CBGA was nineteen times faster than the vortex search algorithm. Other comparisons with the sine–cosine algorithm and the black hole optimizer confirmed the efficiency of the proposed optimization method regarding running time and objective function values.

A damaging beam-lattice model for quasi-brittle fracture

2022 ◽  
pp. 111404
Author(s):  
Margaux Sage ◽  
Jérémie Girardot ◽  
Jean-Benoît Kopp ◽  
Stéphane Morel
Keyword(s):  
Brittle Fracture ◽  
Lattice Model ◽  
Beam Lattice

3D Lattice Fracture Model: Application to Cement Paste at Microscale

2010 ◽  
Vol 452-453 ◽  
pp. 65-68 ◽  
Author(s):  
Z. Qian ◽  
Guang Ye ◽  
Erik Schlangen ◽  
Klaas van Breugel
Keyword(s):  
Cement Paste ◽  
Peak Load ◽  
Fracture Model ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Degree Of Hydration ◽  
Load Displacement ◽  
Portland Cement Paste ◽  
Displacement Diagram ◽  
Fracture Processes

The fracture processes in cement paste at microscale are simulated by the 3D lattice fracture model based on the microstructure of hydrating cement paste. The uniaxial tensile test simulation is carried out to obtain the load-displacement diagram and microcracks propagation for a Portland cement paste specimen in the size of 100×100×100 µm3 at the degree of hydration 69%. The Young's modulus, tensile strength, strain at peak load and fracture energy are computed on the basis of the load-displacement diagram.

A new and efficient procedure for dispersive tsunami simulations on spherical coordinates based on a hyperbolic approach

2020 ◽  
Author(s):  
Cipriano Escalante Sanchez ◽  
Manuel J. Castro Díaz ◽  
José Manuel González Vida ◽  
Jorge Macías Sánchez ◽  
Stefano Lorito ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Water Waves ◽  
Numerical Scheme ◽  
Applied Mathematics ◽  
Computational Effort ◽  
Numerical Results ◽  
Spherical Coordinates ◽  
Tsunami Propagation ◽  
Time Step ◽  
Curvature Effects

<p>When tsunamigenic events are simulated in deep to moderately deep waters, frequency dispersion effects may become mandatory. In the framework of dispersive systems, non-hydrostatic pressure type models have been shown to be able to describe weakly dispersive waves [2,3]. Although promising results begin to glimpse nowadays, dispersive solvers are still far from being robust, efficient and able to compute on a faster than real-time (FTRT) basis. The main difficulty that presents this type of systems is that at each time step a parabolic-elliptic problem has to be numerically solved and a high computational effort is required.</p><p>In [1] a novel weakly non-linear and weakly dispersive system that takes into account dispersive effects is presented. The main advantage is that the system is strictly hyperbolic and that any explicit numerical scheme can be applied to solve numerically the equations.</p><p>We will present new numerical results from an upgrade of the system presented in [1], considering curvature effects through a rewriting of the system in spherical coordinates. The numerical results will cover some standard field validation tests involving tsunami propagation waves. Besides, the explicit numerical scheme has been implemented exploiting the power of modern GPU architectures (CUDA). Then, numerical results along with some computational times will show that this numerical model opens a new line on tsunami simulation scenarios, using a new, efficient and accurate procedure to produce FTRT tsunami propagation including dispersive effects.</p><p>Acknowledgments: This research has been partially supported by the Spanish Government Research project MEGAFLOW (RTI2018-096064-B-C21), Universidad de Málaga, Campus de Excelencia Internacional Andalucía Tech and ChEESE project (EU Horizon 2020, grant agreement Nº 823844), https://cheese-coe.eu</p><p>[1] C. Escalante, M. Dumbser, M. Castro, An efficient hyperbolic relaxation system for dispersive non-hydrostatic water waves and its solution<br>with high order discontinuous galerkin schemes, Journal of Computational Physics 394 (2019) 385 – 416.</p><p>[2] C. Escalante, T. Morales, M. Castro, Non-hydrostatic pressure shallow flows: Gpu implementation using finite volume and finite difference<br>scheme, Applied Mathematics and Computation (2018) 631–659.</p><p>[3] Y. Yamazaki, Z. Kowalik, K. Cheung, Depth-integrated, non-hydrostatic model for wave breaking and run-up, Numerical Methods in Fluids<br>61 (2008) 473–497.</p>

scholarly journals Evidence against a three-phase point in a binary hard-core lattice model

1999 ◽  
Vol 60 (3) ◽  
pp. 2501-2509 ◽  
Author(s):  
Alain Verberkmoes ◽  
Bernard Nienhuis
Keyword(s):  
Lattice Model ◽  
Hard Core ◽  
Phase Point ◽  
Three Phase

Pre-Swirled Cooling Air Delivery System Performance

2005 ◽  
Author(s):  
J. W. Chew ◽  
F. Ciampoli ◽  
N. J. Hills ◽  
T. Scanlon
Keyword(s):  
System Performance ◽  
Computational Effort ◽  
Measured Data ◽  
Numerical Results ◽  
Simplified Model ◽  
Swirl Chamber ◽  
Aero Engine ◽  
The Difference ◽  
Cooling Air ◽  
Good Agreement

This paper reports results from numerical simulations of the flow in pre-swirl cooling air delivery systems. Two different systems have been investigated corresponding to experimental rigs for which measured data is available. The rigs are representative of aero-engine conditions. The difference in the performance of the two rigs has been addressed. The flow in the pre-swirl nozzles and in the pre-swirl chambers has been investigated separately. For the pre-swirl chamber a simplified model, in which the nozzle is replaced by a slot, has been used to reduce the computational effort required. Nevertheless numerical results are in good agreement with experimental measurements. It is shown that the difference in the geometry of the pre-swirl chambers is largely responsible for the difference in performance of the rigs. Numerical results have also been compared with predictions from a previously published simplified model. An adjustment of the empirical constants in the simple model has been proposed in order to improve the prediction of the moments in the pre-swirl chamber.

scholarly journals Analysis of Stationary- and Synchronous-Reference Frames for Three-Phase Three-Wire Grid-Connected Converter AC Current Regulators

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8348
Author(s):  
Israel D. L. Costa ◽  
Danilo I. Brandao ◽  
Lourenço Matakas Junior ◽  
Marcelo G. Simões ◽  
Lenin M. F. Morais
Keyword(s):  
Steady State ◽  
Reference Frames ◽  
Computational Cost ◽  
Transient Behavior ◽  
Computational Effort ◽  
Superior Performance ◽  
Positive Sequence ◽  
Voltage Source ◽  
Three Phase ◽  
Grid Connected Inverter

The current state of the art shows that unbalance and distortion on the voltage waveforms at the terminals of a grid-connected inverter disturb its output currents. This paper compares AC linear current regulators for three-phase three-wire voltage source converters with three different reference frames, namely: (1) natural (abc), (2) orthogonal stationary (αβ), and (3) orthogonal synchronous (dq). The quantitative comparison analysis is based on mathematical models of grid disturbances using the impedance-based analysis, the computational effort assessment, as well as the steady-state and transient performance evaluation based on experimental results. The control scheme devised in the dq-frame has the highest computational effort and inferior performance under negative-sequence voltage disturbances, whereas it shows superior performance under positive-sequence voltages among the reference frames evaluated. In contrast, the stationary natural frame abc has the lowest computational effort due to its straightforward implementation, with similar results in terms of steady-state and transient behavior. The αβ-frame is an intermediate solution in terms of computational cost.

Numerical Simulation of Taylor Vortex Flow by GDQ Method

2000 ◽  
Author(s):  
L. Wang ◽  
C. Shu ◽  
Y. T. Chew
Keyword(s):  
Vortex Flow ◽  
Stokes Equations ◽  
Outer Cylinder ◽  
Three Dimensional ◽  
Computational Effort ◽  
Numerical Results ◽  
Numerical Code ◽  
Taylor Vortex ◽  
Specific Flow ◽  
Taylor Vortex Flow

Abstract In this study, the GDQ method was used to simulate a specific flow regime, Taylor vortex flow, of the motion of fluids between two concentric cylinders with rotating inner cylinder and stationary outer cylinder. An approach combining the SIMPLE strategy and GDQ discretization based on non-staggered mesh was proposed to solve the time-dependent, three-dimensional incompressible Navier-Stokes equations in primitive variable form. The numerical solution obtained has the accuracy of second-order in temporal discretization and high-order in spatial discretization. Also, this numerical code may allow the direct numerical simulations for the various regimes of Couette-Taylor flow problem. The performance of this approach was studied through a test case of Taylor vortex flow. The reported numerical results were compared with those from others. For this approach, accurate numerical results can be obtained by using fewer grid points compared with low-order methods. As a consequence, the computational effort can be greatly reduced.

scholarly journals Area-Based Approach in Power Quality Assessment

2008 ◽  
Vol 2008 ◽  
pp. 1-6 ◽  
Author(s):  
Surajit Chattopadhyay ◽  
Samarjit Sengupta ◽  
Madhuchhanda Mitra
Keyword(s):  
Power Quality ◽  
Quality Parameters ◽  
Computational Effort ◽  
Phase System ◽  
Transformation Technique ◽  
Three Phase ◽  
Harmonic Voltage ◽  
Park Transformation ◽  
Harmonic Components ◽  
Good Agreement

This paper presents an approach for assessment of power quality parameters using analysis of fundamental and harmonic voltage and current waveforms. Park transformation technique has been utilized for the analysis in three-phase system, which has reduced the computational effort to a great extent. Contributions of fundamental and harmonic components in power system voltage and current signals have been assessed separately. An algorithm has been developed to calculate the power quality parameters from online signals. This algorithm has been simulated for a radial system, and the results have been compared with that obtained from a standard FFT-based system. The results are seen to be in good agreement with that of the standard system.

scholarly journals Numerical and Experimental Analysis of Full Scale Arches Reinforced with GFRP Materials

2014 ◽  
Vol 624 ◽  
pp. 502-509 ◽  
Author(s):  
Ismael Basilio ◽  
Roberto Fedele ◽  
Paulo B. Lourenço ◽  
Gabriele Milani
Keyword(s):  
Upper Bound ◽  
Limit Analysis ◽  
Experimental Analysis ◽  
Failure Mechanisms ◽  
Peak Load ◽  
Numerical Results ◽  
Masonry Arches ◽  
Reinforced Masonry ◽  
The University

In this contribution, original limit analysis numerical results are presented dealing with some reinforced masonry arches tested at the University of Minho-UMinho, PT. Twelve in-scale circular masonry arches were considered, reinforced in various ways at the intrados or at the extrados. GFRP reinforcements were applied either on undamaged or on previously damaged elements, in order to assess the role of external reinforcements even in repairing interventions. The experimental results were critically discussed at the light of limit analysis predictions, based on a 3D FE heterogeneous upper bound approach. Satisfactory agreement was found between experimental evidences and the numerical results, in terms of failure mechanisms and peak load.

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