scholarly journals Automation of calibration process adopting metaheuristic optimization method

2019 ◽  
Author(s):  
Pavel Koudela ◽  
Juraj Chalmovský
Keyword(s):  
Constitutive Models ◽  
Small Strain ◽  
Optimization Method ◽  
Theoretical Description ◽  
Fe Model ◽  
The Finite Element Method ◽  
Input Parameters ◽  
Soil Constitutive Models ◽  
Strain Model

Optimization procedures offer a possibility for time-effective determination of input parameters values for complex soil constitutive models. The following paper presents a combination of the metaheuristic Particle swarm optimization method (PSO) and commercially available solver based on the finite element method (FEM). After the brief theoretical description, different alternatives to the PSO method are reviewed and tested. An optimal alternative is chosen and further used. In the second part of the paper, the combination PSO – FEM is utilized for a fully automatic derivation of input parameters values for the Hardening small strain model from pressuremeter tests. Predicted pressurevolume curves from the axisymmetric FE model gradually converge towards the measured curve until the accuracy criterion is reached.

scholarly journals The influence of the soil constitutive models on the seismic analysis of pile-supported wharf structures with batter piles in cut-slope rock dike

2020 ◽  
Vol 42 (3) ◽  
pp. 191-209
Author(s):  
Lylia Deghoul ◽  
Smail Gabi ◽  
Adam Hamrouni
Keyword(s):  
Constitutive Models ◽  
Small Strain ◽  
Loose Sand ◽  
Cut Slope ◽  
Linear Elastic ◽  
Perfectly Plastic ◽  
Soil Constitutive Models ◽  
Elastic Perfectly Plastic ◽  
Batter Piles ◽  
Hardening Soil Model

AbstractIn coastal regions, earthquakes caused severe damage to marine structures. Many researchers have conducted numerical investigations in order to understand the dynamic behavior of these structures. The most frequently used model in numerical calculations of soil is the linear-elastic perfectly plastic model with a Mohr-Coulomb failure criterion (MC model). It is recommended to use this model to represent a first-order approximation of soil behavior. Therefore, it is necessary to accommodate soil constitutive models for the specific geotechnical problems.In this paper, three soil constitutive models with different accuracy were applied by using the two-dimensional finite element software PLAXIS to study the behavior of pile-supported wharf embedded in rock dike, under the 1989 Loma Prieta earthquake. These models are: a linear-elastic perfectly plastic model (MC model), an elastoplastic model with isotropic hardening (HS model), and the Hardening Soil model with an extension to the small-strain stiffness (HSS model).A typical pile-supported wharf structure with batter piles from the western United States ports was selected to perform the study. The wharf included cut-slope (sliver) rock dike configuration, which is constituted by a thin layer of rockfill overlaid by a slope of loose sand. The foundation soil and the backfill soil behind the wharf were all dense sand. The soil parameters used in the study were calibrated in numerical soil element tests (Oedometer and Triaxial tests).The wharf displacement and pore pressure results obtained using models with different accuracy were compared to the numerical results of Heidary-Torkamani et al.[28] It was found that the Hardening Soil model with small-strain stiffness (HSS model) gives clearly better results than the MC and HS models.Afterwards, the pile displacements in sloping rockfill were analyzed. The displacement time histories of the rock dike at the top and at the toe were also exposed. It can be noted that during the earthquake there was a significant lateral ground displacement at the upper part of the embankment due to the liquefaction of loose sand. This movement caused displacement at the dike top greater than its displacement at the toe. Consequently, the behavior of the wharf was affected and the pile displacements were important, specially the piles closest to the dike top.

scholarly journals DESIGN OPTIMIZATION OF A CIVIL STRUCTURE USING NUMERICAL SIMULATIONS

2020 ◽  
Vol 10 (2) ◽  
pp. 5-13
Author(s):  
Florian VLĂDULESCU
Keyword(s):  
Geometric Model ◽  
Input Parameter ◽  
Element Model ◽  
Design Parameters ◽  
Fe Model ◽  
Shell Elements ◽  
Optimization Study ◽  
Input Parameters ◽  
Parametric Relationships

This optimization study aims to determine the effect of each input parameter on the output parameters, how the input parameters can interact with each other and also it is emphasized the determination of the values for the input parameters that optimize the responses. In this study, the objective is to obtain an optimal configuration for a resistance structure specific to a telecommunications tower. For this purpose, a variable geometric model using design parameters is created, based on which a 3D finite element model (FEM) is obtained, which is used in the optimization study. The FE model is updated automatically for each version of geometric model and is made using beam and shell elements. Design of Experiments (DOE) methodology allows for using a mathematical model that predicts how input parameters interact to create output responses in an optimization process. Parameters’ correlation and monitoring allow for identifying important parameters and the correlation matrix and sensitivity graphs also help understanding the parametric relationships. Variation limits for design parameters are defined and these parameters can have integer or fractional values.

scholarly journals Determination of the anisotropic elasticity tensor by mechanical spectroscopy

2021 ◽  
Author(s):  
Thomas Obermayer ◽  
Christian Krempaszky ◽  
Ewald Werner
Keyword(s):  
Base Alloy ◽  
Rectangular Cross Section ◽  
Optimization Method ◽  
Anisotropic Elasticity ◽  
Elasticity Tensor ◽  
Precise Determination ◽  
The Finite Element Method ◽  
Mechanical Spectroscopy ◽  
Nickel Base

AbstractA method is proposed to identify the fully anisotropic elasticity tensor by applying the impulse excitation technique. A specially designed batch of several differently oriented bar-shaped specimens with rectangular cross section is analyzed with respect to the eigenfrequencies of their fundamental flexural and torsional modes. Estimations based on the equations for the calculation of the isotropic Young’s modulus and the shear modulus from the ASTM standard allow a first approximation of the elasticity tensor from a selected subset of the measured eigenfrequencies. Subsequently, a more precise determination of the elasticity tensor is achieved by a numerical modal analysis using the finite element method. In this course, a Newton–Raphson optimization method is applied to solve the inverse problem. The proposed approach is demonstrated on a batch of specimen fabricated from the nickel-base alloy IN718 by selective laser melting.

Analysis of methodologies for determination of DEM input parameters

2021 ◽  
Author(s):  
Rondinelli M. Lima ◽  
Rodolfo J. Brandao ◽  
Raphael L. Santos ◽  
Claudio R. Duarte ◽  
Marcos A. S. Barrozo
Keyword(s):  
Input Parameters

scholarly journals Determination of Transverse Shear Stiffness of Sandwich Panels with a Corrugated Core by Numerical Homogenization

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1976
Author(s):  
Tomasz Garbowski ◽  
Tomasz Gajewski
Keyword(s):  
Transverse Shear ◽  
Shear Stiffness ◽  
The Finite Element Method ◽  
Homogenization Procedure ◽  
Plate Structures ◽  
Corrugated Board ◽  
Energy Equivalence ◽  
The Stability ◽  
Global Stiffness Matrix

Knowing the material properties of individual layers of the corrugated plate structures and the geometry of its cross-section, the effective material parameters of the equivalent plate can be calculated. This can be problematic, especially if the transverse shear stiffness is also necessary for the correct description of the equivalent plate performance. In this work, the method proposed by Biancolini is extended to include the possibility of determining, apart from the tensile and flexural stiffnesses, also the transverse shear stiffness of the homogenized corrugated board. The method is based on the strain energy equivalence between the full numerical 3D model of the corrugated board and its Reissner-Mindlin flat plate representation. Shell finite elements were used in this study to accurately reflect the geometry of the corrugated board. In the method presented here, the finite element method is only used to compose the initial global stiffness matrix, which is then condensed and directly used in the homogenization procedure. The stability of the proposed method was tested for different variants of the selected representative volume elements. The obtained results are consistent with other technique already presented in the literature.

Determination of a Rubber-Like Material Model as an Inverse Problem

2011 ◽  
Vol 70 ◽  
pp. 225-230 ◽  
Author(s):  
Agnieszka Derewonko ◽  
Andrzej Kiczko
Keyword(s):  
Selection Process ◽  
Axial Stress ◽  
Constitutive Models ◽  
Material Model ◽  
Polyester Fabric ◽  
Point Of View ◽  
Air Cushion ◽  
Ill Conditioning ◽  
Stress States

The purpose of this paper is to describe the selection process of a rubber-like material model useful for simulation behaviour of an inflatable air cushion under multi-axial stress states. The air cushion is a part of a single segment of a pontoon bridge. The air cushion is constructed of a polyester fabric reinforced membrane such as Hypalon®. From a numerical point of view such a composite type poses a challenge since numerical ill-conditioning can occur due to stiffness differences between rubber and fabric. Due to the analysis of the large deformation dynamic response of the structure, the LS-Dyna code is used. Since LS-Dyna contains more than two-hundred constitutive models the inverse method is used to determine parameters characterizing the material on the base of results of the experimental test.

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