Analysis of an Idealized Directionally Solidified FCC Material

1983 ◽  
Vol 105 (4) ◽  
pp. 307-312 ◽  
Author(s):  
J. H. Laflen
Keyword(s):  
Nonlinear Optimization ◽  
Crystalline Structure ◽  
Continuum Theory ◽  
Optimization Techniques ◽  
Plastic Behavior ◽  
Aircraft Engines ◽  
Local Orientation ◽  
Directionally Solidified ◽  
Grain Sizes ◽  
Anisotropic Plastic

Directionally solidified materials are being increasingly used in aircraft engines. These alloys are anisotropic due to the well aligned crystalline structure with additional considerations including large grain sizes and perturbations in the local orientation. In this paper, the Bishop-Hill method is combined with nonlinear optimization techniques to predict the anisotropic plastic behavior of an ideal directionally solidified FCC material subjected to off-axis uniaxial loadings. A comparison of these results is made with a continuum theory.

Modeling of Anisotropic Plastic Behavior of Advanced High Strength Steel Sheet TRIP 780

2011 ◽  
Vol 410 ◽  
pp. 232-235 ◽  
Author(s):  
Sansot Panich ◽  
Vitoon Uthaisangsuk ◽  
Surasak Suranuntchai ◽  
Suwat Jirathearanat
Keyword(s):  
High Strength Steel ◽  
Steel Sheet ◽  
Plastic Anisotropy ◽  
High Strength ◽  
Uniaxial Tensile ◽  
Plastic Behavior ◽  
Biaxial Test ◽  
Advanced High Strength Steel ◽  
Yield Criteria ◽  
Anisotropic Plastic

Anisotropic plastic behavior of advanced high strength steel sheet of grade TRIP780 (Transformation Induced Plasticity) was investigated using three different yield functions, namely, the von Mises’s isotropic, Hill’s anisotropic (Hill’48), and Barlat’s anisotropic (Yld2000-2d) criterion. Uniaxial tensile and balanced biaxial test were conducted for the examined steel in order to characterize flow behavior and plastic anisotropy for different stress states. Especially, disk compression test was performed for obtaining balanced r-value. All these data were used to determine the anisotropic coefficients. As a result, yield stresses and r-values for different directions were calculated according to these yield criteria. The results were compared with experimental data. To verify the modelling accuracy, tensile tests of various notched samples were carried out and stress-strain distributions in the critical area were characterized. By this manner, the effect of stress triaxiality due to different notched shapes on the strain localization calculated by the investigated yield criteria could be studied.

scholarly journals Calibration of a Nonlinear DC Motor under Uncertainty Using Nonlinear Optimization Techniques

2021 ◽  
Vol 65 (1) ◽  
pp. 42-52
Author(s):  
Hamed Keshmiri Neghab ◽  
Hamid Keshmiri Neghab
Keyword(s):  
Nonlinear Optimization ◽  
Model Calibration ◽  
Optimization Methods ◽  
Dc Motor ◽  
Optimization Techniques ◽  
Unknown Parameters ◽  
Labview Software ◽  
Dc Motors ◽  
Industrial Software ◽  
Nonlinear Optimization Methods

The use of DC motors is increasingly high and it has more parameters which should be normalized. Now the calibration of each parameters is important for each motor, because it affects in its performance and accuracy. A lot of researches are investigated in this area. In this paper demonstrated how to estimate the parameters of a Nonlinear DC Motor using different Nonlinear Optimization techniques of fitting parameters to model, that called model calibration. First, three methods for calibration of a DC motor are defined, then unknown parameters of the mathematical model with the nonlinear optimization techniques for the fitting routines and model calibration process, are identified. In addition, three optimization techniques such as Levenberg-Marquardt, Constrained Nonlinear Optimization and Gauss-Newton, are compared. The goal of this paper is to estimate nonlinear parameters of a DC motor under uncertainty with nonlinear optimization methods by using LabVIEW software as an industrial software and compare the nonlinear optimization methods based on position, velocity and current. Finally, results are illustrated and comparison between these methods based on the results are made.

scholarly journals A DAMAGE PROGNOSIS METHODOLOGY FOR A SIMPLE CRACKED BEAM

2018 ◽  
Vol 48 (1) ◽  
pp. 43-49
Author(s):  
E. A. PRESEZNIAK ◽  
J. E. PEREZ IPIÑA ◽  
C. A. BAVASTRI
Keyword(s):  
Fracture Mechanics ◽  
Nonlinear Optimization ◽  
Optimization Techniques ◽  
Crack Identification ◽  
Remaining Life ◽  
Damage Prognosis ◽  
Mechanics Concepts ◽  
Dynamic Structures ◽  
High Level

Damage prognosis uses numerical and experimental responses to identify damage in structures or part of them, thus allowing the remaining structural life estimation at a high level of precision. Current methods focalize on crack identification; however, a complete methodology to estimate the remaining life of a cracked structure is less developed. A methodology is presented in this paper drawing on concepts such as wavelets transform, dynamic structures, and vibration signals for crack identification; and fracture mechanics and nonlinear optimization to obtain the remaining life. Finite element theory was applied to obtain its vibration modes. The crack was modeled as a flexural spring connected to the elements in the crack position and the crack identification was performed in the wavelet domain. Nonlinear optimization techniques and fracture mechanics concepts were used to estimate the remaining fatigue life. A numerical-experimental case study is solved to show the fundamentals of this methodology.

Improved estimation of elastic attributes from prestack seismic data for reservoir characterization

Geophysics ◽  
2020 ◽  
Vol 85 (1) ◽  
pp. R41-R53
Author(s):  
Yijie Zhou ◽  
Franklin Ruiz ◽  
Yequan Chen ◽  
Fan Xia
Keyword(s):  
Nonlinear Optimization ◽  
Seismic Data ◽  
Reservoir Characterization ◽  
Layer Structure ◽  
High Sensitivity ◽  
Optimization Techniques ◽  
Earth Model ◽  
L1 Norm ◽  
Linear Inversion ◽  
Elastic Impedance

Seismic derivable elastic attributes, e.g., elastic impedance, lambda-rho, mu-rho, and Poisson impedance (PI), are routinely being used for reservoir characterization practice. These attributes could be derived from inverted [Formula: see text], [Formula: see text], and density, and usually indicate high sensitivity to reservoir lithology and fluid. Due to the high sensitivity of such elastic attributes, errors or measurement noise associated with the acquisition, processing, and inversion of prestack seismic data will propagate through the inversion products, and will lead to even larger errors in the computed attributes. To solve this problem, we have developed a two-step cascade workflow that combines linear inversion and nonlinear optimization techniques for the improved estimation of elastic attributes and better prediction and delineation of reservoir lithology and fluids. The linear inversion in the first step is an inversion scheme with a sparseness assumption, based on L1-norm regularization. This step is used to select the major reflective layer locations, followed in the second step by a nonlinear optimization process with the predefined layer structure. The combination of these two procedures produces a reasonable blocky earth model with consistent elastic properties, including the ones that are sensitive to reservoir lithology and fluid change, and thus provides an accurate approach for seismic reservoir characterization. Using PI, as one of the target elastic attributes, as an example, this workflow has been successfully applied to synthetic and field data examples. The results indicate that our workflow improves the estimation of elastic attributes from the noisy prestack seismic data and may be used for the identification of the reservoir lithology and fluid.

scholarly journals Global vs. local nonlinear optimization techniques for human-like movement of an anthropomorphic robot

2015 ◽  
Author(s):  
Eliana Costa e Silva ◽  
M. Fernanda Costa ◽  
Wolfram Erlhagen ◽  
Estela Bicho
Keyword(s):  
Nonlinear Optimization ◽  
Optimization Techniques
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